致密油体积压裂水平井流固全耦合流动模拟

Fluid-solid fully coupling flow simulation for SRV-fractured horizontal wells in tight oil reservoirs

针对致密油储层水平井体积改造存在复杂缝网、开发过程存在应力敏感的特征,基于有效应力原理及改造区多重孔隙介质流体流动特征,建立考虑基质、天然裂缝和网络裂缝系统特征的流固耦合数学模型,进行应力场–渗流场全耦合有限元数值求解;并与现有软件对比验证该算法的正确性,分析未耦合与全耦合情况下体积压裂水平井生产动态的差异,揭示了致密油流动特征及产能影响因素。结果表明:当考虑流固耦合效应时,水平井初期产量较高但递减较快,存在经济最优的储层压裂改造参数,采用水平井大规模体积压裂的"井工厂"开发模式对提高采收率较为有利。研究结果可为致密油水平井体积压裂优化设计及高效开发提供一定的理论指导。

In terms of the characteristic of complex fracture network and stress sensitivity for stimulated reservoir volume(SRV)-fractured horizontal wells in tight oil reservoirs,based on the effective stress principle and flowing features of stimulated areas with multi-porosity media,the fluid-solid coupling mathematical model considering the system characteristics of the matrix,natural fractures and network fractures is presented.The fully coupling numerical solution of the stress field and flow field is solved by the finite element method.The accuracy of this model is verified by comparing the existing software solution,analyzing the difference of the production performance of SRV-fractured horizontal well under the condition of the non-coupled and full-coupled model,and revealing the fluid flow characteristics and productivity influence factors of tight oil.The results show that for full-coupled model,the production rate of SRV-fractured horizontal well is large but declines quickly.There is an economically optimal reservoir fracturing parameter.And the development pattern of'well factory'involving horizontal wells with large scale SRV fracturing is more favorable for enhanced oil recovery(EOR).This study could provide a certain theoretical and technical guidance for the optimization design of horizontal wells with SRV fracturing and efficient development of tight oil reservoirs.