水平井分段压裂平面三维多裂缝扩展模型求解算法  

A numerical method for simulating planar 3D multi-fracture propagation in multi-stage fracturing of horizontal wells

作　　者：陈铭[1,2] 张士诚 胥云[3,4] 马新仿[1] 邹雨时 CHEN Ming;ZHANG Shicheng;XU Yun;MA Xinfang;ZOU Yushi(China University of Petroleum,Beijing 102249,China;Texas A&M University,College Station 77840,USA;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;The Key Laboratory of Research Stimulation,PetroChina,Langfang 065007,China)

机构地区：[1]中国石油大学(北京),北京102249 [2]Texas A&M University,College Station 77840,USA [3]中国石油勘探开发研究院,北京100083 [4]中国石油油气藏改造重点实验室,河北廊坊065007

出　　处：《石油勘探与开发》2020年第1期163-174,共12页Petroleum Exploration and Development

基　　金：国家科技重大专项“储层改造关键技术及装备”（2016ZX05023）;国家重点基础研究发展计划（973）项目“陆相致密油高效开发基础研究”（2015CB250903）

摘　　要：针对多层油气藏水平井分段多簇压裂设计问题,提出平面三维多裂缝扩展模型高效解法。采用三维边界积分方程计算固体变形,考虑井筒-射孔-裂缝耦合流动及缝内流体滤失。利用显式积分算法求解流固耦合方程,根据尖端统一解析解和最短路径算法计算裂缝扩展边界。方法的准确性通过与径向裂缝解析解、隐式水平集算法和有机玻璃压裂实验对比得到全面验证。与隐式水平集算法相比,新算法计算速度大幅提高。以浙江油田页岩气水平井为例,重点分析了平面应力分布、射孔数分布等对多簇裂缝扩展与进液的影响。研究表明,减小单簇射孔数可以平衡簇间应力非均质分布的影响;调整各簇射孔数量可以实现均衡进液,各簇射孔数差别应控制在1~2孔;增加高应力簇的射孔数有利于均匀进液,但进液均匀并不等于裂缝形态一致,裂缝形态受应力干扰和层间应力剖面共同控制。To resolve the issue of design for multi-stage and multi-cluster fracturing in multi-zone reservoirs, a new efficient algorithm for the planar 3D multi-fracture propagation model was proposed. The model considers fluid flow in the wellbore-perforation-fracture system and fluid leak-off into the rock matrix, and uses a 3D boundary integral equation to describe the solid deformation. The solid-fluid coupling equation is solved by an explicit integration algorithm, and the fracture front is determined by the uniform tip asymptotic solutions and shortest path algorithm. The accuracy of the algorithm is verified by the analytical solution of radial fracture, results of implicit level set algorithm and results of organic glass fracturing experiment. Compared with the implicit level set algorithm(ILSA), the new algorithm is much higher in computation speed. The numerical case study is conducted based on a horizontal well in shale gas formation of Zhejiang oilfield. The impact of stress heterogeneity among multiple clusters and perforation number distribution on multi-fracture growth and fluid distribution among multiple fractures are analyzed by numerical simulation. The results show that reducing perforation number in each cluster can counteract the effect of stress contrast among perforation clusters. Adjusting perforation number in each cluster can promote uniform flux among clusters, and the perforation number difference should better be 1-2 among clusters. Increasing perforation number in the cluster with high in situ stress is conducive to uniform fluid partitioning. However, uniform fluid partitioning is not equivalent to uniform fracture geometry. The fracture geometry is controlled by the stress interference and horizontal principal stress profile jointly.

关 键 词：水平井 分段压裂 多裂缝扩展 三维边界元 平面应力非均质 射孔优化 

分 类 号：TE357[石油与天然气工程—油气田开发工程]