METHOD FOR GENERATING A THREE-DIMENSIONAL, LOCALLY-UNSTRUCTURED HYBRID GRID FOR SLOPING FAULTS

A method of generating an automatic, three-dimensional, locally-unstructured, hybrid grid for geological formations with a sloping fault. The grid generation system replaces the portion of an existing finite-difference grid around the sloping fault with a finite-element grid made of triangular prisms and tetrahedrons. The process comprises decomposing the part of the reservoir around the sloping fault into topologically and geometrically simple volume, face and line components, generating a wire-frame construction of the domain by discretization of the line components, calculating the exact crossings of horizons with the fault, generating a finite-element grid for the face components using an automatic triangulation process, generating a finite-element grid for the volume elements using an automatic tetrahedronization process and assembling the finite-element grid for all volume elements and the finite-difference grid to create a locally-unstructured hybrid grid with enhanced detail around the sloping fault.