石油学报 ›› 2022, Vol. 43 ›› Issue (9): 1295-1304.DOI: 10.7623/syxb202209008

• 油田开发 • 上一篇    下一篇

页岩储层水相渗吸作用规律实验

郭建春1, 陶亮2, 胡克剑3, 邓咸安2, 陈迟1, 李鸣2, 赵志红1   

  1. 1. 西南石油大学油气藏地质及开发工程国家重点实验室 四川成都 610500;
    2. 中国石油长庆油田公司油气工艺研究院 陕西西安 710018;
    3. 中国石油长庆油田公司第三采油厂 宁夏银川 750005
  • 收稿日期:2021-04-30 修回日期:2022-06-12 发布日期:2022-10-08
  • 通讯作者: 郭建春,男,1970年9月生,1998年获西南石油学院博士学位,现为西南石油大学教授、博士生导师,主要从事油气开采领域的教学与科研工作。
  • 作者简介:郭建春,男,1970年9月生,1998年获西南石油学院博士学位,现为西南石油大学教授、博士生导师,主要从事油气开采领域的教学与科研工作。Email:guojianchun@vip.163.com
  • 基金资助:
    国家杰出青年科学基金项目(No.51525404)和国家自然科学基金项目(No.51704249)资助。

Experiment on imbibition law of aqueous phase in shale reservoir

Guo Jianchun1, Tao Liang2, Hu Kejian3, Deng Xian'an2, Chen Chi1, Li Ming2, Zhao Zhihong1   

  1. 1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Sichuan Chengdu 610500, China;
    2. Research Institute of Oil and Gas Technology, PetroChina Changqing Oilfield Company, Shaanxi Xi'an 710018, China;
    3. Third Oil Production Plant, PetroChina Changqing Oilfield Company, Ningxia Yinchuan 750005, China
  • Received:2021-04-30 Revised:2022-06-12 Published:2022-10-08

摘要: 页岩富含多组分矿物和发育多尺度微米—纳米孔隙使得微观渗吸作用机理十分复杂。以四川盆地川南地区龙马溪组页岩为研究对象,自主研发了考虑储层温度和压力条件下的页岩渗吸实验装置,并结合低场核磁共振技术实现了对流体在页岩孔隙中运移与分布规律的在线监测。在此基础之上,利用场发射电镜与纳米CT扫描技术对页岩微观结构动态变化进行定点观测,分析了诱导微裂缝动态扩展规律和微观作用机理。实验结果表明,页岩水相渗吸过程分为渗吸扩散段、渗吸过渡段、渗吸平衡段3个阶段,其中渗吸扩散段为渗吸能力主要贡献段,在渗吸初期,毛细管压力为主要渗吸动力。储层围压对页岩渗吸能力有抑制作用,水相在岩心内部分布形状呈梯形,当渗吸5 d时,渗吸深度为4~6 cm。页岩渗吸作用诱导微裂缝以页理缝为主,具有明显的方向性,沿着矿物与岩石胶结弱面进行扩展。能谱测试显示,诱导微裂缝区域碳和硅元素含量最高。黏土矿物在诱导裂缝产生与扩展中起主导作用,起裂时间与渗吸能力呈负相关,在实验条件下,测试页岩气井最短焖井实验时间为5 d。

关键词: 页岩, 四川盆地, 龙马溪组, 渗吸深度, 诱导微裂缝, 焖井时间

Abstract: The mechanism of micro-imbibition is very complex as a result of the abundant multi-component minerals and multi-scale micro-nano pores in shale.This paper is case study of the shale of Longmaxi Formation in southern Sichuan Basin;the authors has independently developed the shale imbibition experimental device considering reservoir temperature and pressure,based on which the online monitoring and visualization of migration and distribution laws of fluid in shale pores are realized using low-field NMR technology.On this basis,fixed point observation on the dynamic changes of shale microstructure is implemented using FESEM and nano-CT scanning technology,and the dynamic propagation law and micro-mechanism of the induced microfractures are also analyzed.The experimental results show that the imbibition process of aqueous phase in shale can be divided into three stages:imbibition diffusion stage,imbibition transition stage and imbibition equilibrium stage;among them,the imbibition diffusion stage has the main contribution to imbibition capacity,and capillary pressure is the main imbibition force in the initial imbibition stage.The confining pressure of reservoirs can inhibite the imbibition capacity of shale,and the aqueous phase is distributed inside the core,shown as a trapezoidal shape.After 5 days of imbibition,the imbibition depth is 4 to 6 cm.Most microfractures induced by shale imbibition are lamellation fractures,characterized with obvious directionality and propagated along the weak cementation surface of minerals and rocks.The energy spectrum test shows that the carbon and silicon contents are the highest in the zone of induced microfractures.Clay minerals play a leading role in generating and propagating of the induced fractures,and the fracture initiation time is negatively correlated with the imbibition capacity.When the experiment conditions are met,the shortest soak time for shale gas well testing is 5 days.

Key words: shale, Sichuan Basin, Longmaxi Formation, imbibition depth, induced microfractures, soak time

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