Seismic rock physics of steam injection in bituminous oil sands
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Transcript of Seismic rock physics of steam injection in bituminous oil sands
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