支撑剂回流对页岩人工裂缝导流能力影响试验  

Experiment of proppant backflow effect on shale artificial fracture conductivity

作　　者：陈浩[1,2] 高帅强 吴天鹏 张鉴 樊怀才 周涛[1,2] 杨胜来[1,4] CHEN Hao;GAO Shuaiqiang;WU Tianpeng;ZHANG Jian;FAN Huaicai;ZHOU Tao;YANG Shenglai(National Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;School of Safety and Ocean Engineering,China University of Petroleum(Beijing),Beijing 102249,China;Shale Gas Research Institute,PetroChina Southwest Oil&Gas Field Company,Chengdu 610021,China;College of Petroleum Engineering,China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]油气资源与工程全国重点实验室,中国石油大学(北京),北京102249 [2]中国石油大学(北京)安全与海洋工程学院,北京102249 [3]中国石油西南油气田公司页岩气研究院,四川成都610021 [4]中国石油大学(北京)石油工程学院,北京102249

出　　处：《中国石油大学学报（自然科学版）》2024年第1期142-149,共8页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家科技重大专项(2017ZX05037-001,2016ZX05062-002);北京市自然科学基金项目(3173044);中国石油天然气股份有限公司科技重大专项(2016E-0611)。

摘　　要：支撑剂回流对页岩人工裂缝导流能力的伤害不容忽视,须对实际应力加载条件下支撑剂回流进行定量表征。利用自主研发的导流能力测试系统,通过添加支撑剂回流腔体模块,实现压裂液返排过程中支撑剂回流的定量表征,在实验室尺度下开展不同应力加载方式(变围压测试和变流压测试)下的页岩人工裂缝长期导流能力对比试验。结果表明:不同应力加载方式对支撑剂破碎量和嵌入量的影响相似,但变围压测试下支撑剂回流量随围压变化维持在约4.46%,与现场支撑剂回流数据不符;变流压测试下支撑剂回流量在流压20 MPa时的支撑剂回流量为20.53%,且随着流压的降低,回流量下降,与现场支撑剂的回流变量变化规律一致;忽略支撑剂的回流会导致对裂缝导流能力伤害率的计算值偏低,不利于制定施工方案;页岩人工裂缝导流能力的准确测试,应采用与实际应力加载更符合的变流压测试方法,以便更好地体现支撑剂回流对导流能力的影响。Proppant backflow is one of the key factors causing damage to the conductivity of artificial shale fractures,and a quantitative characterization of proppant backflow under actual stress loading conditions is required.In this study,an in-house developed conductivity test system was used to simulate the proppant backflow during fracturing fluid flowing back by adding a proppant backflow chamber module,and long-term conductivity comparison tests of shale artificial fractures with different stress loading methods(variable confining pressure test and variable flow pressure test)were carried out.The results show that different stress loading methods have similar effects on the amount of proppant crushed and embedded,but the change of proppant backflow rate with confining pressure is about 4.46%,which is inconsistent with the field proppant backflow data.Under the variable flow pressure test,the proppant backflow rate is 20.53%with the flow pressure 20 MPa,and the backflow rate decreases with flow pressure decrease,which is Consistent with the field proppant backflow phenomenon.In addition,ignoring the backflow of proppant will lead to a low damage rate to the fracture conductivity,which is not conducive to the formulation of construction plans.Therefore,an accurate test of the hydraulic conductivity of artificial fractures in shale should adopt the variable pressure test method,which is more consistent with the actual stress loading,in order to better reflect the influence of proppant backflow on the hydraulic conductivity.

关 键 词：页岩 人工裂缝 导流能力 支撑剂回流 铺砂 

分 类 号：TE357[石油与天然气工程—油气田开发工程]