关键词: 非结构网格, PEBI网格, CVFE网格, 数学模型, 渗透率张量, 油藏数值模拟

Abstract: According to the discrete material balance equation of control-volume,a new numerical scheme based on PEBI grid and CVFE grid is provided,where absolute permeability is in tensor form. Because of PEBI grid's orthogonalization,its discrete equation is similar with that of finite-difference method. The mobility coefficient and interface permeability can be calculated as same as finite-difference method. For CVFE grid,reduced pressure gradient is approximated using finite-difference and finite-element methods simultaneously,and a new upstream weighting approach is proposed based on the signal of flow term,which is more reasonable. The final discrete form of CVFE grid is different from that of PEBI grid and finite-difference method. Numerical model tests show that the method proposed by this paper is as accurate as nine-point finite-difference when permeability tensor is in diagonal form, and it can simulate more complicated cases when permeability is in full-tensor form. Its application prospect is more extensive in fine detailed reservoir simulation.

Key words: unstructured grid, PEBI grid, CVFE grid, mathematical model, permeability tensor, reservoir numerical simulation