摘要
页岩气水平井分段压裂后,大量滑溜水被滞留在页岩基质纳米孔隙中,对压后产量的长期稳定性影响较大。以页岩基质的复杂纳米孔隙结构的分形特征和受限性为基础,考虑受限纳米孔隙空间内滑溜水流动的滑移效应和毛细管压力作用,建立了反映页岩纳米孔隙中的压裂液滤失速度分形计算新模型,新模型与经典滤失速度在机理方面存在一致性。分别讨论了滑移长度、压裂液黏度、基质纳米孔隙半径、毛细管压力等4个因素对滤失速度的影响:滑溜水滤失速度随滤失时间增加而降低,最后趋于稳定;纳米基质孔隙中压裂液滑移效应不容忽视,滑移长度越大,滤失速度越大;滑溜水压裂液黏度越大,流体流动阻力亦越大,滤失速度就越小;基质纳米孔隙半径越小,滤失速度越小,其降低幅度也越快;毛细管压力越大,滤失速度越大,其降低幅度也越慢。该研究结果可为页岩气压裂后返排与焖井制度及优化提供理论参考。
A large amount of slick water is trapped in shale matrix nano-pores after staged fracturing of shale gas horizontal wells,which has a great influence on the long-term stability of post-fracturing production.Based on the fractal characteristics and limitation of the complex nano-pore structure of shale matrix,considering slippage effect and capillary pressure effect of slick water flow in confined nano-pore space,a new fractal model for calculating filtration rate of fracturing fluid in shale matrix nano-pores was established,which is consistent with the classical filtration rate in terms of the mechanism.The influences of slip length,fracturing fluid viscosity,matrix nano-pore radius and capillary pressure on the filtration rate were discussed respectively.The results show that the filtration rate of slick water decreases with the increase of filtration time and finally tends to be stable;The slippage effect of fracturing fluid in the matrix nano-pores cannot be ignored,and the longer the slip length is,the greater the filtration rate is;The greater the viscosity of slick water fracturing fluid is,the greater the resistance of fluid flow is and the lower the filtration rate is;The smaller the matrix nano-pore radius is,the lower the filtration rate is and the faster the reduction rate is;The higher the capillary pressure is,the higher the filtration rate is and the slower the decrease rate is.The results of this study can provide theoretical reference for the system and optimization of shale gas flowback and soak after fracturing.
作者
纪国法
丁江
张琦
王可可
高仪君
刘炜
JI Guofa;DING Jiang;ZHANG Qi;WANG Keke;GAO Yijun;LIU Wei(Hubei Cooperative Innovation Center of Unconventional Oil and Gas(Yangtze University),Wuhan 430100,Hubei;School of Petroleum Engineering,Yangtze University,Wuhan 430100,Hubei;Research Institute of Exploration&Development,Tuha Oilfield Company,PetroChina,Hami 839009,Xinjiang;College of Energy,Chengdu University of Technology,Chengdu 610059,Sichuan;Geological Exploration&Development Research Institute,Chuanqing Drilling Engineering Company Limited,CNPC,Chengdu 610051,Sichuan;Research Institute of Petroleum Engineering,Jianghan Oilfield Company,SINOPEC,Wuhan 430035,Hubei)
出处
《长江大学学报（自然科学版）》
2022年第1期86-91,共6页
Journal of Yangtze University(Natural Science Edition)
基金
国家自然科学基金项目“基于分形理论及多尺度方法的页岩体积改造压裂液滤失机理研究”(51804042)
国家科技重大专项“涪陵页岩气开发示范工程”(2016ZX05060004)
油气资源与勘探技术教育部重点实验室开放基金项目“页岩复杂网状裂缝内支撑剂双尺度输送机理研究”(K2018-09)
湖北省教育厅科学研究计划资助项目“页岩裂缝网络导流能力研究”(Q20181313)
长江大学青年科研支持计划长江青年基金项目“基于页岩储层裂缝分形特征的缝内压裂液滤失机理研究”(2016cqn045)。
关键词
压裂液
滑移效应
分形计算
滤失速度
纳米孔隙
页岩基质
fracturing fluid
slippage effect
fractal calculation
filtration rate
nano-pore
shale matrix
