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本文研究的碳酸盐岩油藏储集体属于缝洞型多孔介质。这类缝洞型多孔介质由裂缝、溶蚀孔洞和低孔隙度低渗透率的基岩组成.裂缝是空隙流体流动的主要通道;溶蚀孔洞大小从几厘米到数米不等,渗透率和孔隙度都很高,是流体主要的储集空间。由于缝洞型多孔介质空隙空间的复杂性和强非均质性,数值计算中基本控制方程的空间离散应采用非结构化网格的计算模型。本文采用有限体积法模拟缝洞型多孔介质中多相流体的流动,并给出了相应的单元中心格式有限体积法的计算公式。裂缝介质和溶洞介质中单元间多相流体的流动考虑为高速非达西流,其质量通量采用Forchheimer定律计算。非线性方程的离散选取全隐式格式,并采用Newton-Raphson迭代进行求解。通过两个二维模型注水驱油的数值模拟,验证了本文方法的有效性.
The carbonate reservoirs studied in this paper belong to fractured-cavity porous media. This type of fractured-cavity porous media consists of bedrock, dissolved pores and low porosity and low permeability bedrock, which is the main channel for the flow of the interstitial fluid. The size of the dissolution pores ranges from several centimeters to several meters, and the permeability and porosity Are high, is the main reservoir of fluid storage space. Due to the complexity and strong heterogeneity of void space in fractured-cavity porous media, the unstructured grid computing model should be used for the spatial discretization of the basic governing equations in numerical computation. In this paper, the finite volume method is used to simulate the flow of multiphase fluid in a fractured porous media, and the corresponding calculation formula of the finite volume method for the central form of a cell is given. The flow of multiphase fluid in the cracked media and the cell in the cave is considered as high velocity non-Darcy flow, and its mass flux is calculated according to Forchheimer’s law. The nonlinear equations are discretized and selected in all implicit format and solved by Newton-Raphson iteration. The numerical simulation of waterflooding and flooding by two two-dimensional models validates the effectiveness of the proposed method.