石油与天然气地质 ›› 2017, Vol. 38 ›› Issue (3): 610-616.doi: 10.11743/ogg20170321

• 技术方法 • 上一篇    下一篇

低渗致密气藏注超临界CO2驱替机理

史云清1,2, 贾英1,2, 潘伟义1,2, 严谨1,2, 黄磊3   

  1. 1. 中国石化 石油勘探开发研究院, 北京 100083;
    2. 中国石化 海相油气藏开发重点实验室, 北京 100083;
    3. 中国石油 勘探开发研究院, 北京 100083
  • 收稿日期:2016-08-02 修回日期:2017-03-07 出版日期:2017-06-28 发布日期:2017-07-10
  • 第一作者简介:史云清(1962-),博士、教授级高级工程师,特殊气田开发与管理。E-mail:syq.syky@sinopec.com。
  • 基金项目:
    国家科技重大专项（2016ZX05048003-004）；中国石油化工股份有限公司科技部项目（P15031）；中国石油化工股份有限公司科技部基础前瞻项目（G5800-14-ZS-KJB033-5）。

Mechanism of supercritical CO2 flooding in low-permeability tight gas reservoirs

Shi Yunqing1,2, Jia Ying1,2, Pan Weiyi1,2, Yan Jin1,2, Huang Lei3   

  1. 1. Petroleum Exploration & Production Research Institute, SINOPEC, Beijing 100083, China;
    2. SINOPEC Key Laboratory of Marine Oil and Gas Reservoirs, Beijing 100083, China;
    3. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
  • Received:2016-08-02 Revised:2017-03-07 Online:2017-06-28 Published:2017-07-10

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摘要： 为了提高低渗致密气藏采收率，探索研究将CO2注入气藏中，实验与数模相结合论证超临界CO2驱替天然气的驱替机理。首先，通过超临界CO2-天然气相态实验研究CO2与天然气混合规律。平衡相行为实验定量测定了储层条件CO2与天然气的物性参数，结果表明CO2与天然气的物性差异有利于CO2驱替天然气提高采收率以及封存。超临界CO2-天然气扩散实验论证了CO2与天然气混合过程中驱替前沿的混合程度，结果表明CO2在天然气中的扩散度不高，可形成较窄的互溶混相带，实现CO2有效驱替。在分析了CO2与天然气混合特征的基础上，开展致密储层CO2驱替天然气长岩心驱替实验。实验结果表明，CO2提高天然气采收率12%，超临界CO2驱可有效提高致密气采收率。最后，以相态及驱替实验为基础，应用数值模拟方法，建立了长岩心模型，单注单采倾角机理模型及背斜模型，系统证实了超临界CO2驱替天然气的驱替机理。通过分析认为，CO2与天然气驱替前沿部分混溶，一方面保持了气藏压力，另一方面超临界CO2沉降在气藏圈闭下部形成“垫气”提高了天然气采收率。从实验及数值模拟两方面系统论证超临界CO2的驱替机理，为探索注CO2提高天然气采收率选区评价奠定了基础。

关键词: 数值模拟, 天然气, CO2驱, 低渗致密气藏, 提高采收率

Abstract: The mechanism of supercritical CO2 flooding in gas reservoirs was studied through both laboratory and numerical simulations to explore ways to increase recovery of low-permeability tight gas reservoirs.Behaviors of mixing supercri-tical CO2 with natural gas were observed first to reveal the mixing patterns of the two phases.A laboratory quantitative measurement was carried out for an equilibrium phase behaviors to define the in-situ physical properties of both carbon dioxide and natural gas.The results show that the differences between the properties of the two gases are favorable for CO2-based flooding and storage in gas reservoirs.A supercritical CO2-natural gas diffusion test offered opportunities for observing behaviors of mixed gas front during flooding process.The result indicates that CO2 does not diffuse much in na-tural gas and can form only a narrow mixing phase belt,which is good for an effective CO2 displacement.Based on an analysis of CO2 and natural gas mixing behaviors,we carried out a CO2 displacement experiment on a long core from tight gas reservoirs.The results show that gas recovery rate can be increased by 12% after supercritical CO2 flooding.Finally,based on the experiments,we used numerical simulation method to establish long core model,single injector-single producer dip mechanism model as well as anticline model.These models were then used to systematically verify the mechanism of supercritical CO2 displacing natural gas.It suggests that a higher gas recovery is possible because of a partial mixing of natural gas with CO2 at the flooding fronts helping maintain gas reservoir pressure and of a supercritical CO2 "pad" formed at the lower part of gas traps favorable for gas recovery.The displacement mechanisms expounded through both laboratory works and numerical simulations provide a basis for selecting potential CO2 flooding target in tight gas reservoirs.

Key words: numerical simulation, natural gas, CO2 flooding, low-permeability tight gas reservoir, EOR

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