致密油藏体积压裂水平井半解析渗流模型

Semi-analytical seepage model of horizontal well with complex fracture networks in tight oil reservoirs

由于致密油藏特殊的地质条件,导致在进行大规模水力压裂过程中形成了复杂的裂缝网络,复杂缝网的出现导致油藏渗流规律发生了较大变化。文中基于新建面源函数,首先在准确描述复杂缝网形态的基础上,建立了油藏渗流模型;其次应用"星-三角形"变换方法,建立了复杂缝网内渗流模型;最后依据连续性条件,将油藏渗流模型以及复杂缝网内部渗流模型耦合在一起,建立了致密油藏体积压裂水平井半解析渗流模型。应用该模型将体积压裂水平井划分了8个渗流阶段,揭示了体积压裂水平井渗流规律。对关键性参数如:缝网间距、储容比、窜流系数以及压裂区体积等进行了敏感性分析,为现场体积压裂水平井的应用提供了理论依据。

Due to the special geological conditions of tight oil reservoir, many complex fracture networks are generated during fracturing operation, and the complex fracture network affects fluid flow. Based on the improved plane source function of Ozkan, the seepage model for reservoir was established. Secondly, using method of ＂star-triangle＂ conversion, the seepage model of complex fracture can be obtained. Coupling the above two models by continuity conditions, we can get the semi-analytical model of horizontal well with complex fracture networks. Using this method, eight flow patterns are defined and the seepage law of volume fracturing horizontal well is revealed. Sensitivity analysis is conducted, such as the distance of fracture networks, storage ratio, transfer coefficient volume of fracture networks, et. al. This paper provides theoretical basis for field application of horizontal well with complex fracture networks.