基于离散缝洞网络模型的缝洞型油藏混合多尺度有限元数值模拟

Multiscale mixed finite element numerical simulation for fractured-vuggy reservoir based on DFVN model

针对缝洞型油藏具有多尺度特征,基于离散缝洞网络模型,建立了Darcy/Stokes-Brinkman多尺度耦合数学模型,采用多尺度混合有限元方法,对缝洞型油藏的流体流动问题进行了研究。阐述了多尺度混合有限元方法的基本原理,推导得到了Darcy/Stokes-Brinkman多尺度模型的多尺度混合有限元计算格式。数值计算结果表明,在大尺度模型上进行计算能够捕捉到小尺度上的流动特征;相对于传统有限元,多尺度混合有限元能够捕捉小尺度上的非均质特征而具有更高的计算精度,在保证计算精度的同时能够减少计算量。

Multiscale Mixed Finite element method（MsMFEM）has been applied to the numerical simula-tion of single phase flow in fractured-vuggy porous media in this paper and Darcy/Stokes-Brinkman model is developed,in which Darcy model is approximated as pressure and fluxes on a coarse grid and Stokes-Brinkman model captures fine-scale effects.The fundamental theory of MsMFEM was explicitly described,and then the multiscale calculating formulas were deduced.The method is applied to two different test cases.The test cases demonstrate that MsMFEM can capture fine-sclae features;it is better not only in calculation speed but also in accuracy ,and valid for fractured-vuggy reservoirs.