Acta Petrolei Sinica ›› 2024, Vol. 45 ›› Issue (2): 403-411.DOI: 10.7623/syxb202402006

• OIL FIELD DEVELOPMENT • Previous Articles     Next Articles

The mechanism of hydraulic fracturing-assisted oil displacement technique applied to enhance oil recovery by high-pressure reduced adsorption

Wang Fengjiao1,2, Xu He1, Liu Yikun1, Du Qinglong3, Zhang Dong1,2   

  1. 1. Laboratory of Enhanced Oil Recovery of Ministry of Education, Northeast Petroleum University, Heilongjiang Daqing 163318, China;
    2. Postdoctoral Research Center, Daqing Oilfield Company Limited, Heilongjiang Daqing 163453, China;
    3. Exploration and Development Research Institute, Daqing Oilfield Company Limited, Heilongjiang Daqing 163712, China
  • Received:2023-02-13 Revised:2023-09-05 Online:2024-02-25 Published:2024-03-07

压驱技术高压降吸附提高采收率机理

王凤娇1,2, 徐贺1, 刘义坤1, 杜庆龙3, 张栋1,2   

  1. 1. 东北石油大学提高油气采收率教育部重点实验室 黑龙江大庆 163318;
    2. 大庆石油管理局博士后工作站 黑龙江大庆 163453;
    3. 大庆油田有限责任公司勘探开发研究院 黑龙江大庆 163712
  • 通讯作者: 刘义坤,男,1963年8月生,1999年获大庆石油学院博士学位,现为东北石油大学石油工程学院教授、博士生导师、提高油气采收率教育部重点实验室主任,主要从事特高含水油田提高采收率技术研究。Email:liuyikun111@126.com
  • 作者简介:王凤娇,女,1988年9月生,2017年获东北石油大学博士学位,现为东北石油大学石油工程学院教授、博士生导师,主要从事油气多尺度渗流机理及提高采收率技术等方面的研究工作。Email:wangfengjiao@nepu.edu.cn
  • 基金资助:
    国家自然科学基金项目"振击压驱方法孔隙流体瞬时聚能微观力学机制及渗流机理研究"(No.52374035)、国家自然科学基金项目"压裂-渗流-驱油方法多场耦合渗流机理研究"(No.52074087)和中国博士后科学基金项目"基于溶质运移的压裂-渗流-驱油方法多场耦合渗流机理研究"(2021M690528)资助。

Abstract: The hydraulic fracturing assisted oil displacement (HFAD) technique, which is based on large-scale hydraulic fracturing, has been applied to the old oilfields with extra high water cut, achieving a remarkable effect of enhanced oil recovery (EOR). To further clarify the impact of HFAD technique on the oil displacement efficiency of HFAD agents, the paper investigates the adsorption loss of HFAD agents on the porous media surface under high pressure. Firstly, by carrying out dynamic adsorption experiments under ordinary pressure and high pressure conditions, changes in the dynamic adsorption capacity of HFAD agents on the core surface during HFAD process were compared and analyzed. In combination with conventional mercury injection experiment and scanning electron microscope (SEM)test, the mechanism of reduced absorption under high pressure was clarified. Then the impact of high-pressure reduced adsorption on enhanced oil recovery by HFAD technique was confirmed by the physical simulation experiment of reverse hydraulic fracturing-assisted oil displacement. Research shows that the dynamic adsorption capacity of HFAD agents on the core surface is decreased with the increase of the displacement pressure difference. When the displacement pressure differences are 0.5 MPa, 1.0 MPa and 1.5 MPa, the dynamic saturated adsorption capacity of HFAD agents on the core surface is decreased by 40.67 %, 62.17 % and 72.38 %, respectively, as compared with that under the displacement pressure difference of 0.1 MPa. At a high pressure, the core pore structure is changed, i.e., the average pore radius and seepage velocity are increased, fluid seepage resistance is decreased, and the dynamic saturated adsorption capacity of HFAD agents on core surface is reduced. Additionally, the oil displacement efficiency of HFAD agents can be improved by reduced absorption under high pressure, which is 1.96 times higher than that under ordinary pressure. In conclusion, high displacement pressure in the HFAD process can effectively reduce the dynamic adsorption capacity of HFAD agents in reservoirs, thus improving the oil displacement efficiency. The research results are of important guiding significance for further EOR in the field application stage of HFAD technique.

Key words: hydraulic fracturing-assisted oil displacement, high pressure displacement, dynamic adsorption capacity, pore radius distribution, enhanced oil recovery

摘要: 以大规模压裂为基础的"压驱"技术,应用于特高含水老油田取得了显著的提高采收率效果。为进一步明确压驱技术对压驱剂驱油效率的影响,对高压作用下其在储层多孔介质表面的吸附损耗展开研究。通过开展常压/高压动态吸附实验,对比分析压驱过程压驱剂在岩心表面动态吸附量变化情况;结合常规压汞和扫描电镜测试,阐明了高压降吸附机理;通过反向压驱物理模拟实验,明确了高压降吸附作用对压驱提高采收率的影响。研究表明,压驱剂在岩心表面的动态吸附量随驱替压差升高而呈现降低趋势;驱替压差分别为0.5 MPa、1.0 MPa、1.5 MPa条件下,压驱剂在岩心表面的动态饱和吸附量分别可较驱替压差为0.1 MPa时降低40.67%、62.17%和72.38%;高压作用下岩心孔隙结构发生改变,平均孔隙半径增加,流体渗流阻力降低,渗流速度升高,压驱剂在岩心表面的动态饱和吸附量降低;高压降吸附作用可提高压驱剂驱油效率,为常压条件下的1.96倍;因此,压驱过程中高压作用可有效降低压驱剂在地层内的动态吸附量从而提高驱油效率。研究成果对压驱技术矿场应用阶段进一步提高采收率具有重要的指导意义。

关键词: 压驱, 高压驱替, 动态吸附量, 孔隙半径分布, 提高采收率

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