页岩气水平井缝网压裂施工压力曲线的诊断识别方法  

Study on diagnosis model of shale gas fracture network fracturing operation pressure curves

作　　者：赵金洲[1] 付永强[2] 王振华 宋毅[2] 任岚[1] 林然[1] 胡东风[3] 周小金[2] ZHAO Jinzhou;FU Yongqiang;WANG Zhenhua;SONG Yi;REN Lan;LIN Ran;HU Dongfeng;ZHOU Xiaojin(State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation//Southwest Petroleum University,Chengdu,Sichuan 610500,China;PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China;Sinopec Exploration Company,Chengdu,Sichuan 610041,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 [3]中国石化勘探分公司

出　　处：《天然气工业》2022年第2期11-19,共9页Natural Gas Industry

基　　金：国家自然科学基金项目“页岩油气高效开发基础理论”(编号:51490653)、“深层超深层页岩气水平井压裂缝网高效建造理论与方法研究”(编号:U19A2043)、“基于DEM-LBM流固耦合的深层页岩气水力裂缝长效支撑理论与方法研究”(编号:52104039)。

摘　　要：受储层非均质性、天然裂缝发育和层理等的影响,页岩气水平井压裂时施工压力曲线形态复杂,所蕴含的大量信息难以被充分挖掘。为了准确表征水力压裂裂缝参数进而评价压裂效果,基于页岩气缝网压裂理论,采用套压、泵注排量、支撑剂浓度等实时数据,建立井底净压力折算模型,构建净压力斜率和净压力指数两个关键表征参数,动态划分净压力曲线阶段,用以描述压裂过程中不同裂缝延伸行为所对应的力学条件,识别出缝网延伸、裂缝延伸受阻、裂缝延伸正常、裂缝沿层理延伸、裂缝沿缝高延伸、液体快速滤失等6种裂缝延伸模式,综合形成了页岩气水平井缝网压裂施工压力曲线诊断识别方法。研究结果表明:①所形成的方法摒弃了常规储层压裂施工曲线诊断识别方法的不足,提出了缝网复杂指数这一新概念;②缝网复杂指数越大,代表缝网延伸和层理延伸的时间越长,储层改造效果越好;③以四川盆地东南缘地区页岩气井为研究对象开展应用,单井平均缝网复杂指数为0.3,与该区微地震监测结果吻合度较高,证实所形成的方法具有较高的可靠性。结论认为,该模型方法有助于提升页岩气储层压裂改造潜力和水平,对于完善页岩气储层缝网压裂压后评价技术、指导现场压裂施工实时动态调整具有重要的意义。The operation pressure presents complex shapes affected by reservoir heterogeneity,developed natural fractures and bedding fractures during the fracturing of shale gas horizontal wells.And a large amount of information contained in it is difficult to fully excavate.Based on the theory of shale gas fracture network fracturing,the bottom hole net pressure conversion model is established combining with the real-time data such as casing pressure,pumprate,proppant concentration.Two key parameters of net pressure slope and net pressure index are constructed and the stage of the net pressure curve is divided dynamically to describe the mechanical conditions corresponding to the propagation behavior of different fractures during the fracturing process.Six fracture propagation modes were identified including fracture-network,blocked,normal,bedding-fracture,fracture-height,and rapid-filtration propagation and the operation pressure curve diagnosis and identification method were formed comprehensively for shale gas fracture network fracturing in horizontal wells.The shortcomings of conventional fracturing construction curve diagnosis and identification methods are abandoned and the fracture network complexity index is put forward.The larger the index,the more time occupied by fracture network extension and bedding extension,and the better the effect of reservoir stimulation.The model is applied by taking the shale gas wells in the southeastern of the Sichuan Basin as the object and the average fracture network complexity index of a single well is 0.3,which is in good agreement with the microseismic monitoring results in this area,which proves that the method developed in this paper has good reliability.It is concluded that the method is helpful to improve the potential and level of fracturing stimulation of shale reservoirs,and is of great significance for improving the post-fracturing evaluation technology of fracture network and guiding the real-time dynamic adjustment of field fracturing operation.

关 键 词：页岩气 水力压裂 施工压力曲线 诊断识别 缝网复杂指数 压裂效果评价 四川盆地东南缘 

分 类 号：TE377[石油与天然气工程—油气田开发工程]