play analysis methodology

Dr. Alfred Kjemperud1

Dr. Alfred Kjemperud

1

Play Analysis Methodology

Dr. Alfred KjemperudThe Bridge Group AS



2

Definitions

• Petroleum system.– A group of plays within a given geographical

area having a common source rock.

• Play.– A geographically and stratigraphically

delimited area where common geological factors exist in order that petroleum accumulation can occur.

• Prospect.– A potential petroleum trap.– With a mappable reservoir rock volume.



3

Petroleum system

Reservoir/Seal distribution

ature

Play 2 (confirmed)Play 1

(unconfirmed)

Source Rock Distribution

Field/Discovery

Prospect

Geographical extent of Petroleum System

Limit of mand active Source

Modified from R. Birtles, 2000



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Level of Knowledge

Delphi and Analogue methodsNone or very little exploration has taken place in the basin. No or little seismic exists.

Very Low

PlaysPlay analysis level C

Little exploration has taken place. No plays are confirmed. Onlya few regional seismic lines or a very coarse grid of 2D seismic exists

Low

Plays and ProspectsProbabilistic prospect analysisPlay analysis level C

The basin is moderately explored. At least one play is confirmed, but most plays are unconfirmed. Only 2D seismic data exists outside of the discoveries

Moderate

New fields and discoveriesProbabilistic volumetric calculationsPlays and ProspectsProbabilistic prospect analysisPlay analysis level B

The basin is well explored and has several discoveries. Most of the plays are confirmed, but some are still unconfirmed. Some 3D seismic surveys exist outside of the discoveries and the 2D grid is dense.

The success rate is on an increasing trend

High

Mature fieldsMaterial balanceDecline analysisNew fields and discoveriesQuantitative Reservoir Simulations.Probabilistic volumetric calculationsPlay and ProspectsProbabilistic prospect analysisPlay analysis level A

The basin is very well explored and has a multitude of discoveries in all plays. Most plays are regarded as mature but some will be regarded as emerging. A large proportion of the basin is covered by 3D seismic.

The success rate is on a decreasing trend

Very High

MethodologyBasin DescriptionLOK



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Play Analysis Level

The analysis is based on a poor understanding of the basin.Structure maps are not available. The areal distribution of source and reservoir are estimated based on

key seismic lines and wells.Single well basin modeling make up the basis for maturation profiles. Migration pathways are

estimatedThe estimation of the average prospect size and the total number of prospects are based on data from

analogue basin

C

The analysis is based on a good to fair understanding of the basin.Simplified structure maps of the major source rock and reservoir intervals are availableSeveral 1D basin models make up the basis for maturation profiles.Migration pathways are estimatedThe estimation of the average prospect size and the total number of prospects are based on data from

the basin

B

The analysis is based on a very good understanding of the basin.Structure maps are available for the main source intervals and reservoir intervals.Quantitative basin modeling (3D or 2D or a grid of 1D well and pseudowell analysis) makes up the

basis for maturation profiles and hydrocarbon migration paths.The play area is known and can be calculated with high confidence.The estimation of the average prospect size and the total number of prospects are based on data from

the basin.

A

DescriptionPlay analysis level



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Play Families and Plays

• Play Families– Identified by first order processes

• Extentional tectonism• Compressional tectonism• Depositional processes• Basin compaction

• Play–Unique closure generating process

Modified from Duff and Hall 1996



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Compressional ThrustAN-1: Shallow long wavelength anticlines independent of faults or thrust planeAN-2: Thrust fault dependant anticlinesAN-3: Deep-seated, steep buckle folds near detachment surfaceAN-4: Inverted autochthon



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Reef Build-up

RB-1: Reef build-up with associated depositsRB-2: Calciclastic gravity flow deposits



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Extentional BlockFB-1: Reservoir in hanging wall block juxtapositioned to sealing rock in footwallFB-2: Pinch out inverted by block faultingFB-3: Erosional products from crest of fault blockFB-4: Drape above fault block creating 4-way closureFB-5: Truncated fault block



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Basement Drape

BD-1: Four-way closure (anticline) draping basement high



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Mud diapir

MD-1: Diapir induced anticline. Trap independent of faultingMD-2: Diapir induced normal faults crucial for trappingMD-3: Closure created by drag along diapir wallMD-4: Pinch out inverted by mud flowMD-5: Gravity flow deposits induced by diapir movement



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Stratigraphic plays

Subfamily: Shallow deposits (s)STs-1: Fluvial channel depositsSTs-2: Deltaic depositsSTs_3: Shelfal deposits (bars)

Subfamily: Deep deposits (d)STd-1: Proximal turbidite pinch outSTd-2: Basin floor turbidite mound

STd-3: Distal turbidite pinch out



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Play Fairway

• The play fairway is the area within the basin where the specific geological attributes necessary for the existence of a hydrocarbon accumulation exist.

• The extent of the play fairway is initially determined by the depositional or erosional limits of the gross reservoir rock

and then modified by other play elements



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Common Risk Segment Mapping

The probability that the attribute is present and effective in the area is low (0.4-0.0, high risk)

Red

The probability that the attribute is present and effective in the area is moderate (0.6-0.4)

Yellow

The probability that the attribute is present and effective in the area is high (1.0-0.6, low risk)

Green

DescriptionColour



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CRS Risk

Further data which strengthen the model prediction to “Play/prospect will probably be denied by drilling”0.0-0.2

High risk(red)

Sufficient data on which to base a model which predicts that model may possibly be denied by subsequent data acquisition, including drilling

0.2-0.4

Moderate risk (yellow)

Little or no available data on which to base a model. Play/prospect may be proved valid or invalid with equal likelihood.

0.4-0.6

Sufficient data on which to base a model which predicts that play/prospect may possibly be affirmed by subsequent data acquisition, including drilling

0.6-0.8

Low risk(green)

Further data which strengthen the model prediction to “Play/prospect will probably be affirmed by drilling”0.8-1.0

Qualitative risk assessment

(CRS maps)Description

QUANTITATIVE PROBABILITY

RANGE



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Common Risk Maps (CRS)Reservoir presence Effective reservoir

Grant et al. 1996



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CRS mapsCharge Top Seal

Grant et al. 1996



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Composite Common Risk Segment Map (CCRS)

Grant et al. 1996



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Play Fairway Map

Grant et al. 1996



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Area for area-number factorcalculation (high LOK)n = no.of mapped P&L/area

Green area (Prob.: 0.6-1.0)Max. no. P&L = Area * n * 1.0Mean no. P&L = Area * n * 0.8 Min. No. P&L = Area * n * 0.6

Yellow area (Prob.: 0.4-0.6)Max. no. P&L = Area * n * 0.6Mean no. P&L = Area * n * 0.5 Min. no. P&L = Area * n * 0.4

Total no.of P&LNo. in green area + No in yellowarea

Prospect

Lead

Seismic lines

Calculation of P&L number



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Play Analysis in GeoXNumber of prospects



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Prospect volume

• The value of the largest known prospect or discovery in the play can be plotted at 0.1% cummulative probability

• A reasonable economic minimum size canbe plotted at 95% cummulative probability



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Lognormal Probability Plot

5025 75 90 99 99.910510.1

1

10

100

AreaVolum

e

Exp

ecte

d(P

50)

95

To be entered into GeoX.Area of closure (directly)Reservoir thickness = Rock Volume/Areaof closure

(Can be entered as 7 fractiles or as a predefined statistical distribution)



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Prospect volume



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Field sizesField Sizes

1

10

100

1000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Field No.

Field Size

Ranked Field Size

Fractile %

1 140 200 8.3 %2 22 140 16.7 %3 45 105 25.0 %4 8 75 33.3 %5 15 60 41.7 %6 200 45 50.0 %7 12 30 58.3 %8 30 22 66.7 %9 105 15 75.0 %

10 60 12 83.3 %11 75 8 91.7 %11 Av. 65

Fractile %= Field #/(No. of fields+1)



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Exercise 1

Field No.

Field Size

Arranged by size Formula*

Fractile (%)

1 1502 203 404 55 156 3207 108 309 90

10 5511 70

• Make a field size distribution plot on lognormal probability paper based on the field sizes given to the right (numbers in million bbl)

• What is the average field size?

• What is the median (P50) field size?

• What is the chance of finding at least a 100 million bbl field given a 25% success ratio?

* Formula: Rank number/Number of fields+1



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Solution 1

No of Fields

Field Size

Ranked Field Size

Fractile %

1 150 320 8,3 %2 20 150 16,7 %3 40 90 25,0 %4 5 70 33,3 %5 15 55 41,7 %6 320 40 50,0 %7 10 30 58,3 %8 30 20 66,7 %9 90 15 75,0 %

10 55 10 83,3 %11 70 5 91,7 %

• Average Field Size = 73

• Median Field Size = 40

• Probability of Success = 6.5%



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Overall features



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Play Analysis in GeoX



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Reservoir equations



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Oil FVF vs. DepthOil FVF vs. depth

(Oil density sensitivity)

1.00

1.20

1.40

1.60

1.80

2.00

2.20

2.40

250

500

750

1000

1250

1500

1750

2000

2250

2500

2750

3000

3250

3500

3750

4000

4250

4500

4750

5000

5250

5500

5750

6000

6250

6500

6750

7000

Depth (m)

Bo

303540

Oil gravity (degr. API)

Gas gravity: 0.7Temp. Grad.: 3 degr C/100m

Vasquez-Beggs Equation (JPT, June 1980)(Oil gravity > 30 degr. API)



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GOR vs. DepthGOR vs. depth

(Oil density sensitivity)

0

50

100

150

200

250

300

350

400

450

250

500

750

1000

1250

1500

1750

2000

2250

2500

2750

3000

3250

3500

3750

4000

4250

4500

4750

5000

5250

5500

5750

6000

6250

6500

6750

7000

Depth (m)

GO

R (m

3/m

3)

403530

Degr. API

Gas gravity: 0.7Temp. Grad.: 3 degr C/100m

Vasquez-Beggs Equation (JPT, June 1980)

(Oil gravity > 30 degr. API)

Max

Mode

Min



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Play Analysis in GeoX



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Trap geometric multiplier

play analysis methodology

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