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