Fully Implicit Simulation on the Connection Machine

Abstract

ABSTRACT A fully-implicit, black-oil, reservoir simulator has been successfully ported to the Connection Machine massively parallel computer. Several problems with up to sixty-four thousand cells were simulated on a 4K processor Connection Machine 2 with performance similar to that of a large-scale, shared-memory, supercomputer. Scaled performance on a 64K processor CM-2 exceeded 1 GFLOP. Key to the parallelization of the model was the development of a fully-implicit linear equation solver based on the constrained pressure residual technique of Wallis1. Implementation of the solver involved the use of both multigrid-like and conjugate residual acceleration techniques. The effect of implicit well equations on the solver performance was investigated. Degradation of solver performance with problem and time step size was also investigated. Finally, the effect of communication overhead on model performance was evaluated for several cases.