Coupled Geomechanics and Reservoir Modelling in SAGD Recovery

The Steam Assisted Gravity Drainage (SAGD) process is a thermal enhanced oil recovery (EOR) method which appears tremendously successful, especially for bitumen. SAGD process results in a complex interaction of geomechanics and multiphase flow in cohesionless porous media. In this process, continuous steam injection changes reservoir pore pressure and temperature, which can increase or decrease the effective stress in the reservoir. Quantification of the state of deformation and stress in the reservoir is essential for the correct prediction of reservoir productivity, seal integrity, hydro fracturing and well failure. In SAGD process, reservoir geomechanics analysis is concerned with the simultaneous study of fluid flow and the mechanical response of the reservoir. The objective of this paper is to show the importance of taking into account the role of geomechanics in SAGD numerical modelling and to provide a better description of the rock contribution to fluid flows in the SAGD process. Therefore, we introduce a geomechanics-reservoir partially coupled approach, which allows a better prediction of the SAGD process to be performed. The results of numerical simulations show that the classical treatment of deformation of reservoir through the rock compressibility in the conventional reservoir theory is not a rigorous framework to represent the evolution of high porous rock strains that play a significant role in the performance of SAGD.