An Efficient Approach to Adaptive-Implicit Compositional Simulation With an Equation of State

Abstract

Summary This paper describes a robust and efficient method for solving the equations corresponding to an equation-of-state (EOS) compositional model. The method is developed for an adaptive-implicit simulator in which only a small number of blocks need to be solved implicitly while the remaining blocks are solved explicitly. The salient features of the method are decoupling of the solution of flow equations from the flash calculations and switching from explicit to implicit formulations on the basis of a stability criterion. The performance of the adaptive-implicit approach is compared with that of a hilly implicit approach and an explicit-transmissibility approach. Results show that the adaptive-implicit approach is two to three times faster than the other two methods.