低渗透变形介质气藏数值模拟

Numerical Simulation of Gas Reservoir with Low Permeability Deformation Media

气田开发实践和室内实验表明,低渗透气藏岩石孔隙喉道狭窄、连通性差、渗透率较低,加之气液固相间表面吸附力的作用等原因,在低渗透气藏中存在启动压力梯度;随着气藏的开发,储集层岩石的变形对渗透率的影响很大。常规气藏数值模拟技术基于线性的达西定律,无法对启动压力梯度和介质变形的情况予以准确描述。基于前人的研究成果,建立了一个考虑启动压力梯度和介质变形的气藏非线性渗流的数学模型,最后给出了计算实例。结果表明,启动压力梯度和介质变形对气藏开发动态有重要影响。

Gas field development and indoor experiment indicate that start-up pressure gradient exists in low permeability gas reservoirs owing to influence of narrow pore throats, poor connectivity, extremely low permeability, and the effect of interfacial tension among gas, liquid and solid, etc. The impact of rock deformation on permeability is significantly obvious. Conventional gas reservoir simulation technique is based on Darcy's Law, and cannot accurately describe the percolation with start-up pressure gradient and rock deformation. On the basis of the predecessors' research work, a mathematical model of non-linear percolation in gas reservoir is developed, and a case is given in this paper. The results show that the star-up pressure gradient and rock media deformation have serious effect on the performance for gas reservoir development.