Analysis and development of algorithms for fully compositional, thermal and reactive numerical simulation of in-situ combustion at laboratory scale

Abstract

In this work, we study the numerical simulation of computational, thermal and reactive flow in porous media. We built, tested and verified a robust numerical framework to obtain solutions of the coupled and non-linear system of partial differential equations. We illustrate that some of the models typically used in isothermal simulations need to be adapted in the presence of thermal effects. Our cases are largely impacted by the evaporation and condensation of components, and we demonstrate that lumping has a strong influence on the accuracy of the solutions. Aggressive lumping of the heavy components results in premature evaporation and an overestimation of the recovery. We designed a new multi-level delumping method suitable to thermal recovery processes and were able to lower the error made in the phase behavior calculations by an order of magnitude. Finally, we propose a new family of multi-stage preconditioners dedicated to thermal and reactive cases, reducing the number of iterations of a GMRES linear solver by 40-85% compared to the usual CPR method. The new preconditioners exhibit little to no sensitivity to the thermal regime (advection or diffusion dominated)