Abstract

Steam Assisted Gravity Drainage (SAGD) is a thermal process that has found wide application in high permeability heavy oil or bitumen reservoirs, mainly in the Western part of Canada.

In this process, steam injection continuously modifies reservoir pore pressure and temperature, which can change the effective stress in the reservoir, resulting in a complex interaction of geomechanical effects and multiphase flow in the cohesionless porous media. Quantification of the state of deformation and stress in the reservoir is therefore essential for the correct prediction of reservoir productivity but also for the interpretation of 4D seismics used to follow the development of the steam chamber. On another side, this quantification is crucial for the evaluation of surface uplift, risk of loss of seal integrity, hydro fracturing and well failure. Simultaneous study and analysis of interrelated geomechanics and fluid flow in the reservoir are thus crucial for the management of the process at different stages.

The objective of this paper is to show the importance of taking into account the role of geomechanics in the numerical modelling of SAGD and to provide a better description of the rock contribution to fluid flow in this process. A geomechanics- reservoir partially coupled approach is presented that allows to iteratively take the impact of geomechanics into account in the fluid flow calculations and therefore performs a better prediction of the process. The proposed approach is illustrated on a realistic field case.

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