天然裂缝带对深层页岩压裂裂缝扩展的影响规律  

Influence of natural fracture zones on the propagation of hydraulic fractures in deep shale

作　　者：易良平 杨长鑫 杨兆中[1] 宋毅 何小平[3] 周小金 李小刚[1] 胡俊杰 YI Liangping;YANG Changxin;YANG Zhaozhong;SONG Yi;HE Xiaoping;ZHOU Xiaojin;LI Xiaogang;HU Junjie(State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Shale Gas Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China;Development Department,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China)

机构地区：[1]“油气藏地质及开发工程”国家重点实验室·西南石油大学 [2]中国石油西南油气田公司页岩气研究院 [3]中国石油西南油气田公司开发事业部

出　　处：《天然气工业》2022年第10期84-97,共14页Natural Gas Industry

基　　金：四川省科技计划项目“页岩压裂的损伤力学特征研究”(编号:2020JDJQ0059);中国石油西南油气田公司科研项目“深层页岩气水平井裂缝控藏体积压裂工艺优化研究”(编号:JS2021-08)。

摘　　要：四川盆地页岩气资源丰富,深层页岩气将是我国未来页岩气开采的重点领域,而掌握深层页岩气体积压裂技术则是实现高效开发的核心技术之一。为了认识天然裂缝带对深层页岩压裂裂缝扩展影响,基于位移不连续法与有限体积法建立水平井压裂裂缝扩展流固耦合模型,提出压裂裂缝扩展特征评价方法,并针对水平井压裂前置液造缝阶段,模拟分析了天然裂缝与完井压裂参数对压裂裂缝扩展的影响。研究结果表明:(1)深层页岩天然裂缝带增加了压裂改造的难度与裂缝扩展的复杂性,使得压裂裂缝会影响相邻压裂段并难以对远井区域进行改造;(2)天然裂缝带宽度越小、天然裂缝带与水平井筒间夹角和距离越大,目标区域压裂改造率越高且对相邻压裂段的影响越小,钻井时应尽量避免钻进方向与天然裂缝带呈小角度斜交;(3)增加簇间距与施工排量,可削弱天然裂缝带对压裂裂缝的捕获与阻隔作用,建议针对天然裂缝带附近的压裂段采用大簇间距、高排量的压裂工艺。结论认为,取得的研究成果有利于优化复杂构造区域页岩气压裂设计,对于指导深层复杂裂缝区的压裂工艺优化完善具有重要意义,并将有助于我国深层页岩气早日实现规模效益开发。There are abundant shale gas resources in the Sichuan Basin,and deep shale gas will be the important field of shale gas production in China in the future.The volumetric fracturing technology is one of the core technologies for the efficient development of deep shale gas.In order to clarify the influence of natural gas zones on the propagation of hydraulic fractures in deep shale,this paper establishes a fluid-solid coupled model for the propagation of hydraulic fractures in horizontal wells by means of displacement discontinuity method and finite volume method,and then proposes a method for evaluating the propagation characteristics of hydraulic fractures.In addition,the influence of natural fractures and completion fracturing parameters on the propagation of hydraulic fractures in the stage of fracture initiation by prepad fluid during horizontal well fracturing is analyzed.And the following research results are obtained.First,the natural fracture zones in deep shale increase the difficulty of fracturing stimulation and the complexity of fracture propagation.As a result,the adjacent fracturing sections are influenced by the hydraulic fractures,and the zones far from the well can be hardly stimulated.Second,the narrower the natural fracture zone and the greater the included angle and distance between natural fracture zone and horizontal wellbore,the higher the stimulation rate of target area and the less the influence on the adjacent hydraulic section.Therefore,it is necessary to avoid small angle intersection between drilling direction and natural fracture zone as much as possible during drilling.Third,large cluster spacing and high injection rate can weaken the capture and barrier effect of natural fracture zones on hydraulic fractures,so it is suggested to apply the fracturing process with large cluster spacing and high injection rate in the fracturing sections near the natural fracture zones.In conclusion,the research results are beneficial to optimize the design of shale fracturing in complex structural zone

关 键 词：四川盆地 深层页岩气 天然裂缝带 裂缝扩展 数值模拟 参数优化 

分 类 号：TE377[石油与天然气工程—油气田开发工程]