石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (2): 553-564.doi: 10.11743/ogg20240218

• 方法技术 • 上一篇    下一篇

二氧化碳置换法开采天然气水合物研究进展

柏明星1,2(), 张志超1,2(), 陈巧珍3, 徐龙4, 杜思宇1,2, 刘业新1,2   

  1. 1.东北石油大学, 黑龙江 大庆 163318
    2.东北石油大学 提高采收率教育部重点实验室, 黑龙江 大庆 163318
    3.大庆师范学院, 黑龙江 大庆 263311
    4.龙煤鹤岗矿业有限公司 益新煤矿, 黑龙江 鹤岗 154100
  • 收稿日期:2023-09-12 修回日期:2024-03-19 出版日期:2024-04-30 发布日期:2024-04-30
  • 通讯作者: 张志超 E-mail:bai510714@163.com;1209712605@qq.com
  • 第一作者简介:柏明星(1984—),男,教授、博士生导师,CO2驱油与地质埋存。E‑mail: bai510714@163.com
  • 基金项目:
    国家自然科学基金项目(52174020)

Advances in research on CO2 replacement for natural gas hydrate exploitation

Mingxing BAI1,2(), Zhichao ZHANG1,2(), Qiaozhen CHEN3, Long XU4, Siyu DU1,2, Yexin LIU1,2   

  1. 1.Northeast Petroleum University,Daqing,Heilongjiang 163318,China
    2.Key Laboratory of Enhanced Oil Recovery (Northeast Petroleum University),Ministry of Education,Daqing,Heilongjiang 163318,China
    3.Daqing Normal University,Daqing,Heilongjiang 263311,China
    4.Yixin Coal Mine,Hegang Branch of Heilongjiang Longmei Mining Co. ,Ltd. ,Hegang,Heilongjiang 154100,China
  • Received:2023-09-12 Revised:2024-03-19 Online:2024-04-30 Published:2024-04-30
  • Contact: Zhichao ZHANG E-mail:bai510714@163.com;1209712605@qq.com

摘要:

应用CO2置换法开采天然气水合物被认为是一种极具潜力的提高CH4采收率和CO2埋存率的技术。论述了CO2及其混合气置换法开采天然气水合物的机理,梳理了CO2混N2/H2及地热辅助CO2提高水合物中CH4采收率的技术进展。研究表明:①应用纯CO2置换开采天然气水合物时,CH4的采收率较低,而将CO2与N2、H2以不同比例混合后注入天然气水合物藏中进行CH4开采,能够有效提高CH4的采收率。②CO2与N2或H2混合注入水合物层时,多种气体分子在竞争吸附作用下降低了CH4分子与水合物分子笼之间的范德华力,同时降低了混合气中CO2的分压,导致水合物相平衡曲线上移,抑制了置换过程中CO2水合物的生成速率,减轻了包裹作用的不利影响,从而提高CH4采收率。③CO2混合N2注入开采水合物时,N2的混入虽然能够减轻包裹作用的影响,但新形成的N2水合物会堵塞CO2进入水合物分子笼的通道,因此提高CH4采收率效果有限。④在水合物层条件下H2并不会形成新的水合物,而且混入少量的H2又会与N2发生吸附竞争,从而抑制N2水合物的形成,故将低浓度的H2气混入CO2与N2的混合气中能够进一步提高对水合物中CH4的置换率,从而提高CH4的采收率。因此,混入H2被认为是提高CO2置换开发水合物效果的重要途径。⑤混合气周期注气方式可明显提高水合物中CH4的采收率和CO2水合物藏封存率。⑥应用地热辅助CO2开采水合物的方法也能够降低新形成水合物的包裹作用,同时实现CO2在地热层和水合物层的两次埋存,在提高CH4采收率的同时,大大提高CO2在地层中的埋存率。

关键词: 相平衡, 包裹作用, 埋存率, 采收率, CO2混N2/H2置换, CO2置换法, 天然气水合物

Abstract:

The application of CO2 replacement method to develop natural gas hydrates (NGHs) is considered a highly promising technology for enhancing both CH4 recovery and CO2 sequestration. This study presents a review of the replacement mechanisms with CO2 and its mixed gas for NGH exploitation, as well as technological advances in the replacement with CO2 mixed with N2/H2 and geothermal-assisted CO2 replacement for enhancing CH4 recovery from NGHs. Key findings are as follows: (1) To replace NGHs with pure CO2 yields a low CH4 recovery. In contrast, injecting CO2 mixed with N2/H2 at varying ratios into NGH reservoirs proves effective in enhancing CH4 recovery. (2) Injecting CO2 mixed with N2 or H2 into NGH reservoirs can reduce the Van der Waals’ forces between CH4 molecules and NGHs’ molecular cages through the competitive adsorption among various gas molecules. Furthermore, it can decrease the partial pressure on the CO2 phase in the mixed gas, resulting in an upward shift in the phase equilibrium curve of NGHs. Such shift can inhibit the generation rate of CO2 hydrates during the replacement process and mitigate the adverse effects of hydrate encapsulation, thus enhancing CH4 recovery. (3) Injecting CO2 mixed with N2 for NGH exploitation can reduce the adverse effects of hydrate encapsulation. However, the newly formed N2 hydrates can block the pathways through which CO2 molecules enter the molecular cages of NGHs, thus leading to limited performance in enhancing CH4 recovery. (4) Unlike CO2 and N2, H2 does not form new hydrates under the conditions of hydrate reservoirs. Furthermore, competitive adsorption will occur between H2 and N2 when a minor amount of H2 is injected, further curbing the formation of N2 hydrates. Therefore, introducing H2 of low concentration to mixed CO2-N2 gas can further increase the displacement rate of CH4 in NGHs, thus boosting the CH4 recovery, establishing it as a crucial method to enhance the performance of CO2 replacement for NGH exploitation. (5) Cyclic injection of mixed gas can significantly enhance both the CH4 recovery from NGHs and the sequestration rate of CO2 hydrates. (6) Geothermal-assisted CO2 replacement for NGH exploitation can not only reduce the encapsulation effect of newly formed CO2 hydrates but also facilitate CO2 sequestration in geothermal and hydrate reservoirs, thereby markedly increasing subsurface CO2 sequestration rate while simultaneously enhancing CH4 recovery.

Key words: phase equilibrium, encapsulation, sequestration rate, recovery, replacement with a mixture of CO2 and N2/H2, CO2 replacement method, natural gas hydrate (NGH)

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