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Environmental Impact Assessment Report

For

Exploratory Drilling Activities In NELP Block

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QCI Accreditation Certificate SENES Consultants India Pvt. Ltd.


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CONTENTS

EXECUTIVESUMMARY ......................................................................................................................... E-1

1

INTRODUCTION .................................................................................................................................. 1

1.1

PURPOSE .............................................................................................................................................. 1

1.2

IDENTIFICATION OF PROJECT PROPONENT &PROJECT ................................................................. 2

1.3

SCOPE OF STUDY ................................................................................................................................ 2

1.4 POINT WISE COMPLIANCE OF TOR ................................................................................................. 3

2

PROJECTDESCRIPTION .................................................................................................................... 9

2.1

TYPE OF PROJECT ................................................................................................................................ 9

2.2 LOCATION OF PROJECT ...................................................................................................................... 9

2.3

DRILLING WELL LOCATIONS ........................................................................................................... 14

2.3.1

CZR Regulation ................................................................................................................ 14

2.3.2 Proposed Sethusamudram Ship Channel Project ............................................. 17

2.3.3

Proposed Project Schedule ......................................................................................... 20

2.4 TECHNOLOGY AND PROCESS DESCRIPTION ................................................................................. 20

2.5

SOURCE OF WATER &PERMISSION FOR DRAWL OF WATER ..................................................... 28

2.6

WATER BALANCE ............................................................................................................................. 28

2.7

WASTEWATER GENERATION &DISCHARGE ................................................................................. 28

2 7 1 Bilge Fluids 29


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3.1

INTRODUCTION ................................................................................................................................ 33

3.2

STUDY AREA AND STUDY PERIOD ................................................................................................. 33

3.3 STUDY COMPONENTS ..................................................................................................................... 34

3.4

STUDY METHODOLOGY .................................................................................................................. 35

3.5

BASELINE ENVIRONMENT FOR ENVIRONMENTAL COMPONENTS............................................... 36

3.5.1

Bathymetry and Seabed Morphology .................................................................... 36

3.6

GEOLOGY AND SEDIMENTOLOGY .................................................................................................. 38

3.6.1

Climate and Hydrology of Gulf of Mannar........................................................... 38

3.6.2

Wind Patterns ................................................................................................................... 39

3.6.3

Circulation and Currents .............................................................................................. 40

3.6.4

Waves .................................................................................................................................. 42

3.7

CLIMATOLOGY &METEOROLOGY ................................................................................................. 43

3.8 MARINE WATER &SEDIMENT QUALITY ....................................................................................... 48

3.8.1

Physico-Chemical Aspects Sea Water & Sediment ....................................... 51

3.8.2 Ecological Aspects Sea Water & Sediment ...................................................... 54

3.9

MARINE ECOLOGY ........................................................................................................................... 58

3.9.1 Gulf of Mannar ................................................................................................................. 58

3.9.2

Marine & Coastal Ecosystems of GOM .................................................................. 61

3.9.3

Biodiversity in GOM ....................................................................................................... 66

3.10 SOCIOECONOMIC CONDITIONS .......................................................................................... 78


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4.1.3

Marine Ecological Impacts .......................................................................................... 95

4.1.4

Socio-Economic Impacts ............................................................................................. 97

4.2 MITIGATION MEASURES FOR SIGNIFICANT ENVIRONMENTAL IMPACTS................................... 98

4.2.1

Mud make-up and Mud & Cuttings disposal ..................................................... 98

4.2.2

Restoration Plans and Rig Decommissioning Measures ................................ 99

4.2.3

Restoration of On-Shore Support Facilities On-Land ...................................... 99

4.2.4

Membership of Common Disposal Facilities ....................................................... 99

4.2.5

Measures to Handle Oily Waste Discharges ........................................................ 99

4.2.6

Sewage Treatment and Disposal ............................................................................ 100

4.2.7

Solid Waste Handling ................................................................................................. 101

4.2.8

Spent Oil Handling ....................................................................................................... 101

4.2.9

Oil Handling from Well Test Operations ............................................................. 101

4.2.10 Noise Abatement Measures ..................................................................................... 102

4.2.11

Measures to Minimize Disturbance Due to Light and Visual Intrusions 102

5

ENVIRONMENTALMONITORINGPROGRAM .................................................................... 104

6

ADDITIONAL STUDIES ......................................................................................................................... 108

6.1

RISK ASSESSMENT ......................................................................................................................... 108

6.1.1

Different Stages during Which Risk Assessments Are Undertaken.......... 108

6.1.2 Objective of the QRA .................................................................................................. 109

6 1 3 Risk Assessment Methodology 110


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6.1.18

H2S Emission Control Plans ...................................................................................... 136

6.2

OIL SPILL RISK ASSESSMENT ......................................................................................................... 138

6.2.1 Oil spill scenarios ..........................................................................................................138

7

ENVIRONMENTMANAGEMENTPLAN ................................................................................. 144

7.1

SELECTION OF DRILLING LOCATION AND NAVIGATIONAL PATH WAYS .................................. 144

7.2

ATMOSPHERIC EMISSIONS ............................................................................................................ 145

7.3

STORAGE AND HANDLING OF CHEMICALS AND SUPPLIES ........................................................ 146

7.4

MANAGEMENT OF DRILL CUTTINGS &DRILLING MUD ............................................................ 147

7.5

OILY WATER DISCHARGES AND OTHER WASTES ...................................................................... 148

7.6 MANAGEMENT OF TRANSPORT OPERATION TO DRILLING RIG ................................................ 150

7.7

OILS MANAGEMENT SYSTEM ..................................................................................................... 151

7.7.1 Policy.................................................................................................................................. 152

7.7.2

Management Manual .................................................................................................. 153

7.7.3

Management System Procedures and Documentation ................................ 154

7.7.4 Implementation, Operation, Infrastructure and Work Environment........ 154

7.7.5

Management of Occupational Health & Safety Aspects .............................. 155

7.8 ORGANIZATIONAL STRUCTURE AND IMPLEMENTATION FRAMEWORK .................................... 156

7.9 CAPITAL AND RECURRING COST FOR ENVIRONMENTAL POLLUTION CONTROL MEASURES. 157

8 DISCLOSUREOFCONSULTANTSENGAGED ....................................................................... 159


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LIST OF TABLES

TABLE 1-1:COMPLIANCE WITH TORPROVIDED BY EXPERT APPRAISAL COMMITTEE OF MOEF ............ 3

TABLE 2-1:GEOGRAPHICAL COORDINATES OF BLOCK CY-OSN-2009/2 ........................................... 12

TABLE 2-2:PROSPECT AREAS &TENTATIVE WELL LOCATIONS IN BLOCK CY-OSN-2009/2 ........... 12

TABLE 2-3:BLOCK CY-OSN-2009/2&DISTANCE FROM COASTLINE................................................ 14

TABLE 2-4:PROSPECT DISTANCE FROM COAST &CRZLINE ................................................................. 15

TABLE 2-5:WATER BALANCE ...................................................................................................................... 28

TABLE 2-6:COMMON CHEMICALS LIKELY TO BE USED FOR PREPARATION OF DRILLING FLUIDS........ 31

TABLE 3-1:DETAILS OF STUDY COMPONENTS,STUDY AREA AND STUDY PARAMETER....................... 34

TABLE 3-2:SEA WATER &SEDIMENT SAMPLING LOCATIONS DETAILS ................................................. 49

TABLE 3-3:SEA WATER ANALYSIS DATA ................................................................................................... 51

TABLE 3-4:SEDIMENT ANALYSIS RESULT ................................................................................................... 53

TABLE 3-5:PLANKTON PROFILE OF MARINE SURFACE WATER ............................................................... 54

TABLE 3-6:BENTHIC PROFILE OF SEDIMENT SAMPLE .............................................................................. 56

TABLE 3-7:BIODIVERSITY INDEX FOR PHYTOPLANKTON &ZOOPLANKTON.......................................... 57

TABLE 3-8:PEOPLE INVOLVED IN FISHING AND RELATED ACTIVITIES ..................................................... 81


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TABLE

6-5:O

ILS

PILLS

CENARIOS............................................................................................................. 138

ANNEXURE I:TORISSUED BY MOEFFOR BLOCK CY-OSN-2009/2 ................................................. 160

ANNEXURE II:PROPOSED SETHUSAMUDRAM SHIP CHANNEL ALIGNMENT ......................................... 163

ANNEXURE III:DEMOGRAPHY DETAILS OF COASTAL VILLAGES AS PER CENSUS OF INDIA,2011 ..... 164

ANNEXURE IV:DISTRICTS WISE FISHERMEN AND KEY DETAILS ............................................................ 168

ANNEXURE V:DETAILS OF FISHERMEN POPULATION FOR COASTAL VILLAGES AS PER ..................... 170


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LIST OF FIGURES

FIGURE E-1:LOCATION MAP OF THE BLOCK CY-OSN-2009/2 .............................................................. 1

FIGURE 2-1:LOCATION MAP OF THE BLOCK CY-OSN-2009/2 ........................................................... 11

FIGURE

2-2:M

APINDICATING

PROSPECT

AREAS

&T

ENTATIVEW

ELLL

OCATIONS INB

LOCKCY-OSN-2009/2ALONG WITH NEARBY COASTAL AREAS................................................................. 13

FIGURE 2-3:BLOCK BOUNDARY WITH RESPECT TO COASTAL ZONE MANAGEMENT PLAN MAP...... 16

FIGURE 2-4: BLOCK BOUNDARY WITH RESPECT TO PROPOSED SETHUSAMUDRAM SHIP CHANNEL

PROJECT ................................................................................................................................................. 19

FIGURE 2-5:IMAGES OF DRILL SHIPS &SEMI-SUBMERSIBLE DRILLING RIG.......................................... 22

FIGURE 2-6:TYPICAL SCHEMATIC OF SUBSEA BLOWOUT PREVENTERS (BOP)SYSTEM....................... 24

FIGURE 2-7:TYPICAL DRILLING FLUID CIRCULATION SYSTEM ................................................................. 26

FIGURE 2-8:TYPICAL DRILLING RIG MODULE ........................................................................................... 27

FIGURE 3-1:BATHYMETRIC VARIATIONS IN THE BLOCK AREA ................................................................ 37

FIGURE 3-2:WIND PATTERN OF INDIAN OCEAN ...................................................................................... 39

FIGURE 3-3: SCHEMATIC REPRESENTATION OF CURRENTS OBSERVED DURING JANUARY-FEBRUARYAND JULY-AUGUST ............................................................................................................................... 40

FIGURE 3-4:COASTAL CURRENTS FOR TAMIL NADU COAST DURING SOUTHWEST AND NORTHEAST

MONSOON 42


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FIGURE 3-10:MEAN AIR TEMPERATURE (C)............................................................................................ 47

FIGURE 3-11:MEAN SEA SURFACE TEMPERATURE (C) .......................................................................... 48

FIGURE 3-12:SEA WATER &SEDIMENT SAMPLING LOCATIONS............................................................ 50

FIGURE 3-13:GOMBR&GOMNPAND PROJECT BLOCK .................................................................... 60

FIGURE 3-14:LOCATION OF LIVE CORALS AROUND GULF OF MANNAR.............................................. 63

FIGURE 3-15:SHORELINE CHANGE DUE TO EROSION/ACCRETION/STABLE COAST IN COASTAL AREAS

NEAR BLOCK CY-OSN-2009/2 ........................................................................................................ 85

FIGURE 6-1:RISK ASSESSMENT METHODOLOGY .................................................................................... 111

FIGURE 6-2:RISK MATRIX &ACCEPTABILITY CRITERIA .......................................................................... 115


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EEXXEECCUUTTIIVVEESSUUMMMMAARRYY

1 Introduction

Oil India limited (OIL) is a premier national Oil Company engaged in the business of

Exploration, Production and transportation of Crude Oil and Natural gas. OIL was awarded

the Cauvery offshore block CY-OSN-2009/2 (area: 1621 km) under NELP VIII bidding round

in the Gulf of Mannar. As Operator with 50% participating interest (PI) with OIL (50%PI), OIL

has a program of drilling six (6) exploratory drilling wells in the above block.

As per the EIA notification 2006 and its amendments, all projects of offshore oil and gas

exploration, development & production are included in Schedule 1(b) in Category A and they

require environmental clearance from Ministry of Environment and Forest (MoEF). OIL had

applied for the Terms of Reference to MoEF in August 2013. The project was discussed in

12thExpert Reconstituted Appraisal Committee (Industry) held during 30thSeptember to 1st

October, 2013. Terms of Reference (ToR) for the preparation of Environmental Impact

Assessment were issued by MoEF to OIL vide letter dated 29th Nov 2013. ToR copy is

attached as Annexure I.

OIL have appointed SENES Consultants India Pvt. Ltd. (SENES India) as environmental

consultant to obtain Environmental Clearance from the Ministry of Environment and Forests

(MoEF) for the proposed activities as per the EIA Notification, 2006. SENES has received QCI-

NABET accreditation (NABET/EIA/RA016/040) for carrying out EIA studies for Category A

projects of Off shore and on shore oil and gas exploration, development & production,

valid up to October 08 2013


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2 Project Details

2.1 Project Locations and Access

The offshore exploratory block lies in the Gulf of Mannar of Cauvery basin in the east coast

of India, Tamil Nadu. The offshore exploratory block lies near Ramanathapuram & Tuticorin

District.

The northeast (Point B) and northwest (Point A) points of the block are located closer to

coast with approximate aerial distance of around 13 km from Dhanushkodi coast and 18 km

from Ervadi coast, respectively. The southeast corner (Point C) is located at approximate

aerial distance of around 43 km from Dhanushkodi coast. The southwest corner (Point F) is

located at approximate aerial distance of around 51 km from Thanichiyam coast.

Nearest Railway stations are Mandapam and Rameshwaram located at approximate aerial

distance of 25 km from block boundary towards north. Tuticorin Port is located at

approximate aerial distance of 72 km from block boundary towards west. The nearest airport

is Madurai which is located at approximate aerial distance of 100 km from nearest coast to

block boundary towards northwest. The Shree Ramanathaswamy Temple in Rameshwaram

and Kothandaramaswamy Temple in Dhanushkodi are located towards north side of coastal

areas of block but these not located on Gulf of Mannar side but are located on Palk Bay side

at approximate aerial distance of 34 km and 30 km respectively from the nearest prospect

area - Prospect Area 3. The Adam's Bridge, also known as Rama's Bridge or Rama Setu is

located at approximate aerial distance of 25 km towards northeast from the nearest prospect

area - Prospect Area 3. Location map of the block is given in figure below.

2.2 Well Locations

Based on the 3D seismic survey, OIL has come up with 6 prospect areas where hydrocarbon


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Maps of Tamil Nadu for Ramanathapuram on the Google Earth image, it is evident that

prospect areas within which wells are proposed to be drilled, are located much beyond 12

Nm from LTL i.e. CRZ IV area. CRZ clearance is therefore not applicable for this project.

2.3 Onshore Support Services for Project

Being an offshore block, exploratory activity will require logistic support from Tuticorin

and/or Kakinada supply base. The logistic support would involve supply of Fuel Oil and freshwater, storage and transport of drilling related equipment (chemicals, etc), Shipping waste

disposal facilities, Oil spill response facilities and equipment (for contingency management).

2.4 Operational Details

Phases covered by exploratory drilling are 1) MODU mobilization 2) Drilling and well Testing

3) Decommissioning. Drilling activity under normal conditions would be completed in about

90-100 days for each well in the block from the day of spudding in. Drilling will be performed

using a self contained Mobile Offshore Drilling Unit (MODU), Semi-Submersible or drill

ship, capable of performing drilling at water depth in block areas [20m (approx.) to 985m].

Based on discovery of hydrocarbon bearing formations, well testing will be conducted

at such formation to establish hydrocarbon potential in terms of flow rates and reservoir

pressure. Following drilling and well testing activities, wells will be plugged and sealed as per

laid down guidelines of OISD P&NG Rules 2008. Once well has been secured and all

necessary equipment has been retrieved, MODU will be mobilized to the next drill location.


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P a g e |E-1

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FIGURE E-1:LOCATION MAP OF THE BLOCK CY-OSN-2009/2


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3 Baseline Environment

To assess the baseline environmental status of the block, primary monitoring has been

conducted at 6 locations in prospect areas which included 6 marine surface water & 6

sediment samples in the block. Secondary information on meteorology, ecology of Gulf of

Mannar, socio-economic profile of coastal villagers, etc. have been collected from literature

reviews and information available in public domain by various government departments andagencies.

Average rainfall:Average rainfall of the project area from January 2013 to December 2013,

for the proposed exploratory block is in the range of 4.12 mm to 4.75 mm /day

Mean Wind Speed:mean wind speed measured in m/sec for the period area of January 2013

to December 2013 for the study area lies in the range of 6.25 to 6.75 m/se

Mean Air Temperature: Maximum and minimum value of mean air temperature in the

Arabian Sea is of the order of 30.2 C and 24.4 C, respectively. Mean air temperature of the

area of exploratory block lies in the range of 26.5 C to 27.5 C

Mean Sea Surface Temperature:Mean air temperature of the area of exploratory block lies inthe range of 27.75 C to 28.05 C.

3.1 Marine Water & Sediment Quality

Based on the physico-chemical analysis of marine surface water samples, pH values were in

the range of 7.45 to 8.05. Turbidity of the water samples ranges from 0.9 to 1.5 NTU. Salinity

of sea water sample collected range from 35% to 38 %. Total Suspended Solids (TSS)

ranged from 13 to 20 mg/L. Oil & Grease was found to be within range of 12 to 17 mg/L.

Polycyclic aromatic Hydrocarbons (PAH) were found to be 0.009 to 0.05 mg/L and Total

Petroleum Hydrocarbons (TPH) ranged as 2 to 2 9 ppm The higher Petroleum Hydrocarbon


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concentration of Barium in collected sediment found in range of as 0.2 ppm to 0.35 ppm

whereas the concentration of mercury in collected sample found in below detection limit

(BDL). The petroleum hydrocarbon concentrations in sediments may be mainly from the land

based sources such as municipal waste waters, industrial discharge, urban runoff, river

discharges, ocean dumping and fishing vessels operating in the localized area.

3.2 Biological Environment Phytoplankton & Zooplankton

Marine surface water samples were analyzed for planktons. Around 26 families of

phytoplanktons were observed with species like Zygnemataceae, Volvocaceae, Naviculaceae,

Pyrocystaceae, Stephanopyxidaceae, Volvocaceae, Naviculaceae, Rhizosoleniacea and

Stephanopvxidaceae. Zooplankton families observed were Bosminidae, Pontellidae,

Lumbriculida, Calanoida, Collothecidae and Asterigerinacea. Phytoplankton and zooplanktoncount ranged between 19,000 to 21,000 cells/ml and 1800 to 2000 cells/m3.

Sediment samples were analyzed for presence of benthic species. Prominent macro bethos

species observed were Nephtyidae, Stylasteridae, Ampharetidae, Stylasteridae, Sabellidae.

Carterinidae, Centropagidae, Ammodiscacea, Carterinidae, Acartiidae, Chaetonotidae and

Misophriidae are the prominently observed in Meio bethos. Micro benthos showed presenceof Bacillariaceae, Cercomonadidae and Euglenaceae families.

3.3 Marine Ecology Gulf of Mannar

Project block is located in Gulf of Mannar (GoM) which has diverse ecology, mainly reported

from the areas closer to Gulf of Mannar Islands. GoM has a chain of 21 islands stretching

from Mandapam to Tuticorin to a distance of 140 km along the coast with total area of 623

hectares which form Gulf of Mannar Marine National Park (GoMNP) and Gulf of Mannar

Biosphere Reserve (GoMBR). GoM shows presence of variety of marine organisms because of

its varied ecosystems of coral reefs rocky shores sandy beaches mud flats estuaries


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Montipora, Favia, Favites, Goniopora, Goniastrea, Platygyra, echinopora, Galaxea, Turbinaria,

Leptoria, Pavona and Pachyseries. Seagrass species like Hydrocharitaceae and

Potamogetonaceae are reported which provide food sources and nursing ground for many

epiphytic fauna and feeding grounds for the Sea Cow - Dugong dugong. Marine algae or

seaweeds species observed in GoM are Gelidiella acerosa, Gracilaria edulis, G. follifera, crassa,

Gracilaria spp.; Hvpnea spp., Acanthophora spp..Mangroves are observed in coastal area with

dominant genera as Avicennia, Rhizophora, Bruguiera. Around 126 species of plankton and

360 species of zooplanktons are reported. 51 species of foraminiferans, 257 species of

sponges, 14 species of gorgonids, 75 species Polychaeta, 9 species Nematoda, 731 species of

mollusks are reported from GoM. Though pearl yielding species like Pinctada fucata, P.

chemnitzii, P. anomioides, P. atropurpura and Chank varieties likeXancus pyrum are reported

from GoM, their existence has reduced due to trawler operations. Various varieties of crabs,lobster, prawns, and shrimps are present. There are about 450 species of fishes belonging to

107 families inhabiting the coasts of Gulf of Mannar and Palk Bay. Though dolphins like

Dolphinus delphis, Stenella longirostris, Sousa chinensisand Tursiopstruncatesare reported in

GoM, no mass landing is reported. A total of 187 species of shore birds including wadors,

terns and gulls were recorded in the Gulf of Mannar, of which 84 were of aquatic species and

the remaining terrestrial. Five species of marine turtles - Chelonia mydas (green turtle),

Hepidochelys olivacea (olive ridley), Caretta caretta (loggerheads turtle), Eretmochelys

imbricata (Hawk bill turtle), Dermochelys coriacea (leather bask turtle) are reported in the

Gulf of Mannar. All are endangered species as per Wildlife (Protection) Act, 1972. Various

studies/reports mentioned in this section indicate turtle occurrence in Gulf of Mannar marine

waters and nearby coastal areas but no specific study/report could be traced indicating turtle

occurrence specific to block area.

Marine capture fishery is the major economic activity of coastal villages located near Gulf of


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The major towns/villages in nearby coastal areas are Ramanathapuram, Rameshwaram,

Peripattinam, Devipattinam, Sayalgudi, Mandapam, Keelakarai, Muttayyapuram and

Srivaikutram, etc. Fishing, chank and seaweed collection are prominent source of livelihood

in coastal villages with farming practiced in other areas. Salt farming is done majorly in

villages from Tuticorin district compared to Ramanathapuram district villages. The primary

schools are located in every village with higher secondary school within 5 km distance.

Colleges are located at Ramanathapuram, Tuticorin and Mandapam. Though electrify is

supplied to all villages, power cut are very frequent. Public transport is provided to all coastal

villages with frequency of bus at 1 hour. Primary health centers are located in each village

with big hospitals in Ramanathapuram, Tuticorin and Mandapam.

4 Impact Assessment

4.1 Potential Impacts on Noise Quality

Potential impacts on noise quality may arise from air borne noise generated during drilling

operations of rotary drilling equipment as part of rig, diesel engines for power generation

and mud pumps, helicopter movements, leading to perceptible increase in noise levels in

immediate vicinities.

4.2 Potential Impact on Marine Water Quality and Ecology

Activities related to various phases of the proposed drilling like physical presence of MODU,

disposal of drill cuttings and WBM, operational discharges like sanitary waste water, food

waste and residuals, washing fluids (deck drainage, rig floor washing etc), cooling water,

non-routine discharges that may be caused by ballast water, chemical spills has the potential

to impact marine water quality and consequently marine ecology adjacent to the drilling

locations. Some marine water quality impacts will also occur along corridors that are

proposed to be used for providing logistic support to MODU The non routine discharges


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The prominent commercial activities in the coastal villages near Block CY-OSN-2009/2 are

fishing and salt production. During exploratory drilling of wells, sea traffic will get marginally

increased due to supply vessels. Probably 1 or 2 vessels/week (as per the requirements) will

voyage from Tuticorin or Kakinada or both supply base to exploration area. But this being a

short term activity, effect on fishing activity in the region will be minimal. Impact on fishing

or salt framing may occur in the event of any accidental oil spill, depending upon severity of

spill.

5 Environmental Management Plan

5.1 OIL Management System

OIL is committed to protect the environment through improving the effectiveness of

management and reporting systems and ensuring the reduction of local environmental

impact from operations by improving environmental performance and implementing

initiatives for the conservation of biodiversity and the resource recovery and reuse. This is

achieved through the implementation of OIL HSE Policy and management system.

5.2 Organization Structure and Responsibility

In addition to regular operational roles & responsibilities defined for the drilling

organization, all personnel directly or indirectly have a role to play towards effective

environment management in the project, by implementing the HSE policy and the

environment management plan. The entire drilling organization will co-operate with

government agencies, regulatory authorities and other stakeholders who may haveenvironmental concerns associated with the project.

5.3 Management Plans for Environment

S l ti f D il li L ti d N i ti l P th W


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At present Gulf of Mannar Biosphere Reserve area is expected to overlap with project block

on north side but no exploratory drilling well is proposed in this region.

Occurrence of sensitive species in close proximity or within the block will also govern the

selection of drilling locations. If sensitive species viz. sea turtles or marine mammals are

observed/anticipated in the block area, their presence will be monitored in accordance with

the international sighting guidelines for marine mammals. Such monitoring will be

conducted before the onset of drilling activities, and will be maintained throughout the

offshore exploratory operations. In areas where significant impacts to sensitive species are

anticipated, experienced observers will be used for the monitoring exercise.

Selection of Navigational Pathway for MODU & Supply Vessels

Appropriate measures will be adopted by the project proponent to avoid migratory routes of

turtles and ecologically and culturally sensitive coastal areas during vessel movement. In

addition, consultations with relevant stakeholders (Directorate of Fisheries, Coast Guard,

government agencies related to Gulf of Mannar, Port Management Board, etc) will be carried

out to aid in the routing of supply vessels from the logistic base. The support vessels will also

have the relevant permits and certifications to comply with the requirements of theInternational Maritime Organization for operation in Gulf of Mannar.

Drill Cutting Management

The Hazardous Waste Rules require OIL to analyze the drill cuttings and establish whether

toxicity of constituents is high enough for the waste to be considered as hazardous. The

disposal of the drill cuttings shall also be conforming to the guidelines pertaining to the

Disposal of Drill Cuttings and Drilling Fluids for Offshore Installations provided by the

Ministry of Environment & Forests (MoEF) G.S.R. 546(E) August 2005.


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Bilge waters from machinery spaces in offshore facilities and support vessels will be routed

to the facility closed drainage system, or contained and treated before discharge to meet the

MARPOL 73/78 requirements.

Management of Transport Operation to MODU

Helicopter Operations Management Plan which will delineate operation procedures for

helicopter operations to the MODU helideck would be drawn up and a competent person

would be made responsible for the same. On the land side, necessary coordination would be

established with respective airport authorities from where the helicopters would fly.

Vessel Management Planwill be formulated and implemented to reduce collision risk, both

vesselvessel and MODUvessel and a person made responsible for all vessel operations. The

plan would establish a 500 m safety zone around platform, define operational procedures for

approach, movements during bad weather, no go areas, etc.

Management of Occupational Health & Safety Aspects

OIL places high emphasis on health and safety aspects of workers and staff on MODU and

will ensure that all activities will be conducted in a safe and skill full manner with staffappropriately trained and equipment maintained in safe condition. Safety cases will be

developed for appropriate facilities. Potential health, safety or fire hazards will be removed or

managed, based on risk assessments, safe systems of work, HSE management system

requirements, competency and skills of staff and workers, etc. and would be in line with

requirements specified in the OISD Rules (Chapter VII : Health and Welfare Measures). In

addition OIL would ensure that a trained Medical Officer or Paramedic is available on the

MODU during the drilling activity.

Monitoring Frame Work


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OIL will record daily discharge of drill cuttings & drilling fluids in Sea and also to monitor the

effluent quality. Compliance reports will be submitted to Regulatory Agencies. Monitoring

results would be to be documented, analyzed and reported internally to Offshore Drilling

Supervisor, Wells Operations Manager and HSE Coordinator.


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11 IINNTTRROODDUUCCTTIIOONN

11..11 PPUURRPPOOSSEE

Oil India limited (OIL) is a premier national Oil Company engaged in the business of

Exploration, Production and transportation of Crude Oil and Natural gas. OIL was awarded

the Cauvery offshore block CY-OSN-2009/2 (area: 1621 km) under NELP VIII bidding round

in the Gulf of Mannar. As Operator with 50% participating interest (PI) with OIL (50%PI), OIL

has a program of drilling six (6) exploratory drilling wells in the above block.

As per the EIA notification 2006 and its amendments, all projects of offshore oil and gas

exploration, development & production are included in Schedule 1(b) in Category A and they

require environmental clearance from Ministry of Environment and Forest (MoEF). OIL had

applied for the Terms of Reference to MoEF in August 2013. The project was discussed in

12thExpert Reconstituted Appraisal Committee (Industry) held during 30thSeptember to 1st

October, 2013. Terms of Reference (ToR) for the preparation of Environmental Impact

Assessment were issued by MoEF to OIL vide letter dated 29th Nov 2013. ToR copy is

attached as Annexure I.

OIL has appointed SENES Consultants India Pvt. Ltd. (SENES India) as environmental

consultant to obtain Environmental Clearance from the Ministry of Environment and Forests

(MoEF) for the proposed activities as per the EIA Notification, 2006. SENES has received QCI-

NABET accreditation (NABET/EIA/RA016/040) for carrying out EIA studies for Category A

projects of Off shore and on shore oil and gas exploration, development & production.


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11..22 IIDDEENNTTIIFFIICCAATTIIOONNOOFFPPRROOJJEECCTTPPRROOPPOONNEENNTT&& PPRROOJJEECCTT

Oil India Limited (OIL) is a National Oil Company engaged in Exploration & Production of

hydrocarbons. The story of Oil India Limited (OIL) traces and symbolizes the development

and growth of the Indian petroleum industry. From the discovery of crude oil in the far east

of India at Digboi, Assam in 1889 to its present status as a fully integrated upstream

petroleum company, OIL has come far, crossing many milestones. In 1981, OIL became awholly-owned Government of India enterprise. In a recent CRISIL-India Today survey, OIL was

adjudged as one of the five best major PSUs and one of three best energy sector PSUs in the

country.

Now, OIL intends to carry out drilling of six (6) exploratory drilling wells in the Block CY-OSN-

2009/2 which is located in the Offshore off the coast of Thoothukudi (Tuticorin) in the Gulf of

Mannar. The Block area is around 1621 sq. km. The block has been awarded on by

Government of India under Production Sharing Contract (PSC) in NELP-VIII bidding ground

to Oil India Limited (OIL) with 50% participating interest as operator along with 50%

participating interest of Oil & Natural Gas Corporation Limited (ONGC).


discovery potential is high and exploratory drilling will be undertaken. Based on further

detailed study, the exact drilling well locations will be finalized in these prospect areas.

Offshore rigs will be deployed for the proposed drilling. One temporary shore base set up

with ware house and office facilities will be installed either at Tuticorin or Kakinada or at

both, to facilitate supply chain for rig operations. The personnel will be transported to the rig

by helicopters and supply boats.

11..33 SSCCOOPPEEOOFFSSTTUUDDYY


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Assess potential environmental impacts that may arise as a result of the project and

evaluate them.

11..44 PPOOIINNTTWWIISSEECCOOMMPPLLIIAANNCCEEOOFFTTOORR

OIL had applied for ToR to MoEF in August 2013. Terms of Reference (ToR) for the

preparation of Environmental Impact Assessment were issued by MoEF to OIL during the 12

th

Reconstituted Expert Appraisal Committee (Industry) held during 30th September to 1st

October, 2013. The salient points of ToR given by MoEF on 29thNovember, 2013, have been

duly addressed in EIA Report. Summary of the same is given below:

Table 1-1: Compliance with ToR provided by Expert Appraisal Committee of MoEF

S.No.

Points Of TOR Issues Addressed In EIA-EMP and RAReport

1 Executive summary of the project Executive summary included in EIA report

2 No. of exploratory wells for which

environmental clearance is accorded

and No. of new wells proposed during

expansion. Status and No. of the wellswhich are completed and closed.

No environmental clearance has been

accorded so far in this block.

OIL plans to drill 6 offshore exploratory

wells in the NELP Block CY-OSN-2009/2.Refer Chapter 2 - Project Description

3 Project Description and Project Benefits; The offshore exploratory block CY-OSN-

2009/2 covering an area of 1621 sq. km.

lies in the Offshore off the coast of

Tuticorin in the Gulf of Mannar. OIL plans

to drill 6 exploratory wells, which in case ofhydrocarbon discovery will help in

meeting the energy requirements of the

country.

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S.

No.

Points Of TOR Issues Addressed In EIA-EMP and RA

Report

5 Commitment for no drilling will be

carried within 1.0 Km

The nearest prospect area is located at an

approximate aerial distance of 31 km from

nearest coast. Thus no drilling will be

carried within 1.0 Km from coast.

Refer Chapter 2, Section 2.3 Drilling Well

Locations

6 Details of sensitive areas such as coral

reef, marine water park, sanctuary and

any other eco-sensitive area.

Gulf of Mannar National Park (GoMNP) is

located away from block boundary and

none of the block area overlaps with

GoMNP area. Gulf of Mannar Biosphere

Reserve (GoMBR) boundary passes

through block area on north side. The

nearest prospect area located to GoMBR

and GoMNP boundary is Prospect Area 3

with approximate aerial distance of 8 km

and 21 km respectively.

Refer Chapter 3, section 3.7 Ecologically

Sensitive Marine Areas

7 Approval for the forest land from the

State/Central Govt. under Forest

(Conservation) Act, 1980, if applicable

Being an offshore exploratory drilling

project, forest clearance is not applicable.

8 CRZ Clearance as per CRZ notification

dated 6thJanuary 2011.

As the project will not involve any

construction / operation activities in any

CRZ areas and hence CRZ clearance is not

applicable.

Refer Chapter 2, section 2.11 CRZ

Regulation

EEIIAA RReportt FFor EE pllorattor DDriilllliing AActtii iittiies IIn NNEELLPP BBllockk CCYY OOSSNN 22000099//22 GG llff OOff MMannar


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S.

No.


Report

for the drawl of water from the

Competent Authority. Detailed water

balance, waste water generation and

discharge.

be 20-30 m3/day for drilling; will be

supplied from temporary onshore supply

base of OIL. Wastewater generation from

the drilling well is expected to be 9

m3/day. Sewage will be treated in a

sewage treatment plant (STP). The dirty

oil from bilge fluid will be periodically

sent to shore in drums or special

containers by supply vessels deployed for

the purpose.

Refer Chapter 2, Section 2.5 - Source of

Water & Permission for Drawl of Water,

Section 2.6 - Water Balance, Section 2.7 -

Wastewater Generation & Discharge

12 Noise abatement measures and

measures to minimize disturbance due

to light and visual intrusions in case

coastally located.

Chapter 4, section 4.2.10 - Noise

Abatement Measures and Section 4.2.11 -

Measures to minimize disturbance due to

light and visual intrusions

13 Procedure for handling oily water

discharges from deck washing, drainage

systems, bilges etc.

Chapter 7, Section 7.5 - Oily Water

Discharges and Other Wastes

14 Procedure for preventing spills and spill

contingency plans

Refer Chapter 6, Section 6.1.1.3 - Oil Spill

Contingency Plan

15 Procedure for treatment and disposal of

produced water

Produced Water from well testing, if

carried out, will be stored in storage tanks,

gas will be flared, and water will be

discharged to sea after treatment Oil will

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S.

No.


Report

18 Storage of chemicals on site Chapter 2, Section 2.9- Chemical Storage

at Rig and In On-Shore Facility

19 Commitment for the use of WBM and

synthetic oil based mud in special case

OIL is committed towards using of only

Water Based Mud (WBM) for the offshore

exploratory drilling operations. However,

Low Toxic synthetic oil based mud

(LTSOBM) will be used to combat specific

hole problems.

Refer Chapter 2, Section 2.4 -Technology

and Process Description

20 Risk assessment and mitigation

measures including whether any

independent reviews of well design,

construction and proper cementing and

casing practices have been followed

Refer Chapter 6, Section 6.1 and Section

6.1.9 - Risk Mitigation Measures

21 Handling of spent oils Chapter 4, Section 4.2.8 - Spent oil

Handling

22 Handling of oil from well test

operations

Chapter 4, Section 4.2.9 - Oil Handling

From Well Test Operations

23 Mud make up and mud and cuttings

disposal procedures

The disposal of the drill cuttings will be

conforming to the guidelines pertaining to

the Disposal of Drill Cuttings and Drilling

Fluids for Offshore Installations providedby the Ministry of Environment & Forests

(MoEF) G.S.R. 546(E) August 2005.

Refer Chapter 7, Section 7.4 -

Management of Drill Cuttings & Drilling

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TTaammiillNNaadduu

S.

No.


Report

including Occupational Health

Surveillance Programme etc.

26 Restoration plans and measures to be

taken for decommissioning of the rig

and restoration of on-shore support

facilities on land

After drilling and initial testing, if the well

does not contain commercial quantities of

hydrocarbon, the well is plugged and

abandoned as per OISD guidelines of

P&NG rules 2008. Open rock formations

are sealed with cement plugs to prevent

upward migration of wellbore fluids. The

hazardous waste from onshore support

facility - Temporary supply base will be

sent to authorized hazardous waste

disposal facility.

Refer Chapter 4, Section 4.2.2 -Restoration

Plans and Rig Decommissioning Measures

and Section 4.2.3 - Restoration of on-

shore support facilities on-land.

27 Documentary proof for membership of

common disposal facilities, if required.

The solid waste generated on the rig will

be segregated and stored in colour coded

bags. The solid waste will be transported

back using support vessels or with the rig,

to the temporary supply base of OIL. At

Temporary supply base the segregated

waste will be treated separately.

Hazardous waste, if any, will be sent to

authorized hazardous waste recyclers and

disposal facility

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TTaammiillNNaadduu

S.

No.


Report

measures. control measures

30 A tabular chart with index for point wise

compliance of above TOR.

Chapter 1, Table 1-1



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pp pp yy gg // ,, ff ff ,,

TTaammiillNNaadduu

22 PPRROOJJEECCTTDDEESSCCRRIIPPTTIIOONN

22..11 TTYYPPEEOOFFPPRROOJJEECCTT

The offshore exploration blocks CY-OSN-2009/2 lies in the Gulf of Mannar of Cauvery basin

in the east coast of India. The block has been awarded by Government of India under

Production Sharing Contract (PSC) in NELP-VIII bidding round to Oil India Limited (OIL) with

50% participating interest as operator along with 50% participating interest of Oil & Natural

Gas Corporation Limited (ONGC). The proposed project is offshore exploratory drilling in the

block CY-OSN-2009/2 in the Gulf of Mannar of Cauvery basin in the east coast of India, TamilNadu state. OIL plans to drill 6 offshore exploratory wells in the block CY-OSN-2009/2. Wells

will be located within prospect areas identified based on the interpretation of 3D seismic

data collected.

22..22 LLOOCCAATTIIOONNOOFFPPRROOJJEECCTT

The offshore exploratory block covering an area of 1621 km2 lies in the Gulf of Mannar of

Cauvery basin in the east coast of India, Tamil Nadu. The offshore exploratory block lies near

Ramanathapuram & Tuticorin District.

The northeast (Point B) and northwest (Point A) points of the block are located closer to

coast with approximate aerial distance of around 13 km from Dhanushkodi coast and 18 km

from Ervadi coast, respectively. The southeast corner (Point C) is located at approximate

aerial distance of around 43 km from Dhanushkodi coast. The southwest corner (Point F) is



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pp pp yy gg

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The Shree Ramanathaswamy Temple in Rameshwaram and Kothandaramaswamy Temple in

Dhanushkodi are located towards north side of coastal areas of block but these not located

on Gulf of Mannar side but are located on Palk Bay side at approximate aerial distance of 34

km and 30 km respectively from the nearest prospect area - Prospect Area 3. The Adam's

Bridge, also known as Rama's Bridge or Rama Setu is located at approximate aerial distance

of 25 km towards northeast from the nearest prospect area - Prospect Area 3.

Location map of the block and the nearby coastal area are given in figure below.



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P a g e |11


FIGURE 2-1:LOCATION MAP OF THE BLOCK CY-OSN-2009/2



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TTaammiillNNaadduu

The geographical coordinates of the CY-OSN-2009/2 exploratory block are provided in the

table below.

Table 2-1: Geographical Coordinates of Block CY-OSN-2009/2

Location Longitude Latitude

Deg Min Sec Deg Min Sec

A 78 50 00 09 04 19.51B 79 22 11.05 09 04 19.51

C 79 14 09 08 49 21

D 79 03 45 08 47 56

E 78 52 07 08 44 02

F 78 50 00 08 44 5.77

A 78 50 00 09 04 19.51


discovery potential is high for exploratory drilling. In each prospect area, tentative well

locations are represented in the table below. Based on the further detailed study, the specific

well locations for exploratory drilling will be established within each of these prospect areas.The geographical range of Prospect Areas is also are represented below.

Table 2-2: Prospect Areas & Tentative Well Locations in B lock CY-OSN-2009/2

Prospect

Area

Geographical

Coordinates of

Tentative Well Locations

Geographical Range of

Prospect AreasApprox. Water Depth

for Prospect Area(m)Latitude

Range

Longitude

RangeLatitude Longitude Minimum Maximum

P-1 8515.644" 785415.31"852'28.39"N848'24.62"N

7851'47.17"E7857'51.34"E

373.16 568.27

P-2 8554" 785833"856'55.24"N853'29 35"N

7855'6.05"E790'9 76"E

254.68 531.01



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FIGURE 2-2: MAP INDICATING PROSPECTAREAS &TENTATIVE WELL LOCATIONS IN BLOCK CY-OSN-2009/2ALONG WITH NEARBY COASTALAREAS



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TTaammiillNNaadduu

22..33 DDRRIILLLLIINNGGWWEELLLLLLOOCCAATTIIOONNSS

MoEF, through its ToR issued for EIA studies, has sought from OIL a commitment on not

undertaking drilling within 1.0 km from coastline. Though the nearest land area for block

boundary is Dhanushkodi, which is at approximate aerial distance of 13 km from block

boundary (Point B) towards northeast, the nearest prospect area - Prospect Area 3 to

Dhanushkodi town land area is located at approximately at an aerial distance of 28 km. Thus

OIL will not have any drilling activity within 1.0 km distance from coast line. The location of

identified prospect areas and their approximate distance from the nearby coastare given in

table below.

Table 2-3: Block CY-OSN-2009/2 & Distance from Coastl ine

Prospect Area Approximate Distance From

Nearby Coast (Km)

P-1 40

P-2 34

P-3 28

P-4 34P-5 47

P-6 44

As per provisions of Forest (Conservation) Act, 1980 and its subsequent amendments,

clearance/approval from state/central government is required for diversion of forest land for

non-forestry purposes. Since this project is for offshore exploratory drilling, there is nodiversion of forest and hence forest clearance/approval for the forest land from the

State/Central Govt. under Forest (Conservation) Act, 1980 is not applicable.

There is no litigation pending against the project or any directions/order passed by any


l d


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TTaammiillNNaadduu

district are prepared by Department of Environment GIS Cell, Government of Tamil Nadu

which gives the CRZ demarcation with Low Tide Line (LTL).

Based on the superimposition of above mentioned Coastal Zone Management Plan Maps on

the Google Earth image, line delineating distance of 12 Nm from the low tide line (indicating

CRZ IV limit) is projected to assess the CRZ applicability. It is evident that only northwest and

northeast corners of block fall within 12 Nm zone and all 6 prospect areas are located well

beyond 12 Nm from LTL. The nearest prospect area to land i.e. Prospect Area - 3 is located 9

km further away toward sea from the 12 Nm distance line from the coast i.e. CRZ IV area.

Thus the prospect areas within which wells are proposed to be drilled, are located much

beyond 12 Nm from LTL i.e. CRZ IV area. CRZ clearance is therefore not applicable for this

project.

Table 2-4: Prospect Distance From Coast & CRZ line

Prospect

Location

Approximate Distance From

Nearby Coast 12 Nm Line

Km Nm Km

P-1 40 21.6 19

P-2 34 18.4 13

P-3 28 14.6 9

P-4 34 18.4 14

P-5 47 25.4 26

P-6 44 23.7 23



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P a g e |16


FIGURE 2-3:BLOCK BOUNDARY WITH RESPECT TO COASTAL ZONE MANAGEMENT PLAN MAP


TTaammiill NNaadduu


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22..33..22 PPrrooppoosseeddSSeetthhuussaammuuddrraammSShhiippCChhaannnneell PPrroojjeecctt

A navigation channel connecting the Gulf of Mannar and Palk Bay through north of Adam's

Bridge has been proposed by Government of India, called as Sethusamudram Ship Channel

Project. This proposed project is envisaged to reduce the steaming distances between the

East and West Coast of India and to improve the navigation within territorial waters of India.

The project was conceptualized with first route proposed in 1961. There were severalchanges in alignment of channel due to eco-sensitivity, cost, feasibility, presence of religious

structure Ram Sethu or Adams bridge, etc.

The proposed alignment which has received environmental clearance in 2005 by MoEF

passes through Adams bridge. The first phase proposes channel width as 300 m which

eventually can be expanded upto 500 m in third phase.

With proposed involvement of dredging and alignment route passing through Ram Sethu or

Adams bridge, various litigations started on the project, which resulted in temporary

suspension of the work. In July 2008, Prime Minister constituted panel headed by TERI

Director General which submitted report in July 2008 saying the project is ecologically and

economically not viable. In Feb 2013 Center rejected the report and decided to go ahead

with the alignment which passes through Adams bridge or Ram Sethu. In April 2013, Tamil

Nadu government urged Supreme Court to direct Center government on scrapping the

project. As per the latest proceedings on this, Central Government has taken the stand that

the 'Ram Sethu' or Adams bridge will not be broken as there are different geological and

religious theories behind the origin of the bridge. The Central government has certain"alternatives" in mind and will inform the Supreme Court an option 1. Thus there might be

revision in alignment of shipping channel.

B d th i f ti t li t f S th d Shi Ch l il bl i


TTaammiill NNaadduu


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TTaammiillNNaadduu

figure below. The reference map used for the proposed Sethusamudram Ship Channel

alignment is attached as Annexure II.

It indicates that the proposed Sethusamudram Ship Channel alignment is likely to pass

through the southern part of the project block area. OIL will therefore ensure that any

development with regard to this alignment is monitored and co-ordination with

Sethusamudram Corporation Ltd is also ensured specifically prior to planning any permanent

offshore installations, although no such installations are anticipated during this exploratory

drilling stage of the project.



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FIGURE 2-4:BLOCK BOUNDARY WITH RESPECT TO PROPOSED SETHUSAMUDRAMSHIP CHANNEL PROJECT


TTaammiill NNaadduu


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TTaammiillNNaadduu

22..33..33

PPrrooppoosseeddPPrroojjeecctt SScchheedduullee

The project activities lifecycle for the proposed offshore drilling project has been divided into

three phases- Mobilization of drilling rig, Drilling and finally Decommissioning. Drilling

activity under normal conditions would be completed in about 90-100 days for each well in

the block from the day of spudding in.

The wells drilled will be tested by perforation in the production casing if sufficient indications

of the hydrocarbons presence are noticed. The well will be sealed off for further

development upon discovering it as a successful hydrocarbon bearing structure.

22..44 TTEECCHHNNOOLLOOGGYYAANNDDPPRROOCCEESSSSDDEESSCCRRIIPPTTIIOONN

The different phases covered for the exploratory drilling are

Mobilization of the drilling rigs

Drilling and testing

Decommissioning

These phases are explained in the subsequent sections

Drilling and Testing Phase

Exploitation of hydrocarbons requires the construction of a conduit between offshore

platform and reservoir. This is achieved by the drilling process. Offshore exploration wells will

be drilled using a rig and equipped with a Top Drive System for rotating the drilling string

including the drilling bit.

There are two basic categories of offshore drilling rigs those that can be moved from place


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FIGURE 2-5:IMAGES OF DRILL SHIPS &SEMI-SUBMERSIBLE DRILLING RIG

An opening called moon pool is equipped in the centre of the drill ship from the main deckto the water. Drilling assembly, riser joints, Blowout Preventer (BOP), wellhead equipment,

etc. are lowered through the moon pool to the sea floor to facilitate the drilling

process. The marine riser system consists of riser joints, riser tensioners and ancillary

equipment. The riser joints are connected to the top of subsea BOP and are pulled up by

the riser tensioning system onboard to keep a vertical configuration. The riser joints serve as

a conduit for returning drilling mud to surface from borehole and as guide for running drill

string and casing from the rig to the hole below seafloor.

Initial Well Construction

Offshore wells are drilled in sections, with the diameter of each section decreasing with

increasing depth. Lengths and diameters of each section are determined prior to drilling and

depend on geological conditions through which the well is to be drilled. The conduit or pipe

section will be set in place by jetting operations. Drilling starts with spudding a hole of

di t 26" th b d f ll d b li i it ith t l i f 20" Th b


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iilllliinnggAAccttiivviittiieessIInnNNEELL

TTaammiillNNaadd

BBlloocckkCCYY--

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circulation system after separation of drill cuttings /solids through solids control equipment.

Drilling fluid is essential to drilling operations in order to:

Control down-hole pressure

Lift soil/rock cuttings from the bottom of the borehole and carry them to settling pit

Allow cuttings to drop in the mud pit so that they are not re-circulated (influenced by

mud thickness, flow rate in settling pits and shape/size of pits)

Prevent cuttings to settle rapidly.

Particles on the borehole wall to prevent caving and to ensure that the upward flowing

stream of drilling fluid does not erode the adjacent formation.

Seal the borehole wall to reduce fluid loss. (Formation of filter cake)

Cool and clean the drill bit and lubricate drill bit, bearings, mud pumps and drill pipes

OIL is committed towards using only Water Based Mud (WBM) for the offshore exploratory

drilling operations. However, Low Toxic synthetic oil based mud (LTSOBM) will be used to

combat specific hole problems. Water-based mud is made up of clay (bentonite) and water;

it may include barite, a heavy mineral used as to add weight. Chemical additives are mixed into stabilize the drilling fluid during use, and to reduce corrosion and bacterial activity. Some

chemicals, called coagulants thicken and others, known as anticoagulants, thin the mud.

Water-based mud is increasingly used for most offshore wells and in the shallower parts of

deep wells. Chemical additives viz. glycols and salts may be used in conjunction to mitigate

potential problems related to hydrate formation.

The mud to be used will be continuously tested for its density, viscosity, yield point, water

loss, pH value etc. to ensure that drilling operations are successful and continued without

any down-hole complication The mud will be prepared onsite (drill location) using


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Cuttings will be then separated from drilling mud using solids- control equipment. This will

comprise of a stepped system of processes consisting of linear motion vibrating screens

called shale shakers, hydro-cyclones (including de- sanders and de-silters), and centrifuges

to mechanically separate cuttings from the mud. Thoroughly washed drill cuttings, separated

from mud will be discharged offshore into sea intermittently. An estimated average volume

of 300 m3 of drill cuttings per well and 5-10 KL/day of drilling fluid waste is likely to be

generated. Once cuttings have been separated, drilling fluid used for the drilling operationswill be processed or reused after further treatment for the maximum possible extent.

The whole process by which drilling fluid will be reused during drilling operations is

commonly known as a closed loop mud circulating system. This system is ideal for drilling

operations in sensitive environments as it reduces the total water consumption for

formulation of drilling mud and it saves on consumption of chemicals. The unusable portionof mud will be discharged off shore into sea intermittently so as to have proper dilution and

dispersion without any adverse impact on marine environment.

FIGURE 2-7:TYPICAL DRILLING FLUID CIRCULATION SYSTEM


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FIGURE 2-8: TYPICAL DRILLING RIG MODULE

The time taken to drill a bore hole depends on the depth of the hydrocarbon bearing

formation and the geological conditions, but it is commonly of the order of one or two

months. Where hydrocarbon formations is found, initial well tests, possibly lasting another

month, are conducted to establish flow rates and formation pressure. These tests may

generate oil, gas and formation water, each of which needs to be disposed of.

After drilling and initial testing, the rig is usually moved to the next site after ensuring thatthe well has been plugged and sealed as per laid down guidelines of OISD P&NG Rules 2008.

If the exploratory drilling has discovered commercial quantities of hydrocarbons, a wellhead

valve assembly may be installed. If the well does not contain commercial quantities of


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22..55 SSOOUURRCCEEOOFFWWAATTEERR&& PPEERRMMIISSSSIIOONNFFOORRDDRRAAWWLLOOFFWWAATTEERR

Water requirement in a drilling rig is mainly meant for preparation of drilling mud apart from

washings and domestic use. While the former consumes the majority of water requirement,

the water requirement for domestic and wash use is very less. The average daily water

consumption will be 20-30 m3/day for drilling. The potable and drill water shall be supplied

from shore base by supply vessels. The shore base will be set up apart from this; the offshore

drilling unit shall have its own water maker which can be source of water for drill fluid. For

this, the onshore base will be setup in Tuticorin or Kakinada area. Thus the water required for

project will be taken from Tuticorin or Kakinada.

22..66 WWAATTEERRBBAALLAANNCCEE

The average daily water consumption will be 20-30 m3 /day for drilling including water

requirement for mud preparation, washing and domestic activities. Wastewater generation

from the proposed drilling activity will be from domestic activity @ 80 percent of the

domestic water requirement and from washing @100 percent of the washing water

requirement. Thus, wastewater generation from the drilling well is expected to be 9 m3

/day.

Table 2-5: Water Balance

Sr. No Particulars Water Requirement (m3/day)

Water Requirement

1 Mud preparation 20

2 Washing activities 5

3 Domestic purpose 5

Total water requirement 30


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The International Convention for the Prevention of Pollution from Ships (MARPOL) is the

main international convention covering prevention of pollution of the marine environmentby ships. The Convention includes regulations aimed at preventing and minimizing pollution

from ships - both accidental pollution and that from routine operations MARPOL has been

updated by amendments through the years and the rig to be used will always have certified

and annually endorsed by Classification society for compliance.

Procedure for disposal of Drill cutting wash-water has been furnished subsequently in the

paragraph 7.4 of Section-7 (EMP).

22..77..11 BBii llggeeFFlluu iiddss

Bilge fluids are a mix of sea water, petroleum products and other brackish material that

settles to the bottom of a ship. The collection and disposal system for this fluid will be done

in compliance with the International Convention for Prevention of Pollution from Ships,

1973 as modified by the protocol of 1978 (MARPOL 73/78). Bilge fluids mainly constituting

of water, diesel and oil. The rig will be having provision to collect bilge fluids into a sludge

tank and then to a water/oil separator. Separated oil will then be diverted into "dirty oil"

tank, where also exhaust oil coming from engine lubricant change is collected.

The dirty oil will be periodically sent to shore in drums or special containers by supply vessels

deployed for the purpose. Separated water can be directly discharged overboard, provided

that oil content does not exceed 15 ppm as per MARPOL standards.

22..77..22

DDeecckkDDrraaiinnaaggee

Drainage water generated from precipitation or routine operations, such as deck, rig floor

and equipment cleaning will be routed to separate drainage systems on the rig. This includes


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22..77..33 GGrreeyyaannddBBllaacckkWWaatteerr

Grey and Black Water will be generated from showers, toilets, laundry and kitchen facilities

on the rig and will primarily contain waste material, paper, soap etc. Rig operations will

typically result in the generation of sewage and wastes. Once collected through headers,

they will be passed through a sewage treatment plant (STP). The wastes will then be passed

through a screen of less than 25 mm diameter and an extended aeration system prior to

their discharge into the marine environment. In this case also, sewerage treatment on-site

will be done in compliance with MARPOL 73/78 requirements.

22..88 NNOOIISSEEGGEENNEERRAATTIIOONN

Major noise generating sources during offshore drilling and testing activities will:

Rotary drilling equipment as part of rig;

Diesel engines for power generation;

Mud pumps;

Cranes and material handling equipment;

Supply vessels and helicopter movement

As drilling activity is continuous, part of noise associated with the functioning of rig and

ancillaries will be generated only during drilling hours.

Sound pressure levels associated with drilling are the highest with maximum broadband (10

Hz to 10 kHz) energy of about 190 dB re 1Pa @ 1 m2.

22..99 CCHHEEMMIICCAALLSSTTOORRAAGGEEAATTRRIIGGAANNDDIINNOONN--SSHHOORREEFFAACCIILLIITTYY


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chemicals likely to be used during the drilling phase includes cement, surfactants, de-

foamers, lignin, inorganic salts, bentonite and barite.

Table 2-6: Common Chemicals Likely to be used for Preparation of Drilling Fluids

S. No. Name of Chemical S. No. Name of Chemical

1 Barytes 20 Mod. Guar Gum

2 Bentonite 21 PAC-LV

3 Biocide 22 PAC-RG4 Cal. Carb, Coarse 23 PGS

5 Lime Stone Powder (Marble) 24 PHPA

6 Cal. Carb, micronised 25 Pot. Chloride

7 Cal.Chloride 26 Resinated Lignite

8 Caustic Soda 27 Saw Dust

9 Citric Acid 28 Sodium Bicarbonate

10 CMC 29 Soda Ash

11 Common Salt 30 Sp. Fluid (N.W.)

12 Defoamer 31 Sp. Fluid (W)

13 Drilling Detergent 32 Sul. Asphalt

14 E.P. Lube 33 Thermogel

15 HEC 34 Walnut Shell

16 Hydrated Lime 35 XC-Polymer17 Ironite Sponge 36 Zin

09102014pcm7g26bannexure eia&emp oil

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