特种油气藏 ›› 2022, Vol. 29 ›› Issue (1): 134-140.DOI: 10.3969/j.issn.1006-6535.2022.01.020

• 油藏工程 • 上一篇    下一篇

CO2驱气溶性降混剂提高采收率机理实验

孙大龙1, 张广东1, 彭旭2, 敬豪1, 吕华3, 任超峰4, 王宁1   

  1. 1.西南石油大学,四川 成都 610500;
    2.四川省科源工程技术测试中心,四川 成都 610091;
    3.中国石油长庆油田分公司,陕西 靖边 718500;
    4.中国石油长庆油田分公司,陕西 西安 710000
  • 收稿日期:2020-05-11 修回日期:2021-11-04 出版日期:2022-02-25 发布日期:2023-01-10
  • 通讯作者: 张广东(1980—),男,高级实验师,硕士生导师,2003年毕业于西南石油学院勘查技术与工程专业,2014年毕业于成都理工大学油气田开发工程专业,获博士学位,现主要从事油田开发、分子模拟等领域研究工作。
  • 作者简介:孙大龙(1996—),男,2018年毕业于西南石油大学石油工程专业,2021年毕业于该校油气田开发工程专业,现主要从事储层保护方向研究工作。
  • 基金资助:
    国家青年科学基金项目“基于多场耦合的二氧化碳驱油机理研究”(51904252)

Experiment on the Mechanism of Enhancing Oil Recovery by CO2 Flooding with Gas-soluble Demixing Agent

Sun Dalong1, Zhang Guangdong1, Peng Xu2, Jing Hao1, Lyu Hua3, Ren Chaofeng4, Wang Ning1   

  1. 1. Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    2. Keyuan Engineering Technology Testing Center of Sichuan Province, Chengdu, Sichuan 610091, China;
    3. PetroChina Changqing Oilfield Company, Jingbian, Shaanxi 718500, China;
    4. PetroChina Changqing Oilfield Company, Xi′an, Shaanxi 710000, China
  • Received:2020-05-11 Revised:2021-11-04 Online:2022-02-25 Published:2023-01-10

摘要: 针对CO2驱气溶性降混剂降低混相压力、提高采收率机理认识不清的问题,综合利用室内实验、数值模拟和权重分析法,通过分析原油组分、原油黏度、油气界面张力、原油相态特征的变化,明确了气溶性降混剂的降混机理。实验结果表明:注入体积分数为3%和20%的气溶性降混剂后,原油重质组分含量分别减少25.07%和48.21%,平均原油黏度分别降低61.51%和96.88%,相同压力下的原油与CO2界面张力分别降低30.36%和91.16%,饱和压力分别降低6.22%和15.90%;气溶性降混剂的主要降混机理为裂解原油的重质组分、降低原油的黏度和降低油气界面张力。对气溶性降混剂与CO2混合注入和段塞注入2种方式的提高采收率驱油机理进行了分析,明确了地层中不同波及区域的渗流特征:混合带区域主要为CO2或气溶性降混剂与地层原油的两相渗流,混相带区域主要为CO2、气溶性降混剂与地层原油的三相渗流。该研究为CO2驱气溶性降混剂优化和矿场实践提供了依据。

关键词: 气溶性降混剂, CO2驱, 提高采收率, 渗流特征, 机理

Abstract: In view of unclear understanding of the mechanism of reducing mixed-phase pressure and enhancing oil recovery by CO2 flooding with soluble demixing agent, the demixing mechanism of gas-soluble demixing agent was clarified by analyzing the changes in crude oil composition, crude oil viscosity, oil-gas interfacial tension and crude oil phase characteristics in combination with laboratory experiment, numerical simulation and weight analysis. The experimental results showed that after injecting the gas-soluble demixing agents of 3% and 20% volume fraction, the content of heavy components in crude oil was reduced by 25.07% and 48.21%, the average crude oil viscosity reduced by 61.51% and 96.88%, the interfacial tension between crude oil and CO2 reduced by 30.36% and 91.16% at the same pressure, and the saturation pressure reduced by 6.22% and 15.90%, respectively. The dominant demixing mechanism of gas-soluble demixing agent was to crack the heavy components of crude oil, reduce the crude oil viscosity and decrease the oil-gas interfacial tension. The study also analyzed the oil displacement mechanism for oil recovery enhancement by mixed injection and plug injection of gas-soluble demixing agent and CO2, and clarified the seepage characteristics of different affected areas in the formation, namely there was two-phase seepage of CO2 or gas-soluble demixing agent and formation crude oil in the mixed injection area, and three-phase seepage of CO2, gas-soluble demixing agent and formation crude oil in the mixed-phased area. This study provides a basis for the optimization and field practice of the gas-soluble demixing agent for CO2 flooding.

Key words: gas-soluble demixing agent, CO2 flooding, enhance oil recovery, seepage characteristics, mechanism

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