考虑压敏的双重介质分形油藏非线性渗流模型

Nonlinear flow model of dual-medium fractal reservoir considering pressure sensitivity

姜瑞忠 张春光 崔永正 张伟 张福蕾 沈泽阳

中国石油大学（华东）石油工程学院，山东 青岛 266580

College of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China

双重介质储层具有较强的非均质性和复杂孔隙结构，经典渗流理论已不能很好地描述其非均质性与复杂性，而引入分形原理所建立的双重介质分形油藏模型更符合实际储层。目前对双重介质分形油藏的研究多数仅停留在线性渗流的层面上，对于非线性渗流的研究较少，且未形成理论体系。文中通过建立考虑压力敏感性的双重介质分形油藏非线性渗流模型，并应用有限元原理进行数值求解，绘制压力动态曲线，对影响参数进行敏感性分析。研究结果表明：随着窜流非线性增强，流体从基质向裂缝系统的窜流强度减弱，压力导数曲线下凹程度减弱，且曲线出现下凹的时间提前；分形维数越小，压力变化越快，曲线上翘越早，且上翘幅度越大；随着异常扩散系数增大，曲线整体上移幅度增加，总径向流段压力导数曲线上翘幅度也增大。文中得出的渗流规律对双重介质油藏的开发具有一定的理论指导意义。

The dual-medium reservoir is characterized by strong heterogeneity and complex pore structure that classical seepage mechanics cannot describe its heterogeneity and complexity well. Therefore, fractal theory is applied to establish a dual-medium fractal reservoir model which is closer to real reservoirs. At present, most researches on dual-media fractal reservoirs only remain the level of linear seepage. There are few researches on nonlinear seepage and no theoretical system has been formed about nonlinear seepage. By establishing the nonlinear seepage model of dual-medium fractal oil reservoirs considering pressure sensitivity and applying the finite element principle to make the numerical solution, the pressure dynamic curve can be plotted and the sensitivity analysis of each parameter can be analyzed. The results show that with the non-linear enhancement of turbulence, the turbulence intensity weakens from the matrix to the fracture system, the degree of concave of the pressure derivative curve weakens, and the time at which the concave appears in the curve advances; the smaller the fractal dimension is, the faster the pressure changes, the earlier the upturn appears and the larger the upturn is; the larger the anomaly diffusion coefficient is, the larger the shift of the pressure derivative curve is, and the upturn of the pressure derivative curve of the total radial flow section also increases. The seepage law obtained in this paper has certain theoretical significance for the development of dual-medium reservoirs.

10.6056/dkyqt201805014