Stability-Based Switching Criterion for Adaptive-Implicit Compositional Reservoir Simulation

Abstract

ABSTRACT A stability criterion for determining the degree of implicitness in adaptive-implicit compositional reservoir simulation is derived and discussed. The criterion is based on the Courant-Friedrichs-Lewy (CFL) condition for the stability of explicit discretizations of hyperbolic systems of partial differential equations. The criterion can be computed using quantities either directly available from the Jacobian-building sections of the compositional simulator, or obtainable through minor modifications to the simulator. The criterion can be used for switching both from explicit to implicit and from implicit to explicit discretizations of a block. Several strategies for applying the criterion to determine an appropriate degree of implicitness in practical reservoir simulations are proposed and tested.