Download - FIERY ICE 2014

FIERY ICE 2014

CSIR - NATIONAL GEOPHYSICAL RESEARCH INSTITUTE

HYDERABAD - INDIA

FIERY ICE 2014ORGANIZED BY

9th International Methane Hydrate R&D (IMHRD) WorkshopHYDERABAD, INDIA

THEME:

SCIENCE & TECHNOLOGY OF GAS HYDRATES: WHEN CAN THEY BE PRODUCED

EFFICIENTLY AND SAFELY?

ORGANIZED BY CSIR - NATIONAL GEOPHYSICAL RESEARCH INSTITUTE

SPONSORED BY MINISTRY OF EARTH SCIENCES (MOES)

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH (CSIR)

DEPARTMENT OF SCIENCE & TECHNOLOGY (DST)

CSIR-NATIONAL GEOPHYSICAL RESEARCH INSTITUTE

NATIONAL CENTER FOR ANTARCTIC & OCEAN RESEARCH

CSIR-NATIONAL INSTITUTE OF OCEANOGRAPHY

NATIONAL INSTITUTE OF OCEAN TECHNOLOGY

OIL INDIA LIMITED (OIL)

GAS AUTHORITY OF INDIA LIMITED

OFFICE OF NAVAL RESEARCH GLOBAL

US DEPARTMENT OF ENERGY, NATIONAL ENERGY TECHNOLOGY LABORATORY

UNIVERSITY OF BERGEN, NORWAY

HAWAII NATURAL ENERGY INSTITUTE, UNIVERSITY OF HAWAII,USA

CONTENTS

SPONSORS ……........................................................................................................................... (i)

Committees............................................................................................................................... (ii)

Background .............................................................................................................................. (iii)

About Golkonda Fort ............................................................................................................... (iv)

Program Schedule …………………................................................................................................. 9

Abstracts.................................................................................................................................. 19

UMASHANKAR

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SPONSORS

Oil India Ltd.

University of Hawai’i Office of Naval Research

National Geophysical Research Institute

National Institute of Ocean Technology

Gas Authority of India Ltd.

Ministry of Earth Science National Centre for Antarctic & Ocean Research

Ministry of Petroleum & Natural Gas

Department of Energy

University of Bergen

National Institute of Oceanography

Department of Science & Technology

CSIR

UMASHANKAR

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UMASHANKAR

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(i)

COMMITTEES

International Steering Committee

Richard B. Coffin,Department of Physical and Environmental Sciences, Texas A&M University -Corpus Christi, USA

Bjørn Kvamme,Department of Physics and Technology, University of Bergen, Norway

Stephen M. Masutani,Natural Energy Institute,University of Hawaii, Honolulu, USA

Hideo Narita,National Institute of Advanced Industrial Science and Technology,Sapporo, Japan

Tsutomu Uchida,Division of Applied Physics, Faculty of Engineering, Hokkaido University, Japan

Local Advisory/Organizing Committee

Prof. Harsh K. Gupta (Chair), Atomic Energy Regulatory Board (AERB), Mumbai

Dr. Shailesh Nayak, Ministry of Earth Sciences, New Delhi

Shri B. N. Talukdar, Directorate General of Hydrocarbons, Noida

Dr. S.K. Srivastava, Oil India Limited, Dhuliajan

Dr. Y.J. Bhaskar Rao, CSIR-National Geophysical Research Institute, Hyderabad

Dr. S.W.A. Naqvi ,Director, CSIR-National Institute of Oceanography, Goa

Dr. M.A. Atmanand, National Institute of Ocean Technology, Chennai

Dr. S. Rajan, National Centre for Antarctic & Ocean Research, Goa

Dr. Pushpendra Kumar, Gas Hydrates KDM Institute of Petroleum Exploration, ONGC, Dehradun

Dr. Kalachand Sain (Convener), CSIR-National Geophysical Research Institute, Hyderabad

Workshop Secretariat

Local Organizing Secretariat of Fiery Ice-2014

CSIR-National Geophysical Research Institute

Gas-hydrate Group,

Uppal Road, Hyderabad - 500 007, India

E-mail: [email protected]

Ph No. +91 040-2701 2799 (O)

Mob: +91 9440964038

Website: http://www.fieryice2014.org/

mailto:[email protected]

http://www.fieryice2014.org/

UMASHANKAR

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(ii)

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It was omud forcenturieprincipaand a hibuilding

Golconhistory followerests onstructur

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da Fort is lon Sagar Lakters in lengt

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da fort is unof Golcond

ed by Qutubn a granite hre.

nitially callon this rock

ed to the ruly spot and aShahi kingsrt is considen 1687 whe

s.

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Golc

ocated in thke. The outeth.

nown as Mae reign of Raahmani Sultf the Qutub lion, which

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led Shepherky hill a sheling Kakatiyafter 200 ye converted t

ered a mute en it was run

sts of mounstables etc. TAurangzeb

witness fantels at Golcontes which isas a warnin

muses visitoge structure

conda

e western per fort occup

ankal, and bajah of Wartans and theShahi kingsrises about

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nted cannonsThe outermo’s army ma

tastic acoustnda. Clappis heard cleang note to thors. The fortes of India a

Fort, H

part of Hydepies an area

built on a hirangal. Lateen the rulings. The inner130 meters

st magnificerly 13th cened the regionhile huge cre

eaning Gollhad come ahat time. Th

mani rulers tassive granihistoric eve

Mughal emp

s, four drawmost enclosuarched succetical effectsing your hanarly at the hihe inhabitant gains an imand is a testi

Hydera

erabad city aa of three sq

illtop in the er it was fortg Qutub Shar fort contais high and g

ent fortress cntury, whenn in 16th anenellated ra

la Konda in across an idhe king contook possessite fort extennts. The Queror Aurang

wbridges, eire is called essfully thros, which is ond at a certaill top pavil

nts of the formpressive pimony to H

abad

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ough this gaone among tain point neaion, almost rt of any im

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’s eye view

in India. Thd by the Katury. The foround this

hile accordinnformation

mud fort aroplace. Laterin circumfereign at Go

intentionally

ys, and majwaza meaninate. At Fatehthe many faar the dome

t one kilomempending dag the architeglorious pa

m the h is 4.8

inally a d 17th was the

osques of other

he akatiya’s ortress

ng to was

ound r the erence. olconda y left it

estic ng h

amous e eter anger, ectural ast.

UMASHANKAR

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(iii)

Background

The growing demand of energy and depletion of fossil fuels necessitate looking for an alternate source

for sustainable development. Among various forms of renewable and unconventional energy resources,

gas hydrates seem to be the major unconventional energy resource for the next generation because of

their abundant occurrences in nature. The energy potential of gas hydrates is so huge that even 15%

production from global reserve meet the world’s energy requirement for about two hundred years.

Successful production tests through carbon dioxide replacement method in the permafrost of Alaska

(USA) in 2012 and by depressurization method in the Nankai Trough off Japan in 2013 have increased

tremendous interests to the national gas hydrates programs of many countries, particularly in the Asian

countries. It is expected that gas hydrates will be produced commercially by another 10 years times. The

’Fiery Ice’ International Methane Hydrates R&D (IMHRD) Workshops were earlier held in Honolulu,

Hawaii; Washington DC; Vina del Mar, Chile; Victoria, British Columbia; Edinburgh, Scotland; Bergen,

Norway; Wellington, New Zealand; and Sapporo, Japan. The 9th IMHRD Workshop is being organized

by CSIR-National Geophysical Research Institute in Hyderabad, India during November 9-12, 2014. We

have 11 national reports, 2 keynote speeches, 16 invited talks, 30 posters and 6 break-out sessions. This

will provide a platform for deliberation, interaction and sharing information on new advances of several

perspectives of gas hydrates. The leading edge topics covering the natural systems, energy,

environmental impacts, flow assurance, advancement in production technology, etc will be presented

and discussed by an outstanding and diverse group of scientists (academic and industries) from different

countries, fostering an opportunity for International collaboration. The total participants in the

workshop are around 90 and the credit goes to all members of the international steering committee and

local advisory committee, and all participants for their joint efforts. The financial support from various

international and national organizations and institutions has made it possible to organize this workshop.

Wishing you all a fruitful discussion and pleasant stay at Hyderabad, India From Organizing Committee

UMASHANKAR

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(iv)

9th International Methane Hydrate R & D Workshop, Hyderabad India 9

Program Schedule for the Fiery Ice - 2014 9th IMHRD Workshop A. Geologic Field Excursion to Precambrian Geology at Nagarjuna Sagar, near Hyderabad 8th November, 2014:

Arrival and Check-in to CSIR-NGRI Guest House 18:00-19:00 Hrs - Registration for Field Trip 19:30-21:00 Hrs - Dinner at CSIR-NGRI 9th November, 2014:

06:30 Hrs - Departure from CSIR-NGRI Guest House for Field Trip

(Breakfast, Lunch, Snacks, Soft Drinks will be arranged during the Field Excursion)

19:30 Hrs - Arrival and Check-in to Hotel Novotel, adjacent to HICC -------------------------------------------------------------------------------------------------------------------- B. International Methane Hydrates R&D Workshop at HICC, Hyderabad Day 1: 9th November, 2014

Arrival and Check-in to Hotel Novotel, adjacent to HICC

19:30- 20:30 Hrs - Registration 20:30-22:00 Hrs – Dinner -------------------------------------------------------------------------------------------------------------------- Day 2: 10th November, 2014

7:00 to 8:00 Hrs - Breakfast 7:15 to 9:00 Hrs - Registration ---------------------------------------------------------------------------------------------------------------------

9:00 to 10:00 Hrs - Inaugural Session Chair: Prof. Harsh Gupta

Inviting Dignitaries & Welcome Dr. Y.J. Bhaskar Rao

(Director, CSIR-NGRI)

5 min

Lighting of Lamp, Invocation (Vandana) Dignitaries 5 min

Concept of IMHRD Workshop Dr. Richard Coffin

(Chair, Texas A&M Univ.)

10 min

Report from 8th Fiery Ice workshop Dr. Jiro Nagao ( AIST, Japan) 10 min

Release of Abstract Volume & Inaugural Address by Chief Guest

Shri S.K. Srivastava

(CMD, OIL)

10 min

Release of Technical Program & Remarks by Guest of Honour

Prof. V.P. Dimri

(INSA Senior Scientist)

5 min

Remarks by Chairman, LOC Prof. Harsh Gupta

(President, IUGG)

10 min

Vote of Thanks Dr. Kalachand Sain

(Convener, IMHRDW)

5 min

---------------------------------------------------------------------------------------------------------------------

10:00 to 10:20 Hrs - Tea/Coffee

10:20 to 10:30 Hrs - Group Photo --------------------------------------------------------------------------------------------------------------------- 10:30 to 13:00 Hrs - Session-I: Chair: Shri S.K. Srivastava Keynote Talks (30 minutes each)

ID No Title of presentation Author

Key-1 Feasibility of simultaneous Co2 storage and CH4 production from natural gas hydrate using mixtures of Co2 and N2

Bjorn Kvamme

Key-2 An overview of gas-hydrate exploration using geo-science data

Richard Coffin

National Reports (30 minutes each)


19 Recent progress of the methane hydrate research and development program in Japan

Jiro Nagao(Japan)

16 The German gas hydrate initiative SUGAR

from exploration to exploitation of marine gas hydrates Werner F Kuhs (Germany)

55 Gas hydrate R&D activities at KIGAM Jong-hwa Chun (South Korea)

---------------------------------------------------------------------------------------------------------------------


13:00 to 14:00 Hrs – Lunch --------------------------------------------------------------------------------------------------------------------- 14:00 to 15:00 - Session-II Chair: Prof. Ramesha Kolar National Reports - (30 minutes each)


54 The status of natural gas hydrate research in Chinese and the Green Solid fluidization development principle of natural gas hydrate in shallow layers of deepwater

Zhou Shouwei (China)

49 Energy recovery from natural gas hydrates: prospects and challenges for Singapore

Praveen Linga (Singapore)

--------------------------------------------------------------------------------------------------------------------- 15:00 to 16:30 - Session-III Posters and Tea/Coffee ---------------------------------------------------------------------------------------------------------------------

16:30 to 18:00 - Session-IV Breakout Sessions

I Challenges in Producing Methane Hydrates and When can they be produced Efficiently

&Safely? Mod: Dr. Richard Coffin, Dr. Praveen Linga & Dr. Sudeep Punnathanam

II Resource Assessment of Methane Hydrates and Key Parameters for Drilling Moderators: Dr. Jun Matsushima & Dr. Uma Shankar

III Methane Hydrates System: Origin of Methane Hydrate Reservoir Moderators: Dr. Shyam Chand & Dr. Nittala Satyavani

--------------------------------------------------------------------------------------------------------------------- 19:15 to 20:45 - Cultural Program --------------------------------------------------------------------------------------------------------------------- 20:45 to 22:45 – Dinner --------------------------------------------------------------------------------------------------------------------- Day 3: 11th November, 2014 7:30 to 8:30 Hrs – Breakfast --------------------------------------------------------------------------------------------------------------------- 9:00 to 11:00 Hrs - Session-V Chair: Dr. Jiro Nagao National Reports (30 minutes each)


50 Fluid flow and gas hydrate formation along Norwegian offshore: Recent results from the SW Barents Sea

Shyam Chand (Norway)

59 A review of United States methane hydrate energy exploration and research

Richard Coffin (USA)

48 An update on the state of gas hydrates research in New Zealand

Gareth Crutchley (New Zealand)

47 Present status and planning of the gas hydrate program of NEPII in Taiwan

Tsanyao Frank Yang (Taiwan)

--------------------------------------------------------------------------------------------------------------------- 11:00 to 11:15 Hrs - Tea/Coffee ---------------------------------------------------------------------------------------------------------------------


11:20 to 13:00 Hrs ‐ Session‐VI Chair: Prof. Werner F. Kuhs National Reports (30 minutes each) & Oral Presentations (20 minutes each)

ID No. Title of presentation Author

43 Recent results and discoveries on gas‐hydrates in the eastern Nankai Trough, Japan

Tetsuya Fujii

23 Recent results on gas‐hydrates research – statistical prediction of gas hydrate occurrence

Warren Wood

60 Risks associated with drilling and producing in marine gas hydrates ‐ An analysis based on recent field experience and computer simulations

Richard Birchwood

18 The possibility of compartment‐fluid system in methane‐hydrate reservoir in the Daini‐Atsumi Knoll, off central Japan

Kiyofumi Suzuki

45 The use of gas venting and chemosynthesis community in exploration of gas hydrate, offshore SW Taiwan

Saulwood Lin

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 13:00 to 14:00 Hrs – Lunch ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 14:00 to 15:20 Hrs ‐ Session‐VII Chair: Dr. Richard Coffin Oral presentations (20 minutes each)


13 Broadband frequency response of seismic attenuation in methane hydrate‐bearing sediments

Jun Matsushima

22 Controlled dissociation of methane hydrates: use of mixed hydrates with C4H8O

Seetha Rama Prasad Pinnelli

30 In situ micro‐structural studies of gas hydrate formation in sedimentary matrices

Werner F Kuhs

52 Natural gas hydrates and its exploitation for innovative energy solutions

Rajnish Kumar

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 15:20 to 17:00 ‐ Tea/Coffee and Posters ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 17:05 to 18:35 ‐ Session‐VIII Breakout Sessions

I Methane Hydrates Related Geohazards: Slope Stability & Climate Change Moderators: Dr. Richard Birchwood & Dr. Pawan Dewangan

II Methane Hydrates in Sand and Clay Reservoirs, and Their Response to Geo‐science data Moderators: Dr. Tetsuya Fujii & Maheswar OJha

III Multidisciplinary Approach for Linking Subsurface Fluid flow and Gas hydrates Moderators: Dr. Machiko Tamaki & Dr. Aninda Mazumdar

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 18:35 to 19:30 – Free Time ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 19:30 to 21:30 – Dinner ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Day 4: 12th November, 2014 7:30 to 8:30 Hrs – Breakfast ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 9:00 to 10:50 Hrs ‐ Session‐IX Chair: Prof. Bjorn Kvamme National Report (30 minutes) & Oral presentations (20 minutes each)


58 National Gas‐Hydrates program in India ‐an update Pushpendra Kumar (India)

15 CMR log analysis of the first offshore production test at Daini‐Atsumi knoll in the eastern Nankai Trough

Takashi Kotera

57 Geophysical investigation of gas hydrates at NGRI Kalachand Sain

10 Pressure core based study on geomechanical properties of hydrate‐bearing sediments: post cruise analysis on the 2012‐13

Japan drilling program in the Eastern Nankai Trough

Jun Yoneda

51 Formation and Growth of Hydrate Phase from Molecular Simulations

Sudip Roy

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 10:50 to 11:10 Hrs ‐ Tea/Coffee ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐


11:10 to 12:20 Hrs ‐ Session‐X Chair: Dr. Kiyofumi Suzuki Oral presentations (20 minutes each)


24 Integrated reservoir characterization and the 3D geo‐cellular modeling for methane hydrate‐bearing sediments around the 1st offshore production test in the Eastern Nankai Trough

Machiko Tamaki

8 Towards a thermodynamically consistent theory for clathrate hydrates

Sudeep Punnathanam

56 Some new findings from the Krishna‐Godavari and Mahanadi basins: NIO's contribution in gas hydrate science

Pawan Dawangan & Aninda Majumdar

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

12:30 to 13:30 Hrs – Lunch ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 13:30 to 17:05 Hrs ‐ Session‐XI 13:30 to 14:30 Hrs: Rapporteurs from Breakout sessions (10 minutes each) 14:30 to 16:00 Hrs: Concluding Session (Plenary Discussion (Transportation!), Next workshop, Remarks, any other issues) ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 16:00 to 16:20 ‐ Tea/Coffee ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 16:45 to 20:30 ‐ Visit to Historical Place: Golconda Fort and back to Hotel ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 20:30 to 22:30 – Dinner ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Day 5: 13th November, 2014

7:00 to 8:00 Hrs – Breakfast ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 8:30 to 12:30 Hrs ‐ 'Laboratory Visit to CSIR‐NGRI' ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 12:30‐13:30 Hrs ‐ Lunch and Departure


Poster Presentations

Poster Panel No.


1 1 Experimental observation of effect of initial pressure on

hydrate formation and dissociation in CH 4 and CO 2 mixture

Himangshu Kakati

2 2 Carbon Dioxide Capture and Storage in Various Fixed Bed Media Asheesh Kumar

3 3 Dissociation of Methane Hydrate in presence of Polyvinylpyrrolidone: Molecular Dynamics

Simulation

Nilesh Choudhary

4 4 Lessons from Simulation studies on Natural Gas extraction by thermal stimulation of submarine natural gas hydrate

P Sandilya

5 5 Low Dissociation Rate of Molded Natural Gas Hydrate with Electrolyte at 253 K and 1 atm

Hiroko Mimachi

6 6 Reflection Move out of fracture-filled gas hydrate deposits Sriram Gullapalli

7 9 Investigation on the influence of some novel packing media on CO2 capture through hydrate formation

Gaurav Bhattacharjee

8 11 A novel methodology to compute seafloor reflection coefficients from multi-channel seismic data

Pawan Dewangan

9 14 Methane storage in double hydrate (C4H8O + CH4) at higher temperature

Sowjanya Yalavarthi

10 17 OBS studies in the Indian offshore for Gas Hydrate Investigations Satyavani Nittala

11 20 Seismic signatures of gas hydrate deposits in high resolution sparker data from Krishna-Godavari offshore basin

Pawan Dewangan

12 21 Tomographic velocity analysis to evaluate the gas hydrates resource potential of different geological environment in Krishna-Godavari basin, India

Rakesh Mandal

13 25 Self-Preservation of Methane Hydrates in the Host Sediments Dhanunjana Chari Vangala

14 26 Understanding the Formation Kinetics of Mixed Hydrate CH4 -C3H8 and comparison with Pure CH4 Hydrates

Ch.V.V.Eswari

15 27 Gas hydrate characterization and saturation from logs and seismic data in the Mahanadi Basin

Uma Shankar

16 28 Seismic attenuation for the delineation of gas hydrates: Application to seismic data in Krishna-Godavari basin, eastern Indian margin

Veligeti Jyothi

17 31 Estimation of Gas hydrates for heterogeneous model constructed from well log in Krishna-Godavari basin, Eastern Indian Offshore

Soumya Jana

18 32 Sediment pore fluid chemistry in the oxygen minimum zone of the Arabian sea: organoclastic degradation and the anaerobic oxidation of methane

Svetlana Fernandes

19 33 Quantification of gas hydrates in fracture media: A new Approach Vivekanand Pandey

20 34 Inorganic and organic carbon geochemistry of a core (MD161-15) from the Krishna-Godavari Basin, Bay of Bengal.

Mary Ann Carvalho

21 35 Sediment provenance variations in the Krishna Godavari basin, Bay of Bengal for the last 80 ky: Role of climate

Aditya Peketi

22 36 Characterization of organic matter in Mahanadi basin, Bay of Bengal: Source and Diagenetic imprints

Rheane Dasilva

23 37 Pyritization trends within a sediment column off Mahanadi basin, Bay of Bengal, India

Brahmanand Sawant

24 38 Inferring the free gas occurrence in Krishna-Godavari basin using log and seismic data

Alekhya Gurajada

25 39 Pore Pressure and Porosity Mapping in Gas Hydrate Bearing Sediments in Krishna-Godavari Basin, India

Rima Chatterjee

26 40 Formation of methane-related authigenic carbonates in a highly dynamic biogeochemical system in the Krishna-Godavari Basin, Bay of Bengal

Muralidhar Kocherla

27 41 Effect of topography on estimates of the geothermal gradient derived from BSR and drilling estimates in the Krishna Godavari and Andaman forearc basins

Uma Shankar

28 42 Depressurization of Layered Unconfined Hydrate Reservoir for Gas Production

Piyush Bhade


29 53 Role of Bio‐surfactants in Natural Gas Hydrate Formation Kinetics

Amit Arora

30 44 Resources assessment of methane hydrates in offshore surround Japan

Toshiaki Kobayashi

31 12 Influence of supercooling degree during formation of hydrates from methane propane mixture on their equilibrium dissociation conditions

Anton P. Semenov

Keynote Author Name

1 Bjron Kvamme

Feasibility of simultaneous CO2 storage and CH4 production from natural gas hydrate using mixtures of CO2 and N2

Bjørn Kvamme University of Bergen, Department of Physics and Technology, 5007 Bergen, NORWAY

ABSTRACT Production of natural gas from hydrate using carbon dioxide opens up for a win-win situation in which carbon dioxide can be safely stored in hydrate form while releasing natural gas from in situ hydrate. This concept has been verified experimentally and theoretically in different laboratories worldwide, and lately also through a pilot plant in Alaska. The use of carbon dioxide mixed with nitrogen has the advantage of higher gas permeability and less tendency for blocking flow channels. The fastest mechanism for conversion involves the formation of a new hydrate from free pore water and the injected gas. As a consequence of the first and second laws of thermodynamics the most stable hydrate will form first in a dynamic situation, which involves that carbon dioxide will dominate the first hydrates formed from water and carbon dioxide / nitrogen mixtures. This selective formation process is further enhanced by favorable selective adsorption of carbon dioxide onto mineral surfaces as well as onto liquid water surfaces, which facilitates efficient heterogeneous hydrate nucleation. In this work we examine limitations of hydrate stability as function of gradually decreasing content of carbon dioxide. It is argued that if the flux of gas through the reservoir is high enough to prevent the gas from being depleted for carbon dioxide prior to subsequent supply of new gas then combined carbon dioxide storage and natural gas production is still feasible. Otherwise the residual gas dominated by nitrogen will still dissociate the methane hydrate and the nitrogen / methane dominated gas may also re-dissociate the formed carbon dioxide hydrate. The ratio of nitrogen to carbon dioxide in such mixtures is therefore a sensitive balance between flow rates and rates for formation of new carbon dioxide dominated hydrate. If nitrogen is the preferred gas to add to carbon dioxide then also additional components can be added to the mixture in order to promote conversion kinetics as well as stability of the new hydrate which is being formed. Some alternatives for such components will also be discussed Keywords: methane hydrates, carbon dioxide storage, nitrogen, methane production


Keynote Author Name

2 Richard coffin

An Overview of Gas-Hydrate Exploration Using Geo-Science Data

Richard Coffin, Ph.D. Department Chair

Physical and Environmental Sciences Texas A&M University – Corpus Christi

Corpus Christi, Texas, USA

Methane hydrates are known to be distributed in high concentrations through coastal regions around the world. These deposits are being investigated for better understanding of climate change and coastal stability, as well as a future energy reserve. Japan leads the world in methane hydrate energy assessment with a focus in the Nankai Trough, off the coast of Tokyo. This investigation has lead to Arctic tundra hydrate energy evaluation in the Mackenzie Delta and Prudhoe Bay by international governments, universities and industry. There are also strong efforts in methane hydrate energy exploration that are on-going and developing by teams of scientists and industry off the coasts of India, China, Korea, and many other nations.

Exploration of deep system gas hydrates depends on data from seismic profiling and deep sediment drilling. This approach to hydrate exploration is expensive and may limit the capability to predict hydrate reserves. Recent studies have combined seismic profiles, shallow sediment geochemistry, heatflow and controlled source electromagnetics to predict deep sediment hydrate deposits. This approach provides a more thorough, less expensive, investigation prior to deep drilling assessment. This presentation will compare geochemical, geophysical, and geological assessment of methane hydrate assessment in a variety of locations around the world. Data presented will show regions where seismic and geochemical data focus regions for hydrate exploration and locations where seismic data indicates deep system hydrate deposits while geochemical data suggest hydrate instability, lower than expected hydrate loading, or no presence of methane hydrates. The presentation will also include controlled source electromagnetic and heat flow data used to assist in combining the interpretation of seismic and geochemical data. Data is presented from the Gulf of Mexico, Mid Chilean Margin, Arctic Ocean and two regions off the coast of New Zealand.

Paper ID Author Name

1 Himangshu Kakati

Experimental observation of effect of initial pressure on hydrate formation and dissociation in CH4 and CO2 mixture

Himangshu Kakati, Ajay Mandal, Sukumar Laik Gas Hydrate Laboratory, Department of Petroleum Engineering,

Indian School of Mines, Dhanbad 826004, India Abstract: Understanding gas hydrate formation and dissociation is of importance in evaluating the energy potential of naturally occurring natural gas hydrate, promoting deep water drilling safety and geological mass flow mechanisms. This understanding is also vital where the controlled growth of gas hydrate is desired, such as in separation processes, and where the unwanted hydrate formation occur, such as in flow assurance of the hydrocarbon transportation systems. The formation and dissociation of CH4+CO2 gas hydrate at an interface between water and gas mixture have been experimentally investigated at different initial pressures in the present work. The gas mixture contains 95% (by mole) methane and 5% (by mole) carbon-dioxide. Experiments were carried out with three different initial pressures 8.27 MPa, 11.72 MPa and 15.86 MPa. It has been noticed that with increase in initial pressure, both hydrate nucleation and hydrate equilibrium pressure and temperature shifted to high temperature and high pressure. Experimental phase equilibrium data shows that with increase in initial pressure, equilibrium curve shifts towards higher temperature. As high pressure is a favorable condition for hydrate formation, hydrate exists at higher temperature as pressure increases. Enthalpy of dissociation of CH4+CO2 hydrates in the water has been calculated using the Clausius−Clapeyron equation based on the measured phase equilibrium data. The kinetics of hydrate formation has also been studied to observe the induction time of hydrate formation and gas consumption. Experimental result shows that induction time decreases as initial pressure increases. As mentioned earlier, high pressure environment favors hydrate formation, hydrate forms at lesser time when initial pressure of the system is high. Gas consumption during hydrate formation is also calculated using real gas equation.



2 Asheesh Kumar

Carbon Dioxide Capture and Storage in Various Fixed Bed Media

Asheesh Kumar1, Praveen Linga2, Rajnish Kumar*1 1Chemical Engineering and Process Development Division, National Chemical Laboratory, Pune, India 2Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore

*Corresponding Author: Phone: +91202590 2734 Email: [email protected] Abstract: Carbon dioxide capture and storage from point source like coal based thermal power stations is considered as a short term solution to tackle climate change concerns. It is proposed that CO2 from flue gas mixture coming out of coal based conventional power stations or from other point sources can be separated by a hydrate based gas separation (HBGS) process. Faster kinetics of HBGS process can bring this process one step closer to commercialization. In the current work water saturated silica sand bed along with silica gel & non porous metallic packing were used as a packing material in a fixed bed setup for faster hydrate growth kinetics. A kinetic promoter was also used to enhance the rate of hydrate formation. This work shows the experimental results of CO2 hydrate formation kinetics through gas uptake measurement at a constant temperatures (274.15 K) and pressures 3.0 MPa in batch mode.



3 Nilesh Choudhary

Dissociation of Methane Hydrate in presence of Polyvinylpyrrolidone:

Molecular Dynamics Simulation

Nilesh Choudhary, † and Rajnish Kumar*†1 †Chemical Engineering & Process Development Division, CSIR-National Chemical Laboratory,

Pune-411008, India Sudip Roy*2‡

‡ Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune-411008, India Keywords: Gas Hydrate, Polyvinylpyrrolidone, Dissociation Abstract: Methane gas hydrates are known as a potential energy source due to its methane storage capacity and huge resource availability in deep oceans1. The formation of gas hydrate requires typical high pressure and low temperature. This research is aimed to recover methane from these resources by dissociating the hydrate in controlled manner by thermal stimulation. The recovery can be further enhanced in the presence of kinetic hydrate inhibitors (KHIs) like Polyvinylpyrrolidone (PVP), Polyvinylcaprolactam and various antifreeze proteins. KHIs also used to stop gas hydrate plug formation in oil and gas pipeline2. In this work dissociation of gas hydrate in presence of PVP polymer are studied. We have carried out a microcanonical ensemble molecular dynamics simulation of solid-liquid interface of methane hydrate under different concentration distribution and chain length of PVP polymer in amorphous water. Force field parameters for PVP are obtained and optimised against experimental density and glass transition temperature. SPC/E water model were used for all the simulations. The different dissociation characteristics in all systems have been analysed and quantified. References: 1. Sloan Jr, E. Dendy, and Carolyn Koh. Clathrate hydrates of natural gases. CRC press, 2007. 2. Perrin, Andrea, Osama M. Musa, and Jonathan W. Steed. "The chemistry of low dosage clathratehydrate inhibitors."Chemical Society Reviews 42.5 (2013): 1996-2015.



4 P Sandilya

Lessons from simulation studies on natural gas extraction by thermal

simulation of submarine natural gas hydrate

P Sandilya Cryogenic Engineering Centre

Indian Institute of Technology Kharagpur Kharagpur – 721302, West Bengal, India

Email: [email protected] Abstract: Various methods have been proposed to extract natural gas from submarine natural gas hydrates. These methods aim at destabilizing the hydrates thermodynamically by either shifting the zone of temperature and pressure, or causing chemical instability. Even though many of the proposed techniques seem to be effective for this purpose, in principle, grave challenges are encountered when it comes to commercial production because of the inconvenient location of the gas hydrates. Studies at various levels from laboratory scale to field scale have been going on for past few decades to establish a commercial technology for natural gas production from the vast source of natural gas hydrate. These studies are broadly classified into two groups: simulation-based, and experiment-based. At IIT Kharagpur, under the National Gas Hydrate Program of India, a simulation-based study was conducted in collaboration with ONGC, to study the efficacy of thermal stimulation in producing natural gas from submarine natural gas hydrate. At that juncture (2010-12), it was first simulation study in India on natural gas production from submarine gas hydrates, though internationally many simulation studies have been reported on this aspect. Important lessons were learnt in course of carrying out the work that would help in making significant progress for exploitation of the vast source of energy. The purpose of presenting this paper is two folds: (i) to present some of the results of numerical simulation on natural gas production from submarine natural gas hydrates by thermal stimulation, and (ii) the lessons learnt on using the simulation as a tool to understand the efficacy of a given technique. Simulation study: The simulation was performed considering a deformable hydrate bed subjected to thermal stimulation. The heat may be inputted by various means; in our case, heat input was considered to be provided by hot water injection, as shown in Figure 1. Such an arrangement for heat supply was earlier made in the field trial at the Mallik site. It may be noted that it is important to ensure that the heat dissipation to the surrounding is minimised for getting good return on energy (ratio of energy output to energy input).

Figure 1: Schematic for simulation of thermal stimulation for production of natural gas

In developing the model for the above system, the likely instability of the bed due to loss of hydrate was considered. Accordingly, in addition to the conventional equations for mass-, momentum- and energy conservation, along with thermodynamics and kinetics of hydrate formation/dissociation, constitutive relations for the sediment were included in the model. As a first attempt, the elastic deformation of the sediment was considered. Considering axi-symmetry, a two-dimensional model was developed. The simulation was carried out by an in-house code and the results were validated by adjusting some modelling parameters, with the data reported from the field test at Mallik site. Lessons from the simulation study: A model is as good as the knowledge about the process. Both modelling and experimental works are essential, the results of which would complement each other to develop them further to get better understanding of the process for gas production. Through the present study, it was felt that many important issues need to be studied as a part or independently of the modelling. These encompass the fluid flow, heat and mass transfer, phase change of hydrate, occurrence and distribution of gas hydrates in the sediment, and sediment bed deformation. A review of the existing literature and the present study indicated that a hybrid method with appropriate operational protocol to carry out the natural gas production should be explored. The production strategy would depend on the type of gas hydrate reservoir. The model equations involve many properties associated with the hydrates and the sediments to determine the flow of the gas and water through the sediment bed and the associated heat and mass transfer phenomena. These properties are related to the thermo-physical-, transport-, thermodynamic-, and kinetic- properties of the gas hydrates inside the sediment, as well as morphological and mechanical properties of the sediment bed. All these properties are not available as a consolidated database, especially for the hydrate sediments. Some databases on gas hydrate have been developed liked CODATA, and later by NIST, NETL. Because of the varied nature of the hydrate deposits, case specific data are required for simulation, which are lacking at times. In such cases, some estimations and approximations are often made from the reported data to carry out the simulation. Experimentations have to be done to test novel ideas with the insights gathered from the simulation studies. In order to accomplish the ultimate goal of gas production, sustained R&D studies need to be carried out through industry-academia collaborations at both national and international levels. Our work may be considered as a stepping stone towards this mission, exposing us to the challenges in the area of gas hydrate utilization and helping us to plan the future R&D studies. Key words: Gas hydrate, natural gas, energy, thermal stimulation


0.5

0.6

0.7

0.8

0.9

1.0

0 50 100 150 200 250 300 350

Mas

s Fra

ctio

n of

Hyd

rate

Storage Time (h)

Purified Water 0.1 mol / m³0.4 mol / m³ 2.5 mol / m³137 mol / m³


5 Hiroko Mimachi

Low Dissociation Rate of Molded Natural Gas Hydrate with Electrolyte at 253 K and 1 atm

Hiroko Mimachi a, Masahiro Takahashi a, and Takeshi Sugahara Mitsui Engineering and Shipbuilding Co., Ltd., 1 Yawatakaigandori, Ichihara, Chiba 290-8531, Japan bDivision of Chemical Engineering, Graduate School of Engineering Science, Osaka University, 1-3

Machikaneyama, Toyonaka, Osaka 560-8531, Japan Gas hydrate, a clathrate compound, traps gases within cages consisting of water molecules, and it can contain approximately 170 times as larger gas as its volume. Gas hydrates are normally stabi-lized at high pressures and low temperatures. But their dissociations are suppressed below ice point and at ambient pressure though the temperature and pressure are outside thermodynamically stable zone. This phenomenon is so-called self-preservation. For the large capacity and pre-servation ability of gas at mild conditions, research on the application of gas hydrates to gas transportation media has been developed. But dissociation behavior of gas hydrates is still unclear, for the dissociation rates are affected by a number of factors: temperature, gas composition, electrolyte, and so on. It is important to investigate the effect of water-soluble ingredients on the dissociation rate of gas hydrates, because water-soluble ingredients are concentrated into residual water with hydrate formation.

Figure 1 Dissociation behavior of NGH pellets with NaCl at 253 K and 1 atm.

In this report, gas hydrate pellets that include multi-component gas with an electrolyte as a water-soluble ingredient are formed by means of a semi-batch system, and dissociation rate of the pellets are investigated. Simulated natural gas (mixture of CH4, C2H6, C3H8, iso-C4H10, n-C4H10, and iso-C5H12) and NaCl solutions of which concentrations are 0.2 mol / m3, 1.0 mol / m3, 8. 6 mol / m3, and 513 mol / m3 are agitated to form gas hydrate slurry in a reactor at 281 K and 5.5 MPa. And then slurry of the natural gas hydrate (NGH) is dewatered and molded to pellet by pelletizing machine. NGH pellets are obtained at ambient pressure after temperature decrease to 253 K. In addition, another NGH pellet is formed from simulated natural gas and purified water as a reference sample in the same way. Gas compositions of NGH pellets are analyzed by gas chromatography (Micro GC CP4900, Varian, Walnut Creek, CA): 83.66% CH4, 10.89% C2H6, 4.58% C3H8, 0.42% iso-C4H10, 0.45% n-C4H10, and under 0.01% iso-C5H12 on average. The micro-Raman spectroscopy (NRS-1000, JASCO Corporation,

Japan) is carried out at 183 K to identify crystal structure of the NGH sample. Six peaks originated form CH4, C2H6, and C3H8 are observed from Raman spectra in the C-H stretching region. The peaks of the other gases are below a detection limit. The NGH crystal is found to be structure II with a small amount of structure I after the peak deconvolution of the C-H stretching vibration by Lorentz function is applied. Dissociation rate of the hydrate pellet samples (φ33 × 30 mm) has been investigated at 253 K and ambient pressure for two weeks. Concentration of NaCl in the samples are 0.1 mol / m3, 0.4 mol / m3, 2.5 mol / m3, and 137 mol / m3. Changes of mass fractions of hydrate are shown in Figure 1. The NGH sample with the highest NaCl concentration dissociates approximately 3% in mass fraction after storage, or equivalently, average dissociation rate is 0.2 percentage points per day, while the other samples dissociate slightly or under the detection limit. Also, dissociation of the NGH formed from purified water is not detected, and all samples in this experiment are kept over 0.7 in mass fraction of hydrate after two-week storage. Consequently, it is revealed that the NGH pellets are preserved at 253 K and ambient pressure, even though the NGH pellets contain 137 mol / m3 and less of NaCl.



6 G. Siram

Reflection Moveout of fracture-filled gas hydrate deposits

G. Sriram*+ , P. Dewangan+ , T. Ramprasad+

National Centre For Antarctic and Ocean Research, Goa, India CSIR-National Institute of Oceanography, Goa, India

Abstract: The aligned fracture-filled gas hydrate deposits can be modeled as an effective anisotropic medium. The

anisotropic parameters can be estimated from the properties of pure hydrates and the background marine

sediments. In case of single set of fracture, the effective medium will be represented by a transversely

isotropic medium with symmetry axis oriented normal to the fractures. The near vertical fractures, as

observed in the KG offshore basin, can be modeled as an HTI (TI with a horizontal symmetry axis)

medium. Some important features of HTI medium are the azimuthal variation of normal moveout (NMO)

velocity and non-hyperbolic moveout. In HTI medium, the P-wave velocity varies with azimuth and

incidence angle influencing NMO velocity and non-hyperbolic moveout. The reflection moveout of an

HTI medium can be expressed in terms of normal moveout velocity (V nmo), horizontal velocity (Vhor),

quartic term (A4), convergence parameter A, and azimuth (α). The NMO velocity will usually differs

from vertical velocity leading to misties in timeto-depth conversion. In the present study, the reflection

moveout of fractured-filled gas hydrate deposits are estimated as a function of azimuth for different gas

hydrate concentration to understand the effect of gas hydrate on reflection moveout. Two different

models are considered: a homogemeous HTI medium representing fracture-filled gas hydrate deposits

and a two-layered media representing an isotropic water column and a homogeneous HTI medium. The

stiffness coefficients are computed for different gas hydrate concentration (GHCs) using Backus

averaging method (Backus, 1962), and are expressed in terms of Thomsen-style anisotropic parameters to

understand the variation in traveltimes of HTI medium (Tsvankin, 1997). The traveltime moveout

parameters (V nmo , V hor) and quartic terms (A4 and A) are computed theoretically as a function of

azimuth (α) for different GHCs using the equations given by Al-Dajani & Tsvankin (1998). The

traveltimes for homogeneous HTI medium are also estimated using anisotropic ray tracing (Gajewski &

Pˇsenc´ık, 1987) assuming 10-40% GHCs for varying azimuth (0 and 90◦). The theoretical and exact

traveltimes for GHCs (10-40%) are shown in the symmetry axis (α=0) and isotropy planes (α = 90◦ ) in

Figure 1. The estimated traveltimes for 10-40% GHCs match well with that estimated from ray tracing

method suggesting high accuracy of the analytical expression even for large offset (Fig.1a-d). A

representative two layer model (seafloor + HTI medium) is considered to simulate the observed gas

hydrate deposits in KG offshore basin. The seafloor is assumed to be at the depth of 1029 m and the

fracture filled gas hydrate deposit, represented by HTI medium, is assumed to be 156 m thick. Similar to

homogeneous HTI medium, the moveout parameters are obtained for the layered medium using the

equations given by Al-Dajani & Tsvankin (1998). The traveltime moveout parameters (V nmo, Vhor) and

quartic terms (A4 and A) are studied for different GHCs and azimuth (α) in a twolayered (ISO+HTI)

media (Fig.2). The traveltimes (Fig.2a) match well for smaller GHC (10 and 20%) in the symmetry axis

plane while minor deviations are observed at offset/depth>4 in the isotropy plane. A significant deviation

is observed between the approximate and the exact traveltimes for higher GHCs (30-40 %) beyond the

offset/depth ratio of three (Fig.2c,d). Therefore, at larger offset such approx imate expression are no longer valid for high GHCs. The traveltimes for a homogeneous HTI medium as well as the layered HTI media are studied as a function of GHCs and azimuth. The approximate expression for the NMO-velocity and the quartic moveout term remains accurate for homogeneous HTI medium and for low GHC in a layered model. The analytical expression can be used for inversion of moveout parameters from the traveltime data in a homogeneous HTI medium. In the case of layered media and strong anisotropy (high

GHC>20%), the approximate expressions break down for o_set/depth >3 and cannot be used for traveltime inversion.

References: Al-Dajani, AbdulFattah, & Tsvankin, Ilya. 1998.Nonhyperbolic reection moveout for horizontal transverse isotropy. Geophysics, 63(5), 1738{1753. Backus, G.E. 1962. Long-wave elastic anisotropy produced by horizontal layering. Journal of Geophysical Research, 67(11), 4427{4440. Gajewski, D., & P_senc__k, I. 1987. Computation of high-frequency seismic wave_elds in 3-D laterally inhomogeneous anisotropic media. Geophysical Journal International, 91(2), 383{411. Tsvankin, I. 1997. Reection moveout and parameter estimation for horizontal transverse isotropy. Geophysics, 62(2), 614{629.

Figure 1: Comparison between traveltime moveout

of homogeneous HTI medium from ray tracing

method (solid black line) and analytical

approximation (dots) for different GHCs (10-40%).

Figure 2: Comparison between traveltime moveout

of two-layered media from ray tracing method

(solid black line) and analytical approximation

(blue dots) for different GHCs (10-40%).



7 Katie B. Taladay

Interpretation of the Gas Hydrate System of the Kumano Forearc Basin, Nankai Trough, Japan

Katie B. Taladay, Gregory F. Moore and Stephen Masutani Bottom simulating reflections (BSRs), appearing in seismic surveys along continental margins worldwide, are considered to be robust indicators of the presence of gas hydrates. Yet despite several decades of research, the nature of BSRs including their occurrence, distribution patterns, amplitude strength, continuity, and phase characteristics continues to present a challenge to seismic interpretations. It is commonly agreed that a hydrate-related BSR marks a phase boundary of hydrate stability and that a BSR’s amplitude strength depends heavily on the presence of free gas below. However, a lack of consensus exists regarding the meaning of double BSRs (DBSRs), how susceptible the base of hydrate stability is to temperature-pressure perturbations, and the usefulness of seismic amplitude analysis as a viable exploration method to identify resource quality hydrate deposits. This study introduces a new explanation of DBSRs and demonstrates how ancillary data can enhance the utility of seismic amplitude analysis as an exploration tool. We characterize the gas hydrate system within the Kumano Forearc Basin, Nankai Trough, Japan using a 3D PSDM seismic volume and corresponding data from IODP NanTroSEIZE drilling. Seismic horizons were manually picked to map the occurrence of a basin-wide BSR, regional DBSRs, and high amplitude reflections (HARs) indicative of gas occurring beneath the base of the gas hydrate stability zone (GHSZ). The seismic data reveal a complicated geological system as a result of subduction related tectonics; a strong, continuous BSR at approximately 400mbsf throughout the basin; extensive, but patchy, DBSR distributions; high amplitude reflections (HARs) correlating with gas charged sands in a buried channel complex; horizon phase reversals across the BSR; and specific gas migration routes. Geochemical data from IODP Expedition 338, site C0002, suggest that the gas beneath the GHSZ is largely sourced by the burial and dissociation of gas hydrates indicated by a dramatic drop in salinity and chlorinity interstitial water measurements just above 400mbsf. This drop is evidence of pore water freshening due to hydrate dissociation. Simultaneously, the presence of mud volcanism, chimney structures, bright spots over anticlinal structures and ethane in increasing concentrations with depth are supportive evidence of thermogenic gas migration upward into the basin sediments. We conclude that (1) gas fractionation may lead to the formation of some of the observed DBSRs based on different phase stability conditions for Type I and Type II hydrate formation and (2) seismic amplitude response analysis for identifying prospective hydrate deposits is aided by the addition of various attribute analyses.


8 Sudeep Punnathanam

Towards a thermodynamically consistent theory for clathrate hydrates

Sudeep Punnathanam

The thermodynamic properties of clathrate hydrates are very well described by theory of van der Waals and Platteuw. The parameters of the theory are typically regressed from phase equilibria data of clathrate hydrates. However, the theory suffers from many drawbacks. These include inconsistencies in the guest-water interactions used in the theory with those obtained from other independent measurements; errors in predicting compositions ofclathrate hydrates; errors in predictions outside the range of fitting; etc. Although many improvements have been suggested over the years leading to enhancement in the performance of the theory, the deficiencies have not been fully addressed. The research in our group have shown that flexibility of the water lattice, which has not been addressed previously, plays a significant role in determining the properties of clathrate hydrates. In this talk, we will be describing methods for computing occupancies, chemical potentials and free energies that account for the flexibility of water lattice. The methods are validated for a wide variety of guest molecules such as methane, ethane, carbon dioxide, tetrahydrodfuran, propane, iso-butane and n-butane, 2,3-dimethyl butane and 2,2-dimethyl butane. The proposed method is a significant breakthrough towards addressing the problems of the van der Waals and Platteuw theory and developing a consistent and robust thermodynamic theory for clathrate hydrates.



9 Gaurav Bhattacharjee

Investigation on the influence of some novel packing media on CO2 capture through hydrate formation

Gaurav Bhattacharjee, Tushar Sakpal, Asheesh Kumar and Rajnish Kumar*

Chemical Engineering and Process Development Division, National Chemical Laboratory, Pune, India Abstract: Owing to the ever-increasing levels in emissions of greenhouse gases, the threat of global warming on the Earth’s climate system looms larger than ever before. Carbon dioxide is one of the major greenhouse gases and contributes significantly to the Earth’s greenhouse effect. It has been widely acknowledged that energy related processes such as the burning of fossil fuels are the largest source of surplus CO2 emissions. Efficient capture and storage of CO2 has therefore become the need of the hour and poses as an attractive solution to immediately tackle the aforementioned problems. CO2capturethrough hydrate formation has proven to be very advantageous in the past. It is always desirable to enhance the hydrate formation kinetics and increase the real time efficiency of hydrate based process. In the present study, the influence of some novel packing media on CO2 capture through the hydrate formation process has been investigated. The novel packing material was used to form a fixed bed setup in a bid to enhance hydrate formation kinetics. The experimental results obtained using the novel packing materials have been compared with those obtained using the more standard silica sand as packing material. Two different types of experiments were carried out. In the first case, the amount of water used was the same in case of all the packing materials. The effect of bed height was investigated in the second case where bed height was kept constant. This means that the amount of water used was different in each case depending on the porosity of the packing material in question. The effects of these two parameters, namely the amount of water used and the bed height, on the hydrate growth kinetics were investigated and have been reported. All experiments were carried out at a constant temperature of 274.15 K and initial pressure of 3.0MPa using pure CO2 gas.


10 Jun Yoneda

Pressure core based study on geomechanical properties of hydrate-bearing sediments: Post cruise analysis on the 2012-13 Japan drilling

program in the Eastern Nankai Trough

Jun Yoneda*, Akira Masui*, Yoshihiro Konno**, Yusuke Jin**, Masato Kida**, Jiro Nagao**, Norio Tenma*

*Methane Hydrate Research Center (MHRC), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan

Tel: +81-29-861-8306, e-mail: [email protected]: [email protected] **MHRC, AIST, Sapporo, Japan

In March 2013, Japan extracted methane gas from offshore natural gas hydrates; this is the first time that this has been done. Methane hydrate (MH) is a solid compound in which a large amount of methane is trapped within the crystalline structure of water, forming an ice-like solid. It is known to be stable only under certain temperature and pressure conditions; in particular, its existence has been confirmed in permafrost layers and the deep ocean floor. Although Japan has no permafrost zones, it is believed that MH exists in the seafloor, and development is underway for MH to be a future energy resource. To date, MH extraction has been simulated in several ways to help ensure the safe and efficient production of gas, with a particular focus on the investigation of landsliding, uneven settlement, and production well integrity. The mechanical properties of gas-hydrate-bearing sediments, typically obtained through material tests, are essential for the geomechanical response simulation to hydrate extraction. Soil mechanics laboratory tests have previously included a triaxial compression test designed to investigate the mechanical properties of hydrate-bearing sediments by using synthetic gas hydrate. However, few laboratory tests have been conducted for natural gas hydrate-bearing sediments because such hydrates suddenly dissociate under atmospheric pressure and at normal temperatures. To investigate the true strength of natural gas hydrate-bearing sediments, pressure core technologies have been developed [Santamarina et al. 2012]. The developments of pressure coring and recovery tools have involved research teams around the world, including initiatives such as the International Ocean Drilling Program and the European Union’s Marine Science and Technology Program. It is necessary to keep the samples at all times under pressure-temperature condition within the stability field. In the eastern Nankai Trough, the first Japanese offshore production test region, we conducted pressure coring using a hybrid pressure coring system (Hybrid PCS) in June and July 2012 [Yamamoto, 2014; Kubo et al., 2014]. Pressure cores were subsampled using the pressure core analysis and transfer system (PCATs) [Schultheiss, 2011], and were transported to the laboratory completely within pressure–temperature conditions of hydrate stability to avoid dissociation of natural gas hydrates. For analyzing these pressure cores, we developed a Pressure-core Non-destructive Analysis Tools (PNATs) which include manipulator, cutting tool, observation window, and temporary storage chamber. In addition, an innovative Transparent Acrylic Cell Triaxial Testing system (TACTT-system) that uses an image processing technique was developed [Yoneda et al., 2013]. Our system has been designed to conduct laboratory investigations of the mechanical, hydrological, and geophysical properties of pressure cores for natural-gas-hydrate-bearing sediments recovered from the deep seabed, and our testing apparatus can operate under high water pressures without allowing any depressurization of the pressure core. Transfer of the core from the storage chamber to the triaxial cell and the application of an effective confining pressure to the sediment are achieved through use of a sealing sleeve. It is possible to perform a compression test as an element test. In addition, this system was used to conduct the first visualized triaxial testing under in situ hydraulic pressures using high-pressure cells made from acrylic, thereby allowing the evaluation of localized deformation by using an image processing technique. Figure 1 shows a first photograph of natural hydrate-bearing pressure core sediments under 10 MPa. This natural gas hydrate-bearing sediments were successfully installed to sealing sleeve and compression sheared at in-situ effective


confining pressure and hydraulic pressures as shown in Figure 2. Here we summarize the design of our testing apparatus and describe testing procedures for pressure core. We also conducted triaxial compression test with the local strain obtained using the image processing technique.

Figure 1 Natural gas hydrate-bearing pressure core Figure 2. Photograph after compression sheared. sediments wih hydrate saturation Sh = 63%. (Photographed under 10 MPa of hydraulic pressure) Acknowledgements: The present work was conducted as part of the activity of the Research Consortium for Methane Hydrate Resources in Japan [MH21 Research Consortium] as planned by the Ministry of Economy, Trade and Industry (METI), Japan. We would like to express our sincere thanks for this support. We also wish to thank Mr. Shigenori Nagase, and Ms. Sayuri Kumagai of AIST for technical supports. References: Kubo, Y., Mizuguchi, Y., Inagaki, F. and Yamamoto, K., 2014. A new hybrid pressure-coring system for the drilling vessel Chikyu: Scientific Drilling., 17, 37-43, doi:10.5194/sd-17-37-2014. Santamarina, C., S. Dai, S., J. Jang, J., and M. Terzariol, M., 2012. Pressure core characterization tools for hydrate-bearing sediments: . Sci. Dril., 14, 44–48, doi:10.2204/iodp.sd.14.06.2012. Schultheiss, P., M. Holland, M., J. Roberts, J., Q. Huggett, Q., and M. Druce, M., 2011. PCATS: Pressure core analysis and transfer system: . Proc. 7th Int. Con. Gas Hyd., Edinburgh. Yamamoto, K., N. Inada, N., S. Kubo, S., T. Fujii, T., K. Suzuki, K., Y. Nakatsuka, Y., T. Ikawa, T., M. Seki, M., Y. Konno, Y., J. Yoneda, J., and J. Nagao, J., 2014. Pressure coring operation and analyses on the obtained cores: . Proc. Offshore Technology Conference 2014, OTC-25305. Yoneda, J., A. Masui, A., N. Tenma, N., and J. Nagao, J., 2013. Triaxial testing system for pressure core analysis using image processing technique: . Rev. Sci. Instrum., 84, 114503, doi: 10.1063/1.4831799.


11 P. Dewangan

A novel methodology to compute seafloor reflection coefficients from multi-channel seismic data

P. Dewangan*, N. Thiruvengadam, T. Ramprasad CSIR-National Institute of Oceanography, Goa – India 403004

*corresponding author: [email protected] Seismic amplitude variation with offset/angle (AVO/AVA) analysis is widely used to predict the reservoir rock properties like porosity, density, lithology and fluid content. AVO also provides information about the Poisson’s ratio which along with the velocity information can be used to determine the lithology of the subsurface. The anomalous behavior of the reflection amplitudes can be used as a direct hydrocarbon indicator in gas – saturated sands. AVO study of the anomalous seismic reflector (BSR), a proxy for the gas hydrate deposits, provides useful information about the presence of free gas beneath the BSR. The AVO analysis coupled with a suitable rock physics model can also provide a rough estimation of the gas hydrate saturation. On the other hand, the seafloor reflection coefficients (RCs) can be used to identify the fluid – gas expulsion rate (Roberts et al., 2006). The seafloor bright spots may act as a proxy for the subsurface gas hydrates or it may indicate the presence of gas hydrates as seafloor outcrops. Therefore, it is important to study the AVO response of the seafloor reflection as well as the BSR. The reflection coefficients can be obtained from seismic reflection amplitudes after accounting for geometrical spreading, intrinsic attenuation, source and receiver directivities (Hyndman and Spence, 1992). The effect of geometrical spreading and attenuation can be addressed at the pre-processing stage. The directivity of the hydrophone cable can be estimated as a linear array response, and it depends on the hydrophone spacing. However, the source directivity can only be obtained through appropriate software packages (e. g. NUCLEUS) or by calibrating with the seafloor RCs. It depends on tuned air gun response and other acquisition parameters. There is no established technique to obtain the source directivity directly from the seismic data. In the present study, we demonstrate a methodology to estimate the source and receiver directivities and the seafloor RCs from the multi-channel seismic data using the amplitudes of primary seafloor reflection and its first-order multiples. Generally, AVO is quantified using two terms: the gradient and the intercept. The intercept term of the seafloor can be estimated from the ratio of amplitudes corresponding to zero-offset primary and multiple reflections (Warner, 1990). We extended the Warner’s method for non-zero offset, and demonstrate its applicability for the estimation of directivities and seafloor RCs with the help of synthetic data. We assume that the overburden (water column) is homogeneous and the seabed is horizontal, but the seafloor RCs are spatially variant due to the variations in the sub seafloor parameters. After accounting for geometrical spreading and attenuation correction, the amplitude of the reflected P- wave (AP) from the seafloor can be expressed in terms of incidence angle (θ) as, AP(X,θ)=S(θ) RPP(X,θ) R(θ) (1) where X represents the reflection point on the seafloor, S(θ) is the source directivity, R(θ) is the receiver directivity, and RPP is the P-wave RC as a function of reflection point (X) and angle of incidence (θ). The source and receiver directivities are assumed to be dependent only on the incidence angle, and hence they are spatially independent. Likewise, the first-order multiple (AM) from a horizontal seafloor can be expressed in term of incidence angle (θ) as, AM (X1X2,θ)= S(θ) RPP(X1,θ) (-1) RPP(X2,θ) R(θ) (2)


where X1 and X2 represent the reflection points corresponding to primary reflection points with the same incidence angle. The combined effect of source and receiver directivities can be derived using equation (1) and (2) as, R(θ)S(θ)= – AP(X1,θ) AP(X2,θ) / AM (X1X2,θ). (3) The P-wave RCs can be computed using the P-wave amplitude of [eq. (1)] and the combined source and receiver directivities [eq. (3)]. The 2D finite difference method developed by (Thorbecke and Draganov, 2011) was adopted to generate the synthetic seismic data. The model parameters (Vp1=4000 m/s, Vs1=1000 m/s, rho1=2465 g/cc, Vp2=4000 m/s, Vs2=2500 m/s, rho1=3573 g/cc) have been chosen arbitrarily such that the computed RCs span positive, negative as well as zero values. The amplitudes of the primary and first-order multiples are shown in Figure 1 after geometrical correction. No attenuation correction was required as elastic finite-difference model was used. The P-wave RCs computed using equation (3) are compared with that calculated from the Zoeppritz equation (Figure 2). The estimated RCs matches well with the theoretical RCs computed from Zoeppritz equation. However, the proposed methodology has two limitations: a) the angle of incidence is limited up to the half of the maximum offset as the first-order multiple is involved; b) the method is unstable if the amplitude of primary and multiples are close to zero (in the vicinity of polarity reversal).

References: Hyndman, R. D., & Spence, G. D. 1992. A seismic study of methane marine bottom simulating reflectors. Journal of Geophysical Research, 97(B5), 6683 – 6698. Roberts, H. H., Hardage, B. A., Shedd, W. W., & Hunt Jr., J. 2006. Seafloor reflectivity – An important seismic property for interpreting fluid/gas expulsion geology and the presence of gas hydrates. The Leading Edge. 620 – 628. Thorbecke, J. W., & Draganov, D. 2011. Finite-difference modeling experiments for seismic interferometry. Geophysics, 76(6), H1 – H18. Warner, M. 1990. Absolute reflection coefficients from deep seismic reflections. Tectonophysics, 173, 15 – 23.

Fig.2. Comparison between the exact reflection coefficients obtained from Zeoppritz equation (solid line) and the estimated reflection coefficient (dashed line) from the proposed method.

Fig. 1. Amplitude of primary reflection (solid black) and first-order seafloor multiple (dashed line) extracted from the synthetic data.


12 Anton P. Semenov

Influence of supercooling degree during formation of hydrates from methane propane mixture on their equilibrium dissociation conditions.

Anton P. Semenov, Vladimir S. Yakushev, Vladimir I. Medvedev, Pavel A. Gushchin. Gubkin Russian State University of Oil and Gas

65, Leninskiiprospekt, building 1, 119991, Moscow, Russian Federation [email protected], [email protected]

Obtaining of improved data on gas hydrate equilibrium of gas mixtures of different composition is an important scientific and technical problem. From the point of view of fundamental science, these data are necessary to determine the parameters of thermodynamic models of hydrate phase. From the point of view of applied science, the data on hydrate equilibrium conditions are required to determine the consumption of inhibitors in the production and transportation of hydrocarbons. Hydrate formation from gas mixtures is more complicated process than hydrate formation from individual gases due to the separation and changes in the composition of the gas mixture, resulting in the formation of a mixture of hydrates of different composition. In this study, we investigated the effect of the initial supercooling degree on the equilibrium conditions of decomposition of gas hydrates samples which were obtained from model gas mixture 95.7 % CH4 + 4.3% C3H8 (% mol.). We conducted preparation and decomposition of gas hydrates using Sapphire Rocking Cell RCS6. In order to provide high conversion of water into hydrate we used 0.1 % (mass.) solution of sodium dodecyl sulfate. Samples of gas hydrates were prepared at temperature 1 °С and pressures 30 – 120 bar. For the decomposition the samples of hydrates were heated at rate 0.2 ° C/h. Analysis of the decomposition curves indicates that mixed methane propane hydrates of different compositions are formed from gas mixture of 95.7% CH4 +4.3% C3H8 as well as methane hydrate depending on the initial conditions. With the increasing of the initial supercooling degree before hydrate formation increases the fraction of the methane hydrate. Hydrate decomposition curve for gas mixture is not simply exponential, as previously assumed, but a more complex configuration. Our data indicate the multiplicity of equilibrium conditions of hydrate dissociation for gas mixtures depending on the supercooling degree before hydrate formation. Acknowledgements: This work is supported by Ministry of Education and Science of the Russian Federation (Target funding, project 13.1926.2014/K).




13 Jun Matsushima

Broadband frequency response of seismic attenuation in methane hydrate-bearing sediments

Jun Matsushima

The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo, 113-8656 Japan

Many authors have estimated the amount of methane hydrate (MH) from seismic velocity data (e.g., Wood et al., 1994; Korenaga et al., 1997; Ecker et al., 2000), as MH within sediment pore space stiffens the sediment and results in an increase in seismic velocity. Although seismic velocity is potentially a useful indicator of MH concentration, seismic velocity is also strongly controlled by the microscale MH distribution in pore spaces. While the presence of MH increases the seismic velocity of the host sediment, recent work on sonic logging data shows that sonic waveforms are also significantly affected by the presence of MH (Guerin and Goldberg, 2002; Matsushima, 2005). To reduce the uncertainty in characterizing MH bearing sediments, the combined use of velocity and attenuation data provides greater insight. Although one would expect that the stiffer material is characterized as higher velocity and lower attenuation, high velocity and high attenuation in methane hydrate-bearing sediments has been observed with sonic logging measurements (e.g., Guerin and Goldberg, 2002; Matsushima, 2005; Matsushima, 2006; Suzuki and Matsushima, 2013). Furthermore, laboratory experiments showed a general increase in compressional and shear attenuation with hydrate saturation (Priest et al. 2006; Best et al. 2013). On the other hand, however, Matsushima (2006) used VSP data at the same field to estimate compressional attenuation in methane hydrate-bearing sediments at seismic frequencies of 30-110 Hz, and reported that no significant compressional attenuation was observed in methane hydrate-bearing sediment. Similarly, Lee (2006) demonstrated, by use of VSP data, that attenuation of methane hydrate-bearing sediment is less than that of water-saturated sediments. Rossi et al. (2005) observed high velocities and low attenuations of compressional waves by use of an ocean bottom seismograph (OBS) array in NW offshore Svalbard. Sain et al. (2009) reported that the hydrate-bearing sediments above the bottom simulating reflector (BSR) are associated with low attenuation in the western margin of India. Sain and Singh (2011) observed the low attenuation of the hydrate-bearing sediments in the MakranAccretionary Prism, Arabian Sea. These conflicting observations and opposing views of attenuation of methane hydrate-bearing sediment are due to various factors. Several possible reasons has been pointed out, such as the frequency-dependent attenuation in methane hydrate-bearing sediments (Matsushima, 2007), the different source coupling efficiency (Lee and Waite, 2007), difference in geologic environments. Seismic measurements over a broad frequency range (between seismic and sonic logging frequencies) in various geologic environments will improve our understanding of seismic attenuation of methane hydrate-bearing sediment.Over the last three decades, seismic attenuation has been recognized as potentially very sensitive to hydrocarbon reservoir properties. While there are many possible mechanisms for intrinsic attenuation in composite materials, including the effects of wetting on grain boundaries, viscous shear relaxation, the relative motion of the solid frame with respect to fluid inclusions, and relative motion at solid boundaries, numerous researchers have focused on the physical interactions between fluids and solids. It is widely believed that fluid motion is a primary intrinsic attenuation mechanism. Wave induced fluid flow which is interactive motion between solids and fluids during seismic wave propagation causes frequency dependency of seismic attenuation. However, the application of seismic attenuation is limited because the attenuation mechanisms are often unclear and controversial. Moreover, the methods used to estimate the attenuation have not yet been fully developed. Broadband frequency response of seismic attenuation may lead us to new ways of thinking about MH bearing sediments.

In order to estimate attenuation over the wide frequency range from seismic to ultrasonic frequencies, we should develop advanced seismic attenuation estimation methods and apply them for various seismic methods including ultrasonic laboratory measurement, sonic logging, VSP, and surface seismic. Furthermore, separation of total attenuation into intrinsic and scattering attenuation is challenging research topic. More accurate and reliable attenuation estimation methods lead to elucidating more

definitively attenuation mechanisms and extending the use of seismic attenuation. The author and his group have developed new or modified seismic attenuation estimation methods for various seismic methods including ultrasonic laboratory measurement (Matsushima et al. 2008; 2011; 2014), sonic logging (Matsushima et al. 2005; Suzuki and Matsushima, 2013), VSP (Matsushima, 2006), and surface seismic data (Lee and Matsushima, 2011). Especially, application of seismic attenuation estimation using sonic waveform data is limited. Although the median frequency shift method is considered to be effective and robust compared to the conventional spectral ratio method, our recent study demonstrates that the median frequency shift methods strongly depend on reference data under lower signal-to-noise ratios (Suzuki and Matsushima, 2013). We modified an existing median frequency shift method not to depend on arbitrarily choosing a reference value and to quantify the uncertainties in attenuation estimation (Suzuki and Matsushima, 2013). We can apply this stable method to VSP data. Furthermore, to reduce the inaccuracy in attenuation estimation caused by the effect of windowing, we proposed a method that enables accurate measurement of ultrasonic attenuation using uncorrelated sweep signals (Matsushima et al., 2014). Uncorrelated sweep signal is one of the few situations in which we input a nearly pure frequency into the earth. To validate attenuation phenomena observed in various seismic methods at widely different frequencies and to elucidate the rock physics mechanism responsible for those phenomena, laboratory experiments should be conducted. Priest et al. [2006] developed a laboratory gas hydrate resonant column to simulate the pressure and temperature conditions suitable for methane gas hydrate formation in sand specimens and the subsequent measurement of both the P- and S-wave attenuations at frequencies and strains relevant to marine seismic surveys. They found that the attenuation of seismic waves within hydrate-bearing sands was shown to be sensitive to the volume of the gas hydrate within the pore space. We conducted ultrasonic wave transmission measurements with changing temperature from 0 to –15 °C to estimate the effect of partially frozen liquids grown in both unconsolidated and consolidated porous materials on the velocity and attenuation of P- and S-waves. Our ultrasonic laboratory experimental results in Figure 1 show that the existence of partially frozen liquid in a porous material increases both the velocity and attenuation for temperatures of 0 °C to around the freezing point (i.e., –3 °C). Historically, experimental studies were performed at ultrasonic frequencies so that elasticity and anelasticity at lower frequencies were poorly understood. We emphasize the needs of developing a broadband frequency laboratory measurement system. In this presentation, we describe the technical points of attenuation estimation methods and laboratory measurements we developed, and our attenuation results imply the importance of attenuation measurements in characterizing hydrate-bearing sediments. Acknowledgements: We would like to thank to JOGMEC (Japan Oil, Gas and Metals National Corporation) for permission to use their wireline logging data.


Figure 1 (a) conceptual model of partially frozen unconsolidated sediments consisting of a three-phase (ice - unfrozen brine – unconsolidated sand) to measure attenuation properties, (b) Calculated average P- and S-wave velocity values and Poisson's ratio calculated from the P- and S-wave average velocity values for the unconsolidated material, (c) P-wave attenuation estimates with a frequency range of 350–600 kHz, (d) S-wave attenuation estimates with a frequency range of 100–200 kHz.

Grain

Brine

Ice

(a) (b)

(c) (d)


14 Y. Sowjanya1

Methane storage in double hydrate (C4H8O + CH4) at higher temperature

Y. Sowjanya1 and P.S.R. Prasad1

1. Gas Hydrate Division, National Geophysical Research Institute (CSIR-NGRI), Council for Scientific and Industrial Research, Hyderabad 500007, INDIA

[email protected] Clathrate hydrates are recently paid attention as the novel storage and transportation materials of natural gases. Hydrates with two guest species fitting different-sized cages can form at warm temperatures and/or low pressures, and this extended range of thermodynamic stability is favourable to many hydrate based applications. We synthesised single (methane) hydrate and double hydrate (6mol% of tetra hydro furan + methane) samples with and without hollow silica at particular pressure ~ 9MPa by using a non stirred autoclave and stirred autoclave. Kinetics, stability conditions and yield of single and double hydrate with hollow silica compared with corresponding systems without hollow silica. Present study reveals the following results: i) Formation and dissociation temperatures of single and double hydrate with hollow silica shift higher side (14K) compare to single and double hydrate without hollow silica. ii) Higher yield was observed in single hydrate with hollow silica compared to the pure methane hydrate system. Amount of hydrate yield was same in double hydrate with hollow silica and without hollow silica (~60%). iii) Formation kinetics was slower in single hydrate system compared to the single hydrate with hollow silica. Double hydrate kinetics with hollow silica system is slow compared to the double hydrate without hollow silica Key words: Clathrate hydrates, single hydrate, double hydrate, formation kinetics, stability, hydrate yield, methane, tetrahydrofuran, hollow silica

Figure: Formation kinetics of methane hydrate a) single hydrate b) double hydrate




15 Takashi Kotera

CMR log analysis of the First Offshore Production TestatDaini-Atsumi

knoll in the eastern Nankai Trough

1 Takashi Kotera, Tetsuya Fujii, Kiyofumi Suzuki, TokujiroTakayama 1 Japan Oil, Gas and Metals National Corporation

Abstract: As preparatory drilling operations for the first offshore methane hydrate(MH)production test, monitoring wells (AT1 MC and AT1-MT1) and the upper part of production well (AT1-P) were drilled in FY2011. To confirm methane hydrate bearing circumstances, logging while drilling (LWD) and wireline logging (WL) were performed in AT1 MC.The production test was started on March 12, 2013. After a large amount of sand was produced on March 18, the production test was closed. During well-abandonment operations in August 2013, two LWD wells (AT1-LWD1 and AT1-LWD2) were drilled around theAT1-P, and open-hole WL were performed at the two wells. The objectives of this study are to understand the characteristicsof MHreservoirs and to confirm dissociation behavior of MH in the offshore production test field by analyzing logging data acquired in the wells that of AT1-MC, LWD1 and LWD2, especially CMR(Combinable Magnetic Resonance ; principle is same as NuclearMagnetic Resonance)logging data. In AT1-MC, we acquired CMR data before the Test. In AT1-LWD1 andLWD2, we acquired CMR dataafter the Test. CMR can measure T2 relaxation time, which indicates the amount of proton. But itcan’t measure rigid protonlike in the ice, also included inMHs. This feature is usable to estimate MH dissociation behavior. Because, if the MH dissociate, water volume increasein thesediment. It may causethe change of T2 distributionthatT2relaxation time shiftsto thelongertimeandthe peak of T2 distribution increases.In addition, T2 distribution includespore size information that short T2 relaxation time correspond tosmaller pore and longrelaxation time correspond tolarger pore.Therefore, we might be able to discuss dissociation behavior. In this study, we comparedlog plot of AT1-MC, LWD1andLWD2. We can confirm some T2 distribution shift to the longer relaxation time in MH-bearing sandy layer in the AT1-LWD1, LWD2. Then, to observe the details, we separate the relaxation time to 8bins. As a result of comparison of T2-mean(T2 logarithmic mean) in the each bin, T2 meanshiftparticularlyobserved inshort relaxation time interval. The T2-mean of shortrelaxationtime about AT1 LWD1andLWD2 is longer than AT1-MC. It probably indicatesdissociation of MH. This study is a part of the program of the Research Consortium for Methane Hydrate Resource in Japan (MH21 Research Consortium).


16 W. F. Kuhs

The German Gas Hydrate Initiative SUGAR From Exploration to Exploitation of marine gas hydrates

W. F. Kuhs1, M. Haeckel2, J. Bialas2, K. Wallmann2 and SUGAR partners

1 Georg-August-UniversitätGöttingen, GZG, Abt. Kristallographie, Goldschmidtstr. 1, D-37077 Göttingen, Germany

2 GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, D-24148 Kiel, Germany SUGAR (SUbmarine GAs hydrate Reservoirs) is a collaborative R&D project with 20 partners from SMEs, industry and research institutions. It was launched in 2008, has just successfully finished its second phase and is now starting its third phase running until end of 2017. The portfolio of technologies developed in SUGAR includes state-of-the-art hydro-acoustic, 3-D seismic and electromagnetic devices for the exploration of marine gas hydrate deposits as well as the monitoring of hydrate exploitation operations. The novel joint inversion technique combines the interpretation of seismic and electromagnetic data and was successfully applied to hydrate accumulations e.g. offshore New Zealand and in the Black Sea. New autoclave systems for mobile drilling rigs (MeBo 70 and 200) recovering marine hydrates under in situ pressure have been built that are suitable for deployments from both, drilling vessels and medium research vessels. A further outcome of the project is a unique module of the 3-D basin modeling software PertoMod for the prediction of the formation of gas hydrate deposits in marine and permafrost settings. Exploitation strategies for marine hydrate deposits are being developed in laboratory experiments as well as in numerical reservoir simulations. Their primary focus is on the production of methane by injection of CO2, combining natural gas recovery with the safe sequestration of carbon dioxide in CO2 hydrates below the seafloor. While the reservoir simulations test field-scale strategies and assess these in terms of gas production rates and economics, the laboratory experiments focus on the optimization of the hydrate conversion reaction by application of supercritical CO2, heat supply via in situ combustion and a fundamental understanding of the reaction process on a microstructural scale. In addition, in the second SUGAR phase, novel, low cost, drilling technologies specialized for marine hydrate deposits, which are significantly shallower below the seafloor than standard oil and gas reservoirs have been designed and developed. In the third phase of the project the primary focus is on the preparation of a future field test of the SUGAR technology, also addressing potential technological and environmental risks. The work programme is guided by the needs of the participating companies in developing their specific commercial products.



17 N. Satyavani

OBS studies in the Indian offshore for Gas Hydrate Investigations

N. Satyavani#, Mrinal Sen* and Kalachand Sain#. # Gas Hydrate Group, CSIR-National Geophysical Research Institute, Hyderabad, India.

*University of Texas, Austin, USA. Abstract: Multi-component ocean bottom seismic (OBS) data have a unique quality that they record the full wave field, by employing the 4 component (3 geophone and one hydrophone) receivers for seismic data recording. In addition to the traditional P-wave data the OBS recording also yields the very vital PS converted data that complement each other. Various aspects like seismic anisotropy, S-wave velocity and estimation of the reserves are crucial for the Gas Hydrate Investigations and the role of OBS data is of utmost significance. The present work highlights the results obtained in the above areas of research using the OBS data collected in the Eastern offshore of India, namely the Mahanadi (MN) and Krishna-Godavari (KG) offshore basins, for gas hydrate investigations. The OBS data from the MN basin shows very clear S-wave splitting patterns, indicating azimuthal anisotropy in the region. The subsequent amplitude analysis has revealed the existence of a near vertical dominant fracture system with a fracture angle of 85° and with a strike of 130°N. The P-wave velocity-depth model in the KG basin is delineated by travel time modeling of the reflected P-wave arrivals observed in the vertical component of the OBS data. Similarly the S-wave depth model was also derived using the mode converted arrivals observed in the radial component of the OBS data. Effective medium theory was employed to compute the seismic velocities (Vp and Vs) at a given gas hydrate saturation and these values are matched with observed velocities. The gas hydrate saturation was then varied until the computed velocities match the observed velocities. The modeling results indicate a lateral variation in hydrate saturation that varies between 17 to 20% of the pore space. In this work we also present the emerging techniques that can improve the signal to noise ratio (SNR) and give an increased resolution for the converted waves. Introduction: Multi-component data acquisition has become an important part of the gas hydrate exploration in the recent years due to the fact that such an experiment can effectively record the full wave field, and provide shear wave information in addition to the compressional wave information. The S-wave information is particularly useful in delineating the fracture zones, and in providing the constrained estimates of the gas hydrate reserves. They also give vital information about Vp/Vs (Poisson's) ratio that helps in characterization of the sediments. The OBS records often can be separated into the up and downgoing fields and a direct measurement of the downgoing field is available that can be used for improving the resolution of the seismic records. CSIR-NGRI has collected the OBS data in the Eastern offshore region of India, namely the MN and KG basin in the year 2010 (Sain et al, 2010)with a primary aim of identifying the gas hydrate pockets and estimating the reserves. As a part of this initiative, 25 OBS were deployed in each basin and the recording is done in a grid pattern along 12 profiles with 5 OBS on each profile with a shooting interval of 50m. The target zone was the top few hundred meters below the seafloor (mbsf) and the vertical and radial components recorded good quality data. Using this data sets we carried out anisotropy studies and wave field separation in the MN basin and gas hydrate saturation in the KG basin. Mahanadi basin: Anisotropy study: In presence of anisotropy, the S-waves split into fast (S1) and slow (S2) modes that travel parallel and perpendicular to the axis of symmetry respectively. This is called as S-wave splitting and is the primary indicator of the anisotropy in a region. Azimuthal receiver gathers were prepared for the radial and transverse component. The slow and fast axes (S1 & S2) are identified by locating zones of

amplitude minima and amplitude maxima respectively (Fig.1a). Similar analysis is carried out for all the OBS and a zone of anisotropy has been delineated (Fig.1b). 1D synthetic modeling of the amplitudes and waveforms was carried out using reflectivity code (Mallick and Frazer, 1987) to delineate the fractures and constrain the fracture parameters. The modeling results show that the fracture set has a dip of ~85° and associated with a density of 0.06. The strike of this fracture set was computed using the amplitude variation with azimuth (AVAz) of the vertical component for the real and synthetic data. The amplitudes attain a maximum at ~130° N and this is interpreted as the likely strike direction (Satyavani et al, 2013).

Fig. 1a: The slow and fast axes and corresponding amplitude low and amplitude high seen on the azimuthal radial and transverse gathers. Fig. 1b: Zone of anisotropy delineated from the splitting analysis of all the OBS data. Wave field separation: The hydrophone sensors of OBS are pressure dependent and direction independent while the geophones are particle motion and direction dependent. This discriminating aspect can be utilized to eliminate the free surface multiples by simple summation of the P and Z components, which is very effective in removing all the receiver side multiples (ghost) arrivals, but not the source side multiples. The source side multiples can be removed by separating the full wavefield into the constituent up and downgoing fields and then by deconvolving the upgoing field with the downgoing field. Similarly the PS reflectivity can also be extracted by deconvolution of the radial (X) component of the OBS data with the downgoingwavefield (Backus et al, 2006; Haines et al, 2011). This procedure increases the SNR to a significant level and the efficacy of this method is illustrated using the OBS data acquired in the Mahanadi basin. In addition to the noise free P wave field (PP reflectivity), we also obtain the converted (PS) wave field using the above approach. A remarked increase is noticed in the SNR for the PP reflectivity (Fig.2a) while there is an increased level of resolution in the PS reflectivity (Fig.2b) compared to the radial component.


Fig.2a: Comparison between the vertical component and the noise free P-reflectivity gathers. Fig.2b: Increased resolution noticed on the PS reflectivity gathers. Krishna Godavari basin: Gas Hydrate Saturation: The distribution and quantification of gas hydrates / free gas relies heavily on accurate estimation of seismic velocity. The availability of shear wave velocity better constrains the estimates of the gas hydrate saturation (Dash and Spence, 2011). The S-wave velocity model is delineated using the PS converted phases of the radial component and the P-wave model is delineated using the hydrophone component of the OBS data in the KG basin. Effective medium theory (EMT) is employed to compute the Vp and Vs at a given depth in this region and then the computed values are matched against the observed. The observed velocity is then compared with the computed velocity and the saturation value that best matches the observed value is considered as the gas hydrate saturation at that particular depth. These values are then interpolated to give a saturation estimate along the profile (Fig.3). These studies show that the gas hydrate saturation varies from 17 to 20% of the porespace in the hydrated sediments.

Fig 3: The estimated hydrate saturation from effective medium theory Vp and Vs, superimposed over the seismic depth stack.

References: Backus, M.M., Murray, P.E., Hardage, B.A., Graebner R.J., 2006. High resolution multi-component seismic imaging of deep water gas-hydrate systems, Leading Edge, 25,(5),578-596. Dash. R, and Spence, G.D., 2011. P-wave and S-wave velocity structure of northern Cascadia margin gas hydrates. Geophysical Journal International, 187(3), 1363-1377. Haines, S.S., Lee, M.W., Collett, T.S., Hardage, B.A., 2011. Multi-component seismic methods for characterizing gas hydrate occurrences and systems in deep water Gulf of Mexico. Proceedings of the 7th International conference on Gas Hydrates. Mallick, S., and L. N. Frazer, 1987, Practical aspects of reflectivity modeling: Geophysics, 52, 1355–1364. Sain, K., Ojha, M., Satyavani, N., Ramadoss, G.A., Ramprasad, T. Das, S.K., Gupta, H.K., 2012.Gas-hydrates in Krishna-Godavari and Mahanadi Basins: New Data. Journal of Geological Society of India, 79, 553-556. Satyavani, N, Sen, M.K., Ojha, M and Sain, K (2013).Azimuthal Anisotropy from OBS observations in Mahanadi Offshore, India, 2013.Interpretation, 1(2), p.T187-T198. Acknowledgements: The authors thank Director, NGRI for his consent to publish this work. Ministry of Earth Sciences (MoES) is thanked for funding the OBS experiment. Gas Hydrate Group and staff of M/V. AkademikFersmann are thanked for acquiring this data.



18 Kiyofumi Suzuki

The possibility of fluid-compartment system in methane-hydrate

reservoir in the Daini-Atsumi Knoll, off central Japan

Kiyofumi Suzuki1, Masashi Hoshino1, Tetsuya Fujii1 1 Methane Hydrate R&D Group, Technology Research Center(TRC), Japan Oil,

Gas and Metals National Corporation Abstract: Fluid connectivity in the methane hydrates (MHs) reservoir is quite important to develop MH bearing sediments, especially to apply the depressurizing method for gas production. In case of the Nankai Trough MH reservoir, sediments are consisted from turbidities; sand and mud alternation layer, which mud layers are expected to act as seal layer by their low permeability, thus, the pore fluid system in reservoir acts as isolated in each sand layer during the depressurizing period; hence, short-time scale phenomena. In this case, production fluid, which is mixture of MH-dissociation fluid and original pore water, comes from each isolated MH-bearing sand layers. Thus, production-water salinity was expected to dilution with the elapse time from depressurizing start, because MH-dissociation fluid is pure water from the crystals. However, the salinity change of production water during the gas-production period was slightly higher-salinity water than that of seawater had been produced. It implied that the salinity of original pore water was higher salinity than that of seawater. The volume of the production gas and water had been measured at the depressurizing period, simultaneously. Based on this data, the ratio of the MH-dissociation fluid and the original pore water were calculated. The results of calculation, the gas/water ratio is around 100, so the ratio of the MH-dissociation fluid and the original pore water is 1, approximately; it means pore water salinity was twice of salinity, at least. To estimate the pore fluid salinities, the values of the thermal-neutron-capture-cross section (Sigma) taken by reservoir saturation tools (RST) were analyzed. The other logging-while drilling (LWD) tools took porosity data, which was corrected by core data with high accuracy, so we could use the porosity data for calculating how pore-fluid value was needed to coincident to the measured RST-Sigma value in the MH-bearing intervals. The result of this estimation shows that the pore-fluid salinity was not equal in reservoir; hence, it means that fluid systems in the reservoir have been divided either several compartments or zones, and the pore water was not move actively. It is slight strange because the dense fluid would diffuse to homogenize, usually. However, 80% over MH-saturation was estimated in reservoir, higher salinity could be still possible even if the diffusion had occurred. These fluid-supply system and fluid-diffusion system of MH-crystallization period are fundamental geological issue to consider the MH-petroleum system in future. This study is a part of the program of the Research Consortium for Methane Hydrate Resource in Japan (MH21 Research Consortium). Key words: Gas hydrate, Production water, Salinity, Pore water, Logging-while-drilling, Thermal-neutron-capture-cross section (Sigma), Reservoir saturation tools (RST), MH-petroleum system


19 Jiro Nagao

Recent Progress of the Methane Hydrate Research and Development Program in Japan Jiro Nagao Methane Hydrate Research Center (MHRC), National Institute of Advanced Industrial Science and Technology (AIST), Sapporo, Japan Tel: +81-11-857-8948, e-mail: [email protected] Methane hydrate is a solid state compound where methane is captured in the cage structure of water molecules. Methane hydrate is stable under the low temperature and/or high pressure conditions. In nature, methane hydrate has been confirmed in permafrost layers and the deep ocean floor. The existence of methane hydrate has been confirmed in offshore areas of Japan, particularly in the Nankai Trough, from the observations of bottom simulating reflectors (BSR) [Sato 2002]. Thus, methane hydrate will become a valuable domestic energy resource of Japan once its production technique is established. The Ministry of Economy, Trade and Industry (METI) launched the Methane Hydrate Research and Development Program, and the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) was consisted with Japan Oil, Gas and Metals National Corporation (JOGMEC) and National Institute of Advance Industrial Science and Technology (AIST). Several methods, including depressurization, thermal stimulation and inhibitor injection, have been proposed to recover the natural gas from methane hydrate reservoirs [Sloan 1998]. The depressurization method decreases the reservoir pressure below the equilibrium pressure of methane hydrate formation at the reservoir temperature, which appears to be a cost-effective solution for producing natural gas from methane-hydrate-bearing layers [Kurihara et al. 2008]. In fact, JOGMEC as a part of MH21 Research Consortium and Natural Resources Canada, Aurora Institute (NWT) revealed that continuous and relatively strong gas flow was possible by the depressurization technique at the Mackenzie Delta site, Northwest Territories of Canada in 2008 [Dallimore et al. 2012]. As the result, continuous gas flow for six days with gas production rate of 2000-4000 Sm3/day was confirmed. The target of methane hydrate research and development program in Japan have moved to recover the offshore methane hydrate deposits as Japanese domestic resource. In March 2013, Japan attempted the world first extraction of methane gas from offshore natural gas hydrate deposits. [Yamamoto 2014(b)]. This filed test was performed at the north slope of a subsea knoll (the Daini-Atsumi Knoll) off the coasts of Atsumi and Shima peninsulas, in the eastern Nankai Trough. The location of this offshore field test is shown in Figure 1. Main objectives of the offshore test are 1) confirmation of gas productivity form the offshore methane hydrate reservoir, 2) evaluation of stability and integrity of wells for shallow and unconsolidated sediments, and 3) implementation of monitoring technologies for methane hydrate dissociation behaviors. As the result, gas flow confirmed for six days with gas and water production rates of approximately 20000 Sm3/day and 200 m3/day, respectively. The total production volume of methane gas achieved of 119,500 m3. The methane gas flaring at the stern of the D/V Chikyu during the offshore field test is shown in Figure 2. Stable depressurization and flow of gas and water clearly indicated that methane hydrate dissociation by depressurization is possible even in the marine sedimental methane hydrate reservoir. Before the offshore field test in 2013, the pressure coring using a hybrid pressure coring system (Hybrid PCS) has been performed in June and July 2012 [Yamamoto, 2014(a); Kubo et al., 2014]. Total 21 cores (3m core x 19 including 3 ESCS cores, and 1.5m core x 2) were recovered from the silt zone above the methane hydrate concentrated zone (MHCZ) to the channel sandy zone at the lower part of MHCZ. The core samples with three different forms (conventional core,pressure core, and LN2 core) based on type of sediments, pressure conservation, and request from the science party were prepared. The sedimental properties, permeability, mechanical properties have been investigated to understand the reservoir characteristic and establish the methane hydrate reservoir model in the eastern Nankai Trough.



In this presentation, the Japanese world first offshore production test of methane hydrates in the Eastern Nankai Trough and rerated progress of R&D in Japan are introduced.

Acknowledgements: The present work was conducted as the activity of the Research Consortium for Methane Hydrate Resources in Japan [MH21 Research Consortium] as planned by the Ministry of Economy, Trade and Industry (METI), Japan. References : Dallimore, S. R., Wright, J. F., Yamamoto, K., Bellefleur, G., 2012. Proof of concept for gas hydrate production using the depressurization technique, as established by the JOGMEC/NRCan/Aurora Mallik 2007-2008 Gas Hydrate Production Research Well Program; Scientific results from the JOGMEC/NRCan/Aurora Mallik 2007-2008 gas hydrate production research well program, Mackenzie Delta, Northwest Territories, Canada, Geological Survey of Canada, Bulletin 601, p.1. Kubo, Y., Mizuguchi, Y., Inagaki, F. and Yamamoto, K., 2014. A new hybrid pressure-coring system for the drilling vessel Chikyu: Scientific Drilling., 17, 37-43, doi:10.5194/sd-17-37-2014. Kurihara, M., Sato, A., Ouchi, H., Narita, H., Masuda, Y., Saeki, T., and Fujii, T., 2008. Prediction of gas productivity from Eastern Nankai Trough methane-hydrate reservoirs, Proc. Offshore Technology Conference 2008, OTC–19382. Sato, M., 2002. Distribution and resources of marine natural gas hydrates around Japan, Proc. 4th Int. Conf. Gas Hydrate, p.175. Sloan, E.D., 1998. Clathrate Hydrates of Natural Gases, 2nd edn. (Marcel Dekker). Yamamoto, K., Inada, N., Kubo, S., Fujii, T., Suzuki, K., Nakatsuka, Y., Ikawa, T., Seki, M., Konno, Y., Yoneda, J., and Nagao, J., 2014(a). Pressure coring operation and analyses on the obtained cores, Proc. Offshore Technology Conference 2014, OTC-25305. Yamamoto, K., Terao, Y., Fujii, T., Ikawa, T., Seki, M., Matsuzawa, M., and Kanno, T., 2014(b). Operational overview of the first offshore production test of methane hydrates in the Eastern Nankai Trough, Proc. Offshore Technology Conference 2014, OTC-25243

Figure 1 Location of the first offshore production test

from the eastern Nankai Trough. BSR distribution is

also depicted.

Figure 2. Photograph of the flared methane during the

offshore gas production test.


20 P. Dewangan

Seismic signatures of gas hydrate deposits in high resolution sparker data from Krishna-Godavari offshore basin

P. Dewangan*, S. Tulasi Ram, T. Ramprasad CSIR-National Institute of Oceanography, Goa – India 403004

*corresponding author: [email protected]

The drilling/coring experiments carried out along the Indian continental margins have confirmed the presence of gas hydrate in Krishna-Godavari (KG) offshore basin during NGHP Expedition-01. In KG basin, the bottom-simulating reflector (BSR) a commonly used proxy for gas hydrates deposits is widely observed in the conventional seismic data (Mandal et al., 2014). The BSR shows its characteristic features such as mimicking the seafloor, reverse polarity with respect to the seafloor and cross cutting the existing geological strata. The BSR appears to be patchy, but it can be followed continuously in low frequency (20-120 Hz) seismic data. In KG basin, high resolution seismic data (150-1000 Hz) are also acquired for gas hydrate exploration (Dewangan et al., 2010). In the present study, we compare the low frequency seismic (MCS) data with high resolution sparker (HRS) data to define the seismic signatures in high resolution seismic data as well as to understand the formation and distribution of gas hydrate deposits in KG basin.

The profiles in MCS data and HRS data are selected such that they share the same

geographic coordinates and are shown in Figure 1. The major structure appears to be similar between the MCS and HRS data. The seafloor, BSR and one key horizon are picked on the MCS data. The seafloor is picked on the HRS data and is compared with that from the MCS data to estimate the time shift. The difference in the seafloor traveltime may occur due to tides as these data are acquired at different times. The seafloor, BSR and the key horizon are mapped into the HRS data after applying the tidal correction. The time corresponding to the key horizon in the MCS data matches well with one the reflector in the HRS data suggesting good correlation between the data sets. The BSR appears to be continuous in the MCS data, however, it is not at all observed in the HRS data. The layers immediately below the BSR show high reflectivity and appear to be truncated at BSR level in HRS data. In fact, a sudden change in amplitude across the layer suggests the presence of BSR in HRS data. The instantaneous phase of the reflector is continuous across the BSR suggesting that the presence of hydrate significantly lower the amplitude of the reflection while preserving the continuity of the reflector. The enhanced amplitude below the BSR is related to the presence of free gas below the BSR. The amplitude below the gas layer is significantly attenuated and BSR acts as an acoustic basement in the high frequency data. The preliminary interpretation of the MCS and HRS data shows that gas is migrating along several permeable horizons which upon entering the hydrate stability zone forms hydrate within the layer. The formation of hydrate leads to amplitude blanking (Lee and Dillon, 2001) and the layers appear dim in the HRS data.

Our data shows that BSR appears differently on the high frequency data and have

distinct seismic signatures. Similar comparison between the MCS and HRS seismic data elsewhere also show that the BSR is either absent or have very low amplitude in high frequency seismic data as compared to low-frequency data and the presence of enhanced reflection below the BSR (Vanneste et al., 2001; Chapman et al., 2002). The low amplitude of BSR in high frequency data may be related to horizontal resolution of seismic data; low frequency data with larger Fresnel zone shows a continuous BSR whereas high frequency data with smaller Fresnel zone shows a discontinuous BSR (Spence et al., 1995; Dewangan et al., 2007). Amplitude



reduction of BSR at high frequencies may also be related to gradational velocity structure in the vicinity of the base of the hydrate stability zone (Chapman et al., 2002). The gradational change of velocity in high frequency data, results in smaller impedance contrast that weakens the amplitude of the BSR. We plan to carry out similar comparison along different profile in KG basin to study the seismic signature of gas hydrate in HRS data and to understand the formation and distribution of gas hydrate. References: Chapman, N.R., Gettrust, J.F., Walia, R., Hannay, D., Spence, G. D., Wood, W. T. & Hyndman, R. D. 2002. High Resolution deep-towed multichannel seismic survey of deep sea gas hydrates off western Canada, Geophysics, 67, 1038-1047. Dewangan, P., Ramprsad, T. & Ramana, M. V. 2007. Finite difference modelling of scattered hydrates and its implications in gas hydrate exploration, Current Science, 93, 1287-1290. Dewangan, P., Ramprasad, T., Ramana, M.V., Mazumdar, A., Desa, M. & Badesab, F., 2010. Seabed morphology and gas venting features in the continental slope region of Krishna-Godavari basin, Bay of Bengal: implication in gas-hydrate exploration. Marine and Petroleum Geology 27(7),1628-1641. Lee, M.W. & Dillon, W.P., 2001. Amplitude blanking related to pore-filling of gas hydrate in sediments. Marine Geophysical Researches 22, 101-109. Mandal, R., Dewangan, P., Ramprasad, T., Kumar, B. J. P. & Vishwanath, K., 2014. Effect of thermal non-equilibrium, seafloor topography and fluid advection on BSR-derived geothermal gradient, Marine and Petroleum Geology (In press). Spence, G. D., Minshull, T. A. & Fink, C. R. 1995. Seismic studies of methane hydrates offshore Vancouver Island. Proceeding of the Ocean Drilling Program, vol. 146, pp. 163-174. Vanneste, M., Batist, M. D., Golmshtok, A., Kremlev, A. & Versteeg, W. 2001. Multi-frequency seismic study of gas hydrate-bearing sediments in Lake Baikal, Siberia. Mar. Geol., 172, 1-21.

Fig. 1. (a) Conventional seismic section (20-120 Hz) in KG offshore basin showing continuous BSR; (b) high resolution sparker data (150 - 1000 Hz) along the same track. The seafloor (blue color), BSR (yellow color) and a key horizon (green color) are highlighted in both the MCS and HRS data.



21 R. Mandal

Tomographic velocity analysis to evaluate the gas hydrates resource potential of different geological environment in Krishna-Godavari

basin, India.

R. Mandal, P. Dewangan*, S.S. Panwar, S.K. Bhattacharya, T. Ramprasad CSIR-National Institute of Oceanography, Goa, India.

*Corresponding author: pdewangan@nio,org

The Indian National Gas Hydrate Program (NGHP) Expedition 01 confirmed the presence of gas hydrates in Krishna-Godavari (KG) basin. Detailed analysis of 3D seismic data shows distinct geological environment in KG basin such as sedimentary ridges, inner and outer toe-thrust zones, intra-slope basin, and prominent topographic mounds (Mandal et al., 2014). The mid-slope basin and mounds originated from the prevalent shale tectonism in KG basin. Several regional and linear local fault systems and mass transport deposits (MTDs) are also inferred from the analysis of seafloor time structures and seismic sections. The geothermal gradient (GTG) computed from the temperatures and depths of the seafloor and bottom simulating reflector (BSR) is largely influenced by these regional and local geological structures. The GTG decreases by ~13-20% over the mounds formed due to toe-thrust faults and recent MTD. In the vicinity of fault zones, the GTG increases by 10-15% probably due to the advection of warm fluids through the fault system. The resource potential of gas hydrates vis-à-vis the geological environment is not established in the KG offshore basin. In the present study, we attempt to establish the resource potential for different geological environment using tomographic velocity analysis. The occurrence of BSR in a seismic section reflects the presence of hydrate or free gas or both. In contrast, the increase in interval velocity reflects the presence of gas hydrate and decrease reflects free gas zone. Therefore, the subsurface velocity can be used to evaluate the resource potential of a particular depositional environment. Conventionally, the interval velocities are computed from the stacking velocities derived from the multi-channel seismic data using the semblance analysis (Dix, 1955). The approach is one-dimensional and limited to only near offset data. Hence, it is not capable of handling the lateral/vertical velocity variations as well as the geological structures in large offset seismic data. Therefore, we adopted reflection tomographic velocity analysis to handle lateral/vertical velocity variation and structures. The traveltimes for the key horizons (Layers 1- 4 in Figure 1) are picked in multi-channel seismic (MCS) data at a regular interval of 250 m for large offset/depth ratio (~5) in the common-mid point (CMP) domain. The initial estimate of model parameters (depth and velocity) is obtained assuming only vertical variations by minimizing the differences between the observed and calculated traveltimes. The RayInvr, freely available software, is used to perform the forward modeling (Zelt and Smith, 1992). The Genetic Algorithm (GA), a non-linear optimization algorithm, is used as an inversion tool to estimate the model parameters. The process is repeated for deeper layers using the estimates of shallower layers to generate the 1D velocity model. The same methodology is used to update the 1D velocity into 2D velocity model after accounting for lateral velocity variation and structures. The preliminary velocity model for the mid-slope basin suggests marginal presence of gas hydrate. We plan to obtain velocity models for different geological environments and evaluate its resource potential. References: Dix, C. H., 1955, Seismic velocities from surface measurements, Geophysics, 20, 68-86. Mandal, R., Dewangan, P., Ramprasad, T., Kumar, B.J.P., Vishwanath, K., 2014, Effect of thermal non-equilibrium, seafloor topography and fluid advection on BSR-derived geothermal gradient, Journal of Marine and Petroleum Geology, in press. Zelt, C. A., Smith, R. B., 1992, Seismic traveltime inversion for 2-D crustal velocity structure, geophysics Journal International, 108, 16-34.

Figure 1. Seismic section depicts four key horizons (green), BSR (blue) and Gas layer (yellow) for which the travel time is picked in the pre-stack MCS data for tomographic velocity analysis.



22 Pinnelli S.R. Prasad

Controlled Dissociation of Methane Hydrates: Use of Mixed Hydrates

with C4H8O

Pinnelli S.R. Prasad* and Vangala Dhanunjana Chari Gas Hydrate Division, CSIR-National Geophysical Research Institute (CSIR-NGRI), Council for

Scientific and Industrial Research, Hyderabad 500007, India (*Corresponding author e-mail: [email protected])

The hydrates hosting methane (dominant constituent in natural gas) can be preserved for a longer time in the temperature window 240 to 270 K at ambient pressure condition and this is most popularly known as “anomalous (or self-) preservation” effect. Though this metastable nature of methane hydrates (MH) is known for several years, detailed mechanism is quite indistinct. For example, is it an exclusive property for methane hydrates (sI) alone or is it true for all sI hydrates. Will the mixed hydrates (sII), with CH4 as dominant fraction, poses this exceptional property? How can one model the mechanism for this unique property without ambiguities?

In recent studies Kida et.al., (2011) proposed that the “direct measurements of the dissociation behaviors of pure methane and ethane hydrates trapped in sintered tetrahydrofuran (THF) hydrate through a temperature ramping method showed that the THF hydrate controls dissociation of the gas hydrates under thermodynamic instability at temperatures above the melting point of ice”. In order to gain further understanding we compared the dissociation behaviour of MH in its pure (sI) and mixed (with THF – 0.05 & 0.01 mol) form.

All the experiments were conducted by the procedure already described (Chari et.al., 2011, Sharma

et.al., 2014), using a stirred reactor of 400 mL volume. We allowed 70 % empty volume for CH4 gas and the rest was filled with water or THF aqueous solution. Upon attaining the saturation of hydrates, the reactor was quenched to 173 K by immersing it in liquid nitrogen. The reactor was then placed in a bath at 250 K for equilibration, and residual gas was completely removed. The bath temperature was slowly increased and p, T of the reactor was recorded with 60 s interval.

Figure 1 shows observed methane gas release at different temperature. It is clearly seen that the pure methane hydrates continues to exist in metastable, upon depressurization and rapid gas release occurred in the close vicinity of ice melting temperature (273 K). This observation is according to well known self-preservation effect and thereafter the dissociation is essentially driven by the stability conditions of MH. Observed pressure (2.5 MPa) matched well with earlier reports (Takeya and Ripmeester 2008). Well accepted reason for this metastable nature outside MH region is formation of the ice layer over MH grains. Further, the mixed MH formed with 0.056 mol fraction of THF (C4H8O) (Navy blue) has shown interesting dissociation behaviour. In this system there was no noticeable gas release until temperature reached to 282 K. However, at lower mole fractions of THF (0.01) (olive colour points) the gas release occurred around T ≥ 274 K. It is interesting to note that in both cases gas release pattern follows the stability boundary of respective composition. Open circles and red triangles in the figures indicate the phase boundary points measured in our laboratory and reference points from the literature. While the green line shows the computed phase boundary curve for mixed hydrates (XTHF = 0.056). At lower mole fractions the dissociation pattern is complex. It has not shown any signatures of self-preservation pattern unique for sI MH, indicating that the hydrates thus formed could be sII. It is also known that the phase boundary shifts to left for THF diluted systems. Overall the dissociation pattern of mixed hydrates is following respective phase stability curves.

Thus our study clearly demonstrates that the methane gas could be stored in mixed hydrates to a much higher temperature (282 K) at ambient pressure. References: Chari,V.D.; Sharma, D.V.S.G.K.; Prasad, P.S.R., Fluid Phase Equilib., 2011, 315, 126–130. Kida, M., Jin, Y., Narita, H., Jiro Nagao, J., Phys. Chem. Chem. Phys., 2011, 13, 18481–18484 Sharma, D.V.S.G.K., Sowjanya, Y, Chari, V.D., Prasad, P.S.R., Ind. J. Chem. Technol., 2014, 21, 114–119 Takeya, S., Ripmeester, J.A., Angew. Chem. Int. Ed., 2008, 47, 1276–1279



23 Warren T. Wood

Recent results on gas-hydrates research –Statistical prediction of gas hydrate occurrence

Warren T. Wood1, Joseph J. Becker2, and Kylara Martin2

1Naval Research Laboratory, Stennis Space Center, MS 2Post-Doc, Naval Research Laboratory, Stennis Space Center, MS

Harvestable methane hydrate accumulates only near the pressure-temperature stability boundary, and only in sediments with sufficient permeability, either inter-granular or crack permeability. Direct measurements of many of the parameters relevant to methane hydrates, like many marine geoscience observations, are expensive and sparsely acquired. However, globally extensive estimates of several attributes (e.g. water depth, seafloor temperature, sediment thickness, heat flow and crustal age) relevant to the formation of gas hydrates, as well as large data sets of individual points are readily available from on-line databases. Further, we can apply machine learning techniques, specifically the technique of random decision forests (RDF), to estimate or predict gas hydrate occurrences based on similarity of key environmental parameters to the same values in areas where methane hydrates are quantitatively observed. The RDF technique has been proven effective for agricultural purposes, and is quickly being adopted by other earth scientists to accurately predict not only quantities of interest where they have not been measured, but also providequantitative. Such techniques are ideal for leveraging the measurements made in Europe and the US to predict gas hydrates in regions such as India.

60 9th

International Methane Hydrate R & D Workshop, Hyderabad India


24 Machiko Tamaki

Integrated Reservoir Characterization and the 3D Geo-cellular Modeling for Methane Hydrate-bearing Sediments around the 1st

Offshore Production Test in the Eastern Nankai Trough

Machiko Tamaki1, Kiyofumi Suzuki2, Tetsuya Fujii2, Akihiko Sato1

1Japan Oil Engineering Co., Ltd.; 2Japan Oil, Gas and Metals National Corporation Abstract: Methane hydrates (MHs) constitute an unconventional energy resource that is expected to become an important alternative source of energy. Several potential MH deposits are believed to exist in offshore Japan. Among them, the eastern Nankai Trough which is located in offshore central Japan, is a well-investigated area as an attractive MH potential resource. The characteristics of MH bearing sediments have been evaluated by the integrating 2D/3D seismic, well log and core data, and it is founded that MHs in the eastern Nankai trough are well developed in pore spaces of the unconsolidated sandy sediments in the turbidite formations as are conventional hydrocarbon-bearing reservoirs. In 2013, the first offshore MH production test was conducted by the depressurization technique, and several observed data, such as gas/water production rate, pressure, and temperature were obtained. In order to accurately capture the behavior of the MH dissociation and gas production during the test, it is necessary to perform the detailed MH reservoir evaluation that characterizes the turbidite alternation of MH-bearing sandy sediments and non-bearing muddy sediments. Additionally, turbidite distributions in the test field show lateral heterogeneity, especially for the channel filled deposits. Then, fine-scale 3D geo-cellular models are needed to be used for the prediction performances in dynamic flow simulation. In this study, we introduce MHs reservoir characterization integrated from 3D seismic and well log and core data. And also, we present the 3D geo-cellular models constructed based on geostatistical approach. In accordance with the geological modeling workflow, (1) layering and gridding along the geological horizon and facies variations (framework modeling) and (2) defining internal properties (property modeling) were performed for the MH reservoir. Property modeling includes calculation of the distribution of facies and petrophysical properties such as hydrate saturation, porosity, and permeability, which are required as input to the reservoir flow simulation for predicting gas production performance. This study is a part of the program of the Research Consortium for Methane Hydrate Resource in Japan (MH21 Research Consortium).



25 Vangala Dhanunjana

Self Preservation of Methane Hydrates in the Host Sediments

Vangala Dhanunjana Chari and Pinnelli S.R. Prasad* Gas Hydrate Division, CSIR-National Geophysical Research Institute (CSIR-NGRI), Council for


Anomalous or self preservation is a well-established phenomenon, causing the ultra high stability for gas hydrates, normally outside of their thermodynamic phase stability (Stern et al, 2003). The plausible reason could be formation of a thin ice sheath on partially decomposed hydrates and normally such behavior is observed in the temperature range between 240 and 273 K. The effect of ice layer thickness was addressed by Andrzej and Kufs (2009). The literature shows the rate of dissociation is higher at 240 K and becomes slow as the temperature increased to 270 K. The use of self preservation phenomenon paves way to wide scale applications based on hydrate technologies, in particular, for gas storage and transport applications (Gudmundson et al, 2006) . The self preservation of hydrates depends on the particle size of the hydrates, elevated pressures and the state of the temperature where the hydrates are stored. In this study we examined the self preservation of methane hydrates (MH) in sediments (silica) with different grain sizes and compared with a pure MH system. The hydrates were synthesized under similar initial conditions and were depressurized & thermally stimulated to dissociate. The hydrates were formed water saturated silicas. Upon reaching the saturation in hydrate formation the reactor was quenched to 173 K in liquid nitrogen and residual gas is released at 240 K. During the temperature rage 173 K to 240 K the observed rise in the pressure levels is merely due to gas expansion but not due to hydrate dissociation.

Figure 1. Self preservation effect of methane hydrates in different particle sizes The results are encouraged to see that the self preservation of hydrates is dependent on the host sediment particle size corroborating with the literature (Hachikobo et al, 2011).

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Figure 2. The temperature window showing the maximum hydrate dissociation. The released gas pressure is normalized to see effect of the particle size on hydrate stability. The hydrate dissociation is started at lower temperatures for smaller grain size (10-20nm) and the significant gas release occurred at higher temperatures towards 273 K as the grain size increased to 30-50 µm and 50-100µm. And finally the dissociation is pure hydrates is observed at 273 K. The thermo dynamic stability of the hydrate and rate of release of gas from the hydrate are important aspects for considering the hydrate technology for storage and transport applications. The early dissociation of hydrates were observed in 10-20nm and 15-30 µm system and continued up to 270 K with a released gas rate of 0.00324 to 0.00634 MPa/min. However the released gas pressure of ~ 0.00848 to 0.01034 MPa/min was observed at higher temperatures in case of pure and hydrates in larger particle sizes. References: Stern L.A, Circone S, Kirby S. H, W. B. Durham. Can. J. Phys, 2003, 81, 271–283. A.Falenty and W. F. Kuhs. J. Phys. Chem. B 2009,113, 15975–15988. Gudmundsson J. S, Parlaktuna M, Levik O. I, Andersson. V. Annals New York Academy of Sciences, 2006, 912, 851−858. Hachikubo A, Takeya S, Chuvilin E, Istomin V. Phys. Chem. Chem. Phys., 2011,13, 17449–17452.



26 Ch. V.V. Eswari

Understanding the Formation Kinetics of Mixed Hydrate CH4-C3H8 and comparison with Pure CH4 Hydrates

Ch. V.V. Eswari, Vangala Dhanunjana Chari and Pinnelli S.R. Prasad* Gas Hydrate Division, CSIR-National Geophysical Research Institute (CSIR-NGRI), Council for


Dominant constituent in natural gas is methane (94-99 %) and some impurities like ethane (C2H6), propane (C3H8), carbon dioxide (CO2) etc., are also found. The phase boundary for natural gas hydrates critically depends on the gas composition. So, it is necessary to develop through understanding on phase boundary of methane hydrates with such impurities. It is well known that impurity, such as, propane promotes thermodynamically and the resultant structure is sII, whereas it is sI for methane hydrates. We carried out set of experiments to understand the drift in phase boundary curves for the two systems. Detailed experimental procedure has already described by Eswari et.al. (2014). We conducted experiments in a 100 mL stirred reactor and the composition of gas mixture is 87.13 volume% of methane and 12.87 volume% of propane. The reactor vessel is filled with 30 mL of water and pressurized with gas by using Teledyne ISCO Syringe Pump. The constant stirring (500 rpm) was applied throughout the experimental duration of ~20hr. All the experiments were conducted at different pressures with fixed speed of stirring. All the experiments were repeated at least three times in order to find phase boundary point. The dissociation point was determined from the p–T trajectories recorded during cooling and warming cycles in isochoric method. It is clear from Figure 1 that the temperature stability of mixed hydrates varies in the range 280 to 295 K in the pressure range 0.61 to 6.57 MPa. Interestingly the difference in the dissociation temperature between the mixed and the pure MH is ~ 11K (@ 6.4 MPa) and this is around 15 K (@ 2.8 MPa). The stability of mixed hydrates is above the ice melting temperature at pressures higher than 0.6 MPa. Our results are comparable with the Deaton and Frost et.al. (1946) and also the phase boundary curve computed from CSMGem is in agreement with our results.


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Figure 1. Phase boundary curves computed for pure Methane hydrates and C3H8+CH4 mixed hydrates from CSMGem.

Figure 2 shows the gas consumption due to hydrate formation in pure (black) and mixed (red) hydrates systems. Time zero corresponds to the time at which the system intersects with phase boundary curve. The kinetics is almost same during initial 60 minutes in both the cases indicating that the nucleation and growth of hydrate to critical size occur in comparable time scales. However subsequent consumption is slower in mixed gas system, e.g., the time taken for 80 % of maximum gas intake is ~ 220 and ~100 minutes for pure MH and mixed gas hydrates respectively. This possibly could be due to the fact that methane molecules have to diffuse into already formed cages with propane, whereas continuous growth is feasible in MH hydrates.

Figure 2: Consumption of gas as a function of time in CH4+H2O and CH4+C3H8+H2O systems @ 5.0 MPa. In summary, a shifted towards higher temperatures in mixed gas hydrate is clearly established. Time

required to attain similar gas consumption (@ 5.0 MPa) is almost double in mixed hydrates. References: Eswari, Ch. V.V.; Raju, B.; Chari, V.D.; Prasad, P.S.R.; Sain. K., Marine and Petroleum Geology, 2014,17. Deaton, W.M.; Frost, E.M.; Jr. Gas hydrates and their relation to the operation of natural-gas pipe lines, U.S. Bureau of mines monograph 8, 1946, 101. Dickens, Gerald, R.; Quinby-Hun, Mary S.; Geophysical Research Letters, 1994, 21, 2115-2118.



27 Uma Shankar

Gas hydrate characterization and saturation from logs and seismic data in the Mahanadi Basin

Uma Shankar*1, Michael Riedel2, Anne Trehu3 1CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad, India

*Email:[email protected] (Corresponding and presenting author) 2Pacific Geoscience Center, Geological Survey of Canada, 9860 W. Saanich Rd. Sidney, B.C., Canada

3College of Oceanic and Atmospheric Science, Oregon State University, Corvallis, OR 97331, USA Seismic reflection data were analyzed for the evidence of gas hydrate occurrences and a bottom-simulating reflector (BSR) was imaged along the seismic profiles in the Mahanadi Basin (Fig. 1a). The gas hydrate stability zone (GHSZ) thickness in the study area varying from ~200 m to ~241 m below seafloor was observed depending on water depth based on the geothermal modeling of the base of gas hydrate stability zone (BGHSZ) from in situ temperature measurements. The occurrence of gas hydrate was observed to be associated with channel and levee complexes (especially at Site NGHP-01-19) based on the regional seismic data, but the cored/logged section lack a significant sand fraction, which does not allow higher accumulations of gas hydrate. As identified from 3-D seismic time-slice data, all sites visited in the Mahanadi Basin are within the steeper slope region of the channel system that is bypassed by sand. Significant sand deposition would occurs further down-slope where typical fan-type deposits was inferred from the 3-D seismic data (Fig. 1b) and thus higher accumulations of gas hydrate would be expected. Down hole log data was acquired from Mahanadi Basin, off the East Coast of India during Indian National Gas Hydrate Program (NGHP) Expedition-01 for gas hydrate exploration and assessment in 2006. Gas hydrate was recovered in the Mahanadi Basin from pressure cores. Coring and infrared imaging confirmed gas hydrate occurs predominantly in discrete layers. Pore water chemistry, electrical resistivity and sonic velocity logs along with seismic data are used to estimate gas hydrate saturations at three available Sites in the Mahanadi Basin: Site NGHP-01-08, -09, and -19. Gas hydrate saturation estimated from chloride concentrations shows values up to ~10% of the pore space at ~200 meter below seafloor just above the base of the gas hydrate stability zone (BGHSZ). Gas hydrate saturations estimated from electrical resistivity using standard Archie’s empirical relations shows the gas hydrate saturations are ~10-15% of the pore space at Site NGHP-01-19 (Fig. 2). Gas hydrate saturations were calculated based on rock-physics modeling utilizing P-wave velocity log measurements through the gas hydrate stability zone shows good correspondence with the gas hydrate saturation directly measured from the pressure core, which is 2.4% of the pore space at site NGHP-01-19. We introduce high frequency data filtering (dotted green line in figure 2) to the resistivity log and find the resistivity log saturation comparable to the gas hydrate saturation obtained from pressure core and sonic log (Fig. 2). Instead of a single log position, we can estimate gas hydrate saturation from the acoustic impedance data along seismic line constrained by log data in a cost effective manner. Acoustic impedance can be obtained from the product of acoustic velocity and density log. The presence of gas hydrate in-pore space of marine sediments increases the acoustic velocity and hence acoustic impedance. Conversely, free gas or water presence below the BSR reduces P-wave velocity in turn provides low acoustic impedance. Post stack model based acoustic impedance inversion was performed at log position and extrapolated along seismic transect crossing drill Site NGHP-01-19 with certain assumptions. These assumptions are: the seismic data are already stacked, migrated and no multiples. Each trace depends only on the impedance directly below the trace location, the wavelet is constant and not varying with time and the noise is random and there is no coherent noise present in the data.

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Gas hydrate saturation obtained from inverted velocity during inversion process invoked rock physics model. Estimated gas hydrate saturation varies maximum up to 3% of pore space along seismic profile and shows good agreement with the well log and pressure core gas hydrate concentration estimates (Fig. 3). This work documents the first gas hydrate saturation along a seismic line rather than a single log position which can give confidence on areal extent of gas hydrate in Mahanadi Basin. Keywords: Gas hydrate, BSR, geothermal modeling of BGHSZ, saturation, acoustic impedance inversion.

Figure 1. (a) Study area map of Mahanadi Basin shown in inset. Detail regional bathymetry contour with NGHP Expedition-01 drill sites location and seismic lines (solid black lines) and observed BSR depth below seafloor superimposed on the seismic lines with color code. Dotted box shows the 3D seismic data location. (b) Time slice of seismic amplitude were taken from a 20 ms thick window just beneath base of gas hydrate stability from the 3D seismic data showing sediment fairway system of meandering channel and early development of fan deposits.


Figure 2 Gas hydrate saturations from resistivity log, sonic log and chlorinity data compared with the measured pressure core value.

Figure 3 (a) Initial model for model based acoustic impedance inversion of 2D multi-channel seismic data, (b) Result from model based P-impedance inversion of the stacked volume along 2D seismic profile crossing well NGHP-01-19. Color-code shows inverted P- impedance in ((m/s) × (g/cc)), (c) Estimated gas hydrate saturation along 2D seismic profile using effective medium rock physics model on inverted velocity. Gas hydrate zone (GHZ) marked with arrow. Black dotted curve shows the BGHSZ.

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28 Veligeti Jyothi

Seismic attenuation for the delineation of gas hydrates: Application to

seismic data in Krishna-Godavari basin, eastern Indian margin

Veligeti Jyothi, Kalachand Sain* CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500007, India

*corresponding author: [email protected] Abstract: Gas hydrates have received global attention as a possible alternative non-conventional energy resource. Hence, the identification and quantification of gas hydrates are very important for evaluating the resource potential. Presence of gas hydrates in sediments above the bottom simulating reflector or BSR is associated with low attenuation or high quality factor (Q), whereas free gas bearing sediments below the BSR exhibit high attenuation or low seismic Q. Here we apply the logarithm spectral ratio (LSR) method to marine seismic reflection data along two cross line (18 and 46) in the Krishna-Godavari (KG) basin in eastern Indian margin, where gas hydrates have already been established by drilling/coring. We calculate the interval Qs for three sedimentary layers (A,B, and C) bounded by the seafloor, BSR, one reflector above and another reflector below the BSR at some common depth points (CDPs) to study the attenuation characteristics of sediments across the BSR. The estimated average interval Q (160) for the hydrate bearing sediments (layer B) is much higher than the average interval Q (80) for both the loose clayey sediments (Layer A) and underlying free gas saturated sediments (layer C). This demonstrates that the gas hydrates bearing sediments exhibit low attenuation or high seismic Q, which can be used as a proxy for gas hydrates. Keywords: Gas hydrates; Attenuation (Q-1); Logarithmic spectral ratio (LSR) method; Krishna-Godavari basin. Introduction: Gas hydrates are ice-like crystalline substance containing low molecular weight gases (mainly methane) in a lattice of water molecules. Globally, they are found in shallow sediments of outer continental margins and permafrost regions. They are formed at high pressure and moderately low temperature when methane concentration exceeds the solubility limit. Globally, gas hydrates have been recognized mainly by identifying an anomalous seismic reflector, known as the bottom simulating reflector (BSR), which is the physical boundary between gas hydrates bearing sediments above and free gas saturated sediments below, and is often associated with the base of gas hydrates stability zone (GHSZ). Sediments above the BSR is also characterized by high velocity and amplitude blanking, and the sediments below the BSR shows high reflection strength and frequency shadow (Sain et al., 2000; Satyavani et al., 2008; Ojha and Sain, 2009; Satyavani and Sain, 2014). Another important characteristic property for identifying gas hydrates bearing zone is high seismic quality factor (Q) or low attenuation, which is the frictional energy loss per cycle (Aki and Richards, 1980) and it is considered as a diagnostic tool for reservoir characterization, and identification of gas hydrates and underlying free gas (Toksöz et al., 1979; Petersen et al., 2007; Sain et al.,2009; Sain and Singh, 2011). The offshore extension of the Krishna Godavari (KG) basin along the eastern coastline of India has gained significant attention after the discovery of large quantities of gas hydrates by the drilling/coring of Indian National Gas Hydrates Program (NGHP) (Collett et al., 2008). The thickness of GHSZ in deep water region of the KG basin under study is calculated as < 300 m (Sain et al., 2011), and most of the inferred BSRs occur between 200 to 300 m below the sea floor in the KG offshore (Ramana and Ramprasad, 2010). Widespread


occurrences of gas-hydrates have been reported from the analysis of newly acquired seismic data in the KG basin (Sain et al., 2012, Sain and Gupta, 2012).

Fig.1 study area in KG basin showing KG-18 & KG-46. Here we calculate the seismic Q at some common depth point (CDP) locations along two cross lines 18 and 46 in KG basin (Fig.1), from where massive gashydrates were recovered by NGHP drilling and coring, with a view to understand the attenuation characteristics of gas hydrate- and free gas-bearing sediments. This type of study is very useful inidentifying gas hydrates without any well-identified BSR on seismic section, and to ascertain hether an identified BSR is related to gas hydrates and underlying free-gas or something else. Methodology: The multi-channel seismic (MCS) data were acquired in KG basin with a nominal fold of 60. The data were recorded with a sampling interval of 1 ms. The processing of seismic data has been carried out using commercial software (ProMAX) to enhance the S/N ratio and to image the broad geological features. The first step is trace editing for removal of noisy traces. Following this, a 5-10-100-120 Hz minimum phase Ormsby bandpass filter is applied. The next step includes the procedure that is generally adopted for seismic data processing such as the spherical divergence correction, predictive deconvolution, velocity analysis (at 20th CDP intervals), normal moveout (NMO) correction, trace equalization and stacking. The seismic Q has been computed from marine seismic reflection data based on Logarithmic Spectral Ratio (LSR) method. We applied this method to NMO corrected raw seismic gather at 40 CDP intervals. We computed the amplitude spectr by standard FFT at seafloor, reflector-1, BSR, reflector-2 for all offsets separately by fixing a time window containing the reflector. Then we take the ratio of spectra for reflector-1, BSR and reflector-2 with respect to the seafloor reflections separately. The LSR approach is valid for zero offset only, the estimated from the nearest trace of the MCS data may not be reliable due to its association with short generated noise. Thus we apply the LSR method to all offsets of the NMO corrected raw CDP gathers and extrapolated back to zero-offset. This produces the desired average Qs of

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sediments upto different subsurface reflectors. Once the average Qs at various subsurface depths are estimated, the interval Qs can be calculated. Results & Conclusions:

Fig.2 2D interval Q for three layers along lines 18 and 46 respectively From Fig.2, we notice higher Qs (red line) or low attenuation for in the second layer (B), which is interpreted as due to presence of gas-hydrates. Since gas-hydrates in KG basin have been observed in both fracture filling and pore spaces of clays, we observe a large variation in Q along both the lines. Because of this the AVO pattern of BSR in the study region has also been observed different (Sriram et al., 2013), indicating different distribution pattern of gashydrates. Both the first layer (A) and the third layer (C) show comparable results, but much lower Q or higher attenuation compared to the values in layer B containing gas-hydrates. It is to be noted that the sediments in the first layer (A) are loose clay and hence exhibit lower Qs (blue line) or higher attenuation, similar to the Q values (green) in layer C. The results show a large increase in seismic Q or low attenuation for the gas-hydrates bearing sediments (layer B) compared to those for the shallow loose clayey sediments (layer A) and underlying clay sediments with small amount of free gas along both the seismic lines. Hence, the study is useful for the identification of gas-hydrates or characterizing a gashydrate reservoir using seismic data.



29 Umberta Tinivella

Gas hydrate researches in Italy: from Antarctica to Arctic

Umberta Tinivella and Michela Giustiniani Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS,

borgo Grotta Gigante 42C, 34010 Sgonico (TS), Italy. Email: [email protected]

Since 1990, the researchers of OGS have developed geophysical methods to detect and quantify natural hydrate in marine sediments. The study areas are localized in several oceans, including Antarctic and Arctic Oceans. It is worth to mention that in Antarctica the OGS researchers on board of OGS-Explora studied an important gas hydrate reservoirs in collaboration with Korean Polar Research Institute (KOPRI). Moreover, the OGS researchers have been involved in several national and international projects to study gas hydrate reservoirs in several areas (Arctic, Chile, China, Nord Sea, Mediterranean Sea, Antarctica, and USA) applying their methodologies. Indirect methods have been applied to study gas hydrates, such as seismic method. OGS has developed acquisition techniques, and procedures to invert, analyze and interpret seismic data, in order to extract elastic parameters of hydrate bearing sediments, which are indispensable to estimate hydrate concentration and distribution (i.e., Tinivella and Carcione, TLE 2001; Tinivella et al., GSSP 2009). Compressional and shear wave velocities are used to estimate gas hydrate and free gas concentrations in pore space. In fact, knowing the theoretical behaviour of velocities versus hydrate/free gas amounts, it is possible to convert velocity anomalies in terms of gas phase presence and, eventually, detect overpressure condition (i.e., Tinivella, JSE 2002). To reach this goal, we have created two codes: ISTRICI and DRAGO. Our codes allowed promoting the collaboration with India (prof. K. Sain, NGRI of Hyderabad) and China (prof. X, Liu, Geoscience University of Bejijng).


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Figure 1: (A) Map of velocity anomalies extracted just above the BSR. White arrows indicate low velocity

anomalies; black arrow indicate the high velocity anomalies; and yellow arrow indicate the Mud

Volcano Vualt; (B) Map of the gas hydrate amount extracted just above the BSR. A mask is over-imposed

on the images to visualize the reliable area. The structural interpretation was over-imposed as red solid

and dashed lines. Modified after Loreto et al. (Energies, 2011).

In Antarctica, we characterized the hydrate reservoir present offshore Antarctic Peninsula, estimating the potentiality of the gas trapped in marine sediments (Fig. 1). The total volume of gas hydrate estimated, in an area of about 600 km2, is in a range of 16 × 109–20 × 109 m3. Assuming that 1 m3 of gas hydrate corresponds to 140 m3 of free gas in standard conditions, the reservoir could contain a total volume that ranges from 1.68 to 2.8 × 1012 m3 of free gas (i.e., Tinivella et al., GSSP 2009; Loreto and Tinivella, MPG 2012). In Arctic, we adressed our researches to improve the knoweledge about the relationship between a warming of the Arctic ocean and gas hydrate stability. We applied a theoretical model estimating the base of the gas hydrate stability zone in the Arctic Ocean considering different bottom water warming and sea level scenarios. We modelled the present day conditions adopting two different geothermal gradient values: 30 and 40°C/km. For each geothermal gradient value, we simulated a rise and a decrease in seafloor temperature equal to 2°C and in sea level equal to 10 m. The results showed that shallow gas hydrates present in water depths less than 500 m would be strongly affected by a future rise in seafloor temperature potentially resulting in large amounts of gas released to the water column due to their dissociation. We estimated that the area, where there could be complete gas hydrate dissociation, is about 4% of the area where there are the conditions for gas hydrates stability (Fig. 2; Giustiniani et al., JGR 2013).

Figure 2: In the red areas, complete dissociation of gas hydrate could talk place with a rise in the

seafloor temperature of 2°C. This simulation is performed using a geothermal gradient of 30°C/km.

Modified after Giustiniani et al. (JGR, 2013).

We have examined the excess pore pressures related to gas hydrate dissociation in marine sediments below the BSR using several approaches. In fact, dissociation of gas hydrates in proximity of the BSR, in


response to a change in the physical environment (i.e. temperature and/or pressure regime), can liberate excess gas incrising the local pore fluid pressure in the sediment, so decreasing the effective normal stress. In order to detect the presence of the overpressure below the BSR, we studied two approachs. The fist approach models the BSR depth versus pore pressure; in fact, if the free gas below the BSR is in overpressure condition, the base of the gas hydrate stability is deeper with respect to the hydrostatic case (Tinivella and Giustiniani, GPC 2013). This effect causes a discrepancy between seismic and theoretical BSR depths. The second approach models the velocities versus gas hydrate and free gas concentrations and pore pressure, considering theoretical theories. Knowing the P and S seismic velocities from seismic data analysis, it is possibile to jointly estimate the gas hydrate and free gas concentrations and the pore pressure regime. Alternatively, if the S-wave velocity is not availbale (due to lack of OBS/OBC data), an AVO analysis can be performed in order to extract information about Poisson’s ratio (Tinivella, JSE, 2002). Our modeling suggested that the areas characterized by shallow waters (i.e. areas in which human infrastructures, such as pipelines, are present) are significantly affected by the presence of overpressure condition. Moreover, the knoweledge of seismic velocities can be considered an powerful tool to detect the overpressure in case that the pore pressure is equal to the hydrostatic pressure plus the 50% of the difference between the lithostatic and the hydrostatic pressure. At the moment, we are studing the sub-sea permafrost, hydrate presence and their distribution in order to predict the effect of climate change, in particular in the Arctic shelf where the climate change could have strong effect because of shallow water. In conclusions, an accurate analysis of the BSR nature and the pore pressure are required to improve the reliability of the gas-phase estimation for different target, such as gas hydrate and free gas exploitations and environmental studies.

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30 Werner F

Kuhs

In-Situ Micro-structural studies of gas hydrate formation in sedimentary matrices

Marwen Chaouachi, Andrzej Falenty, Kathleen Sell, Jens-Oliver Schwarz, Martin Wolf,

FriederEnzmann, Michael Kersten, David Haberthuer and Werner F. Kuhs The formation process of gas hydrates in sedimentary matrices is of crucial importance for the physical and transport properties of the resulting aggregates. This process has never been observed in-situ with sub-micron resolution. Here, we report on synchrotron-based micro-tomographic studies by which the nucleation and growth processes of gas hydrate were observed in different sedimentary matrices (natural quartz, glass beds with different surface properties, with and without admixtures of kaolinite and montmorillonite) at varying water saturation. The nucleation sites can be easily identified and the growth pattern is clearly established. In under-saturated sediments the nucleation starts at the watergas interface and proceeds from there to form predominantly isometric single crystals of 10-20μm size. Using a newly developed synchrotron-based method we have determined the crystallite size distributions (CSD) of the gas hydrate in the sedimentary matrix confirming in a quantitative and statistically relevant manner the impressions from the tomographic reconstructions. It is noteworthy that the CSDs from synthetic hydrates are distinctly smaller than those of natural gas hydrates [1], which suggest that coarsening processes take place in the sedimentary matrix after the initial hydrate formation. Understanding the processes of formation and coarsening may eventually permit the determination of the age of gas hydrates in sedimentary matrices [2], which are largely unknown at present. Furthermore, the full micro structural picture and its evolution will enable quantitative digital rock physics modeling to reveal poroelastic properties and in this way to support the exploration and exploitation of gas hydrate resources in the future. [1] Klapp S.A., Hemes S., Klein H., Bohrmann G., McDonald I., Kuhs W.F. Grain size measurements of natural gas hydrates. Marine Geology 2010;274(1-4):85-94. [2] Klapp S.A., Klein H, Kuhs W.F. First determination of gas hydrate crystallite size distribution using high-energysynchrotron radiation. Geophys.Res.Letters, 2007 ; 34 :L13608, DOI:10.1029/2006GL029134



31 Soumya Jana

Estimation of Gas hydrates for heterogeneous model constructed from

well log in Krishna-Godavari basin, Eastern Indian Offshore

Soumya Jana, Maheswar Ojha* and Kalachand Sain CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad-500007

*Corresponding email: [email protected] Summary: The occurrence of gas hydrates in pore spaces of sediments change geophysical properties like velocities, resistivity, density, which are reflected on both seismic and down-hole logging data. The homogeneous assumption by neglecting the small scale heterogeneities overestimates the saturation of gas-hydrates from seismic data. Since the well-log data have high frequency, it contains small scale heterogeneities of hydrate bearing sediments. Here, we have incorporated these small scale heterogeneities by generating a two dimensional velocity and density model from well log data. These simulated 2-D velocity and density field do not contain any information about phase distribution but includes all heterogeneities of gas hydrate reservoir in the same scale of well log data. Gas hydrate concentration has been estimated over this synthetic 2-D heterogeneous velocity model using three phase biot-type equation. Because of homogeneous distribution assumption, saturation from seismic gives overestimation of hydrate volume as compared to the saturation derived from simulated 2-D heterogeneous model. Keywords: Gas hydrate, Krishna-Godavari basin, heterogeneity, stochastic Study Area and Data: Stochastic model is derived to study the heterogeneity in Krishna-Godavari (KG) basin. To generate 2-D heterogeneous stochastic model we have used P-wave velocity and density log data which are collected during Expedition-01 of Indian National Gas Hydrate Program (NGHP Exp-01) in 2006 (Collett et al. 2008) from site NGHP-01-04 located at 15o57.3794’ N, 81o59.4650’ E in central part of KG basin (Fig. 1a). In P-wave log (Fig. 2a & 2b) the base of gas hydrate stability zone is clear at a depth ~182 meter below seafloor (mbsf) coinciding bottom simulating reflector (BSR) at about 2.30 sec two way time (twt) on seismic section (Fig. 1b & 1c).

Figure 1. (a) Location of the study area in KG basin. Red line indicates the seismic profile. (b) 2-D seismic

section intersecting the well site NGHP-01-04 (red line) showing clear BSR. (c) Part of seismic section

used for the present study.


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Methodology: We have used spectral based approach to derive simulated field. There are six steps for generating synthetic heterogeneous stochastic field:- 1. Select appropriate Autocorrelation function by fitting it to autocorrelation of observed logs. 2. Take FFT or DFT of Autocorrelation Function to generate desired Power spectrum. 3. Take square root of power spectrum to generate Amplitude spectrum. 4. Compute a Phase spectrum, 𝒆xp(𝒊∅), ∅ is a random number uniformly distributed on the interval [0,2ᴨ]. 5. Multiply Amplitude and Phase spectrum to get Fourier spectrum. 6. Take inverse FFT or DFT of Fourier spectrum to generate a field.

Figure 2. (a) P-wave velocity log with a linear background trend (red line) showing BSR at depth of 182

mbsf. (b) P-wave velocity over gas hydrate bearing zone between 75 mbsf to 182 mbsf. (c) Observed

density log with a linear background trend (red line). (d) Density over gas hydrate bearing zone.



32 A. Mazumdar

Sediment pore fluid chemistry in the oxygen minimum zone of the Arabian sea: Organoclastic degradation and the anaerobic oxidation of

methane

S. Fernandes1, A. Mazumdar1*, A. Peketi1, M. Carvalho1, R. Da Silva1, P. Mahalakshmi1, P. L. Srinivas2

1 CSIR-National Institute of Oceanography, Goa - India 403004 2 Gujarat Energy Research & Management Institute, Gujarat - India

* Corresponding author: [email protected] Organoclastic degradation and anaerobic oxidation of methane (AOM) are known to influence the chemistry of sedimentary pore fluids, particularly the concentrations and stable isotope ratios of sulfate, sulfide, ammonia and dissolved carbonates. Ten sediment cores ranging in length from 1.29 – 3m were collected onboard CRV SindhuSankalp at the water depths ranging from 13 to 1200m in the oxygen minimum zones (OMZ) of the Eastern Arabian Sea. The core collection was carried out in December 2012. The sediment pore fluid chemistry was analyzed to delineate the sulfate-methane transition zone and to understand the biogeochemical processes prevailing in the pore fluid of the sediment column. Gravity cores were sub-sampled at a 15 cm resolution using a cut syringe under nitrogen stream immediately after opening the core. Pore fluid was extracted under cryocentrifugation (8000 rpm). The supernatant pore water was extracted with a syringe, filtered through 0.22μm syringe filters and 4 aliquots stored in air tight glass vials with nitrogen head. The aliquot for sulfide was fixed with 1M cadmium nitrate (CdNO3) to precipitate the sulfide as cadmium sulfide (CdS). Hydrogen sulfide and alkalinity concentrations were measured spectrophotometrically using a modified protocol of the method developed by Cline (1968) and Sarazinet. al (1999) respectively. Sulfate concentrations were measured using a Metrohm ion chromatograph. Ammonia was determined using the indophenol blue method. (Koroleff, 1976). The cores from the seasonal and perennial oxygen minimum zones of the Arabian Sea show marked differences in their pore water concentrations of sulfate, sulfide, ammonia and alkalinity. As expected, linear decrease in sulfate and increase in alkalinity with depth were observed in all the cores due to the anaerobic oxidation of methane coupled with dissimilatory bacterial sulfate reduction. The decrease in sulfate is accompanied by a progressive enrichment in the 34S isotope of residual pore water sulfate, due to the preferential partitioning of lighter lighter S isotope (32S) into H2S phase via microbially driven pathway. Sulfate reduction near the sediment water interface is influenced by labile organic matter availability, whereas, focused sulfate consumption at the sulfate methane transition zone (SMTZ) is primarily controlled by AOM (Mazumdar et. al., 2012). The SMTZ, or the zone in the sediment column at which sulfate and methane concentrations are depleted to non-detectable values, is identified at a depth of ~1.5 mbsf in the seasonal OMZ (Fig. 2) and ~ 3 mbsf in the perennial OMZ (Fig 1). Methane was also measured in cores where the SMTZ is present. The difference in the depths of the SMTZ can be attributed either to the variation in the type of organic matter or to the process dominating the sulfate reduction. Pore fluid sulfide was not detectable in the cores taken between water depths of 600m and 1200m. High TOC (~2-3 wt%) content in the sediments of west coast (down to water depth of 800-900m), coupled with requisite temperature and pressure conditions may be conducive for the methane hydrate genesis within the OMZ of the eastern Arabian Sea. However, no geophysical signature of hydrates has been reported from this region so far. The present study could provide the preliminary geochemical data needed for further investigation in this region.


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References: Cline, J.D. (1969) Spectrophotometric determination of hydrogen sulfide in natural waters.Limnology and Oceanography 14, 454-458 Koroleff, F., (1976).Determination of NH4+-N. In: Grasshoff, K. (Ed.), Methods of Seawater Analysis. VerlagChemie, Weinheim, 126-133 Mazumdar A., Joao H. M., Peketi A., Dewangan P., Kocherla M., Joshi R. K., Ramprasad T., (2012) Geochemical and geological constraints on the composition of marine sediment pore fluid: Possible link to gas hydrate deposits, Journal of Marine andPetroleum Geology, 38 35-52 Sarazin, G., Michard, G., &Prevot, F. (1999).A rapid and accurate spectroscopic method for alkalinity measurements in sea water samples.WaterResearch, 33(1), 290-294.



33 Vivekanand Pandey

Quantification of Gas Hydrates in fracture Media: A new Approach

Vivekanand Pandey*, Kalachand Sain and Mrinal K. Sen CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad - 500 007, India

*Email: [email protected] Abstract: Gas-hydrates have been recovered in fracture shale at site 10 in the Krishna-Godavari basin, by Expedition-01 of Indian National Gas Hydrate Program. Higher values of resistivity and sonic velocity log indicate gas-hydrates between 30 to 150 m below sea floor, whereas the shallower and deeper sediments are brine-saturated. We have used the conductivity equation to account for the shale conductivity for the estimation of formation factor (F). It is assumed that Conduction attributed to clay exchange ion is not dependent on conduction attributed to electrolytic ions and saturation of gas-hydrates. We have considered porosity remains same after formation of gas-hydrates and gas-hydrates goes into matrix by fracturing. We have established a relation between formation-factor and velocity for sediments with and without gas-hydrates using the log data. To obtain the background formation-factor, we have used the effective medium background velocity, which is the velocity of medium when gas hydrates are replaced by matrix material. We have then estimated the relative permeability and hence the saturation of gas-hydrates along seismic line calibrated with the pressure core result. We have processed multi-channel seismic data to build the best possible velocity models and improved seismic images along two lines passing through site 10. Velocity has been transformed into pseudo formation-factor log and hence in relative permeability at each CDP using the velocity-formation-factor relation. Results show relative permeability and gas-hydrates saturation as varying both laterally and vertically up to 0.5 and 28% respectively along the lines. Data: Well log data such as sonic, density and resistivity log and pressure core data from site 10 of NGHP Exp-01 and two high resolution MCS lines perpendicular to each other almost passing through the site 10 are taken for the present study. Interval velocity along these two seismic lines was derived by doing Pre-Stack Depth Migration (PSDM). Methodology: High values in the resistivity and sonic velocity logs indicate gas-hydrates within 30 to 150 m below the sea floor. The shallow and deeper sediments outside this range are associated with brine saturated sediments.To obtained formation factor (F) from conductivity of shaly sand conductivity equation (Revil, 1998) for high salinity water saturated porous media have been used to reduce the effect of conduction due to shale. It assumes that conduction attributed to clay exchange ion is not dependent on conduction attributed to electrolytic ions. We assume gas hydrates as a part of matrix and pore spaces are saturated with water. The formation of gas-hydrates will reduce permeability (K) for the water in pore space only that will increase the formation factor related to pore filling water (Fh).

𝜎 =1

𝐹ℎ𝜎𝑓 + 2 (1 −

1

𝐹) 𝜎𝑓𝜖 .1

Fh is formation factor corrected for shale conduction. Archie’s equation (2) forms the basis for resistivity log interpretation. In terms of formation factor it can be written as

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𝑆ℎ = 1 − [𝐹𝑡

𝐹0]

−1

𝑁 .2

We have used equation (3) given by Millington [1964] and model proposed by Masuda [1997] to estimate gas hydrates saturation equation (4).

𝐹 =𝑟2

8𝐾 .3

𝐾ℎ

𝐾0

= (1 − 𝑆ℎ)𝑁 .4

K is the permeability, F is the formation factor and r is the radius of pores. If we assume the development of the fractures are due to formation of gas hydrates remaining pore space is filled with water then the radius of pore will be same after the formation of gas hydrates. Under this assumption we can combine these two equations as equation (5)

𝐾ℎ

𝐾0

=𝐹0

𝐹ℎ

= (1 − 𝑆ℎ)𝑁 .5

Masuda has used equation 4 to estimate gas hydrates saturation from relative permeability and suggested the value of N as (10-15). At the well site since we are having formation factor we can estimate both relative permeability and hence saturation of gas hydrates using equation 5. To estimating gas hydrates saturation from seismic data along the lines we need to establish some relation that transforms seismic velocity to resistivity or formation factor. Faust [1953] has given an equation (6) relating formation factor to velocity that act well only for stiff sediments. Much later in Hacikoylu [2006] revisited Faust's equation and offered a new Equation (7) for soft sediments in Gulf of Mexico (GOM).

𝑉𝑝 = 2.2888(𝑍𝐹)1

6 .6

1

𝑉=

0.9

𝐹+ 𝐶

Where 0.27 ≤ 𝐶 ≤ 0.32 .7 With this motivation we have plotted two best fit curves (Fig.1) one for brine saturated (non-hydrates bearing) sediments and other for hydrates bearing sediments. To establish relation between velocity and formation factor equation (8) for non-hydrates and equation (9) for hydrates bearing sediments.

1

𝐹𝑏

= 1.2657 (1

𝑉𝑒

) − 0.5342 .8

1

𝐹𝑡

= 86.995 (1

𝑉𝑡

)14.963

.9

Fb is back ground formation factor and Ft is true formation factor, Ve is back ground velocity and Vt is true velocity and Ve is derived from Vt equation (10) .

𝑉𝑒 = 0.9944𝑉𝑡 + 0.003 .10 Using equation 10 we get background velocity Ve from Vt at site 10A . Using these in equation (8) and equation (9) we get Fb and Ft at site 10A. Fb and Ft at site 10A can be used in equation (5) to get relative permeability and hence saturation of gas hydrates at site 10A. For different value of N saturation is calibrated from pressure core data and for N=10 we get best match with saturation from pressure core data.


Results: Using equation 10 we get background velocity Ve from Vt at site 10A . Using these in equation (8) and equation (9) we get Fb and Ft at site 10A. Fb and Ft at site 10A can be used in equation (5) to get relative permeability and hence saturation of gas hydrates at site 10A. For different value of N saturation is calibrated from pressure core data and for N=10 we get best match with saturation from pressure core data. Interval velocity at each of CDP along the two seismic lines was used to estimate relative permeability and gas hydrates saturation using this approach. Results show relative permeability and gas-hydrates saturation as varying both laterally and vertically up to 0.5 and 28% respectively along the lines (Fig.2).

Fig. 1 relation between 1/V and 1/F for hydrates-bearing and non-hydrates bearing zones respectively non hydrates curve as background (red) hydrates curve (sky blue).

Fig. 2 fence diagram for Relative permeability and saturation along the two lines.

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References: 1. Archie, G.E. (1942), The electrical resistivity log as an aid in determining some reservoir characteristics,

Transactions of The American Institute of Mining, Metallurgical, and Petroleum Engineers, 146, 54–62. 2. Collett, T.S., M. Riedel, J. Cochran, R. Boswell, J. Presley, P. Kumar, A. V. Sathe, A. K. Sethi, M. Lall,

V. K. Sibal, and NGHP Expedition 01 Scientists (2008), NGHP Expedition 01 (2006), Initial Reports, Directorate General of Hydrocarbons, NOIDA and Ministry of Petroleum & Natural Gas, India, 4 .

3. Faust, L.Y. (1953), A velocity function including lithologic variation, Geophysics, 18, 271-288. 4. Lee, M.W., and T. S. Collett (2009), Gas hydrate saturations estimated from fractured reservoir at Site

NGHP-01-10, Krishna-Godavari Basin, India, Journal of Geophysical Research, 114, B07102, 1-13., 5. Masuda, Y., S. Naganawa, S. Ando, and K. Sato (1997), Numerical calculation of gas production

performance from reservoirs containing natural gas hydrates, paper presented at the Annual Technical Conference, paper 38291, Soc. of Petrol. Eng., San Antonio, Tex.,

6. Millington R. J., and J. P. Quirk (1964), Formation Factor and Permeability Equations, Nature, 202, 143-

145,. 7. Revil, A., L.M. Cathles III, S Losh, and A. Nunn (1998), Electrical conductivity in shaly sands with

geophysical applications, Journal of Geophysical Research, 103B10, 23,925-936.



34 A. Mazumdar

Inorganic and organic carbon geochemistry of a core (MD161-15) from the Krishna-Godavari Basin, Bay of Bengal

M. Carvalho, A. Mazumdar*, P. Mahalakshmi CSIR- National Institute of Oceanography, Dona Paula Goa – 403004

*Corresponding author: [email protected] We report here vertical profiles of total inorganic carbon (TIC wt%), total organic carbon (TOC wt%), TOC/TN ratios and δ13CTOC values from a core MD161-15 acquired off Krishna-Godavari basin, Bay of Bengal onboard R/V Marion Dufrense(May 2007). Based on the AMS 14C dates (generated at the NOSAMS, Woods Hole Oceanographic Institution, USA) and δ18O (G.ruber) values the maximum depositional age of the core is estimated at ~80 ka. The C and O isotope ratio measurement of G.ruber was carried out using a Finnigan MAT 253 IRMS with dual inlet system at the Department of Geological Sciences, University of Florida. TIC and TOC measurements were carried out with an UIC carbon coulometer (CM 5130) and Thermo EA 1112 respectively. The δ13CTOC analyses were carried out using a Thermo Delta V continuous flow isotope ratio mass spectrometer coupled to an EA. The TOC content ranges from 0.2 to 2.2 wt%. TIC content ranges from a negligible amount to ~4 wt%. A sharp rise in the TIC content (high content of foraminifera) is observed between 10 to 13 mbsf spanning the approximate time of the last glacial maxima (LGM) as shown in Fig.1. We presume that the increase in marine productivity during the LGM is due to increased regional aridity and decreased stratification resulting from a weak southwest monsoon (Phillips, S. C., et al., 2014 in press). Within the depth zone of 13 to 27 mbsf several relatively minor TIC peaks are observed which may also be tentatively linked to monsoonal intensity variation/ aridity. The high TIC content (up to 3 wt%) between 27-30 mbsf is attributed to the presence of authigenic carbonates (Joshi et al., 2014 in press) formed via anaerobic oxidation of methane pathway, as evident by the highly depleted δ13C values (−41 to −52‰ VPDB). The authigenic carbonate structures are primarily of tubular and massive type. Well preserved Scaphopoda shells (benthic burrowing mollusc) are observed cemented on the carbonate structures. Fragments of chemosynthetic clam shells (Calyptogenasp.AndLucinomasp.)recovered within the depth range of 27 to 31 mbsf indicate paleo-methane seep events. The TOC/TN ratio shows an overall opposite relationship with the TIC profile. The δ13CTOC values range from - 12.5 to -23‰ VPDB. The δ13C enrichment suggests dominant flux of C4 type vegetation.


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Fig.1. Vertical profile of TIC and TOC contents. Fig.2. Vertical profile of TOC/TN ratio and 13CTOC (‰ VPDB) values. References: Joshi, R. K., Mazumdar, A., Peketi, A., Ramamurty, P. B., Naik, B. G., Kocherla, Mary Ann Carvalho, P. Mahalakshmi, P. Dewangan & Ramana, M. V. (2014). Gas hydrate destabilization and methane release events in the Krishna-Godavari Basin, Bay of Bengal, Marine and Petroleum Geology, http://dx.doi.org/10.1016/j.marpetgeo.2014.08.013 Phillips, S. C., Johnson, J. E., Giosan, L., & Rose, K. (2014). Monsoon-influenced variation in productivity and lithogenic sediment flux since 110 ka in the offshore Mahanadi Basin, northern Bay of Bengal. Marine and Petroleum Geology, http://dx.doi.org/10.1016/j.marpetgeo.2014.05.007



35 A. Peketi

Sediment provenance variations in the Krishna Godavari basin, Bay of

Bengal for the last 80 ky: Role of climate

A. Peketi1, A. Mazumdar1, R.K. Joshi2, V.K.Rai3 1Geological Oceanography, National Institute of Oceanography, Dona Paula, Goa-403004, India

2Geological Survey of India, Kolkata-700 091, India 3Physical Research Laboratory,Ahmedabad, Gujarat-380009, India

For correspondence: [email protected]

Abstract: A ~20m long sediment core (MD161-8) from Krishna Godavari basin, western Bay of Bengal

covering a time span of 80ky was studied for its sediment provenance. Deccan basalts (DB) and granitic terrain in the peninsular India are the major sediment sources of the study area. Major element concentrations in bulk sediment samples were determined by X-ray Fluorescence (PAN analytical Axios) technique using fused pellets. Sediments were digested following the standard acid mixture protocol,Sr and Nd were separated by means of column chromatography. The isotopic ratio measurements of Sr and Nd were carried out by Thermo Neptune MC-ICP-MS. Geochemical studies of the sediment core show considerable provenance variations (Mazumdar et al., 2014). Similarly Sr-Nd isotope ratios of the sediments also show temporal variation in the sediment provenance. It is observed that the temporal variations in the major element distribution are because of change in the relative contribution of the sediments by DB and granitic terrain. Correlation between the major elemental ratios such as Fe/Avalues and oxygen isotope ratios (monsoon intensity) shows the role of climatic conditions on the nature of sediments. References: Mazumdar, A., M. Kocherla, P.Mahalaxmi, M. A. Carvalho, H. M. Joao, A. Peketi, and R. Jisha (2014). Geochemical characterization of the Krishna-Godavari and Mahanadi offshore basin (Bay of Bengal) sediments: A comparative study of provenance, Marine and Petroleum Geology, (in press).


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Figure: Temporal variations of the core MD161-8 A. Sr and Nd isotope ratios. B. Fe/Al ratios.

0.7 0.9 1.1

0

10

20

30

40

50

60

70

80

Fe/Al

Nd

MIS 2

MIS 3

MIS 4

MIS 1

MIS 5?

Age

(ky)

DBGranites

87Sr/86Sr

Granites

GranitesDB

DB

A B

-20 -17 -14

0.72 0.73 0.74

0

10

20

30

40

50

60

70

80



36 Rheane Dasilva

Characterization of organic matter in Mahanadi basin, Bay of Bengal:

Source and Diagenetic imprints.

1R. DaSilva, 1A.Mazumdar*, 2R.K. Joshi, 3A.Shaji 1P.Mahalakshmi, 1B.G. Naik, 1CSIR, National Institute of Oceanography-403004, India

2Geological Survey of India, Kolkata-700 091, India 3Centre for Marine Living Resources & Ecology-682030, India

*Corresponding author: [email protected] We report here vertical profiles of Total inorganic carbon (TIC wt%), and 13CTOC values from a core MD161-19 acquired off Mahanadi basin, Bay of Bengal onboard R/V Marion Dufrense(May 2007). Based on the AMS 14C dates (generated at the NOSAMS, Woods Hole Oceanographic Institution, USA) and 18O (G.ruber) values the maximum depositional age of the core is estimated at ~300 ky.The C and O isotope ratio measurement of G.ruberwas carried out using a Finnigan MATT 253 IRMS with dual inlet system at the Department of Geological Sciences, University of Florida. The age depth model for sediment core is obtained from the correlation of δ18O profile with the SPECMAP data. Eight Marine Isotope Stages (MIS) have been identified. TIC measurements were carried out with an UIC carbon coulometer. The 13CTOC analyses was carried out using a Thermo IRMS (Delta V plus) coupled to an EA. The TIC content ranges from ~0.2 wt% to ~5 wt%. At least six major well defined TIC peaks are recognized in Figure-1. A sharp rise in the TIC content (high content of foraminifera) is observed between 450 to 550cmbsf spanning the approximate time of last glacial maxima (LGM). We presume that the increase in marine productivity during LGM is due to increased regional aridity and decreased stratification resulting from a weak southwest monsoon. Other TIC peaks may also be tentatively linked to monsoonal intensity variation/ aridity (S.C.Philips 2014 in press.) The 13CTOC values range from -15 to -24‰ VPDB (Fig-2). The 13CTOC values show significant vertical variation which islinked to the nature of terrestrial organic flux (i.e., C3vs C4) and marine productivity. The 13CTOC values show remarkable correlation with temporal pCO2 change. Additional effects like rainfall/ aridity and temperature etc., possibly superimposed on the broad 13CTOC variation at MIS scale. Our further study is aimed at high resolution lipid chemistry of the organic content. The study will help in understanding the nature of terrestrial organic loading, marine productivity variation and biomarkers related sulfate methane transition zone SMTZ processes and methanotrophy.

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Fig.1. Vertical profile of TIC (wt %) Fig.2. Vertical profile of 13CTOC (‰ VPDB) References: Mazumdar, A., Peketi, A., Joao, H. M., Dewangan, P., &Ramprasad, T. (2014). Pore-water chemistry of sediment cores off Mahanadi Basin, Bay of Bengal: Possible link to deep seated methane hydrate deposit. Marine and Petroleum Geology, 49, 162-175. Phillips, S. C., Johnson, J. E., Giosan, L., & Rose, K. (2014).Monsoon-influenced variation in productivity and lithogenic sediment flux since 110 ka in the offshore Mahanadi Basin, northern Bay of Bengal.(in press) Marine and Petroleum Geology.



37 Aninda Mazumdar

Pyritization trends within a sediment column off Mahanadi basin, Bay

of Bengal, India

Sawant Brahmanand, A. Mazumdar*,MaqboolYousuf CSIR-National Institute of Oceanography, Goa – India 403004

*corresponding author: [email protected] We report here vertical profiles of Chromium reducible sulfur concentration (CRS-pyrite) along with SO42- , Total alkalinity (TA), and CH4 concentration from a core MD161-19 acquired off Mahanadi Basin, Bay of Bengal on board R/V Marion Dufrense. Chromium reducible sulfur (CRSpyrite) was extracted from the sediment using 6N HCl and boiling 1 M CrCl2 (in 6N HCl) in an oxygen free reaction vessel with continuous nitrogen flow. H2S trapped by reduction of sulfide is trapped as CdS in a cadmium nitrate solution and subsequently reprecipitated as Ag2S by adding AgNO3. The colloidal suspension of Ag2S was boiled for 10 minutes to produce consolidated Ag2S lumps which are subsequently collected on 0.2 um nitro cellulose filter paper and washed with distilled water. The Ag2S lumps were oven dried and weighed for CRS content. (Canfield et al 1986). A total of 220 samples were analysed for CRS concentration. Sulfate concentrations were measured using Dionex-600 Ion chromatograph. Total alkalinity was measured on board following gran titration using MetrohmAutotitrator (Titrino 799 GPT).The CRS concentration varies from 0.00016 to 0.63 wt% and shows an overall increase in background concentration from top to bottom with several intermittent well defined high concentration peaks throughout the core (Fig. A). Sulfate concentration profiles are of quasi-linear type with a gradient of 1.61 mM/m and Sulfate Methane Transition Zone (SMTZ) lies at a depth ranging from 1500 to 1900 cmbsf (Mazumdar et al 2014). High alkalinity is recorded within SMTZ( Fig B).Within a depth zone of 1700 to 1900 cmbsf several high CRS concentration peaks are apparent which may be attributed to high production of H2S in sediment column owing to the intensification of anaerobic oxidation of methane (AOM). We presume that the several large spikes of intense pyritization (CRS) is due to either increased production of H2S gas in the sediment column indicating paleo-SMTZ or due to increased flux of reactive iron in the sediment column which has led to increased pyritization. A high resolution δ34 CRS, δ13 TIC, FeDconcentration measurement may help in detailed understanding of the pyritization process in the sediment column. References: Canfield, D., R. Raiswell, J. Westrich, M. Christopher, C. M. Reaves, and R. A. Berner (1986), The use of chromium reduction in the analysis of reduced inorganic sulphur in sediments and shales, Chem. Geol., 54, 149–155, doi: 10.1016/0009- 2541(86)90078-1. Mazumdar A., Peketi A., Joao H.M, Dewangan P., Ramprasad T. (2014), Pore-water chemistry of sediment cores off Mahanadi Basin, Bay of Bengal: Possible link to deep seated methane hydrate deposit, Mar. Pet.Geol 49,162-175.

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38 G. Alekhya

Inferring the free gas occurrence in Krishna-Godavari basin using log

and seismic data

G. Alekhya, N.Satyavani and KalachandSain* Gas Hydrate Group, CSIR-National Geophysical Research Institute.

Uppal, Hyderabad, pin-500007, India. *corresponding author

Abstract: Amplitude Variation with Offset (AVO) technique is applied to marine seismic data in Krishna-Godavari (KG) basin for the identification of gas-hydrates and/or free gas. To delineate and assess gas hydrates and/or free gas at a single location, we normally use the well- log data, but when the same needs to be done for a larger extent, then we require to use seismic and log data as well. We have carried out reprocessing of seismic data in KG basin and obtained seismic velocities. The seismic data and associated velocity information have been used along with the well log data to understand the distribution of free gas below the BSR. The AVO responses from BSR and the AVO attributes at shallow sediments are summarized and discussed. The Cross-plot of AVO intercept (A) and AVO gradient (B) shows that the AVO class differs from one location to other. The results based on attributes derived from intercept, gradient, and Poisson’s ratio indicate the presence of free gas below BSR and show the spatial distribution of gas-hydrates and free gas in the study region. Key Words: Gas-Hydrates, free gas, BSR, KG basin, AVO analysis. Introduction: Gas hydrates are ice like crystalline substances that form at high pressure and low temperatures (Sloan, et al, 1990). These are commonly identified on seismic section by observing a specific reflection mimicking the sea bottom called as bottom simulating reflection.(BSR) (Stoll and Bryan1979; Hyndman and Spence 1992).Seismic velocities of pure gas-hydrates are much higher than those of oceanic sediments in which they normally occur. Whereas, the presence of free gas below reduces the seismic velocity. This velocity information is important for the present study and is obtained from the reprocessing of seismic data in KG basin. The presence of free gas creates an impedance contrast between the gas hydrate bearing sediments and free gas bearing sediments and this contrast will result in an increase of seismic amplitude with increasing offset. This is called as AVO. From AVO anomaly, we can calculate the reflection coefficients, from where we can determine the elastic parameters either by AVO modeling/AVO inversion. Data: The seismic data used in this work was collected by National Geophysical Research Institute (NGRI) in 2010 with the objective of identifying and quantifying the gas hydrate reserves in the region. The log data used in this work is from two sites of the NGHP Expedition-01, namely NGHP-01-14 (L1) and NGHP-01-06 (L2). Methodology: We have used well logs at L1 and L2 and corresponding CDP gathers (1900 at L1 and 3350 at L2) of KG basin for the computation of AVO attributes and AVO cross plots. S-wave log is a prerequisite for creating an AVO model and synthetic seismogram. There is S-wave log at L1 but not at L2 and hence we created S-wave log using Castagna equation (Castagna and Backus, 1993; Castagna et al., 1998). The methodology can be summarized briefly as follows: (i). Creation of S-wave log. (ii) Fluid replacement (iii) Log correlation for matching seismic and well log data. (iv). Gradient analysis for inferring AVO behavior of the reflectors. (v) Cross plotting of Intercept (A) and Gradient (B) for examination of any


deviation of the hydrocarbon trend against the background trend. (vi) Preparation of AVO attribute volume for deciphering the spatial distribution. Results and discussions: The gradient analysis and the AVO crossplots at two locations (L1&L2) show two different classes of AVO anomaly and both the classes indicate the presence of free gas (Fig1). At L1, a Class IV anomaly is noticed while at L2 a class III anomaly is observed. Normally a class IV anomaly coincides with the shallow burial, unconsolidated sands (Veeken and Davies, 2006), associated with low gas concentrations and hence we infer low gas saturation at L1. The movement of fluid/gas through any fault system often leads to localized high gas saturation close to the potential migration pathways (faults). We assume that this is the reason for the existence of Class III anomaly at L2, possiblyassociated with higher concentration than at L1.

Fig1: AVO curves and Cross plots at L1 and L2.

AVO analysis results in two direct attributes is., Intercept and Gradient. The derived attributes like product of A and B, signed product of A and B, Poisson’s ratio (Fig.2) are computed and plotted. There is a noted presence of free gas at both the locations beneath the BSR.The observation of varying concentration of the free gas can thereby be established while traversing from L1to L2.

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Fig.2: Poisson ratio volumes at L1 and L2. Acknowledgements: The authors thank the Director, CSIR-National Geophysical Research Institute (NGRI) for his kind to present this work. The Ministry of Earth Sciences is thanked for funding the project to acquire the seismic data and National Gas Hydrate Program (NGHP) is thanked for making the log data available to NGRI. References: Castagna, J. P. and Backus, M. M. (1993). Offset dependent reflectivity: Theory and Practice of AVO analysis. Society of Exploration Geophysics, pp. 113-172, doi: 10.1190/1.9781560802624.ch2. Castagna, J. P., Swan, H. W. and Foster, D. J. (1998) Framework for AVO gradient and intercept interpretation. Geophysics, 63, 948-956. Hyndman, R. D. and Spence, G. D. (1992) A seismic study of methane hydrate marine bottom simulating reflectors. Journal of Geophysical Research, 97, 6683-6698. Sloan, E. D, Marcel Dekker, N.Y., (1990).,Clathrate hydrates of natural gases, 641 pp. Stoll RD, Bryan GM (1979) Physical properties of sediments containing gas hydrates. Journal of Geophysics,Res.84:16291634.doi:10.1029/JB084iB04p01629. Veeken, P.C.H., and Rauch-Davies, M (2006), AVO attribute analysis and seismic reservoir characterization, first break.Vol 24, No 2, February 2006, 10.3997/1365-2397.2006004.



39 Rima Chatterjee

Pore Pressure and Porosity Mapping in Gas Hydrate Bearing Sediments in Krishna-Godavari Basin, India

Rima Chatterjee, Dip Kumar Singha and Kalachand Sain*

Department of Applied Geophysics, Indian School of Mines, Dhanbad-826004 *CSIR-National Geophysical Research Institute, Hyderabad-500007

[email protected], [email protected] and [email protected] Summary: Pre-drill estimate of pore pressure (PP) is important for well design especially in areas containing gas hydrate bearing sediments. The pressure distributions in the gas hydrate bearing sediments in Krishna-Godavari (K-G) basin have been predicted from the seismic data at the site 10 of Expedition-01 (Exp-01) conducted by Indian National Gas Hydrate Programme (NGHP). A series of elastic parameters namely P-wave velocity (Vp), S-wave velocity (Vs), density (Dn), Vp/Vs, P impedance (Zp) and S impedance (Zs) have been derived from multi channel seismic data using pre-stack inversion. The estimated porosity (φ) and PP derived from a well has been treated as target log and Zp, Zs, Vp/Vs and Dn have been used as input parameters during the training of multilayer feed forward network (MLFN). The trained outputs such as PP and porosity are validated with nearby wells. Our results demonstrate that the pressure remains hydrostatic within the gas hydrate bearing sediments and is mostly above-hydrostatic below the gas hydrate bearing zone. The predicted PP varies between 10.80 and 11.80 MPa within gas hydrate stability zone (GHSZ) maintaining the hydrostatic pressure gradient. Porosity varies from 50 to 75% in this GHSZ. Two distinct gas hydrate saturated zones have been identified from porosity image and it is in close agreement based on characterization of fractured filled gas hydrate saturation. Introduction: K-G basin is a petroliferous basin, producing oil and gas, located near the mid portion of eastern continental margin of India (Rao, 2001). Gas hydrate distributions in the sediments of K-G offshore are commonly inferred from the occurrence of bottom simulating reflector (BSR) lying at the base of the gas hydrate stability zone (GHSZ) (Shankar and Riedel, 2011). The presence of gas hydrate within the sediments increases the velocity while free gas decreases the velocity thus creating a strong impedance contrast across the base of GHSZ. The wells 10A and 10D separated by 12m were drilled at this site at a water depth of 1038m. The gamma ray, resistivity, density and P wave velocities were logged at these wells (Collett et al., 2008). The log data information from well 10A is available up to a depth of 170 m below seafloor (bsf) whereas this information from well 10D is available up to a depth of 100 m (bsf). Therefore, P wave and density logs from well 10A have been used for well-seismic tie and prestack seismic inversion. Gas hydrate filled sediments show high resistivity and an increase of P wave velocity. Gas hydrate filled fractures (Riedel et al., 2010) display high resistivities in well 10A. Methodology: Seismic inversion is a process of transforming seismic reflection data into a quantitative rock-property description of a reservoir (e.g., Sen, 2006). The main aim of pre-stack seismic inversion is to estimate the subsurface properties such as the P-wave velocity (VP), S-wave velocity (VS), and density (ρ). Hampson et al. (2006) demonstrated simultaneous inversion of pre-stack seismic data to estimate P-impedance, S-impedance and density by perturbing an initial model. For accurate wavelet estimation acoustic P wave log is used for calibration of seismic data. The PP and porosity have been predicted respectively from sonic and the density log of well-10A for the depth interval 1024-1224 m. The estimated PP and porosity have been treated as target logs and Zp, Zs, Vp/Vs and ρ have been used as input parameters during the training of multilayer feed forward network (MLFN). The trained network is then used to train the network to generate PP and subsurface porosity along 2D seismic section at site NGHP01-10 within the time interval of 1.433 – 1.631s corresponding to the depth interval of 1024-1224m.

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Results and Conclusions: The trained networks were applied to the seismic section to obtain the pore pressure and porosity distribution in this part of K-G offshore basin. The predicted pore pressure section show normal hydrostatic pressure in GHSZ but the pressure magnitude is found to be increasing below BSR entering free gas region (Singha et al., 2014a). The predicted pressure and acoustic impedance values follow the sea-floor trend and the geological structures. The predicted PP varies between 10.80 and 11.80 MPa within GHSZ maintaining the hydrostatic pressure gradient (Figure 1). The predicted porosity ranges from 50 to 75% (Figure 2) and is varying laterally (Singha et al., 2014b). The porosity trend follows the geologic structure of the basin. Porosity is increased in the free gas bearing zone below the base of GHSZ. Acknowledgements: Authors are very much thankful to Director, NGRI, Hyderabad for providing the required data to prepare this work. MoES has been acknowledged for giving us financial support. References: Collett, T.S.,Riedel,M.,Cochran, J.,Boswell, R.,Presley, J.,Kumar, P.,Sathe, A.,Sethi, A.,Lall,M., Sibal, V., 2008. The NGHP Expedition 01 Scientists, National Gas Hydrate Program Expedition 01 Initial Reports.Directorate General of Hydrocarbons, New Delhi. Hampson, D., Russell, B. and Bankhead, B., 2006. Simultaneous Inversion of Pre-stack Seismic Data, Geohorizons, January, 13–17. Rao, G.N., 2001. Sedimentation, stratigraphy and petroleum potential of Krishna–Godavari basin, East Coast of India. AAPG Bulletin 85, 1623–1643. Riedel, M., Collett, T. M., Kumar, P., Sathe, A.V. and Cook, A., 2010, Seismic imaging of a fractured gas hydrate system in the Krishna–Godavari Basin offshore India. Marine and Petroleum Geology, 27, 1476–1493. Sen, M. K., 2006. Seismic Inversion. Society of Petroleum Engineers, p. 120. Singha, D. K., Chatterjee, .R., Sen, M. K. and Sain, K., 2014a, Pore Pressure Prediction in Gas-Hydrate bearing Sediments of Krishna-Godavari Basin, India, Marine Geology, 357 (2014) 1–11. Singha, D. K, Chatterjee, R. and Sain, K., 2014b, Application of Multilayer Feed Forward Neural Network: Porosity Mapping in Gas Hydrate Sediment of Krishna-Godavari Basin, India, Annual meeting EAGE , June 16-19, Amsterdam. PID: 20945. Shankar, U. and Riedel, M., 2011, Gas hydrate saturation in the Krishna- Godavari basin from P-wave velocity and electrical resistivity logs, Marine and Petroleum Geology 28, 1768-1778.

Figure 1: Illustrates the pore pressure distribution in gas hydrate bearing sediments, K-G basin.


Figure 2: Illustrates the porosity distribution in gas hydrate bearing sediments, K-G basin

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40 M. Kocherla

Formation of methane-related authigenic carbonates in a highly dynamic biogeochemical system in the Krishna-Godavari Basin, Bay of

Bengal

M. Kocherla1*, B.M.A. Teichert2,Surabhi Pillai1, M. Satyanarayanan3,and D.J. Patil3 1CSIR-National Institute of Oceanography, Dona Paula, Goa, 403004, India

2Institut fürGeologie und Paläontologie, WestfälischeWilhelms-UniversitätMünster, Corrensstr. 24, 48149 Münster, Germany

3CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad-500606, India. *Corresponding author email: [email protected]

Abstract: We report the abundant occurrence of authigenic Fe-rich carbonate, high Mg-calcite (HMC) and low Mg-calcite from 11 cores recovered from the Krishna-Godavari Basin (K-G Basin), Bay of Bengal. The cores were collected as part of the Indian gas hydrate exploration program on board R/V Marion Dufresne (MD-161: May, 2007) in different environments, including mounds (mud diapirs), mass flows, and hemipelagic sediments over a range of water depths from 647 to 2,079 m. Authigenic carbonates range in size from 1 mm to 12 cm and display various morphologies like roundish or platy (micro-) nodules and tube-like forms. From the cores, 173 carbonate samples have been investigated for their depth distribution, mineralogy, geochemical and stable isotopic composition. The stable carbon isotopic composition of the carbonates (around -50 ‰) allows the differentiation into methane-related carbonates (HMC), especially at Sites 8 and 15, but also in low abundance at Sites 1, 5, 9 and 12. Results indicate that the carbonates at Site 8 and 15 represent paleo methane seepage locations. The Fe-rich carbonates occur abundantly at many sites in the K-G Basin. Their varying carbon isotopic composition indicates that probably not only organic sulphate reduction but also methanogenesis are the responsible processes for their formation. The REE concentrations of methane-related carbonates at Site 8 indicate variable redox condition during formations of these carbonates. Keywords: Authigenic Carbonates; Krishna-Godavari offshore basin; Bay of Bengal; Stable carbon isotopes, Stable oxygen isotopes; REE-Geochemistry.



41 Uma Shankar

Effect of topography on estimates of the geothermal gradient derived

from BSR and drilling estimates in the Krishna 3.Godavari and Andaman forearc basins

Uma Shankar*1, 2, Anne M. Trehu2, Robert N. Harris2

1CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad, India *Email:[email protected] (Corresponding and presenting author)

2College of Oceanic and Atmospheric Science, Oregon State University, Corvallis, OR 97331-5503, USA Abstract: The base of the gas hydrate stability zone depends on pressure and temperature and is often associated with observations of a bottom simulation reflector (BSR) on seismic reflection sections assuming that the hydrate-producing gas is methane and that the pore-water salinity is the same as seawater. With these assumptions, the BSR depth can be used to estimate the geothermal gradient if the seafloor temperature can be estimated. This calculation is generally done assuming a 1D model. However, in the presence of seafloor topography, the conductive temperature field in the subsurface is affected by lateral refraction of heat, which focuses heat in topographic lows and away from topographic highs. The 1D estimate of heat flow in the KG and Andaman forearc basins, which has been validated by drilling results from the NGHP Expedition-01, was has been discussed by Shankar and Riedel (2010, 2013), who used 2D analytic modeling to estimate the effects of topography. We extend that analysis to estimate the effect of topography in 3D using a numerical model based on Blackwell (1980) and implemented by Harris et al. (2011). The corrected geothermal gradient data allow us to determine geothermal gradient values free of terrain effect. The difference between the estimated geothermal gradient and values corrected for the 3-D terrain effect varies up to ~5 oC/km. We conclude that the topographic correction is relatively small compared to other uncertainties in the 1D model and that apparent heat flow determined with the 1D model captures the major features of the heat flow, although the correction is needed prior to interpreting subtle features of the derived heat flow maps. Keywords: Gas hydrate, BSR, GHSZ, Geothermal gradient, KG Basin, Andaman forarc Basin, 3-D topographic modeling.



42 Piyush Bhade

Depressurization of Layered Unconfined Hydrate Reservoir for Gas

Production

Piyush Bhade, Jyoti Phirani* Indian Institute of Technology, Delhi, 110016 , India

Gas hydrates are ice like compounds formed at high pressure and low temperature. Large quantities of gas hydrates are present in shallow marine sediments, for example KG basin in India. They are an attractive source of energy and can be produced by depressurization or by thermal stimulation. Reservoirs simulation is used to find the production scenarios in absence of long term production data from hydrate reservoirs. Most of the reservoir simulation studies carried out till date are for homogeneous confined reservoirs. However, the actual reservoirs are heterogeneous in nature (Walker Ridge 313 site, Mount Elbert Unit-D) and can be underlain by an unconfined aquifer. This research is aimed at studying the production of natural gas from layered unconfined hydrate reservoirs in oceanic subsurface. We use a 3-dimensional, thermal, compositional, multiphase, multi-component simulator developed by Sun and Mohanty (2005) to explore the optimum production strategy of natural gas from layered unconfined hydrate deposits. Three components (methane, water and hydrate) and four phases (hydrate, gas, aqueous and ice phase) are considered in the simulator. To mimic the unconfined aquifer below the hydrate bearing zone a constant pressure boundary is considered below the reservoirs. The connectivity of the aquifer is altered by changing the permeability at the bottom of the simulated area. Aquifer connectivity and layering are found to be the two important parameters for optimization of gas production. As the aquifer connectivity increases the gas production decreases as depressurization becomes difficult due to water influx from the aquifer. The gas production from layered reservoir is found to be higher than that of a homogeneous reservoir for same amount of hydrates, unlike confined hydrate deposits. This is due to combined effect of variation in pressure and temperature conditions in the layered reservoir during hydrate dissociation. Keywords: Gas Hydrate Depressurization Reservoir simulation

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43 Tetsuya Fujii

Recent results and discoveries on gas-hydrates in the eastern Nankai Trough,

Japan

Tetsuya Fujii, Koji Yamamoto, and Tatsuo Saeki Methane Hydrate Research & Development Division, Japan Oil, Gas and Metals National Corporation

(JOGMEC), Chiba, Japan Tel.: +81-43-276-9291. E-mail: [email protected]

Since 1996, the Japanese Ministry of Economy, Trade and Industry (METI) has been intensively conducting exploratory surveys of methane hydrates (MHs) in the eastern Nankai Trough, which has been chosen as a model area for MH surveys (Figure 1). Based on results from Ministry of International Trade and Industry (MITI) “Nankai Trough” wells in 1999 (Tsuji et al., 2004) and METI “Tokai-oki to Kumano-nada” exploratory test wells in 2004, MH-bearing sand-rich intervals (i.e., sand pore-filling-type MHs) have been identified in turbidite fan deposits of the eastern Nankai Trough (Fujii et al., 2009).

Based on analyses of the above well data together with2D/3D seismic survey data acquired in 1996, 2001, and 2002, we extracted more than 10 prospective MH-concentrated zones (MHCZs) in this area (Saeki et al., 2008), and resource assessments of methane gas within MHs were performed using a probabilistic approach (Fujii et al., 2008). The total amount of methane gas in place contained in MHs within the survey area was estimated to have a Pmean value of 40 trillion cubic feet (Tcf). The total gas in place for the MH-concentrated zone was estimated to have a Pmean value of 20 Tcf (half the total amount). Among the extracted MHCZs, the “Beta” MHCZ at the Daini–Astumi Knoll (Figure 2) was selected to be the test site for the first offshore production, which was performed from 2012 to 2013. This selection was based on water depth, existing well controls, reservoir formation pressure–temperature conditions (depth from seafloor), characteristics of MH-bearing layers, and the existence of sealing layers (mud-rich layers with sealing capacity) above them (Fujii et al., 2013).

The main objective of the first production test was to understand the behavior of MH dissociation in an in-situ condition. The final goal was to verify the feasibility of using the “depressurization technique” as a commercial gas-production method from offshore MH-bearing sediments (Yamamoto et al., 2012a).

To obtain basic information for the MH reservoir characterization, extensive geophysical logging and pressure coring using the hybrid pressure coring system(Yamamoto et al., 2012b) were conducted in 2012 at a monitoring well (AT1-MC) and coring well (AT1-C). The MHCZ, which was confirmed by geophysical logging at AT1-MC, has a turbidite assemblage (from several tens of centimeters to a few meters) with 60 m of gross thickness; it is composed of lobe/sheet-type sequences in the upper part and relatively thick-channel-sand sequences in the lower part. This MHCZ is thicker than that confirmed in previous wells in 2004 (45 m) located around 150 m to the northeast. This indicates that the predictions provided by seismic interpretations and inversion analyses were reasonable.

Well-to-well correlation between two monitoring wells (AT1-MC and MT1) within 40 m exhibited fairly good lateral continuity of sand layers in the upper part of the reservoir. This suggests an ideal reservoir for the production test.

The values of MH pore saturation (Sh) evaluated from geophysical logging data were compared with those evaluated by pressure core analysis. In the MHCZ, 50–80% of Sh values were observed in sandy layers, which is in fairly good agreement with core-derived Sh values.

Based on the above observations, a production interval was identified. When we consider an effective depressurization, the existence of sealing layers both above and below the interval is critical. We expected that thin silty layers within the lower part of the MHCZ would serve as a sealing layer that would prevent water coning from water-bearing layers. Therefore, we stopped drilling the production well at about 20 m above the BSR and decided to produce from approximately 40 m from the top of the MHCZ.


In March 2013, the world's first offshore production test from MH bearing layers was conducted at the site; the cumulative volume of gas produced during the six day test was approximately 120,000m3 (at atmospheric pressure). The average volume of gas produced was approximately 20,000m3/day (Yamamoto et al., 2014).

We are now analyzing the formation response to depressurization using various types of observation data, such as produced gas and water, temporal variation of formation temperature distribution, and cased-hole geophysical logging and 4C seismic data from an ocean bottom cable. We are also performing a GH petroleum system analysis using biological analyses of core samples and 2D/3D basin simulators (Fujii et al., 2014). Acknowledgement: This study is a part of the program of the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium). References: Fujii et al. (2008):Resource assessment of methane hydrate in the eastern Nankai Trough, Japan. Proceedings of 2008 Offshore Technology Conference, Houston, Texas, U.S.A., 2008, OTC19310. Fujii et al. (2009): Methane-hydrate occurrence and saturation confirmed from core samples, eastern Nankai Trough, Japan.AAPG Memoir 89, p. 385–400. Fujii et al. (2013): Site selection and formation evaluation at the 1st offshore methane hydrate production test site in the eastern Nankai Trough, Japan, Proceedings of 75th EAGE Conference & Exhibition incorporating SPE EUROPEC 2013 London, UK. Fujii et al. (2014): Modeling Gas Hydrate Petroleum Systems of the Pleistocene Turbiditic Sedimentary Sequences of the Daini-Atsumi Area, Eastern Nankai Trough, Japan. Proceedings of the 8th ICGH, Beijing, China, 28 July - 1 August, 2014. Saeki et al. (2008): Extraction of methane hydrate concentrated zone for resource assessment in the eastern Nankai Trough, Japan. Proceedings of 2008 Offshore Technology Conference, Houston, Texas, U.S.A., 2008, OTC19311. Tsuji et al. (2004): Overview of the METI Nankai Trough wells: A milestone in the evaluation of methane hydrate resources. Resource Geology, 54, 3–10. Yamamoto et al. (2012a): The scientific objectives and program of the Japanese offshore methane hydrate production test. Abstract of AGU 2012 Fall Meeting, 3-7 December, 2012, San Francisco, U.S.A., OS43B-1826. http://fallmeeting.agu.org/2012/eposters/eposter/os43b-1826/ Yamamoto et al. (2012b): Pressure Core Sampling in the Eastern Nankai Trough. Fire in the ice (Methane Hydrate Newsletter) Vol. 12, Issue 2. http://www.netl.doe.gov/technologies/oil-gas/publications/Hydrates/Newsletter/MHNews_2012_Oct.pdf Yamamoto et al. (2014) : Operational overview of the first offshore production test of methane hydrates in the Eastern Nankai Trough. Proceedings of 2014Offshore Technology Conference, Houston, Texas,U.S.A., 2014, OTC 25243.

http://fallmeeting.agu.org/2012/eposters/eposter/os43b-1826/

http://www.netl.doe.gov/technologies/oil-gas/publications/Hydrates/Newsletter/MHNews_2012_Oct.pdf

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Figure 1. Map showing the history of methane hydrate exploration surveys in the eastern Nankai Trough (1996–2004) and the location of Daini–Atsumi Knoll (modified from Fujii et al. , 2009).

Figure 2.Time structure map of seafloor from 3D seismic survey data. Pink line outlines the βMH concentrated zone, as interpreted from 3D seismic data.

MITI 2-D Seismic Surveys (2,802km)

2004 Exploratory test wells“Tokai-Oki to Kumanonada”

MITI Nankai Trough Wells (1999)

METI 3-D Seismic Survey (2002), 1960km2

1996 2001

LWDLWD+Coring

Water depth

50 km

3,7

90

,00

03

,79

5,0

00

3,7

60

,00

0

720.000705.000 710.000 715.000

Area 12.3 km2

Water Depth 857～1405m (1000m@β1)Location Off Atsumi/Shima Peninsula

Daini-Atsumi Knoll

1st Offshore Production Test site

Production Test Site

Well location33°56’N 137°19’E

βMH concentrated zone

Atsumi PeninsulaShima

Peninsula

β1(2004)



44 Toshiaki Kobayashi

Resources assessment of methane hydrates in offshore surround Japan

Toshiaki Kobayashi, Yuhei Komatsu, Tetsuya Fujii Japan Oil, Gas and Metals National Corporation

Japan Oil, Gas and Metals National Corporation (hereinafter, JOGMEC), as a member of research

group for resources assessment of Research Consortium for Methane Hydrate Resources in Japan (MH21), is conducting resources assessment of methane hydrates (hereinafter, MHs) in offshore surround Japan.

The seismic interpretation of migrated profiles of two/three dimensions-seismic surveys acquired by

geophysical vessel ‘Shigen’ that JOGMEC owns, are carried out. MHs are being extracted to search the Bottom Simulating Reflector (herein after, BSR) and assumed sand intervals, which is characterized high-amplitude reflected waves. In addition, based on the knowledge of the MHs are correlated to high-velocity, the comparison between extracted MHs and the high velocity anomalies in the velocity-analysis-profiles run in two-dimensions-seismic-survey lines, or the three-dimensions-seismic-survey area carrying out high-density-velocity analysis. This introduced example is an example of seismic interpretation in the data of three dimensions-seismic-survey area , which have not drilled.

The characteristic in this area shows fold structure, which undulates severalfold. In addition, the gaps

of the reflected waves can interpret faults, which does not show the large displacement, are seen. Clear velocity contrast to assume BSR and the high-velocity anomaly above BSR are confirmed in the high-density-velocity-analysis profiles.

Multiplereflectorof assumed sand faciesisestimated by the results of seismic interpretation in the

migrated profiles of three dimensions seismic survey, and each flow showsdifferentsedimentation environment and geological age. In addition, heterogeneity of lithology (different grain size and sand/ mud ratio) is suggested by the variety of amplitude and velocity distribution in the high-density-velocity-analysis profile. In the high-density-velocity-analysis profile, characteristic high velocity anomaliesinthe sand facies above BSR are visible, but these are estimated MHs because those anomalies are shown in the sand faciesaboveBSR.

As above, even the area has not been drilled,the existence of MHs can be estimated from seismic

interpretation of the migrated profileofthe seismic survey, and the velocity distribution of the high-density-velocity-analysis profile. And it is expected that these results become useful information for the plan of the future drilling programme. This introduction is the example of the three dimensions seismic surveyarea; hence, it is a useful information for a programme of three-dimensions-seismic-survey plan by performing similar interpretation in two-dimensions-seismic-survey lines.

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45 Saulwood Lin

The Use of Gas Venting and Chemosynthesis Community in Exploration of Gas Hydrate, offshore SW Taiwan

Saulwood Lin1, WanYen Cheng1, Tsanyao Yang2 1: Institute of Oceanography, 2: Geosciences Department,

National Taiwan University Gas hydrate has been considered as an important future energy source and has been identified widely distributed under the sea floor offshore SW Taiwan. The existence of gas hydrate could be inferred based on BSR (bottom simulated reflector) seismic data. However, actual existence of gas hydrate would require deep drilling in obtaining solid evidence of gas hydrate. Other methods, e.g., gas content and composition, are therefore required to provide additional evidence for the existence of gas hydrate underneath the sea floor. In this report, we will present chemosynthesis communities as well as other geochemical and biological data to demonstrate the existence of gas hydrate and gas migration to the sea floor. Towcam (a deep tow camera with CTD and sampling unit) sea floor visual surveys, coring and a series of chemical analysis, i.e., pore water sulfate, sulfide, methane, chloride, stable isotopic carbon of organic carbon and carbonate, pyrite were conducted to identify gas venting, existence and differences of chemosynthesis communities. Our results show that significant differences existed between seeps at the active and the passive margin. Strong flares were found on top of the Formosa Ridge (FR), weak at the 4WC Ridge, shallow SMTZ (10s cm) vs. deep, large benthic chemocommunites vs. small, as well as types of benthic community. Similarities also were found between the two sets of study environments, e.g., both show conduits from deep strata, carbonate build up, patches of mussel beds, large bacterial mats. Fig. 1A show one dense galathea crab patch on top of the mussel bed at the FR and Fig. 1B the mussel bed on top of 4WCR. Fig. 2A show a largeauthigenic carbonate build up on FR and Fig. 2B the platy carbonate on the 4WCR. Large scale carbonate build up on surface and pyrite the highest concentration ofauthigenic minerals in sediments are the two most typical anomalies at seeps of both the active and passive margin. Existence of dense galathea crab patch at the FR differed that at the 4WCR where mussel beds were mostly dominant observed of that chemo community. Higher concentration of seep methane is the driving mechanism for the observed variations. Our results demonstrated that large scale of gas venting existed in our study areas, which is inferring abundant gas hydrate exist under the sea floor.


References Lin, C,-C., A. T.-S.Lin, C. S. Liu, G.-Y.Chen, W.-Z. Liao, P. Schnurle (2009), Geological controls on BSR occurrences in the incipient arc-continent collision zone off southwest Taiwan. Mar. Petrol. Geol. 26, 1118-1131. Liu, C.-S., P. Schnurle, Y. Wang, S.-H.Chuang, Chen, T.-H.Hsiuan (2006) Distribution and characters of gas hydrate offshore of southwestern Taiwan. Terr. Atmos. Ocean. Sci. 17, 615–644. Lin, S., W.-C. Hsieh, Y. C. Lim, T. F. Yang, C. S. Liu, Y. Wang (2006) Methane migration and its influence on sulfate reduction in the Good Weather Ridge region, South China Sea continental margin sediments.Terr.Atmos. Ocean. Sci. 17, 883–902. Lin, S (2011) Summary Reports of Geochemical Studies on the Gas Hydrate as Resource Potential, the Investigation Offshore Southwestern Taiwan. Central Geological Survey Report 100-25, 130 pp.

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46 Su Xin

Geological controls on gas hydrate occurrence in Qilian Mountain permafrost, China

PANG Shouji1,2 , SU Xin1,*, HE Hao1, ZHU Youhai2, WANG Pingkang2, LI Yonghong3, LI Qinghai3

1.School of Ocean Sciences, China University of Geosciences, Beijing 100083, China，[email protected]；

2. Oil and Gas survey, China Geological Survey, Beijing 100029, China 3. Qinghai No.105 Geological Exploration Team for Coal Resources, Xining 810007, Qinghai, China

Six scientific gas hydrate drilling wells (Holes DK-1, DK-2, DK-3, DK-4, DK-5 and DK-6 within a small area (within 10 km) were drilled in the Muli Coal Field of the Qilian Mountain permafrost during 2008 to 2011. Three gas hydrate interval layers (below permafrost, within depth intervals from 133.50 to 396.00 m) were recognized in Holes DK-1, DK-2 and DK-3. Gas hydrate occurred as very thin layers along fractures (fracture-filled), or within sandstones (pore-filled) in the Middle Jurassic Jiancang Formation in these three holes, with poor correlations of gas hydrate layers between holes. No gas hydrate samples were observed in other three holes. A sedimentary studied on samples from Holes DK-2 to DK-6 were carried out to understand the nature of the hosting rocks and main geological controls on occurrence of gas hydrates in this area. Complex or multi-geologic controls were seen by our study. Firstly, regional main fault F25 was seen as a major conduit for gas migration from much deeper strata. It passed through Holes DK-2 and DK-3 just in the deep intervals where the lowest gas hydrate layers located, and thus might provided enough gas flux for formation of gas hydrate. It is also passed through 500m-away located Hole DK-4 in a shallower depth interval where possible gas hydrate related anomalies were seen, implying clearly reduced gas flux transport in this hole. It also passed through Hole DK-6 that is about 5 km-away located, thus gas flux transport might be significantly reduced. Secondly, coarse grains (sandy-silt) and intervals with abundant fractures of Middle Jurassic Jiancang Formation provided suitable space volume for formation and storage of gas hydrates. And, lithological properties of permafrost strata might play a role in formation of gas hydrates too. They were seen good seal layers when they were composed by thrust folding Middle Jurassic coal beddings with fewer fractures (for example in Holes DK-2 and DK-3); on other hand, when they were sand deposits (e.g. Holes DK-5 and DK-6) with higher permeability, then they might tend to be “gas seeping” layers.




47 Tsanyao Frank Yang

Present status and planning of the gas hydrate program of NEPII in Taiwan

Tsanyao Frank Yang1,2 and Gas hydrate research team of Taiwan3

1. Geothermal Energy and Gas Hydrate Focus Center, National Energy Program-Phase II of Taiwan

2. Department of Geosciences, National Taiwan University 3. Universities and Central Geological Survey, MOEA, Taiwan

Bottom Simulating Reflectors (BSRs), which have been considered as one of major indicators of the gas hydrate in sub-seafloor, have been detected and widely distributed in offshore SW Taiwan. The Central Geological Survey of Taiwan launched two 4-year multidisciplinary gas hydrate investigation programs in 2004 to explore the potential of gas hydrate resources in the area. In addition to the field investigations, phase equilibrium of gas hydrate via experiment, theoretical modeling, and molecular simulations has also been studied. The results can provide insights into gas hydrate production technology. The results indicate that enormous amounts of gas hydrate should occur beneath the seafloor, although none of solid gas hydrate samples have been found. Therefore, another 4-year program started in 2012 to extend the studies/investigation. In the ongoing projects, some specific areas will be studied in detail to assess the components of gas hydrate petroleum system and provide a better assessment of the energy resource potential of gas hydrate in the target area. Considering the high potential energy resources, the committee of the energy national science and technology program initiated a national master program to plan the strategy and timeline for the gas hydrate exploration, exploitation and production in Taiwan. The program includes six components: resource assessment, production and exploitation, exploration safety and sea-floor stability, carbon cycle, deep sea bio-diversity, energy transportation and industrial application. Furthermore, in 2014, the National Energy Program-Phase II has established a Geothermal Energy and Gas Hydrate Focus Center to better support and coordinate the Taiwan gas hydrate investigation efforts. Eventually, we plan to conduct deep gas hydrate drilling investigation to obtain critical information on gas hydrate studies and to assess the gas hydrate energy resource potentials. The present status and details of the program will be introduced in this presentation.

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48 Gareth Crutchley

An update on the state of gas hydrates research in New Zealand

G.J. Crutchley1, I. A. Pecher1,2 K. Kroeger1 and the NZ Gas Hydrates Working Group

1 GNS Science, 1 Fairway Drive, Lower Hutt, New Zealand. 2 University of Auckland, Auckland, New Zealand.

Corresponding author email: [email protected] Gas hydrate research in New Zealand has gained significant momentum in the last five years in response to increased funding targeting a wide-range of gas hydrate-related issues. We are currently approaching the half-way point of a 6-year, government-funded gas hydrate programme designed to explore the potential of gas hydrate as an alternative energy resource. This programme encapsulates a wide range of scientific disciplines that will be important for the potential exploitation of gas hydrates, including quantitative seismic methods, hydrate deposition modelling, hydrate production modelling and environmental impact assessments. In this talk, we will give an update on some key aspects of recently-completed research from within our working group that have focused on gas hydrates on the Hikurangi margin (e.g. Figure 1) – New Zealand’s premier gas hydrate province. In particular, this presentation will focus on 1) high-resolution velocity analysis that we are using to identify localised gas hydrate deposits, 2) hydrate formation modelling with Petromod®, and 3) analysis of double bottom-simulating reflections (BSRs) on the margin. Together, these approaches are improving our understanding of the deep petroleum system beneath gas hydrate deposits and the geological processes that lead to the formation of concentrated hydrate deposits. An example of high-velocity zones related to gas hydrate formation beneath anticlinal ridges is given in Figure 2. In addition to presenting these results, we will give an outline of our on-going and planned research for the coming years as we look to identify the most attractive targets for exploration drilling.

Figure 1.A) Tectonic setting of New Zealand. B) Seismic lines and BSR amplitude in New Zealand's Pegasus Basin on the Hikurangi margin (after Crutchley et al. 2014). The red ellipse shows the location of the seismic section given in Figure 2.



References Crutchley, G.J., Fraser, D.R.A., Pecher, I.A., Gorman, A.R., Maslen, G., Henrys, S.A. (in review, 2014). Natural gas injection into gas hydrate-bearing sediments on the southern Hikurangi margin of New Zealand.Under review in Journal of Geophysical Research. Crutchley, G.J., Fraser, D.R.A., Gorman, A.R., Maslen, G., Henrys, S.A., Pecher, I.A. (2014). Seismic amplitude anomalies and velocities associated with the gas hydrate system on New Zealand’s southern Hikurangi margin: Implications for hydrate deposition. Proceedings of the 8th International Conference on Gas Hydrates (ICGH8-2014), Beijing, China, 28 July - 1 August, 2014.

Figure 2.Seismic interval velocities beneath anticlines of the northern Pegasus Basin, after Crutchley et al. (in review).

98 9th



49 Praveen Linga

Energy Recovery from Natural Gas Hydrates: Prospects and Challenges for Singapore

Praveen Linga

Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, e-mail: [email protected]

Abstract Large amounts of methane exist in the earth in the form of natural gas hydrates (NGH), an ice-like substance with guest gas molecules trapped within water cages. The amount of carbon stored as NGH is more than twice the carbon content present in all fossil fuels combined. It has been demonstrated that conventional gas production techniques can be employed to produce energy from natural gas hydrates. Thermal stimulation, depressurization or a combination of both these methods are the approaches to recover natural gas. One innovative and promising solution to secure the future energy needs and mitigate carbon dioxide emissions simultaneously is to replace methane trapped in the gas hydrate deposits with carbon dioxide. It is noted that there are challenges like sand and water management during production that needs to be overcome to sustain energy production from NGH. There is an overwhelming need to continue to pursue research and development at laboratories in order to exploit this huge resource. In this work, the state of the art experimental work in methane production from natural gas hydrates carried out at the National University of Singapore in Singapore will be summarized and future directions and challenges will be outlined. Keywords: gas hydrates, energy recovery, methane hydrates, thermal stimulation, depressurization




50 Shyam Chand

Fluid flow and gas hydrate formation along Norwegian offshore: Recent results from the SW Barents Sea

Chand S1,2, Crémière A1,2, Knies J1,2, Baranwal S1,2, Jensen H1, Lepland A1,2, Thorsnes T1,2

1. Geological Survey of Norway, Postboks 6315 Sluppen, N-7491, Trondheim, Norway Vadakkepuliyembatta S2, Buenz S2, Jurgen Mienert2

2. CAGE – Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geology, UiTThe Arctic University of Norway, N-9019, Tromsø, Norway

Subsurface and seafloor fluid flow anomalies are gaining large interest after the finding of many new hydrocarbon discoveries and large water column acoustic gas flares in the SW Barents Sea. The SW Barents Sea seafloor has undergone large changes in geomorphology due to the impact of glaciations on its surface and subsurface. Glacial erosion during Plio-Pleistocene removed large thickness of sediments from the seabed resulting in the uplift/overturning of many basins and opening up of existing and new faults causing basin wide spillage of hydrocarbon fluids. High resolution seafloor mapping by MAREANO and other projects indicates a wide distribution of pockmarks all along the SW Barents Sea. Regional fault complexes such as the RingvassøyLoppa Fault Complex have clear indications for open pathways for fluids, consistent with the observation of large acoustic gas flares in the water column. Mapping of large gas anomalies and chimneys in seismic data in the subsurface indicates accumulation and vertical as well as lateral flow of gas and other fluids along structural boundaries and across stratigraphic layers. Analysis of gravity cores and carbonate crusts collected from different parts of the SW Barents Sea provide very interesting results: 1) The pockmarks are dated to have formed a few thousand years after the glaciers retreated from the SW Barents Sea. They were found to be active until recent past although almost all of them are inactive today. 2) The carbonate crusts, fossil expressions of methane seepage, from SW Barents Sea reveal a similar age span, indicating that they also started forming after deglaciation. 3) Estimates of extractable organic matter indicate presence of thermogenic components and methane isotopes indicate fluid flow from deep source rocks 4) Foraminifera related to microseep activity are observed at different levels of the post glacial sediments indicating fluid flow towards the seafloor. Seismic data from different parts of the SW Barents Sea indicate that the fluid flow is governed by the subsurface architecture of the sedimentary units, and in specific basins such as Tromsø Basin, the Opal A to Opal CT transition boundary acts as the guidance layer accumulating and routing upward fluid flow. Gas hydrate modelling incorporating different gas compositions observed in exploration wells indicate a highly varying gas hydrate stability zone in the SW Barents Sea. We show why this multidisciplinary type of study is important in gas hydrate exploration for regions with complex subsurface geology such as SW Barents Sea.

100 9th



51 Sudeep Roy

Formation and Growth of Hydrate Phase from Molecular Simulations

Sudip Roy*,1, Nilesh K. Choudhury2, Bappa Ghosh1, Prajakta Nakate2 and Rajnish Kumar*,2 2Chemical Engineering and Process Development Division,

1Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune, 411008 India

*Sudip Roy: [email protected], Phone 020 2590 2735 *Rajnish Kumar: [email protected], Phone 020 2590 2734

Understanding gas hydrate formation and its growth is the most important aspect of gas hydrate research in connection to flow assurance in natural oil and gas pipelines. Finite interactions and interplay between enthalpy and entropy of the gas and water at a definite thermodynamic condition initiate the process of formation i.e., nucleation. However gas hydrate growth after nucleation depends on supply of gas molecules at the nucleating site and removal of heat from the growing surfaces. So mass transfer and heat transfer plays a central role on the dynamics of the growth of gas hydrate. This growth process can also be understood from molecular properties of gas and water molecules, and the interactions (so the forces) between components of the gas hydrate. Therefore, molecular simulations in atomistic level can be an important tool to bridge the gap between understanding of atomistic level interactions and formation and growth dynamics. In this presentation we are going to show how we can predict intrinsic growth rate of CO2, CH4, CO2:N2 hydrate. We will emphasize on the quantification ofthemolecular level interactions to show the mechanism of the growth and thereby connect mass and heat transfer in these systems. Finally in this presentation we will be exhibiting how molecular simulations can emerge as a tool to design inhibitor for gas hydrate formations and growth.





52 Rajnish Kumar

Natural Gas Hydrates and its Exploitation for Innovative Energy Solutions

Rajnish Kumar1*, Asheesh Kumar1, Subhadip Das2, Nilesh K. Choudhury1, Sudip Roy2* 1Chemical Engineering and Process Development Division,

2Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune, 411008 India

*Rajnish Kumar: [email protected], Phone 020 2590 2734 *Sudip Roy: [email protected], Phone 020 2590 2735

Abstract Rapid growth in energy demand and resulting anthropological release of CO2 into the atmosphere has seen unprecedented growth in natural gas production and consumption. Use of natural gas helps in offsetting CO2 release to the atmosphere. Depletion of conventional reserves of fossil fuel and resulting rise in the prices has led to exploration and exploitation of new resources. Exponential growth of shale gas exploitation in the United States is a perfect illustration of this phenomenon. Methane gas hydrates is one such unconventional fossil fuel energy which is a source of methane gas, trapped in crystalline ice like structure in permafrost regions and beneath the sea in outer continental margins. It is estimated that total amount of carbon in the form of methane hydrates, far exceeds the carbon content in all the fossil fuel reserves put together and hence natural gas hydrates has potentials to become the future of fossil fuel. This presentation briefly takes up the issues related to understanding of gas hydrates at molecular level, its energy potential and exploitation options. In addition, other innovative applications of gas hydrate based technology will be discussed, which we are currently pursuing at National Chemical Laboratory, Pune – India.



102 9th



53 Amit Arora

Role of Bio-surfactants in Natural Gas Hydrate Formation Kinetics

Amit Arora1, Rajnish Kumar 2, Swaranjit Singh Cameotra3, PushpendraKumar4, Chandrajit

Balomajumder1, Sukumar Laik5

1Department of Chemical Engineering, Indian Institute of Technology, Roorkee, India 2 Chemical Engineering and Process Development Division, National Chemical Laboratory, Pune, India

3 Institute of Microbial Technology, Chandigarh, India 4 Keshav Dev Malviya Institute of Petroleum Exploration, Oil and Natural Gas Corporation

(ONGC), Dehradun, India 5 Petroleum Engineering, Indian School of Mines, Dhanbad, India

This paper presents the laboratory investigations on effect of a biosurfactantrhamnolipid on methane hydrate formation kinetics. Rhamnolipid is synthesized from microbe named as pseudomonas aeruginosa (strain A11) which is reported to be present in Gulf of Mexico gas hydrate samples. Presence of surfactant reduces the surface tension of water from 70 mN/m to 31 mN/m with CMC of 70 mg/L. Methane hydrate formation experiments were performed with 90 percent saturation of distilled water (& water - surfactant solution) in porous silica gel with pore volume of 0.920 cc/g. The dosage of biosurfactant varies from 100 ppm to 1000 ppm. The induction time and hydrate formation temperature at a given pressure is compared at 0 PPM, 100 PPM and 1000 PPM of rhamnolipid. Methane hydrate formation in absence of any rhamnolipid shows an induction time of 44.24 minutes at 11.62 MPa and at a temperature of 4.01 oC whereas in presence of 1000 ppm rhamnolipid, methane hydrate is formed with induction time of 34.23 minutes at 11.62 MPa and at a temperature 5.44 oC. This clearly indicates that Rhamnolipid acts as a hydrate promoter. The performance of 1000 PPM concentration is found to be better than at 100 PPM. Thus small dosages of rhamnolipid getting generated from pseudomonas aeruginosamust clearly affect the gas hydrate formation kinetics in natural sites (as in Gulf of Mexico).



54 Zhou Shouwei

The Status of Natural Gas Hydrate Research in Chinese and the Green

Solid Fluidization Development Principle of Natural Gas Hydrate in Shallow Layers of Deepwater

Zhou Shouwei1 Chenwei2 Li Qingping2

1 China National Offshore Oil Corporation [email protected] 2 China National Offshore Oil Research Institute [email protected]

Abstract Natural gas hydrate is mainly distributed in the polar and slopes of in deepwater, nearly 95% is stored in the deepwater. The natural gas hydrate exploration test target in permafrost and sea areas is more like ore body and with free gas, which can be developed by depressurization, heat or chemical injection etc.. This paper presents the main research projects and status of natural gas hydrate exploration and experimental study facilities to simulate the various development methods of natural gas hydrate and risk analysis method in china. However, most of Natural gas hydrates stored in mud-sand layers about ten to 200 meters under the seabed accounted for 80% of the total resource. Because the store layers of this kind of hydrate is near to the seabed, the sediments with dispersible hydrate is looser and poor cementation, no method has been found to develop it at present. The authors in October 2012 in Qingdao, China Natural Science Fund Committee Organization of "Shuangqing BBS" for the first time presented solid fluidization development principle of Natural gas hydrate reservoir in shallow layers of Deepwater, and obtained the patent. Combining with the geological situation of Marine gas hydrates drilling sampling in our country and abroad, focusing on the core idea of fluidization mining, the technical principle is to change uncontrollable Natural gas hydrate in shallow layers of Deepwater by seabed closed fluidization lifting system into a controllable gas hydrate resources, so as to ensure safe production, achieve the goal of green controllable exploration. Key words: Shallow layer with poor cementation in deepwater, Natural gas hydrate, Solid fluidization mining



104 9th



55 Jong-Hwa Chun

Gas Hydrate R&D Activities at KIGAM

*Jong-Hwa Chun, Se-Joon Kim, Sung-Rock Lee, Byong-Jae Ryu Petroleum & Marine Research Division, KIGAM, Korea

*[email protected]

Since 1996, the Petroleum & Marine Research Division of the Korea Institute of Geoscience and Mineral Resources (KIGAM) has been conducting basic research and development (R&D) on natural gas hydrates in the Ulleung Basin, East Sea. Multi-disciplinary research integrating geophysical and geological data conducted between 2000 and 2004 demonstrated the need for intensive R&D on the gas hydrate natural resources in the East Sea. Based on the results, the Gas Hydrate R&D Organization (GHDO) announced the “10-year Korean National Gas Hydrate Program” in 2005. It consists of three phases: Phase 1 (2005–2007), exploration and initial drilling; Phase 2 (2008–2011), reserve assessment, applicable basic production technology, and subsequent drilling; and Phase 3 (2012–2014), development of optimal production technology and test production. In 2012, this national program was revised to extend Phase 3 (2012–2016). The Korean National Gas Hydrate Program is managed by the Ministry of Trade, Industry, and Energy (MOTIE, former Ministry of Knowledge Economy). The program is being conducted by a consortium comprising KIGAM, the Korea National Oil Corporation (KNOC), and the Korea Gas Corporation (KOGAS). KIGAM conducted two gas hydrate drilling expeditions in the Ulleung Basin (2007-UBGH 1 and 2010-UBGH2) that characterized the gas hydrate reservoirs and assessed the gas hydrate resources based on two- and three-dimensional seismic data. We also developed test production technologies and conducted an environmental impact assessment of the production of natural gas hydrate in the deep-water Ulleung Basin, East Sea of Korea.



56 Aninda

Mazumdar Some new findings from the Krishna-Godavari and Mahanadi basins:

NIO's contribution in gas hydrate science Aninda Mazumdar , P. Dewangan and T. Ramprasad

Gas Hydrate Research Group Geological Oceanography

National Institute of Oceanography Donapaula, Goa-403004

Over the last 10 years NIO has contributed markedly in the development of India's gas hydrate program primarily in the understanding of the Krishna-Godavari and Mahanadi basins. We have worked on the geochemitsry, geology and geophysics of these basin and have come up with new finding which may help in developing models for depositional setup, passive tectonics, hydrate formation, paleoceanography and diagenesis. Studies on the pore fluid chemistry of show different types of sulfate profiles like linear, concave up and sigmoidal. The sulfate profiles have been linked to the occurrence of gas hydrate and free gas. The carbon isotope ratios of methane gas and C1/C2+C3 ratios suggest microbiual origin of the methane in both K-G and Mahanadi basins. Discovery of chemosynthetic clams and authigenic carbonate in cores recovered from K-G basin suggest paleo-seepgae activity at the coring sites. The seepage activity took place bewteen 60-80 ky BP. Existing rock physics models fail to explain the low-shear wave velocity for Gas Hydrate Bearing Sediments (GHBS) in clay dominated environments. A modified effective medium model (EMM) is proposed to explain low S-velocity in clay. The model is extended for GHBS and it can be used for predicting the hydrate saturation from both P- and S-wave velocities. An improved Stable and reliable method for Q-estimation has been developed compared to the conventional method. The decrease in peak frequency with offset is indicative of seismic attenuation. The method can be utilized for gas hydrate exploration as the presence of hydrate and free gas with decrease and increase of seismic attenuation, respectively. The time structure map of seafloor from 3D seismic data shows various MTD, faults, mounds and inner toe-thrust area in KG Basin. Several MTDs are observed in the mid-slope basin which are indicative of slope failure possibly associated with fluid/gas migration. Faults and mounds are also favorable locations for the formation of gas hydrates.

106 9th



57 Kalachand

Sain Geophysical investigation of gas-hydrates along the eastern margin of

India

Kalachand Sain CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad - 500 007, India

Email:[email protected]

ABSTRACT The bathymetry, seafloor temperature, total organic carbon content, sediment-thickness, rate of sedimentation, geothermal gradient imply that shallow sediments along the eastern margin of India are good hosts for gas hydrates. Thus, it was felt necessary to delineate the prospective zones and estimate the resource potential of gas-hydrates. We have prepared the gas hydrates stability thickness map, which provides the maximum depth of gas hydrates occurrences, and helps to identify the bottom simulating reflectors or BSRs (marker for gas hydrates). The BSRs on seismic sections often coincide with the base of gas-hydrates stability field. Analysis and scrutinizing of newly-acquired multichannel seismic data have revealed presence of gas-hydrates in the Krishna-Godavari and Mahanadi basins. Seismic attributes like the reflection strength, blanking, attenuation and instantaneous frequency have been computed to characterize whether the BSRs are related to gas-hydrate reservoirs. Several approaches based on seismic traveltime tomography, full-waveform inversion, amplitude versus offset modeling, impedance inversion, each coupled with rock-physics have been developed, and their applications will be presented to seismic data for the delineation and assessment of gas hydrates into these basins.

Keywords: gas hydrates, energy potential, detection, assessment, seismic data, eastern margin of India



58 Pushpendra

Kumar

Indian National Gas Hydrate Program – An Update

Pushpendra Kumar Keshav Dev Malviya Institute of Petroleum Exploration (KDMIPE)

Oil and Natural Gas Corporation Ltd (ONGC), Dehradun-248195

Abstract: Natural gas hydrates are considered to be the vast resources of methane gas, which is entrapped in the hydrate crystals distributed in the marine and arctic sediments. Gas hydrate exploratory research in India is being steered by the Ministry of Petroleum & Natural Gas under National Gas Hydrate Program (NGHP) with participation from Directorate General of Hydrocarbons (DGH), National E&P companies (Oil and Natural Gas Corporation Ltd ‘ONGC’, GAIL India Ltd & Oil India Ltd ‘OIL’) and National Research Institutions (National Institute of Oceanography, National Geophysical Research Institute and National Institute of Ocean Technology). Several initiatives have been taken by NGHP for gas hydrate exploration in Indian offshore. Geophysical, geological and geochemical data have been collected from East and West Coasts and Andaman areas for identification of gas hydrate prospective areas. Based on these studies, areas were identified for gas hydrate coring/drilling operations. The dedicated gas hydrate coring/ drilling/ LWD/ MWD operations were carried out under NGHP at 21 sites (total 39 gas hydrate wells) in four Indian Offshore areas (KG, Mahanadi, Andman and Kerala-Konkan) during 28th April 2006 to 19th August 2006 (NGHP Expedition 01, 2006). The NGHP Expedition 01 established the presence of gas hydrates in Krishna-Godavari, Mahanadi and Andman basins. The close spatial association of gas hydrates with the deeper microbial gas accumulations in the Krishna-Godavari area appears to be controlled by methane flux through fracture systems generated by the regional stress regime. The discovered gas hydrates in Indian Offshore areas are distributed in fractured shale or clay sediment which is not producible with the current technologies. With the completion of NGHP Expedition 01, 2006, it has been established that huge amount of gas hydrate deposits are present in the Indian deep water areas particularly in the East Coast. However, the gas hydrate resources in the Indian Offshore areas and amount of technically recoverable gas hydrates are yet to be assessed. In view of this, from 2007 to 2014, about 7000 sq km seismic data has been studied by ONGC and another 1000 sq km seismic data by DGH, NIO & NGRI for identification of the promising sites with an objective to find gas hydrates in sand facies. Studies have shown areas with good prospects of gas hydrate distribution in sand facies. NGHP is currently planning for the execution of NGHP Expedition 02 for drilling/coring/logging in the East Coast of India. This paper presents an update on the exploratory efforts being made by India under NGHP for developing gas hydrates as an energy resource.

108 9th



59 Richard coffin

A REVIEW OF UNITED STATES METHANE HYDRATE ENERGY EXPLORATION AND RESEARCH Provided by: Dr. Ray Boswell, NETL-DOE, Morgantown West Virginia Presented by: Dr. Richard Coffin, PENS, TAMU-CC, Corpus Christi Texas Since the passage of the Methane Hydrate Research and Development Act of 2000, the DOE has led a coordinated national methane hydrate research and development (R&D) program in collaboration with six other federal agencies, universities, industry, and international R&D programs. The DOE program mission is to advance the scientific understanding of naturally occurring methane hydrate so that its resource potential and environmental implications can be fully understood. Methane hydrate — natural gas trapped in an ice-like cage of water molecules — occurs in both terrestrial and marine environments. Terrestrial deposits have been found in sediments within and beneath permafrost in Arctic regions, such as on the North Slope in Alaska. Prior programs in Alaska have explored gas hydrate reservoir potential and alternative production strategies, and additional testing programs are in development. While not part of this announcement, DOE intends to further evaluate production methods on terrestrial methane hydrate deposits in Alaska. Marine gas hydrates occur in shallow sediments in deepwater settings along the continental margins. Prior marine investigations, primarily through the DOE-supported Gulf of Mexico Joint Industry Partnership’s (JIP), confirmed methods for safe drilling in hydrate-bearing sediments (Leg I expedition in 2005) and documented the occurrence of high-quality gas hydrate reservoirs in areas of the Gulf of Mexico such as Green Canyon and Walker Ridge (Leg II expedition in 2009). However, significant research remains to better define resource volumes and accurately assess the production potential of methane hydrates in deepwater settings. The objectives of the marine gas hydrate program are to: (1) collect a full suite of in situ measurements and core samples to characterize the physical properties of marine methane hydrates; (2) assess their potential response to possible production activities; and (3) further delineate the occurrence and nature of gas hydrates in the U.S. outer continental shelf. This presentation will provide an update on the US DOE efforts and collaborations on methane hydrate research and exploration.



60 Richard Birchwood Risks associated with drilling and producing in marine gas hydrates -

An analysis based on recent field experience and computer simulations.

Richard Birchwood & Kaibin Qiu, Schlumberger

Gas hydrates in marine settings are widely perceived to be hazardous to drilling. Additional hazards associated with producing gas hydrates in marine settings have also been cited in the literature. This talk will examine some of these risks in the light of current experience and future plans for gas hydrate production. Dangerous conditions associated with destabilization of in-situ gas hydrates have been reported in the development of onshore fields in Alaska and Siberia. However scientific drilling expeditions specifically targeting marine gas hydrate accumulations have not reported any significant operational problems associated with thermal destabilization of such deposits. Using computer simulations of heat transfer during the drilling process, we examine why this is so. The simulations elucidate the confluence of factors related to water depth, ocean currents, circulation practices, and drilling fluid rheology that favor preservation of the thermal stability of gas hydrates. We show how these factors converged favorably during gas hydrates drilling campaigns in the Gulf of Mexico and the elsewhere. However we also show that unfavorable scenarios could occur, particular in relatively shallow water (less than 500 m). In the Northern Gulf of Mexico, gas hydrates have been discovered in water depths as shallow as 439 m [Brooks et al. 1994], while in the Caspian Sea, gas hydrates have been dredged from the sea bottom some 480 m deep [Ginsburg et al. 1992]. In the Barent's sea, marine gas hydrates have been inferred to exist in water depths of 345 m [Andreassen, 1990]. Using the Barents sea as an example, we illustrate the high potential for gas hydrate dissociation in shallow water settings. The risks associated with producing gas hydrates will also be examined. Production can potentially weaken gas hydrate bearing layers, promote mass movement and subsidence at the sea bed, destabilize faults, and trigger sand production. Methodologies for evaluating some of these risks will be described. Results will be shown of applying these techniques to evaluate risks associated with the 1st offshore production test in the Nankai Trough.

List of Delegates

Sr. No.

Last Name First Name Organization Country Email

1. Mimachi Hiroko Mitsui Engineering and Shipbuilding Co., Ltd.

Japan [email protected]

2. Yoneda Jun National Institute of Advanced Industrial Science and Technology (AIST)


3. Matsushima Jun The University of Tokyo Japan [email protected]

4. Kotera Takashi JOGMEC Japan [email protected]

5. Suzuki Kiyofumi Methane Hydrate R & D Group Technology Research Center(TRC), Japan, Oil, Gas and Metals National Corporation (JOGMEC)


6. Nagao Jiro Methane Hydrate Research Center (MHRC) National Institute of Advanced Industrial Science and Technology (AIST)


7. Tamaki Machiko Japan Oil Engineering Co.Ltd., Japan [email protected] 8. Tetsuya Fujji Japan Oil, Gas and Metals

National Corporation (JOGMEC) Japan [email protected]

9. Kobayashi Toshiaki Japan Oil, Gas and Metals National Corporation (JOGMEC)


10. Tomaru Hitoshi Chiba University, Japan Japan [email protected]

11. Birchwood Richard Schlumberger Technical Services, Inc

USA [email protected]

12. Coffin Richard Texas A&M University, USA USA [email protected]

13. Kvamme Bjorn University of Bergen Norway [email protected]

14. Weissman Joshua University of Hawaii USA [email protected]

15. Wood Warren Naval Research Laboratory USA [email protected]

16. Zhou ShouWei Cnooc,China China

17. Chen Wei Cnooc,China China [email protected]

18. Yao PinLi Cnooc,China China [email protected]

19. Li QingPing Cnooc,China China [email protected]

20. Yang Tsanyao Frank National Taiwan University Taiwan [email protected]

21. Lin Saulwood Inst. of Oceanography, National Taiwan University

Taiwan [email protected]

22. Crutchley Gareth GNS Science, New Zealand New Zealand

[email protected]

23. Linga Praveen National University of Singapore Singapore [email protected]

24. Kolar Ramesh ONR-GLOBAL, Singapore Singapore [email protected]

25. Anton Semenov Gubkin Russian State University of Oil and Gas

Russia [email protected]

26. Medvedev Vladimir Gubkin Russian State University of Oil and Gas

Russia [email protected]

27. Kuhs Werner F University of Goettingen Germany [email protected]

28. Chand Shyam Norges Geologiske Undersøkelse Norway [email protected]

29. Chun Jong Hwa KIGAM S. Korea [email protected]

30. Sain Kalachand CSIR-NGRI India [email protected]

31. Pinnelli Prasad CSIR-NGRI India [email protected]

32. Shankar Uma CSIR-NGRI India [email protected]

33. Nittala Satyavani CSIR-NGRI India [email protected]

34. Ojha Maheswar CSIR-NGRI India [email protected]

35. Kumar Praveen CSIR-NGRI India [email protected]

36. Prasad ASSSRS CSIR-NGRI India [email protected]

37. A Prasanthi CSIR-NGRI India [email protected]

38. Attar Md. Rafique CSIR-NGRI India [email protected]

39. Singh Satendra CSIR-NGRI India [email protected]

40. Pandey Vivekanand CSIR-NGRI India [email protected]

41. Veligeti Jyothi CSIR-NGRI India [email protected]

42. Jana Soumya CSIR-NGRI India [email protected]

43. Gurajada Alekhya CSIR-NGRI India [email protected]

44. Nandi Rahul CSIR-NGRI India [email protected]

45. Munda Kamal Kumar CSIR-NGRI India [email protected]

46. Nara Damodara CSIR-NGRI India [email protected]

47. Dangi Usha CSIR-NGRI India [email protected]

48. Tanwar Jitender K CSIR-NGRI India [email protected]

49. Kumar Arun CSIR-NGRI India [email protected]

50. Krishnan Sandhya CSIR-NGRI India [email protected]

51. Yalavarthi Sowjanya CSIR-NGRI India [email protected]

52. Vangala Dhanunjana CSIR-NGRI India [email protected]

53. Ch Eswari CSIR-NGRI India [email protected]

54. Rao YJ Bhaskar CSIR-NGRI India [email protected]

55. Chadda RK CSIR-NGRI India [email protected]

56. Tiwari RK CSIR-NGRI India [email protected]

57. Nandan MJ CSIR-NGRI India [email protected]

58. Srinagesh D CSIR-NGRI India [email protected]

59. Dimri VP CSIR-NGRI India [email protected]

60. Gupta Harsh AERB-India India [email protected]

61. S. Ramesh CSIR-NIOT India [email protected]

62. N. Thulasi Prasad CSIR-NIOT India [email protected]

63. N. Vedachalam CSIR-NIOT India [email protected]

64. Majumdar Aninda CSIR-NIO India [email protected]

65. Dewangan Pawan CSIR-NIO India [email protected]

66. S Tulsiram CSIR-NIO India [email protected]

67. Mandal Rakesh CSIR-NIO India [email protected]

68. Carvalho Mary Ann CSIR-NIO India [email protected]

69. Peketi Aditya CSIR-NIO India [email protected]

70. Dasilva Rheane CSIR-NIO India [email protected]

71. Sawant Brahmanand CSIR-NIO India [email protected]

72. Fernandes Svetlana CSIR-NIO India [email protected]

73. Kocherla Muralidhar CSIR-NIO India [email protected]

74. Pandey N K GAIL India [email protected]

75. Singh Chandra S GAIL India [email protected]

76. Kumar Pravesh GAIL India [email protected]

77. Vishwnath Krishna DGH, Delhi India [email protected]

78. Pandey RS DGH, Delhi India

79. Roy Sudip CSIR-NCL India [email protected]

80. Chaudhary Nilesh CSIR-NCL India [email protected]

81. Kumar Asheesh CSIR-NCL India [email protected]

82. Kumar Rajnish CSIR-NCL India [email protected]

83. Bhattacharjee Gaurav CSIR-NCL India [email protected]

84. Kumar Pushpendra ONGC, Dehradun India [email protected]

85. Gullapalli Sriram NCAOR India [email protected]

86. Punnathanam Sudeep Indian Institute of Science India [email protected]

87. Sandilya Pavitra IIT, Kharagpur India [email protected]

88. Arora Amit IIT-Roorkee, India [email protected]

89. Srivastava SK OIL, Noida India [email protected]

90. Roy SB Paul OIL-Noida India

91. Bhade Piyush IIT Delhi India [email protected]

92. Kakati Himangshu ISM, Dhanbad India [email protected]

93. De Anindya GE Global Research India [email protected]

94. Bera Tapan IOCL, Noida India [email protected]

95. Paul Suman Al Habeeb College of E & T, Hyderabad

India [email protected]

96. Syed Shah Zainulabedin

Al Habeeb College of E & T, Hyderabad

India

97. Sharief Ateeb Al Habeeb College of E & T, Hyderabad

India

98. Mahmood Tauseef Al Habeeb College of E & T, Hyderabad

India

99. Ali Md. Irfan Al Habeeb College of E & T, Hyderabad

India

100. Syed Usman Aslam Al Habeeb College of E & T, Hyderabad

India

101. Baseer Mohammed Abdul


India

102. Syed Mujahid Al Habeeb College of E & T, Hyderabad

India

103. Syed Ahmed Ali Al Habeeb College of E & T, Hyderabad

India

104. Khan Abdul Mohsin Al Habeeb College of E & T, Hyderabad

India

105. Ibrahim Mohammed Al Habeeb College of E & T, Hyderabad

India

106. Ghafoor Mohammed Abdul


India

List of participants visited to ‘One day Field’ to Nagarjuna Sagar

Name

1 Prof. Werner F Kuhs 2 Dr. Richard Coffin 3 Dr. A Peketi 4 Mr. Aninda De GE Global 5 Dr. Tsanyao Frank Yang 6 Prof. Saulwood Lin 7 Dr. T Vijaya Kumar 8 Dr. Jong- HWA Chun 9 Dr. Toshiaki Kobayashi 10 Dr. FujiiTestuya 11 Dr. Kotera Takashi 12 Dr. Suzuki Kiyofumi 13 Dr. Machiko Tamaki 14 Dr. Amit Arora 15 Dr. Gareth Crutchley 16 Mr. Zhou Shou Wei 17 Mr. Chen Wei 18 Ms. Li QingPing 19 Mr. Yao PinLi 20 Dr. Warren Wood 21 Mr. Joshua Weissman 22 Dr. M. Kocherla 23 Dr. Uma Shankar 24 Dr. T R K Chetty 25 Mr. Soumya Jana 26 Ms. G. Alekhya 27 Ms. UshaDangi 28 Mr. Kamal Kumar 29 Mr. Arun KP 30 Mr. Vivekananda Pandey 31 Ms. Y. Sowjanya 32 Dr. EVSSK Babu 33 Mr. N Damodara

List of participants visited to Golconda Fort

1. Dr. Richard Coffin, USA

2. Dr. Jong HWA Chun, S. Korea

3. Dr. Kalachand Sain, India

4. Mr. Soumya Jana, India

5. Mr. Arun KP, India

6. Ms. Usha Dangi, India

7. Mr. Jitender Kumar, India

8. Mr. Rahul Nandi, India

9. Prof. Werner F Kuhs, Germany

10. Dr. M. Kocherla, India

11. Dr. Amit Arora, India

12. Mr. Ashish Kumar, India

13. Mr. Gaurav Bhattacharjee, India

14. Dr. Rajnish Kumar, India

15. Dr. Toshiaki Kobayashi, Japan

16. Dr. Takashi Kotera, Japan

17. Prof. Pavitra Sandilya, India

18 .Dr. Anindya Kanthi DE, India

19. Mr. Piyush Badhe, India

20. Dr. Hitoshi Tomaru, Japan

21. Dr. Hiroko Mimachi, Japan

22. Dr. Shyam Chand, Norway

23. Dr. Machiko Tamaki, Japan

24. Dr. Kiyofumi Suzuki, Japan

25. Dr. Tetsuya Fujii, Japan

26. Dr. Jun Matsushima, Japan

27. Ms. Sandhya Krishnan, India

28. Dr Warren Wood, USA

29. Dr. Jiro Nagao, Japan

30. Dr. Anton Semenov, Russia

31. Dr. Vladimir Vedmedev, Russia

32. Dr. Joshua Weissman, USA

33. Dr. Jun Yoneda, Japan

34. Dr. Pushpendra Kumar, India

35. Mr. Nilesh Chowdhary, India

36. Mr. N. Damodara, India

37. Mr. Kamal Kumar Munda, India

38. Dr. Tapan Bera, India

List of people participated in Laboratory Visit to NGRI

1. Dr. Kiyofumi Suzuki, Japan

2. Dr. Tetsuya Fujii, Japan

3. Dr. Tapan Bera, India

4. Dr. Jun Matsushima, Japan

5. Dr. Warren Wood, USA

6. Prof. Werner F Kuhs, Germany

7. Dr. M. Kocherla, India

8. Dr. Amit Arora, India

9. Mr. Ashish Kumar, India

10. Mr. Gaurav Bhattacharjee, India

11. Mr. Nilesh Chowdhary, India

12. Dr. Toshiaki Kobayashi, Japan

13. Dr. Takashi Kotera, Japan

14. Prof. Pavitra Sandilya, India

15 .Dr. Anindya Kanthi DE, India

16. Mr. Piyush Badhe, India

17. Dr. Hitoshi Tomaru, Japan

18. Dr. Hiroko Mimachi, Japan

19. Dr. Shyam Chand, Norway

20. Dr. Machiko Tamaki, Japan

International collaboration continues to be a vital part of the conference since gas hydrates represent research challenges and

resource potential that are important on a global scale.

FIERY ICE 2014

HYDERABAD - INDIA

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