1. Amit Suman and Tapan Mukerji 25th SCRF Annual Meeting May 9 – 11, 2012
Sensitivity Analysis of Rock Physics Parameters for Modeling Time-Lapse Seismic(4D) response of Norne Field
Amit Suman and Tapan Mukerji
25th SCRF Annual Meeting
May 9 – 11, 2012

2. Joint Inversion Loop Predicted flow and seismic response
Observed flow and seismic response
Model
Reservoir
SCRF

3. Δ Pressure Δ Saturation Production data at time t
Motivation
Dynamic modeling
Δ Pressure Δ Saturation
Production data at time t
Rock physics modeling
Velocity at time t
Seismic data at time t
Optimize mismatch
Update parameters 3

4. Previous Work
Last year we investigated parameter sensitivity for modeling time-lapse seismic and flow data of Norne field
One of the investigated parameters was rock physics model
We didn’t investigate sensitivity of varying rock physics parameters on modeling 4D response
SCRF

5. Questions?
“Should we investigate sensitive rock physics parameters in modeling 4D response?”
“What are the sensitive rock physics parameters in modeling 4D response?”
SCRF

6. Norne Field Segment E
F1H
E3H
In this study well log data of two wells are used
SCRF

7. Data Available Well logs (Sw, Sonic, Phi) Horizons Well data
- Oil , gas and water flow rate
- BHP (Bottom hole pressure)
SCRF

8. Rock Physics Modeling Near the Well Rock Physics Reservoir K and G
Well Logs
K and G
(All Brine)
Vp and Vs
(Initial)
K and Phi
G and Phi
Sonic
Sw, Phi
Gassmann’s
Substitution
Calculate
Vp and Vs
(All Brine)
K and G
(All Brine)
Facies
classification
K and G
(at Reservoir)
Populate K ,G
based on Phi
K : Bulk Modulus G: Shear Modulus
SCRF

9. Facies Classification
Shale
Brine Sand
Vp / Vs
Shaly Sand
Oil Sand AI
Vsh
SCRF

10. Rock Physics Modeling Near the Well Rock Physics Reservoir K and G
Well Logs
K and G
(All Brine)
Vp and Vs
(Initial)
K and Phi
G and Phi
Sonic
Sw, Phi
Gassmann’s
Substitution
Calculate
Vp and Vs
(All Brine)
K and G
(All Brine)
Facies
classification
K and G
(at Reservoir)
Populate K ,G
based on Phi
K : Bulk Modulus G: Shear Modulus
SCRF

11. Sensitivity Parameters in fluid substitution
Clay content
Salinity
Gas-oil ratio (GOR)
Pore pressure
The sensitivity of varying above parameters to variations in Response
Response: Sum of seismic P-wave velocity after fluid substitution
SCRF

12. Experimental Design Clay content (%) 20 40 Salinity (ppm) 15000020 40
Salinity (ppm)
150000
155000
160000 
GOR
175
200
225
Pressure (Mpa) 25 27 30
SCRF

13. Results of fluid substitution
Response
Sensitivity to clay content
Sensitivity to GOR
Sensitivity to pore pressure
Sensitivity to salinity 20 40 25 27 30
175
200
225
15000
15500
16000
Clay content and GOR are the first and second most sensitive parameters in fluid substitution

14. Rock Physics Modeling Near the Well Rock Physics Reservoir K and G
Well Logs
K and G
(All Brine)
Vp and Vs
(Initial)
K and Phi
G and Phi
Sonic
Sw, Phi
Gassmann’s
Substitution
Calculate
Vp and Vs
(All Brine)
K and G
(All Brine)
Facies
classification
K and G
(at Reservoir)
Populate K ,G
based on Phi
K : Bulk Modulus G: Shear Modulus
SCRF

15. Varying clay content and GOR (9 cases)
Rock physics model
Varying clay content and GOR (9 cases)
SCRF

16. Constant cement model
Clay content
Cement fraction
Coordination number

17. Fluid mixing
Seismic velocities depend on fluid saturation as well as saturation scale
Reservoirs with gas are very likely to show patchy behavior
Sengupta ,2000
SCRF

18. Effective pressure model
Two effective pressure models are selected for sensitivity study
SCRF

19. Sensitivity Parameters in modeling 4D response
Clay content
Gas-oil ratio (GOR)
Coordination number
Cement fraction
Effective pressure model
Fluid mixing (Uniform or Patchy)
The sensitivity of varying above parameters to variations in Response
Response: L1 Norm of change in seismic P-wave impedance after 4 years

20. Effective pressure model
Experimental Design
Clay content (%) 20 40
GOR
175
200
225
Coordination number 5 7 9
Cement fraction (%) 1 3
Effective pressure model
Model 1
Model 2
Fluid mixing
Uniform
Patchy
Total number of cases: 324

21. Methodology Dynamic modeling (1997-2001) Δ Pressure Δ Saturation
Rock physics modeling
P-wave impedance in 1997 and 2001
Compare
Difference in impedance
SCRF 21

22. P-wave impedance change in 4 years (m/s.kg/m3)
Results
P-wave impedance change in 4 years (m/s.kg/m3)
Clay content = 0 %
Clay content = 20 %
SCRF

23. Results Response Sensitivity to clay content
Sensitivity to coordination number 20 40 5 7 9
175
200
225 1 3
Model 1
Model 2
Uniform
Patchy
Sensitivity to GOR
Sensitivity to cement
Response
Sensitivity to effective pressure model
Sensitivity to fluid mixing

24. Conclusions and Future Work
Clay content is the most sensitive parameter in fluid substitution
Salinity and pore pressure have a lesser impact than clay content
Coordination number is the most sensitive parameter in modeling 4D response of Norne field
The result of this study will be used in joint inversion of time-lapse and production data of Norne field
SCRF

25. Acknowledgement Statoil for data
Norwegian University of Science and Technology (NTNU)
SCRF

26. Conclusions and Future Work
Clay content is the most sensitive parameter in fluid substitution
Salinity and pore pressure have a lesser impact than clay content
Coordination number is the most sensitive parameter in modeling the time lapse seismic signature of Norne field
The result of this study will be used in joint inversion of time-lapse seismic and production data of Norne field
SCRF