We present the development and field application of a high performance, unstructured simulator with parallel capability. The simulator integrates the subsurface with the surface network model. An earlier paper1 described the integrated surface model. This paper emphasizes the subsurface model and multi-field application.
Object oriented concepts are used to gain flexibility, using efficient data structures to retain performance. The reservoir computational domain is composed of "Grids" and inter-grid connection structures that form the basis for parallelization. The Grids are ensembles of cells that are unstructured in general, and need not be contiguous.
Besides unstructured (PEBI) grid simulation capability, this framework also forms the basis for simulating multiple, independently gridded reservoirs, with shared surface facilities, an important business problem. Earlier multireservoir workflows use LGR's in a fixed grid, making changes like adding a new reservoir difficult. Alternately, they use multiple processors with imperfect resolution of inter-reservoir coupling. In this paper, use of grid objects greatly facilitates the workflow; reservoir grids can be easily added or changed. Simultaneous solution of multi-reservoir and facilities system ensures consistent coupling throughout.