三重介质复合油藏椭圆流试井模型

Well test model of triple media composite reservoir based on elliptic flow

对于各向同性油藏,由于内外边界条件不同,其流动状态通常为径向流或线性流;但对于渗透率存在各向异性的油藏,其流动状态可能为椭圆流。为此,文中结合椭圆流渗流理论,建立了针对三重介质的复合油藏椭圆流试井解释模型。利用Mathieu函数性质得到了椭圆流模型的拉普拉斯空间解,采用Stehfest数值反演法得到模型在实空间下的解,并绘制了典型试井曲线,对各参数的敏感性进行了分析。根据典型曲线的特点,三重介质复合油藏椭圆流模型存在13个不同的流动阶段。通过分析井筒半径、内区半径、内外区流度比、裂缝储容比、基岩储容比、溶洞窜流系数、基岩窜流系数对试井典型曲线的影响,讨论了考虑椭圆流时三重介质复合油藏试井模型的基本特征。

For isotropie reservoir, the flow state is usually radial flow or linear flow which changes with the internal and external boundary. However, the flow state may be elliptie flow due to the orientation of the permeability in anisotropic, reservoir. Thus, a triple media composite reservoir well test interpretation model with elliptic flow is established based on the elliptic seepage theory. Using the Mathieu function, the solution in Laplace space to the model is obtained. The solution in the real space is derived by Stehfest numerical inversion, and the type curve of the model is drawn. According to the characteristics of the type curve, there are thirteen flow regimes. By analyzing the effects of the wellbore radius, inner region radius, mobility ratio, fracture storage ratio, matrix storage ratio, rug interporosity flow coefficient and matrix interporosity flow coefficient on the type curves, the basic characteristics of the model are discussed.