Data Acquisition in Kutei Basin - CCOP · 5000 6000 7000 Pre-1988 88-89 90-91 92-93 94-95 96-97...

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M U L T I - C L I E N T 3 D D A T A

Data Acquisition in Kutei BasinWorkshop On PPM Indonesia Case Study

July 21 2003

Stephen Doyle, PGS Vice President, Multi-Client Asia Pacific

EXPLORATION SERV ICES RESERVOIR SERV ICES PRODUCTION MULTI-CLIENT 3D DATA

Petroleum Geo-Services - Company Profile

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Petroleum Geo-Services

Petroleum Geo-Services: Established 1991

• Since its start PGS has:

• Pioneered the development of multi streamer 3D acquisition –faster and better seismic data quality without increasing cost

• Developed in-house expertise in geology, geophysics, reservoir and production

• Expanded product range from geophysics to floating production (FPSO) and production services

• Established leading FPSO market position in the North Sea• Introduced HD3D seismic in all environments: streamer, seafloor

and land seismic

Petroleum Geo-Services

From Prospect to Production

• Today, PGS provides the industry with a complete range of geophysical and reservoir services together with production management and FPSO operations

• PGS offers Safe Operations, Durable Data, Hands-on Experienceand Reliable Solutions: from Prospect to Production

Exploration Appraisal Development ProductionExploration AppraisalAppraisal Development ProductionProduction

L I F E O F T H E F I E L D

Exploration Services and Multi-Client 3D

Production Services

Field Evaluation, Data Integration, Reservoir characterization, 4D

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Data Acquisition In Kutei Basin

Examples Of Makassar MC3D Data

Why 3D Surveys?

Advantages For MC3D Surveys, Indonesia

Future 3D Acquisition In Indonesia

Presentation Overview




Why 3D Surveys?




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Makassar MC3D

Makassar Strait, INDONESIA

• Makassar MC3D - 1999 7,300km²

• Sesulu Extension 2001 929km²

• Total 8,229km2 Contiguous 3D Coverage

• Total 1,197km2 Open Acreage – Jangeru & Taritip

• Muara Bakau PSC Awarded Dec 2002

• Highly Prospective Area. Recent Oil & Gas discoveries

• Amerada – 2 Gas Discoveries in Tangjung Aru - Lower Pliocene

• Unocal – Major Gas Discoveries with Significant Amount of Fluids Encountered in Upper Miocene

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Survey Planning

The Approach:Build representative 1D, “true” 2D, plane-layer 3D and “true” 3D models. Using the “full system response” of the 10 streamer vessel configuration, and for both “dip” and “strike” shooting, model all 3D issues.

The Challenge:Image steep dips, resolve various stratigraphic features, and ensure preservation of AVO, all without acquisition footprint effects

Analysis Examples

Standard DMO cross-line stack EDMO cross-line stack

Dip vs. Strike illumination of a dipping surface

CFP analysis of inline vs. cross-line resolution (PSDM result from a point diffractor)

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m/v Ramform Challenger

Makassar MC3D Acquisition ParametersRamform Challenger Streamer

No. of Streamers : 10Streamer Sep. : 100 mStreamer Length : 4500 mStreamer Depth : 7 mIn-line Offset : 300 m nominalNo. of Groups : 360 per streamerGroup Interval : 12.5 mGroup Length : 12.5 m

Data RecordingRecord Length : 8.0 sSampling Rate : 2.0 msLow-cut Filter : 3Hz / 12dB per OctaveHi-cut Filter : 206 Hz / 276 dB per OctaveFormat : 2 x SEG-D 8036, 3590 Cassette

(i.e. Dual Recording)

NavigationPositioning System 1 : Starfix Plus DGPSPositioning System 2 : Fugro Skyfix Premier DGPS Steered Group : Near-Mids

3D AcquisitionAcquisition mode : 10 streamers

2 sources

Line spacing : 25 mAcquisition bin length : 6.25 mAcquisition bin width : 25 m

Line orientation : 029/209 deg

Energy SourceShot Interval : 25.00 m flip/flopSub Array Separation : 12.5 mArray Separation : 50 mSource Type : Sodera G GunsAir Pressure : 2000 psiVolume : 2 x 3090 cubic inchNumber of Sub-arrays : 3 per array

Source Depth : 6m

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• Total 3600 channels• Total 45km of towed streamer sections• Total 900m spread width

Acquisition Layout – Ramform Challenger

C lient : PGS Pty. Ltd. Area : Makas sar B lock : M akas sar J ob number : 99031 / 62 Sta rt/E nd date : 09/06 – 22/09/99 21/10 – 12/12/99

Valid sequence : Fr om 01 to 220NB Off se ts vary until Seq 4

General Layout

48m'

Ref . p oin t

12.5m

R ef . point - centre sour ce : 320 m

100.0m

25.0 m

14m m

S 2T4S2T 5S 2T6

S 8T4

S3T 4S 3T5S 3T6

S9T 1S 9T2S 9T3

900.0m787.5m

TB 9

TB2

100.0m

S2T 1S2T 2S 2T3

TB 3

S3T 1S3T 2S 3T3

S7 T2S 7T3

T B8

S7T 1

Centre s our ce - centre 1 st grp = 255m

Centre sour ce - centre 1 st group= 337m (S9 same)

S8T 5S 8T6

S9T 4S9T 5S 9T6

S 4T6S 4T7 S4T 5 S 4T4

T B4

S4T 1S4T 2S4T 3

S 5T2S 5T3

TB 5

S 5T1S5T 4S 5T5S5T 6

S6T 2S6T 3

T B6

S 6T1S 6T4S6 T5S6T 6

Centre source - centr e 1s t group= 302m ( S8 same)

C entre source - centr e 1s t group= 276m

S1 0T4S 10T 5S 10T6

T B1 0

S 10T 1S 10T2S10T 3

S1 T4S 1T5S1T 6

TB 1

S1T 1S1T 2S1 T3

1500 float190m fromDiltf lo at

340m

239m

267m

30 0m

150 0 float190 m fromDiltfloat

S 7T 4 S7 T2S7T 3 S7T 1

TB 7

S7 T6S 7T7 S7T 5

C entre source - centr e 1 s t gr p = 263m

Centre sour ce - centre 1st

group= 365m (S10 same)


Makassar MC3D Acquisition – Production Statistics

0

5000

10000

15000

20000

TotalProduction

PrimeProduction

InfillProduction

Total Production Prime Production Infill Production

Prime Production

79%

Infill Production21%

Production / Line change /

Infill73%

Standby + Mob / Demob

14%

Technica l Downtime

13%

Production Kilometers

Production Timing Breakdown

S eism ic In terferenc e

4%

Mobilisa tion/Demobilisation

82%

Crew Change at Sea1%

Weathe r, Currents7% Fishing Activity

0% Obstruc tion6%

Standby-Mob/ DEMOB Timing Breakdown

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Examples Of Makassar MC3D 3D Data

Why 3D Surveys?




E X P L O R A T I O N S E R V I C E S

Water depth

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N

Present Day Depositional System

15 km

E X P L O R A T I O N S E R V I C E SUpper/Middle Miocene

Main prospects, discoveries

and fan complexes

Makassar MC3D Survey

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Gendalo top reservoir depth map

Gendalo 2

Gendalo 1


Gendalo Discovery, Upper Miocene fan-complex

Upper reservoir, 77m g/44m n

Lower reservoir, 22m net

NW SE

M.Miocene unc.

I.U.Miocene

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Muara Bakau depositional systems, Upper Miocene


Muara Bakau depositional systems, N.B.Pliocene

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6 km N.B.Pliocene,central part of block


Muara Bakau depositional systems

N.B.Pliocene,central part of block

N

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Muara Bakau, horizons interpreted (northern area)

M.Miocene unc.

Earle Pliocene

I. Upper Miocene

E./Middle Pliocene

NW SE


Muara Bakau, “Sidi and Segah” area

M.Miocene unc.

I.Upper Miocene

E.Pliocene

E./M.Pliocene

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Muara Bakau, middle part

I.Upper Miocene

N.B.Pliocene

M.Miocene unc.

E/Middle Pliocene

Early Pliocene


Tanjung Aru, I.Upper Miocene Depth map - upper slope prospect

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Tanjung Aru upper slope prospect

I.Upper Miocene


Tanjung Aru, shelf prospect, L.Pliocene/U.Miocene depth map

60 sq closure

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Tanjung Aru, shelf prospect




Why 3D Surveys?




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0

1000

2000

3000

4000

5000

6000

7000

Pre-1988 88-89 90-91 92-93 94-95 96-97 98-99

2D 3D

US$

Increased Rate of Investment in 3-D data as compared to 2-D


Investment Trends over the past 10 yearsInvestment Trends over the past 10 years

88-89 90-91 92-93 94-95 96-97 98-99

Land 2DLand 3D

Marine 2DMarine 3D

0

200

400

600

800

1000

1200

1400

1600Land 2DLand 3DMarine 2D

Marine 3D

US$

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0

20

40

60

80

1990 1991 1992 1993 1994 1995 1996

Year

Per

cent

age

Percentage of prospects covered by 3D

Percentage ExplorationSuccess Rate

Industry AverageSuccess Rate

World Class ExplorationSuccess Rate

From Aylor; Leading Edge1998

Industry Drilling Success Rates on 3D exceeding 40% Industry Drilling Success Rates on 3D exceeding 40% compared to 19% on 2Dcompared to 19% on 2D


Exploratory Well Success Rates

0102030405060

%

1987

1988

1999

1990

1991

1992

1993

1994

1995

1996

1997

YEAR

Source: Energy Information Administration

Success to a large degree caused by increased use of 3D data

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Growth in 3D Seismic Acquired Per Exploration Well(Offshore only, Ex-NSA. Source : Vessel Tracker, Petroconsultants)

020406080

100120140160180200

Sqkm

3D

per

wel

l

1994 1995 1996 1997


Australia: 3D versus 2D

Recent Analysis of Success in the Barrow Sub-basin shows drilling on 3D has a success rate of 1 in 2 wells and is more than double the success rate of drilling on 2D.

• Number of exploration wells : 53

• Number of wells drilled on 2D: 36

• Number of commercial fields on 2D: 5 (14% success rate)

• Number of wells drilled on 3D: 17

• Number of commercial fields on 3D: 9 (53% of success rate)

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3D Seismic Can Today Save 60% of Exploration3D Seismic Can Today Save 60% of ExplorationCosts by Improving Drilling Success RateCosts by Improving Drilling Success Rate

Assume - 20% success rate on 2D- 50% success rate on 3D - Drilling cost $4.0M per well

Drilling on 2D Drilling on 3D$4.0M X 5 wells $4.0M X 2 wells= $20.0M for one successful well = $8.0M for one successful well

3D seismic saves 60% of costs.

3D versus 2D

The Indonesian government often pays for failed drilling campaigns!


Drilling on 2D Drilling on 2D -- East Kalimantan ExampleEast Kalimantan Example

• 80 wells drilled (31/12/1999)• 41 new field wildcats• 7 commercial discoveries• Drilling success rate 17% (commercial success)• $5M cost per well• By drilling on 3D saves $100MM in drilling cost

(assuming 50% drilling success).

3D versus 2D

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•11 WELLS DRIILED;! 2 DISCOVERIES

•DRILLED ON 2D DATA!

•AMERADA HESS 100%DRILING SUCCESS ONTANJUNG ARUUSING 3D DATA.

3D versus 2D – Makassar MC3D Survey


Giram

•Giram drilled on 2Ddata, missed reservoir

Main prospects, discoveries and sub-

marine fans.

3D versus 2D – Makassar MC3D Survey

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Giram

THE WELL MISSED RESERVOIR!

Reservoirs


Benefits of 3D versus 2D seismic data

Mapped Prospect

Well 1

Line A

Line B

Line C

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Benefits of 3D versus 2D seismic data

•New production from Poleng;15000 BOPD (200% increase).

•Producing from a 1.1 sq km (1.5x0.7 km) reef; KE23B, Production 8000 BOPD.

Main reason for therecent drilling successis the 3D surveyM. Welker-Haddock, 2002.


East Java Sea Drilling On 2D

•Total of 50 exploration wells drilled; 15% drilling success(includes Bukit Tua, Payang, etc.)•All drilled on 2D

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Why 3D Surveys?





Multi-Client 3D Seismic SurveysFuture of the Geophysical Industry

What is MC3D?

• MC3D is a business model to enable large volumes of 3D seismic to be acquired economically.

• It usually requires an investment from the seismic contractor and the cooperation of oil companies and government.

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Key Benefits of MC3D

• Increases the number of potential investors in an area (information).

• Increases oil company investment in an area (information).

• Increases the overall investment in an area (seismic contractors subsidize exploration).

• Shortens the exploration cycle (information).

• Reduces the time to production increasing the EMV of projects (timing).

• Reduces overall costs of exploration (Risk).

• Optimises field development


Multi-Client Seismic Surveys - Definitions

Multi-Client data: Data owned (or brokered) by a geophysical or data company and licensed for a fee to E & P companies under a multi-client use license. Usually multi-client surveys have some level of prefunding. The cost is some fraction of the cost of creating the data.

Spec Shoot: A survey in which a contractor carries all the cost and risk. In the past these surveys were often acquired when conditions prevented proprietary specifications from being met and the contractor lowered data quality standards.

Group Shoot: A survey acquired for a group of E & P companies sharing the cost of the survey at market rates. The contractor may have a right to market data to third parties.

Non-Exclusive Data: Non proprietary data; however often used as a synonym for multi-client data or spec data.

Prefunding: License sales before or during acquisition.

Late Sales: License sales after the data have been acquired.

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Benefits of MC3D versus 2D seismic data

• Total 18,230km2 MC3D Contiguous Coverage

• Apache – 12 Wells in 2002 80% success. Monetize within 6 months with Existing Infrastructure.Previously 17% success on 2D data. 29 More Prospects to Drill with 60+ Additional Leads All Identified on PGS MC3D Data

• Santos – Recent Significant Oil Discoveries: Mutiny, Pitcairn, Exeter >80-120mmbbl Recoverable, higher than 50% success.

Australia: Australia: CarnarvonCarnarvonApache Analysis of Success on Apache Analysis of Success on the N.W. Shelf shows drilling on the N.W. Shelf shows drilling on 3D has dramatically increased 3D has dramatically increased the success rate compared to the success rate compared to drilling on 2Ddrilling on 2D

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Areal Efficiency of 3D Survey

26%35%

46%

65%70%

74%

0%

10%

20%

30%

40%

50%

60%

70%

80%

Effic

ienc

y

50 100 200 800 1200 2000

Area Sq Km


Seismic Aperture

100 sq km

AE = 35%

800 sq km

AE = 65%

Aperture is the same irrespective of survey size

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400 SQ KM 175

350

150225

175

100 KM

50 K

M

MC3D = 5000 SQ KM

Equal Cost for Six Proprietary 3D Surveys as for One Large MC3D Survey


Six Proprietary Programs:Cost of Cost of

Size Program Aperture Mob/Demob400 sq km $4.8M $96K $250K175 sq km $2.8M $1.0M $250K175 sq km $2.8M $1.0M $250K350 sq km $4.2M $84K $250K150 sq km $2.4M $1.0M $250K225 sq km $3.16M $1.0M $250K------------------------------------------------------------------------------------1475 sq km $20.16M $5.8M $1.5M

Total Cost = $27.5M

Equal Cost for Six Proprietary 3D Surveys as for One Large MC3D Survey

Large survey covering the basin:1 survey of 5,000 sq km at $5000/sq km is $25M + aperture ($3M) + mob/demob ($250K).

Total Cost is $28.0M

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Year 1 Year 2 Year 3 Year 4 Year 5 Year 6

License Awarded

2D Acquisition/Interp.

1st Expl Well

2nd Expl Well


Appraisal Wells

Commerciality Concl.

Using a traditional 2D approach (with a successful well) allows Commercial Production in Year 6


Year 1 Year 2 Year 3 Year 4 Year 5 Year 6

License Awarded


1st Expl Well

2nd Expl Well


Appraisal Wells

Commerciality Concl.

g y gAward Commercial Production can start < 3 Years after AwardImproved Expected Monetary Value (EMV) of the Project -

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0

10

20

30

40

50

60

70

0 50 100 150 200 250

Reserves MMBBL

Incr

emen

tal V

alue

$M

MIncremental NPVIncremental NPV

Reducing period between discovery and 1st Oil by 1 year Reducing period between discovery and 1st Oil by 1 year

Deepwater


MC3D benefits from larger 3D surveys

• Area interpreted on a basin wide/regional manner; better understanding of petroleum system, reservoir distribution, source rock distribution.

A typical individual 3D survey of 250 km2is inconclusive

A large 3D survey covering 1000 km2is also inconclusive

When amplitude extraction is carried out over 25000 km2 an entire submarine tertiary fan system is clearly outlined


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West Natuna MC3D

"

"

"

Pelican

Gajah Baru

Iguana

Naga

Premier 100% drilling success!


Brunei MC3D Survey

•MC3D initiated by PU•MC3D mandatory•11 IOC bought data

•More oil companies getinvolved in area evaluation•More geological ideas, moreprospects identified.•More competitive bidding.

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Baram and Brunei Bay Drainage Systems

Water bottom absolute amplitude extraction

N


East Java Sea HD-MC3D Survey, INDONESIA

East Java Sea HDMC3D - 3,963km2

! 3D Survey Positioned Over Most Prospective Open Blocks

! High Density 3D Required for Detailed Interpretation of Complex Reservoirs.

! Acquisition Completed – February 2003

! 12 Str. X 3.6km X 62.5m sep 12.5m SP int. DS 15.625m X 12.5m Bins, 72 Fold

! Pre-Stack Time Migration Processing

! Final Data Now Available

! MIGAS Will Offer N. & NE Tanjung LapakBlocks in 4th Round - Sept/Oct 2003 with 6 Month Evaluation Period Prior to Close of Bids – March/April 2004

! Improved PSC terms:

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East Java MC3D Survey - Kujung I Reef – HoloSeis Map


East Java MC3D Survey - Upper Kujung Reef Map

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Top Kujung Reef – MC2D Grid Superimposed


2X2 km 2D seismic coverage East Java Sea example

Approx. 2 km seismic grid

Complicated reservoirgeometries

Cannot be mappedon 2D data.

CNOOC/KUPFEC are producingfrom a 1 sq km reef!

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MC3D Benefits for IndonesiaMC3D Benefits for Indonesia

• More oil companies get involved in area evaluation (Brunei 11 companies!).

• East Java fiscal terms are regarded tough.

• Increased prospectivity understanding = MORE BIDS

• 3D commitment fulfilled on award, having all advantages of 3D immediately upon block award. (Optimizing exploration and development drilling, etc)

• Accelerate time to first oil, with large corresponding increase in NPV.

• Shortening the time to first oil by even 1year can significantly increase the NPV of a field.


MC3D Benefits for IndonesiaMC3D Benefits for Indonesia

• Apache discoveries on NW shelf Australia in production 6 months after discovered.

• More drilling prospects are identified, prospects can further be interpreted beyond lease boundaries and in the context of the geology covered by the large MC3D surveys.

• More geological ideas are generated in area evaluation.

• 3D coverage is available for all prospects within a block prior to drilling and more prospects are drilled in a shorter time.

• The success rate of exploration and appraisal wells is increased (more than double).

• The placement and number of production wells isoptimized.

• Production facilities can be optimized including planning for nearby marginal fields.

•Lower Exploration costs.•The time to production is often shortened by two years.

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Why 3D Surveys?




PGS Research

Drivers for Geophysical Companies

• Technologies for E & P • That are cost effective and efficient• Reduce the E & P cycle

• Focus of Oil Companies today is:• Near field exploration• Deepwater exploration

• Focus on technologies related to:• Reservoir evaluation and production• Deep water E & P

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PGS Research

• Narrow streamer tow

• Wide streamer tow

• Alternating sail lines

• Alternating end-on shooting

• Overlap sail lines

• Alternating overlap sail lines

• Orthogonal sail lines

• Overlapping/alternating orthogonal sail lines

• Decoupled source vessel scenarios

Possible 3D Shooting Scenarios for Streamer Seismic

PGS Research

Innovative Acquisition

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PGS Research

VARG2002 shooting directions

7S

4

6S5

8,8A

9S

10SVarg A

Varg South

Fleming

12

Norwa y

UK

Existing survey - 90/270°

30/2

10°

150/330°

PGS Research

VARG2002 NW-SE shooting directionP G S G E O P H Y S I C A L

001° 50' E 002° E

58° N

58° 10' N

430 000 m 440 000 m

6 430 000 m

6 440 000 m

422 000 m 445 000 m

6 420 000 m

6 450 000 m

16/24b

16/29a

16/29aF1

16/29c

16/29e

22/4a

22/4aX 1

22/5aX 122/5b

22/5bX 1

6/3

15/12a

15/12c

001° 50' E 002° E

58° N

58° 10' N

430 000 m 440 000 m

6 430 000 m

6 440 000 m

422 000 m 445 000 m

6 420 000 m

6 450 000 m

Petrojarl

VARG A

60086024

60406056

60726088

61046120

61366152

61686184

62006216

62326248

62646280

62966312

63286344

63606376

63926408

64246440

64566472

64886504

ARMADA

Norway

UK

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PGS Research

VARG2002 NE-SW Shooting directionP G S G E O P H Y S I C A L

001° 50' E 002° E

58° N

58° 10' N

430 000 m 440 000 m

6 430 000 m

6 440 000 m

422 000 m 445 000 m

6 420 000 m

6 450 000 m

16/24b

16/29a

16/29aF1

16/29c

16/29e

22/4a

22/4aX 1

22/5aX 122/5b

22/5bX 1

6/3

15/12a

15/12c

1008

1024

1040

1056

1072

1088

1104

1120

1136

1152

1168

1184

1200

1216

1232

1248

1264

1280

1296

1312

1328

1344

1360

1376

1392

1408

1424

1440

1456

1472

1488

1504

1520

1536

001° 50' E 002° E

58° N

58° 10' N

430 000 m 440 000 m

6 430 000 m

6 440 000 m

422 000 m 445 000 m

6 420 000 m

6 450 000 m

Petrojarl

VARG A

ARMADA

Norway

UK

PGS Research

Previous PSDM of ST8802 (E-W shooting direction)P G S G E O P H Y S I C A L

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PGS Research

VARG2002 all three directions combinedP G S G E O P H Y S I C A L

PGS Research

VARG2002 Final PSDM stack: East-West only

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PGS Research

VARG2002 Final PSDM stack: All 3 directions combined

PGS Research

• Artifact-free seismic imaging requires perfect surface andsubsurface sampling in the common shot, receiver, offset, azimuth, and CMP domains (in fact, the 5D wavefield of shot and receiver positions, plus travel time, is what must be perfectly sampled).

• Conventional 3D seismic acquisition historically neglects to sample more than one or two of these domains, and typically fails to embrace some kind of universal philosophy for optimal sampling

• The following arguments use Vermeer’s (1998) 3D symmetric sampling (3DSYMSAM) criteria and the “minimal data set” (MDS) criteria as the foundation for discussion

• The motivation is to provide the best possible acquisition platform for a low noise PSM data set that is alias-free

Sampling

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PGS Research

50 m Shot Interval (flip - flop shooting)

PGS Research

25 m Shot Interval (Standard 2D )

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PGS Research

12.5 m Shot Interval (meets sampling theory)

PGS Research

Sampling considerations

• Nigel Anstey (1986) famously proposed the “stack array” concept, where the shot interval = 1/2 group length

• Gijs Vermeer (1990) extended this idea to his “ 2D symmetric sampling” concept, wherein source array length = receiver array length = shot interval and 1998 to “ 3D symmetric sampling”

• This is the optimal acquisition method (land and marine) for suppressing unwanted noise leaking through the stack

• Historically, this has not been done (economic reasons mainly)

• Now, latest acquisition technology can approach satisfying these criteria (technically and cost effectively)

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PGS Research

3D Symmetric Sampling Theory (Vermeer, 1998)

• Shot interval = receiver interval

• Shot line interval = receiver line interval

• Need shot and receiver arrays

• Symmetric source array design

• Sample the midpoint line and the distance between the midpoint lines without aliasing

PGS Research

Progress in 3D seismic vessel streamer capacity

Streamers: 3 4 5 6 8 10

First achieved: 1991 1992 1993 1994 1995 1996

Streamers: 12 14 16

First achieved: 1997 1999 2001

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PGS Research

Ideal 3D pre-stack sampling with the source location in the center of a grid of receiver locations, i.e. for every shot we have a uniform offset distribution for all azimuths.

Orthogonal geometry:

Maximum inline offset = maximum cross-line offset

5D Wavefield Sampling

PGS Research

HD3D Single source acquisition

700m

750m

Conventional 8 Streamer

16 Streamer High Density

4500m

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PGS Research

HD3D - Spatial sampling, Fold and Efficiency

D E N S ED E N S EM E D I U MM E D I U MC O A R S EC O A R S E

L O WL O W M E D I U MM E D I U M H I G HH I G H

S P A T I A L S A M P L I N G(Closer streamers)

F O L D (Single source vs. dual source)

Direct impact on reservoir resolution

Direct impact on data Signal-to-Noise ratio

PGS Research

Advantages of single source shooting

• Shot interval is halved (improved spatial sampling)

• CMP fold is doubled

• 40% improvement in S/N ratio

• Source array control becomes more flexible– Centrally deployed from vessel

– Regular energy output for all sublines

– Output can be substantially varied or increased (if required)

• Processing is improved

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Benefits of reduced shot interval

• Better spatial sampling in the inline direction– Higher recoverable frequencies– Better resolution of dipping events– Less aliasing and associated processing noise

• Greatly reduced requirement for Shot Interpolation during processing– Better preservation of dipping events and subtle stratigraphic

features for input into processes such as Radon demultiple

PGS Research

Data improvement with single source acquisition

DTW2000SKHN99

Continuity, Amplitudes, Resolution

dual Single

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Data improvement with single source acquisition

DTW2000SKHN99

Single sourceDual source

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Improved resolution with single source dataNam Con Son Basin, Vietnam

Courtesy of BP

Single source

Dual source

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HD3D with Single Source - Summary

• Denser sampling = improved imaging• Improved performance in data processing = improved imaging• Fewer acquisition artefacts = improved imaging

Why Single Source?

Tool for Reservoir Seismic (4D)Exploration Tool in Complex Areas

Tool for Improving the imaging of shallower targets

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Azimuths for Parallel and Anti – Parallel shooting

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Parallel multistreamer: COV PSDM vs. TA PSDM

Gesbert, 2002

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Anti-parallel multistreamer: COV PSDM vs. TA PSDM

Gesbert, 2002

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Malampaya HD-MC3D 2002 versus 1991 Acquired 3D

Original 1991 3D Survey New 2002 High Density MC3D Survey

Malampaya Gas Field – NW Palawan, PhilippinesComparison of the New High Density MC3D Survey Acquired in 2002 versus the

Original 3D Survey Acquired in 19914 Streamers at 100m separation 25m Dual Source 12 Streamers at 50m separation 18.75m Dual Source

Anti-Parallel Shooting

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Brunei 3D Dip vs. Strike Illumination Study

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Streamer Technology Development

Past: More streamers (wider)

Current: More receivers & sources (inline)

Future?: Denser cross-line sampling

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3D Symmetric Sampling - Overlap Shooting

1000m

100 % overlap shooting will double the sail lines and also double the fold

3 sail lines

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• A 2D simulation of 3D cross-line imaging indicates that shooting with a large streamer spread width, and 100% overlap, reduces the footprint and possibly increases the imaging quality of dipping events

• If the spatial sampling is tight in the cross-line direction, imaging quality is improved

Hoffmann et al. (SEG, 2002)

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10 streamers 20 streamers

20 streamers Overlap

Offset range:

0 - 3200 m

Offset bin size: 100 m

Number of Offset Bins Covered

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4D Azimuth Preservation by Overlap Shooting

single source/8 streamer, no overlap single source/12 streamer, 50% overlap

4D Azimuth Difference @ 1100m [degree]

Overlap in combination with shot line repetition allows to remove the significant 4D azimuth mismatches across the sail line boundaries.

PGS Research

4D Azimuth Differences at Near Offset

FIELD_Bconventional trace selection

FIELD_Bazimuth constrained trace selection

0 degree

Greenareashave aperfectazimuthmatch!

azimuth mismatchat sail line boundaries

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Previous survey Overlap Shooting

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• Overlap shooting improves illumination and coverage

• Real data example shows improvements in image quality

–Better definition of faults

–Overall improvements in signal-to-noise ratio

• Overlap shooting significantly reduces the need for infill

Rekdal et al. (EAGE, 2002)

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Recommendations for optimal shooting

• Better sampling and illumination can be achieved by:

• 3D Symmetric Sampling

• shooting single source

• shooting in the strike direction

• alternative sail line shooting

• overlap shooting

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OVERALL:

• Centre source optimizes illumination, optimizes azimuth distribution, automatically generates COV gathers, but halves the maximum offsets

• Overlap shooting improves illumination, and halves the near offsets and azimuthal variation

• Alternating shooting improves azimuth distribution and illumination

• Orthogonal shooting improves illumination, and improves azimuth distribution

Shooting Summary

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Thank You

Data Acquisition in Kutei Basin - CCOP · 5000 6000 7000 Pre-1988 88-89 90-91 92-93 94-95 96-97...

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Transcript of Data Acquisition in Kutei Basin - CCOP · 5000 6000 7000 Pre-1988 88-89 90-91 92-93 94-95 96-97...