9th EuroConference on Rock Physics and Geomechanics, Throndheim,

Norway, October, 2011

Dynamic and Static Rock Mechanical

Properties of Heavy Oil Sandstones

Claudio Rabe – Baker Hughes

Jose Odreman Cherrez - PDVSA

Goals of Investigation

– This study investigates the effects of geomechanics on SAGD

operations in the Orinoco Oil Belt in order to obtain a better

perspective of the process

– Identify the effect of high viscosity/temperature in the rock

characterization.

Introduction

Steam Assisted Gravity Drainage (SAGD)

High lateral and verticaldisplacement due toThermal Expansion

High Thermal stress and different drainage condition

Introduction

Outside the steam chamber Inside the

steam chamber

Schimmitt D 2005

Laboratory Characterization

Mineral Percentage Sandtone - Microstructure

Mineral

Percentage

Quartz 95 %Course-23% %Medium-46% %Fine-26%

kaolinite 2.0

Albite 1.0

Muscovite <1

siderite <1

Poly-crystalline quartz with fine grains materials loose from the fine matrix. Poly-crystalline quartz present to be over-grows.

Thin Section

Sands of poor packing, Very loose and Primary poral space well developed. Low content of clay minerals. No expansible clay minerals was detected

Porosity-Permeability Analysis

25.0

27.0

29.0

31.0

33.0

35.0

37.0

39.0

41.0

300 500 700 900 1100 1300 1500 1700

Pressure (psi)

Por

osity

(%

)

20.0

25.0

30.0

35.0

40.0

2500 3500 4500 5500 6500

Depth (ft)

In-s

itu P

oros

ity (%

)

0

1000

2000

3000

4000

5000

6000

7000

Per

mea

bilit

y (m

D)

Porosity

Permeability

Linear (Porosity)

Bulk Compressibility – Porosity - Permeability

Analysis

0

2

4

6

8

10

12

14

16

18

20

05001000150020002500

Reservoir Pressure (psi)

Bul

k C

ompr

essi

bility

x 10

-6 1

/psi

LS1

LS3

LS7

LS8

LS10

20.0

25.0

30.0

35.0

40.0

3000 3100 3200 3300 3400 3500 3600 3700 3800

Depth (ft)

In-s

itu P

oros

ity (%

)

0

1000

2000

3000

4000

5000

6000

7000

Per

mea

bilit

y (m

D)

Porosity

Permeability

20.0

22.0

24.0

26.0

28.0

30.0

32.0

5900 6000 6100 6200 6300 6400 6500 6600 6700

Depth (ft)

In-s

itu

poro

sity

(%

)

0

1000

2000

3000

4000

5000

6000

7000

Per

mea

bilit

y (m

D)

Porosity

Permeability

Young's Modulus

0

1000000

2000000

3000000

4000000

5000000

6000000

0 500000 1000000 1500000 2000000

Dynamic Modulus (psi)

Est

atic

Mod

ulus

(ps

i)Triaxial Test Campaign

Poisson's Coefficient

0.200

0.250

0.300

0.350

0.400

0.450

0.500

0.550

0.200 0.250 0.300 0.350 0.400 0.450

Estatic Value

Dyn

amic

Val

ue

Compressional Velocity Analysis – Field vs Lab.

Compressional velocity

Shale

Sandstone

0

1000

2000

3000

4000

5000

6000

0 1000 2000 3000 4000 5000 6000

Depth (ft)

Com

pre

ssio

nal v

elo

city

(m

/s)

Laboratory

Log

Internal Frictional Analysis – Lab vs Field

Internal friction angle

Shale

Sandstone

0

5

10

15

20

25

30

35

40

45

50

0 1000 2000 3000 4000 5000 6000

Depth (ft)

Inte

rnal

fric

tion

ang

le (

o )

Laboratory

Log

Ultrasonic Triaxial Test – Temperature Effect in

velocity

Immersion Test

Before After 72 hours

Acoustic Log/Image - Stress Direction

From Acoustic tool From Image

Acoustic Log - Anisotropy

Anisotropy in shales - around 9%

In Sandstones - less than 0.5%

Coupled Fluid-Thermal-Geomechanics Simulation

Temperature

Oil Saturation

So=79%

T0=117oF

Variation of Pressure

Time, days

Maximum pressure reached during the steam injection 6.1%

variation

4.3% variation

Pre

ssur

e, p

sia

Reservoir Simulation- Pressure Distribution

Vertical Strain

Oficina Sands

y = 14146x

R2 = 1

y = 13914x + 215.85

R2 = 0.9994

y = -27298x + 371.85

R2 = 0.9957

0

200

400

600

800

1000

1200

1400

-0.06 -0.04 -0.02 0.00 0.02 0.04 0.06 0.08 0.10

Strain (in/in)

Axial S

tress

Differ

ence

(ps

i)

εr εa

+ reach more than 80% of elastic curve

Core test evaluation450 tons/day

Strain reach 0.062 (in/in)

Shear Strain

Drained Zones

Undrained zone

Partially drained Zone-More susceptible to grain crushing, casing collapse and sand production High Shear stress

variation in this area

DilationOficina Sands - Depth: 2038,9 ft

-0.006

-0.004

-0.002

0.000

0.002

0.004

0.006

0.008

0.010

0 200 400 600 800 1000 1200 1400

Axial Stress Difference (psi)

Vol

umet

ric S

trai

n (in

3 /in3 )

Pc=1430 psi

Pp=755 psi

Temperature Distribution

2. Injector Well - Strain Analysis – 0.062 in/in - 450 tons/day

- 0.093 in/in- 650 tons/day

60 ft 15 ft

Acoustic Impedance contrast inside the steam

chamber

Conclusions

• The information generated in this study demonstrates the effects ofthe geomechanics on SAGD operations for the Orinoco Oil Beltreservoirs, and the optimal configuration to apply this technology,obtaining a more realistic and representative results about theSAGD potential for the Orinoco Oil Belt reservoirs.

• The geomechanics play a very important hole for operators tooptimize SAGD:– Design wells - well’s orientation and spacing– Select the optimum injection pressure