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La Cira Case StudyGP170/2001 #8

Tectonic map of Colombia

La Cira - Infantas Oil Field:•Discovered in 1918•OOIP: 3490 MMBO•1742 wells•Production: 721 MMBO•Recovery factor (20%)

2100 150

600

800

1000

1200

1400

1600

1800

2000

2200

GR

Dep

th (ft

)

1879

0 0.5 1Sw

1879

60 80 100120

800

1200

1600

2000

2400

2800

3200

GR

Dep

th (ft

)

1880

0 0.5 1Sw

1880

60 80 100120

500

1000

1500

2000

2500

3000

GR

Dep

th (ft

)

1882

0 0.5 1Sw

1882

Reason for Low Recovery Rate -- Heterogeneity

4 6 8Ip

1879

4 6 8 10Ip

1880

4 6 8 10Ip

1882

GP170/2001 #8

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Geological Heterogeneity is Accompanied by Acoustic Heterogeneity

0 0.5 1

4100

4200

4300

4400

4500

4600

4700

Vsh and Sw

Dep

th (ft

)

1757

0 0.5 1

4300

4350

4400

4450

4500

Vsh and Sw

Dep

th (ft

)

1757

3.0 3.5 4.0Vp (km/s)

1757

3.0 3.5 4.0Vp (km/s)

1757

0 0.5 1

4500

4550

4600

4650

4700

4750

Vsh and Sw

Dep

th (ft

)

1757

3 3.5 4Vp (km/s)

1757

Reservoir heterogeneities compartmentalize reservoirsinto flow units of variable lateral and vertical extent,preventing efficient drainage and sweep of reservoirs

Classification of reservoir heterogeneity types(Weber, 1993).

Deposition Diagenesis Deformation

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Reservoir Heterogeneity

• Fieldwide scale• Interwell scale• Well-bore scale

Levels of reservoir heterogeneity (Weber, 1986 and Slatt et al., 1993)

(From “Infield natural gas reserve growth - Concepts andtechnologies for reserve appreciation”, BEG )

GP170/2001 #8

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Lithofacies and Permeability

Major types of geological and petrophysical data applied to flow unit zonation of a well (Ebanks et al. 1993 )

0.1

1

10

100

1000

0.1 0.2 0.3

Per

mea

bilit

y (m

D)

Porosity

LC 1880 + 1891

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Fault-Related Heterogeneity

Normal Faults

GP170/2001 #8

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E

N

Isometric Projection of Velocity Strata SliceParallel to B4 Seismic Marker

35 ms (Two-Way-Travel-Time) Below B4

La Cira Norte

Seismic Image of Reservoir -- La Cira NorteGoal -- Transform Seismic Image into Lithology

Rock Physics’ Task -- Translate SeismicImages into Reservoir Property Images

GP170/2001 #8

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Large-Scale Rock PhysicsGP170/2001 #8

2.1

2.2

2.3

2.4

2.5

2.6

50 75 100 125 150 175

RH

OB

GR

188218801879

4

6

8

10

50 75 100 125 150 175

P-I

mped

ance

GR

188218801879

0

0.1

0.2

0.3

0.4

50 75 100 125 150 175

Por

osit

y

GR

188218801879

0.2

0.3

0.4

50 75 100 125 150 175

Poi

sson

's R

atio

GR

1882

4

6

8

10

0 0.1 0.2 0.3

P-I

mped

ance

Porosity

188218801879

0.2

0.3

0.4

0 0.1 0.2 0.3

Poi

sson

's R

atio

Porosity

1882

0.2

0.3

0.4

5 6 7 8 9

Poi

sson

's R

atio

P-Impedance

1882

9

0.2

0.3

0.4

5 6 7 8 9

Poi

sson

's R

atio

P-Impedance

1882

5 6 7 8 9

P-Impedance

1882

>2984 ft

5 6 7 8 9

P-Impedance

1882

>1851 ft< 2026 ft

5 6 7 8 9

P-Impedance

1882

>2984 ft

>1851 ft< 2026 ft

1.0 1.5 2.0

Vs (km/s)

1882

50 75 100

1800

2000

2200

2400

2600

2800

3000

GR

Dep

th (ft

)

1882

0 0.5 1

Sw

1882

2 3 4

Vp (km/s)

1882

4 6 8 10

P-Impedance

1882

0.2 0.3 0.4

Poisson's Ratio

1882

0 0.1 0.2 0.3

Porosity

1882

Effect of Depth on P/S PropertiesGP170/2001 #8

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Effect of Depth on P-Impedance

4

6

8

10

0 0.1 0.2 0.3

P-I

mped

ance

Porosity

1882

50 60 70 80 90 100 110 120

430

435

440

445

GR

Dep

th (ft

)

50 60 70 80 90 100 110 120

1530

1540

1550

1560

GR

Dep

th (ft

)

50 60 70 80 90 100 110 120

3154

3156

3158

3160

3162

GR

Dep

th (ft

)

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2 2.5 3 3.5 4Vp (km/s)

Rock Physics Observations and Transforms

3

4

5

0 0.1 0.2 0.3

0 < Clay < 5%10% < Clay < 20%25% < Clay < 35%

P-W

AW

E V

ELO

CIT

Y (km

/s)

POROSITY2

Consolidated SandstonesDRY at 40 MPa

Why does not shale content affectimpedance-porosity trend in La Cira?

GP170/2001 #8

0 0.2 0.4 0.6 0.8 1

2850

2900

2950

3000

3050

Sw and VSHALE

DR

KB

(ft

)

LC 1880

Sw

VSHALE

4

5

6

7

8

9

10

0 0.2 0.4 0.6 0.8 1

LC 1880: Below 2800 ft DRKB

P-I

mped

ance

VSHALE

S A N D SHALE

0

0.1

0.2

0.3

0 0.2 0.4 0.6 0.8 1

PO

RO

SIT

Y

VSHALE

4

5

6

7

8

9

10

11

0 0.1 0.2 0.3

P-I

MPE

DA

NC

E

POROSITY

Expectedtrend

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Core Data: Shale is not ClayGP170/2001 #8

1

2

3

4

5

6

7

0 0.1 0.2 0.3

Is (km

/s

g/cm

3) at

10 M

Pa

Porosity

Dry Rock

SAND

SHALE

4

6

8

10

12

0 0.1 0.2 0.3

Ip (km

/s

g/cm

3) at

10 M

Pa

Porosity

Dry Rock

SAND

SHALE

SAMPLES FROM SHALY ZONESSample ID Porosity Quartz Clay Feldspar Calc+Dolom Other1880/2443' 0.033 0.610 0.290 0.080 0.000 0.0201882/2743' 0.037 0.470 0.190 0.030 0.290 0.0201879/1852' 0.054 0.720 0.260 0.010 0.000 0.0101880/2452' 0.057 0.650 0.250 0.070 0.000 0.0301882/2971' 0.061 0.560 0.240 0.110 0.050 0.0401880/2457'10" 0.062 0.620 0.150 0.180 0.050 0.0001880/2454' 0.062 0.660 0.240 0.060 0.020 0.0201882/2612' 0.069 0.720 0.250 0.020 0.000 0.0101880/2439' 0.073 0.680 0.220 0.090 0.000 0.0101880/2417' 0.084 0.660 0.210 0.130 0.000 0.0001879/1868' 0.091 0.650 0.320 0.020 0.000 0.0101879/1923' 0.091 0.760 0.190 0.030 0.000 0.0201879/1826' 0.092 0.770 0.150 0.060 0.000 0.0201880/2432'4" 0.093 0.660 0.270 0.050 0.010 0.0101879/1872' 0.103 0.660 0.180 0.140 0.000 0.0201880/2399' 0.106 0.570 0.200 0.040 0.170 0.0201879/1919' 0.106 0.830 0.150 0.010 0.000 0.0101879/1871' 0.116 0.680 0.180 0.120 0.000 0.0201879/1805' 0.131 0.680 0.110 0.210 0.000 0.0001879/1877' 0.137 0.720 0.140 0.120 0.010 0.0101879/1902' 0.178 0.820 0.100 0.080 0.000 0.000

0 0.2 0.4 0.6 0.8 1

1800

1850

1900

VSHALEPOROSITYCLAY

Porosity, Clay, VSHALE

DR

KB

(ft

)

LC 1879

13

4

5

6

7

8

9

10

11

0 0.1 0.2 0.3

P-W

ave

Imped

ance

Total Porosity

SHALE

SANDSANDCHANNEL

SHALE

“Rough” InterpretationGP170/2001 #8

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B4 - 20 ms

B4 - 10 ms

“Rough” Interpretation of Images

GP170/2001 #8

0 0.5 1

3600

3700

3800

3900

4000

4100

4200

VSHALE

Dep

th (ft

)

1783

50 100 150GR

1783

B4

15

B4 - 5 ms

B4

“Rough” Interpretation of Images

GP170/2001 #8

0 0.5 1

3600

3700

3800

3900

4000

4100

4200

VSHALE

Dep

th (ft

)

1783

50 100 150GR

1783

B4

16

“Rough” Interpretation of Images

GP170/2001 #8

B4 + 5 ms

B4 + 10 ms

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Careful Rock Physics

GP170/2001 #8

3

4

5

6

7

8

9

10

11

0 0.1 0.2 0.3

P-I

mped

ance

Porosity

1880

3

4

5

6

7

8

9

10

11

50 75 100

P-I

mped

ance

GR

1880

50 75 100 125

1500

2000

2500

3000

GR

Dep

th (ft

)

1800

60 70 80 90

2560

2565

2570

2575

2580

2585

2590

GR

Dep

th (ft

)

1800Select

0.1 0.2Porosity

1800Select

6 7 8P-Impedance

1800Select

0 0.5 1Sw

1800Select

Sonic data are from invaded formation

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Rock Physics Diagnostic

GP170/2001 #8

3

4

5

6

7

8

9

10

11

0 0.1 0.2 0.3

P-I

mped

ance

Porosity

1880

Brine

Oil

Gas

Cement

3

4

5

6

7

8

9

10

11

0 0.1 0.2 0.3

P-I

mped

ance

Porosity

1880

Brine

Clean(80% Quartz + 20% Feldspar)

Clean(20% Quartz + 20% Feldspar

+ 60% Clay)

0.1

0.2

0.3

0.4

5 6 7 8 9

Poi

sson

's R

atio

P-Impedance

Cleanw/Gas

Cleanw/Oil

Cleanw/Water

Clayw/Water

Effective-Medium Models

Elastic-Acoustic Impedance Transform for porosity cube

0

0.1

0.2

0.3

3 4 5 6 7 8 9

Por

osit

y

P-Impedance

Brine

Oil

Gas

Clay/Brine