Seismic rock physics of steam injection in bituminous oil sands

Evan Bianco and Dr. Douglas Schmitt

Institute of Geophysical Research

University of Alberta, Edmonton, CanadaSEG Convention Nov. 12, 2008

Outline

• Description of oil sand and geological setting

• Review SAGD method

• Rock property relations and modified fluid substitution (what to do when Gassmann’s assumption fails)

• Synthetic experiments over steam anomalies (Acous. F.D. scheme); 1 steam zone versus 3 steam zones

• Real experiments over steam anomalies. (11 x 2-D Sh.V.H.R.)

• Conclusions

Geological setting

From wikipedia.com Modified from Wightman, 1997

SEM of oil-sand sample

Dean Rokosh and D. Schmitt, personal communication

Un-cleaned Cleaned

bitumen removed

Immobility of Bitumen

Modified from D. Schmitt, personal documentation

Sample wireline signature

Depositional environment

Meandering river point bar and estuarine facies = abrupt heterogeneity

Type facies of McMurray deposit

Core photographs taken by E. BiancoI.H.S.: Inclined Heterolithic Stratification

Muddy I.H.S Mud Plug (shale)Sand Sandy I.H.S. Shale clast breccia

Reservoir Non-Reservoir

Rock property relationships

Green GR > 90

Yellow GR > 50

FOR FLUID SUBSTITUTION:

“Effective”properites are known (measured in borehole)

Fluid properties are known (measured in lab)

Frame properties are not known . . .

Solving for Kdry from Keff and Kfl

using reverse Gassmann eqn.

Porosity fixed at 0.32 and Ksol = 41 GPa

Empirical relations: Vp(Peff)

Note: Peff = Pc - Pp

Keff(Peff): uncemented sand model

• Three injection scenarios

• Hertz-Midlin Contact Theory

• Modified Hashin-Strikmann

Bounds

• Range of Porosites 0.28-0.36

Effective Pressure [MPa]

Kd

ry [G

Pa]

Increasing Injection Pressure

Low

Med

High

Note: Peff = Pc - Pp

Ternary diagrams: for studying 3 component systems

Diamond denotes 30% water, 50% oil, 20% steam

Keff(Ppore ) = const. Keff (Ppore) ≠ const.

Saturation: 62% oil, 27% steam, 11% water

P-velocity model from thermocouple measurements

P-velocity model imbedded into reflectivity

2-D F.D. wavefield snapshot

1-D conv. versus 2-D F.D.

“3-D” time-lapse visualization

Energy envelope of traces

Repeatability and time-lapse signals

Conclusions

• Oil Sand is not a rock, i.e. frame and fluid sensitivity

Keff=Keff(Peff ,T), µeff=µeff(Peff,T), ρeff=ρeff (Peff ,T)

• Gassmann fails, needed to modify it

• Steam zones are scattering features – time-lapse attributes?

• Monitoring can be difficult if CMP spacing is too coarse, model it!

• Repeat time intervals for monitoring are needed faster than traditional 4D programs

Acknowledgements

• Dr. Douglas Schmitt, Institute of Geophysical Research at Univ. of Alberta

• Sam Kaplan (Ph.D. student Univ. of Alberta)

• CHORUS Consortium

• NSERC Research Grants