油气藏评价与开发 ›› 2023, Vol. 13 ›› Issue (5): 627-635.doi: 10.13809/j.cnki.cn32-1825/te.2023.05.010

• 页岩气 • 上一篇    下一篇

页岩气藏多尺度孔缝介质压裂液微观赋存机理研究

夏海帮1(),韩克宁1,宋文辉2(),王伟1,姚军3   

  1. 1.中国石化华东油气分公司,江苏 南京 210019
    2.中国石油大学(北京)石油工程学院,北京102249
    3.中国石油大学(华东)石油工程学院,山东 青岛 266580
  • 收稿日期:2022-11-08 发布日期:2023-11-01 出版日期:2023-10-26
  • 通讯作者: 宋文辉(1993—),男,博士,副教授,主要从事数字岩心、页岩油气多尺度渗流、微观渗流理论方面的研究工作。地址:北京市昌平区府学路18号,邮政编码:102249。E-mail: song_wen_hui@hotmail.com
  • 作者简介:夏海帮(1974—),男,硕士,高级工程师,主要从事非常规天然气勘探开发工作。地址:江苏省南京市建邺区江东中路375号金融城9号楼,邮政编码:210019。E-mail: 112439883@qq.com
  • 基金资助:
    中国石化科技部“常压页岩气效益开发技术政策优化研究”(P21087-4);中国石化华东石油局“南川地区页岩气藏储层精细描述和开发评价研究”(34600000-21-ZC0613-0006)

Pore scale fracturing fluid occurrence mechanisms in multi-scale matrix-fracture system of shale gas reservoir

XIA Haibang1(),HAN Kening1,SONG Wenhui2(),WANG Wei1,YAO Jun3   

  1. 1. Sinopec East China Oil & Gas Company, Nanjing, Jiangsu 210019, China
    2. School of Petroleum Engineering, China University of Petroleum(Beijing), Beijing 102249, China
    3. School of Petroleum Engineering, China University of Petroleum(East China), Qingdao, Shandong 266580, China
  • Received:2022-11-08 Online:2023-11-01 Published:2023-10-26

摘要:

页岩气藏水力压裂后大量压裂液滞留在基岩孔隙和压裂诱导裂缝内。目前页岩气藏压裂液微观赋存机理认识不清,导致难以准确认识返排过程中页岩气井压裂液返排率差异。建立页岩气藏多尺度孔缝介质压裂液微观赋存分析方法,揭示页岩气藏压裂液微观赋存机理。建立同时考虑岩石-流体作用力和气水界面毛管力的单孔隙气水赋存分析方法,进一步拓展至孔隙网络,采用侵入逾渗研究基岩压裂液赋存模式。基于水力压裂诱导裂缝CT扫描成像结果,采用水平集气、水界面追踪方法计算不同返排压力下气水分布,研究诱导裂缝压裂液赋存模式。研究结果表明:基岩系统返排率呈现缓慢上升—快速上升—趋于平缓的趋势。压裂液主要呈现水相饱和孔隙赋存、角落水相赋存、水膜状赋存3种赋存模式;压裂诱导裂缝系统返排率主要受诱导裂缝周围孔隙连通性影响,呈现快速上升后趋于平缓趋势。滞留压裂液主要赋存在水力压裂诱导裂缝周围盲端基质孔隙。

关键词: 页岩气藏, 数字岩心, 孔隙网络模型, 压裂液, 返排率

Abstract:

After hydraulic fracturing in shale gas reservoir, a significant volume of fracturing fluid retains in the matrix pores and induced fracture network. Currently, the pore scale fracturing fluid occurrence mechanisms are unclear. As a result, it is difficult to accurately understand the difference of fracturing fluid backflow rate of shale gas wells in the backflow process. In this work, the pore scale fracturing fluid occurrence mechanisms analysis method in shale multi-scale matrix-fracture system is developed and the fracturing fluid occurrence mechanisms in shale gas reservoir are elucidated in detail. To understand fracturing fluid occurrence pattern in shale matrix, singe pore gas-water occurrence method is established considering rock-fluid interaction and gas-water capillary pressure and is further extended into the pore network. Invasion percolation is applied to analyze the fracturing fluid occurrence pattern variation during different flowback stages. To understand fracturing fluid occurrence pattern in induced fracture network, the level-set gas-water interface tracking method is applied to calculate gas-water distribution at different flowback pressure based on induced fracture network CT imaging and the fracturing fluid occurrence pattern variation at different flowback stage is studied. Study results reveal that the fracturing fluid flowback rate in shale matrix first increases slowly and then increases fast. In the final stage, the fracturing fluid flowback rate in shale matrix reaches plateau. The fracturing fluid in shale matrix distributes in the forms of water saturated pores, corner water and water film. The fracturing fluid flowback rate in induced fracture network is influenced by pore connectivity around the induced fracture network. The fracturing fluid flowback rate first increases fast and then reaches plateau. The retained fracturing fluid distributes in the dead-end matrix pores around induced fracture network at the final stage.

Key words: shale gas reservoir, digital core, pore network model, fracturing fluid, flowback rate

中图分类号: 

  • TE357