Three-way coupling of multiphase flow and poromechanics in porous media

Abstract

We formulate a three-way coupling for both single phase flow and equation-of-state (EOS) compositional flow in a poroelastic medium. The algorithm is inspired by the previous work of Dean et al. [1]. An error indicator is calculated at each time step to determine if the mechanics equation must be solved and whether the fixed-stress iterative coupling is necessary; otherwise, only the flow equation is solved with an extrapolated mean stress. The convergence of three-way coupling is established by extending the a priori analyses of fixed-stress iterative coupling by Girault et al. [2]. Numerical results for the Mandel's problem confirm these theoretical results for single phase flow. Three-way coupling achieves speedup with a factor 2.7 and 6.6 for Mandel's problem and field-scale coupled compositional flow and geomechanics simulations based on Cranfield field data respectively. Specifically, field-scale simulations of CO2 sequestration and surfactant-alternating-gas (SAG) process show that the three-way coupling substantially reduces mechanics solving time by 99.4% and 97.5% respectively compared to the fixed-stress split.