Study of a New Refinement Criterion for Adaptive Mesh Refinement in Sagd Simulation

The SAGD (Steam Assisted Gravity Drainage) is an enhanced oil recovery process for heavy oils and bitumens. To simulate this thermal process and obtain precise forecasts of oil production, very small-sized cells have to be used because of the fine flow interface. But the use of fine cells throughout the reservoir is expensive in terms of CPU time. To reduce the computation time one can use an adaptive mesh refinement technique which will use a refined grid at the flow interface and coarser cells elsewhere. The first numerical tests of SAGD modelling, using a criterion based on two threshold temperatures, showed that this adaptive-mesh-refinement technique could reduce significantly the number of cells [LLR03]. Nevertheless, the refined zone remains too wide. In this work, we introduce a new criterion for the use of adaptive mesh refinement in SAGD simulation. This criterion is based on the work achieved in [KO00] on a posteriori error estimators for finite volume schemes for hyperbolic equations. It enables to follow more precisely the flow interface. Through numerical experiments we show that the new criterion enables to further decrease the number of cells (and thus CPU times) while maintaining a good accuracy in the results.