页岩气井压裂后焖排模式  

Shut-in and flow-back pattern of fractured shale gas wells

作　　者：杜洋[1] 雷炜[1] 李莉[1] 赵哲军[1] 倪杰[1] DU Yang;LEIWei;LI Li;ZHAO Zhejun;NI Jie(Research Institute of Petroleum Engineering Technology,Sinopec Southwest Oil & Gas Company,Deyang 618000,Sichuan,China)

机构地区：[1]中国石化西南油气分公司石油工程技术研究院,四川德阳618000

出　　处：《岩性油气藏》2019年第3期145-151,共7页Lithologic Reservoirs

基　　金：中国石化科技部"十条龙"项目"威远-永川深层页岩气开发关键技术"(编号:P18058)资助

摘　　要：页岩气井水力压裂过程中注入液量大,但压裂后返排率往往较低,滞留压裂液对储层的影响仍不清晰。针对该问题,选取永川新店子构造YY1井龙马溪组的岩心,开展压裂液渗吸实验,并对比渗吸前后岩心物性、孔隙结构特征及电子显微镜下微观结构等参数的变化规律。实验结果表明:永川新店子构造岩心压裂液渗吸后,岩心平均孔隙度增大了50%,平均渗透率增大了25%,气体吸附量减少了35%,比表面积降低了40%;岩心沿层理方向产生了新的裂缝,并随着渗吸的持续进行,裂缝发生扩展和延伸,逐步沟通裂缝网络,增大了液体的渗吸面积;通过YY1HF井的现场试验发现,焖井30 d后再控产(6万m^3/d)试采,产液量大幅度降低,气井生产稳定。研究认为,压裂后焖井有利于改善储层物性,增加渗流通道,压裂后返排应由小到大逐级控制油嘴排液,以提高气井采收率。Horizontal well staged fracturing is the main technical mean of shale gas reservoir reformation,the large fracturing fluid was injected into the formation but the flow-back rate was relatively low.The pros and cons are still unclear about the retention fracturing fluid in the formation.In order to solve this problem,cores of Longmaxi Formation from well YY1 in Xindianzi structure of Yongchuan were selected to carry out imbibition experiment with slick-water,and the variation rules of core physical properties,pore structure characteristics and micro-structure were compared.The results show that after fracturing fluid imbibition,the average porosity and permeability increased by 50% and 25% respectively,while gas adsorption capacity and specific surface area decreased by 35% and 40% respectively.Micro fissures were created along the bedding direction after imbibition test,and with the continuous infiltration,the fissures expanded and extended,gradually communicated the fracture network,and increased the infiltration area of liquid.Through field test of well YY1HF,it is found that after 30 days of shut-in test under the production rate of 60 000 m3/d,the production of liquid is greatly reduced,and the production of gas wells is stable.Therefore,post-frac shut-in is beneficial to improve reservoir physical properties and increase seepage channels,and gradual enlargement flow-back strategy is better for gas recovery.

关 键 词：页岩气 焖井 压裂液 渗吸 返排率 

分 类 号：TE377[石油与天然气工程—油气田开发工程]