定向射孔水力压裂复杂裂缝形态.doc

石　油　勘　探　与　开　发 2009年2月　　　　　　　　PETROL EUM EXPLORA TION AND DEV ELOPM EN T 　　　　　　　Vol. 36　No. 1　文章编号:100020747(2009 0120103205 103 定向射孔水力压裂复杂裂缝形态 张广清1,2, 陈勉1 (1. 中国石油大学(北京 石油天然气工程学院; 2. 中国石油大学(北京 城市油气输配技术北京市重点实验室 基金项目:国家自然科学基金重大研究计划资助项目; 国家自然科学基金资助项目摘要:在岩石力学试验测试和现场资料解释的基础上, 建立了三维弹塑性有限元模型, 裂缝形态的影响因素。研究结果表明, , 而影响定向射孔水起裂; 定向射孔形成的水力初始裂缝一般为锯齿状; , 地应力方位起始的双裂缝。。图7参13关键词:定向射孔; 水力压裂; 裂缝形态; ; 中图分类号:TE357. 1Complex shapes in hydraulic fracturing with orientated perforations Zhang Guangqing 1,2, Chen Mian 1 (1. College of Pet roleum Engineering , China Universit y of Pet roleum , B ei j ing 102249, China; 2. B ei j ing Key L aboratory of Urban Oil and Gas Distribution T echnology , China University of Petroleum , Bei jing 102249, China Abstract :Based on rock mechanical tests and practical data interpretation , a three dimensional finite element model is established to study factors influencing f racture shape in orientated hydraulic f racturing. The stress interference around neighboring perforations causes f racture initiation , and the main factors influencing f racture shapes are horizontal principal stress difference and the angle between the perforation orientation and the maximum horizontal stress. The computations also reveal that hydraulic f ractures will not always initiate along perforation orientation , and usually the initial hydraulic fracture is in a zigzag shape. When the horizontal stress difference and the perforation angle are great , dual f ractures will happen along perforation and the maximum stress directions. So improving the accuracy of stress measurement and orientated perforation can avoid the generation of complex 2shape hydraulic f ractures. K ey w ords :orientated perforation ; hydraulic f racturing ; f racture shape ; dual f ractures ; finite element model 0引言 水力压裂时形成的裂缝弯曲和多重裂缝不但增加施工压力, 而且使得支撑剂传输困难。定向射孔技术在石油工程中应用广泛, 如在压裂防砂、水平井压裂等方面, 其特点是形成一条平整的规则裂缝, 从而可以避免水力裂缝的弯曲。 Van 等[1]通过室内实验研究了射孔对水力裂缝弯曲程度的影响。Mortia 等[2]采用定向射孔减缓斜井中的套管损害。Aba