多翼裂缝垂直井的瞬态压力分析

水力压裂形成的复杂裂缝网络破坏了单个线性裂缝的流动特性，给油井的动态预测带来了极大的挑战。为了研究多翼裂缝垂直井的瞬态压力特征，基于源函数理论和叠加原理将地层系统分为两个子系统，利用离散坐标法建立了瞬态压力分析的半解析模型。通过Laplace变换及Stehfest反演算法绘制了油藏中各流动阶段的识别曲线。在此基础上，通过改变裂缝数量、裂缝长度、裂缝角度、裂缝分布形式和裂缝导流能力等参数对复杂裂缝网络进行了敏感性分析。研究结果表明，多翼裂缝垂直井的地层流动共经历了4个阶段，其中，裂缝数量及长度对地层内地层线性流影响较大；裂缝分布形式对地层内双线性流及地层线性流影响较大且复杂；裂缝导流能力对地层内的双线性流动影响较为明显；裂缝断裂角度对地层内各流动阶段的动态压力特性影响均较小。

Transient Pressure Analysis of Vertical Well with Multi-wing Fractures

The complex fracture network formed by hydraulic fracturing destroys the flow characteristics of a single linear fracture, which brings great challenges to the dynamic prediction of oil wells. In order to study the transient pressure characteristics of vertical wells with multi-wing fractures, the reservoir system is divided into two subsystems based on the source function theory and the superposition principle, and a semi-analytical model of transient pressure analysis is established using the discrete coordinate method. The identification curves of each flow stage in the reservoir are drawn by Laplace transform and Stehfest inversion algorithm. On this basis, the sensitivity analysis of the complex fracture network is carried out by changing the parameters such as the number of fractures, the length of the fracture, the angle of the fracture, the fracture distribution form and the fracture conductivity. The research results show that the reservoir flow in vertical wells with multi-wing fractures has gone through 4 stages. Among them, the number and length of fractures have a greater impact on the linear flow in the reservoir; the distribution of fractures has a large and complicated influence on the bilinear flow in the reservoir and the linear flow in the formation; the fracture conductivity has obvious influence on the bilinear flow in the reservoir; the fracture angle has little effect on the dynamic pressure characteristics of each flow stage in the reservoir.