maneerat gfe project 3965535 01

8/3/2019 Maneerat GFE Project 3965535 01

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1 Maneerat Kanaree GFE project

Using Borehole Seismic DataUsing Borehole Seismic Data to Enhance Surface Seismic Interpretation to Enhance Surface Seismic Interpretation

GFE Project by…

ManeeratManeerat KanareeKanaree

Borehole GeophysicistBorehole Geophysicist -- DCS BMPDCS BMP

August 2004August 2004




Objectives

• Reduce Time-Depth uncertainty

• Enhance precision of seismic interpretation – attribute analysis andattribute guided well-placement

• Create a model for integrating surface seismic and borehole seismic

data for future Full Field Review (FFR) and Field Development Plan

(FDP)

• Demonstrate the workflow of integrating borehole seismic andsurface seismic as a case study




Outlines

• Currently Used Workflow

• Proposed Workflow (Steps 1, 2 and 3)

Data and Software

STEP-1 Wavelet phase checking

STEP-2 Well seismic Tie

STEP-3 Fluid substitution & AVO

• Conclusions & Recommendations

• Value to Clients

• Value to SLB


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Currently Used Workflow

No VSP data and limited number of checkshot surveys in previous FFRand FDP (Betty and Bokor)Betty: ( 33 wells, 1 Checkshot )Bokor: ( 54 wells, 3 Checkshots )

Surface

Seismic

Time

Surface

Seismic

Depth

Checkshot

Geological

Petrophysics

Reservoir



Proposed Workflow

SurfaceSeismic

Time

SurfaceSeismic

Depth

Checkshot

Sonic Calibration

Geological

Petrophysics

Reservoir

Step (1) Wavelet Phase Checking

Step (2) Well Seismic Tie

Fluid Substitution AVO

Step (3)



Well: North Bunga Pakma-2 (Talisman, Malaysia)

VSI/DSI/PEX/Normal Seismic section

Software: Geoframe/Interactive Petrophysics/AVOLOG

Data & Software




Surface seismic and Borehole seismic survey

Source

Receiver

Up-going

Down-going

Receiverource

Up-going




True Zero Phase wavelet

Surface Seismic Processing can not be True Zero phase wavelet.

VSP Processing

VSP data from North Bunga Pakma-2




GeogramVSP VSP

TD

VSP & GEOGRAM Processing

VSP & GEOGRAM data from North Bunga Pakma-2




Step-1 Wavelet Phase Checking




Wavelet & Surface Seismic interpretation

AI RC

- +

Surface seismic data

from deep water

Sea BedGL=-57m

TWT=0.075s

Surface seismic data

from North Bunga Pakma

Wavelet well defined Wavelet difficult to define




Wavelet & Surface Seismic Interpretation

Surface Seismic from

North Bunga Pakma

Zero Phase

0 deg rotation

Zero Phase

90 deg rotation

Zero Phase

90 deg rotation

Surface seismicDepth Section

Geological Markers

Petrophysical and

Reservoir Data

Static StructralModel

SimulationModel

Zero Phase

0 deg rotation

Client willcome back

to SLB

Time shift =10ms

Off depth = 18m




Wavelet Phase Checking Workflow

Seismic Trace from

VSP Corridor Stack /GeogramSeismic traces from

Surface seismic

GEOGRAMVSP

Cross

Correlation




Cross Correlation

VSP

Surface

Seismic

Same phase wavelet

and time shift 10ms

on surface seismic 45 deg off phase wavelet

on surface seismic45 deg off phase wavelet

and time shift 10mson surface seismic

Same phase wavelet




Step-2 Well Seismic Tie (VSP/GEOGRAM)

Well Seismic Tie (VSP/GEOGRAM)




Well Seismic Tie (VSP/GEOGRAM)VSP GEOGRAM

Surface Seismic

after step-1 VSP GEOData: North Bunga Pakma

Vertical match VSP/GEOGRAM & Surface seismic




Well Seismic Tie (Migrated VSP)

Lateral match VSP & surface seismic

Migrated VSP (red) is compared to surface seismic section




STEP-2Well Seismic Tie

Reprocessing

Surface Seismic

By using borehole

Seismic

(Well Driven Seismic)

STEP-1

Wavelet Phase Checking

STEP-3Fluid Substitution & AVO

Reduce Uncertainty

in Time-Depth

Define Fluid contain

before well-placement

Enhance Surface Seismic Interpretation




Step-3 Fluid Substitution & AVO

Fluid Substitution & AVO




Gas or Water ?

Degree of Sw ?

GAS

Fluid Substitution & AVO

Reference: Oilfield Review “Hydrocarbon Detection with AVO”, Page 43.




Fluid substitution and AVO workflow

Water (100%)

DTCO

DTSM

DSI

PorositySw

Density

Reservoir Fluid

(Sw)

Petrophysics

Reservoir

Gas zone

Gas (100%)

FluidSubstitution

CDP AVO

Modeling

@Well location

Reservoir Fluid

(Sw)

Water (100%)

Gas (100%)

Checkshot

Pre Stack

Seismic Section

(CDP/CMP)

WellLocation

Fluid inarea of

interest???

Fl id S b tit ti




Fluid Substitution

RHOB DTCO DTSM Vp Vs AIMP

V /V C Pl t ft Fl id S b tit ti




Vp/Vs Cross -Plot after Fluid Substitution

WATERGAS

AVO M d li




AVO Modeling

CDP AVO Synthetic-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0 500 1000 1500 2000 2500

Offset

R

TOP-GAS BOTTOM-GAS

TOP-WATER BOTTOM-WATER

R(θ)=Rp+ (Rp -2Rs)sin 2θ




Example AVO Response

Reference : Oilfield Review “Hydrocarbon Detection with AVO”, Page 45.




Conclusions

• Use of borehole seismic data to correct uncertainty in time-depthconversion increases the confidence in surface seismic interpretation

• Use of fluid substitution & AVO study define gas zone and reduces the risk of drilling

Recommendations• Apply this workflow for future FFR/FDP (Samarang, Erb West) in BMP

• Highlight to client where no VSP is currently available (and recommendcased-hole VSP survey, high deviated well VSP)

V l t Cli t




Value to Client

• FFR and FDP clients will benefit from

Reduced uncertainty in time-depth conversion Improve confidence in seismic interpretation

Confidence interpreting gas zones before drilling

Reduce risk of missing a target gas sand

Deep water ($20M per well), Shallow water ($2-10M per well)

V l S hl b




Value to Schlumberger

• FFR/FDP

Reduce uncertainty in time-depth conversion

Enhance surface seismic interpretation

• Revenue to DCS

Geophysics: Processing VSP($10K), WSC&GEO($8K), DSI ($10K)

Petrophysics & Geophysics: Fluid substitution & AVO study ($10K)

• Revenue to REW

Potential to acquire more borehole seismic: VSI($80K), DSI($30K)

maneerat gfe project 3965535 01

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