Abstract
This paper describes a new general purpose three – dimensional multi-phase reservoir simulator that uses fully unstructured curvilinear meshes and employs dynamic mesh adaptivity based on a flow solution. The simulator is based on an unconventional finite element framework called hp finite elements (where h refers to the local mesh size and p refers to the order of the local polynomial approximation). The simulator is coded as an application layer on top of a general-purpose solution-adaptive hp-finite element kernel. This kernel incorporates advanced object-based data structures that allow simultaneous manipulation of h (via refinement/unrefinement) as well as p (via enrichment/ unenrichment).
The simulator supports both IMPES as well as fully implicit schemes. It offers an automatic time stepping strategy. The numerical difficulties associated with advec-tion terms and presence of solution near-discontinuities are overcome using SUPG (Stream-wise Upwind Petrov Galerkin) method with a discontinuity capturing (DC) operator. The simulator achieves higher computational efficiency by anisotropic hp-type mesh adaptation. It does not use a predetermined well model (such as Peace-man’s well model). Instead the wells are represented exactly and modeled right up to (and sometimes including) the well bore. The simulator is equipped with both direct and iterative solvers. The iterative solvers are also parallelized. Several validation and demonstration cases solved using this simulator are presented in the paper. It is anticipated that this simulator will provide unprecedented computational advantages when handling geologically complex reservoirs with non-trivial and non-traditional well shapes and perforations.
