Pereira, LC, Guimarães, LJN & Falcão, FOL 2008, 'Sensitivity Study of Geomechanical Effects on Reservoir Simulation', in Y Potvin, J Carter, A Dyskin & R Jeffrey (eds), Proceedings of the First Southern Hemisphere International Rock Mechanics Symposium
, Australian Centre for Geomechanics, Perth, pp. 309-320.
Classical reservoir simulation considers rock compressibility as the only geomechanical parameter influencing field production. It is assumed to be constant or vary only with oil phase pressure. However, a conventional simulator still cannot explain some phenomena occurring during production, such as compaction, casing damage, wellbore stability, pore collapse, fault reactivation etc. In order to consider the geomechanical influence on the reservoir behaviour, it is necessary to use a coupled model: constitutive laws, mechanical properties of the reservoir and surrounding rocks, state of stress etc. On the other hand, the uncertainties inherent to the mechanical properties are enormous. To properly characterise a rock, lab tests are necessary, but cores are rarely available for destructive tests. Another solution is to use correlations between seismic response and rock properties. But, how reasonable and accurate are such correlations? This work presents a methodology of geomechanical modelling considering a sensitivity study of geomechanical parameters. Simulations with the commercial software STARS® were carried out, which identified the main geomechanical parameters relevant in flow simulation through a sensitivity analysis, based on a sugar cube model. Based on these results, the impact of geomechanics on reservoir simulation is illustrated by comparing permeability, porosity, oil and water production values generated by conventional and coupled simulations.
Biot, M.A. (1941) General Theory of Three-Dimensional Consolidation, Journal of Physics, Vol.12, pp. 155-164.
Chin, L.Y. and Boade, R.R. (1990) Full-Field, 3D Finite Element Subsidence Model for Ekofisk. 3rd North Sea Chalk Symposium, Copenhagen.
Fredrich, J.T., Arguello J.G., Thorne, B.J., Wawersik, W.R., Deitrick, G.L., Rouffignac, E.P., Myer, L.R. and Bruno, M.S. (1996) Three Dimensional Geomechanical Simulation of Reservoir Compaction and Implications for Well Failures in the Belridge Diatomite. SPE Annual Technical Conference and Exhibition. SPE 36698, Denver, Colorado, USA.
Fung, L.S.K., Buchanan, L. and Wan, L.G. (1994) Coupled Geomechanical-Thermal Simulation for Deforming Heavy-Oil Reservoir. J. Cdn. Pet. Tech., 22.
Gai, X., Dean, R.W., Wheeler, M.F. and Liu, R. (2003) Coupled Geomechanical and Reservoir Modeling on Parallel Computers. SPE Reservoir Simulation Symposium, SPE 79700, Houston, Texas, USA.
Gutierrez, M. and Lewis, R.W. (1998) The Role of Geomechanics in reservoir simulation. In: SPE/ISRM Eurock’98, pp. 439–448, Norway.
Hart, R.D. and John, C.M.St. (1986) Formulation of a Fully-Coupled Thermal-Mechanical Fluid Flow Model for Non-Linear Geologic Systems. International Journal Rock Mechanics Min. Sci. and Abstr. Geomech., Vol. 03, pp. 213–224.
Koutsabeloulis, N.C. and Hope, S.A. (1998) Coupled Stress/Fluid/Thermal Multi-phase Reservoir Simulation Studies Incorporating Rock Mechanics. In: SPE/ISRM Eurock’98, SPE 47393, Norway.
Lewis, R.W. and Sukirman, Y. (1993) Finite Element Modeling of Three-phase Flow in Deforming Saturated Oil Reservoirs. Intl. J.for Num. and Anal. Methods in Geomech., 17, p. 577.
Lin, C.C. and Segel, L.A. (1974) Mathematics Applied to Deterministic Problems in the Natural Sciences. 1st edition, New York, MacMillan.
Minkoff, S.E., Stone, C.M., Arguello, J.G., Bryant, S., Eaton, J., Peszynska, M. and Wheeler, M. (1999) Staggered in Time Coupling of Reservoir Flow Simulation and Geomechanical Deformation: Step 1 - One-way Coupling. SPE Reservoir Simulation Symposium, SPE 51920, Houston, Texas, USA.
Osorio, J.G., Chen, H.Y., Teufel, L.W. and Schaffer, S. (1998) A Two-Domain, 3D, Fully Coupled Fluid-Flow/Geomechanical Simulation Model for Reservoirs with Stress-Sensitive Mechanical and Fluid-Flow Properties. In: SPE/ISRM Eurock’98, Norway, pp. 455–464.
Osorio, J.G., Chen, H.Y. and Teufel, L.W. (1999) Numerical Simulation of the Impact of Flow Induced Geomechanical Response on the Productivity of Stress-Sensitive Reservoirs. SPE Reservoir Simulation Symposium, SPE 51929, Houston, Texas, USA.
Settari, A. and Walters, D.A. (1999) Advances in Coupled Geomechanics and Reservoir Modeling with Applications to Reservoir Compaction. SPE Reservoir Simulation Symposium, SPE 51927, Houston, Texas, USA.
Stars Technical Guide (2001) Computer Modelling Group Ltd.
Sulak, R.R., Thomas, L.K., and Boade, R.R. (1991) 3D Reservoir Simulation of Ekofisk Compaction Drive, Journal of Petroleum Technology pp. 1272–1278.
Terzaghi, K. (1943) Theoretical Soil Mechanics. 1st edition, New York, John Wiley & Sons.
Tortike, W.S. and Ali, F. (1992) Reservoir Simulation Integrated with Geomechanics. Proceedings CIM Annual Technical Conference, Calgary, Canada.