An Implementation of a Fully Implicit Reservoir Simulator on an ICL Distributed Array Processor

Abstract

ABSTRACT An oil/water, 3-D fully implicit Reservoir Simulator has been implemented on the ICL Distributed Array Processor (DAP), by a joint BNOC/ICL project team. The DAP is a single instruction, multiple data stream machine with 4096 processors in parallel. The major computational areas of code have been implemented on the DAP, leaving I/O and well calculations as serial code on the host 2976 machine. Matrix assembly is inherently parallel and can be implemented easily and efficiently on the DAP with compact code. Table look-up, though not obviously parallel, has been coded using a very efficient parallel algorithm. The Linear Solver, of Line Gauss-Seidel type, has been chosen for its efficiency on the DAP, with odd and even reduction used for solution of the resulting tri-diagonal equations. Further research will be undertaken to increase the robustness of this solver. The initial implementation has a 1-1 mapping of active grid blocks to processors, thus allowing up to 4096 active grid blocks. It is planned to extend to much larger models, and to 3 phase.