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主办单位:煤炭科学研究总院有限公司、中国煤炭学会学术期刊工作委员会
南海水合物地层的孔隙水合物形成机制模拟研究
  • Title

    A simulation study on the formation mechanisms of gas hydrates in pores of gas hydrate-bearing sediments in the South China Sea

  • 作者

    郑明明周珂锐吴祖锐刘天乐颜诗纯曾国澳

  • Author

    ZHENG Mingming;ZHOU Kerui;WU Zurui;LIU Tianle;YAN Shichun;ZENG Guo’ao

  • 单位

    成都理工大学 地质灾害防治与地质环境保护国家重点实验室中国科学院 天然气水合物重点实验室(中国科学院广州能源研究所)中国地质大学(武汉) 岩土钻掘与防护教育部工程研究中心

  • Organization
    State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology
    Key Laboratory of Gas Hydrate, Chinese Academy of Sciences (Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences)
    Engineering Research Center of Rock-Soil Drilling & Excavation and Protection of Ministry of Education, China University of Geosciences (Wuhan)
  • 摘要

    地层骨架孔隙中水合物的高质量形成是开展水合物实验研究的前提和物质基础,可为我国深水油气及水合物资源开发提供理论指导。依据南海GMGS2-07井水合物层地质条件,利用TOUGH+HYDRATE数值模拟软件和自主研制的水合物反应生成装置开展数值模拟和实验研究,在验证数值模拟方法准确性和可靠性的基础上,通过控制变量法分别开展不同地层导热系数和含水饱和度条件下水合物生成质量的影响研究。结果表明:(1) 数值模拟与室内实验过程中,水合物形成时温度、压力与三相物质变化趋势一致且特征值十分接近,验证了数值模拟方法的准确性和可靠性。(2) 导热系数越大,水合物生成越快,最终形成的水合物饱和度越大,分布也更加均匀。但导热系数与最终形成水合物的饱和度的正负相关性,存在临界边界。本次所选用的反应釜尺寸,临界边界距上、右边界距离为1.8 cm,临界边界内导热系数与水合物饱和度呈正相关性,临界边界外呈负相关性。临界边界随着反应釜尺寸的增大而增大,但临界边界位置不受地层渗透率的影响。(3) 随地层含水饱和度增加,最终形成的水合物饱和度先增大后减小,峰值处含水饱和度小于初始压力条件下的理论气水比。当初始压力为7.8 MPa,含水饱和度约22.23%时,所形成的水合物饱和度最大且分布最不均匀。由此可知,选用高导热系数材料制备地层骨架、使初始含水饱和度低于气水理论比以及调整初始温压条件使之偏向相平衡曲线左方有利于形成分布均匀的高饱和水合物。研究认为深水油气含水合物固井和水合物资源钻采提供依据,为水合物商业化开采提供技术储备。

  • Abstract

    The formation of high-quality gas hydrates in the pores of the sediment matrix serves as the premise and material basis for experimental research on gas hydrates, thus providing theoretical guidance for the exploration of deep-water hydrocarbons and gas hydrates in China. Based on the geological conditions of gas hydrate-bearing sediments in well GMGS2-07 in the South China Sea, this study conducted numerical simulations and laboratory experiments using the TOUGH+HYDRATE code and a self-developed device for gas hydrate reactions and generation, respectively. Firstly, this study verified the accuracy and reliability of the numerical simulation method. Then, it investigated the quality of gas hydrates generated under different thermal conductivities and water saturation of sediments to determine their influencing mechanisms. The results are as follows: (1) Both numerical simulations and laboratory experiments yielded consistent variation trends and nearly identical characteristic values of the temperature, pressure, and three-phase materials in the process of gas hydrate formation. Therefore, the numerical simulation method used in this study is accurate and reliable; (2) A higher thermal conductivity was associated with faster gas hydrate formation, as well as the higher saturation and more uniform distribution of the final gas hydrates. However, the correlation between the thermal conductivity and the final gas hydrate saturation depended on the position relative to critical boundaries, which were determined at a distance of 1.8 cm from the upper and right boundaries of the tank reactor used in this study. There was a positive correlation between the thermal conductivity and the gas hydrate saturation within the critical boundaries. Otherwise, they were negatively correlated. The distances between the critical boundaries and the boundaries of the water bath increased with an increase in the tank reactor size but were not affected by the formation permeability; (3) As the formation water saturation increased, the saturation of the final gas hydrates first increased and then decreased, and the peak water saturation was less than the theoretical gas-water ratio under the initial pressure. The gas hydrates showed the highest saturation and the most ununiform distribution when the initial pressure was 7.8 MPa and the water saturation was about 22.23%. Therefore, the sediment matrix prepared using high-thermal-conductivity materials, the initial water saturation lower than the theoretical gas-water ratio, and the initial temperature and pressure falling to the left of the phase equilibrium curve are conducive to the formation of high-saturation, uniformly distributed gas hydrates. This study will provide a sound material basis for well cementing in deep-water sediments bearing hydrocarbons and gas hydrates, as well as the drilling and exploitation of gas hydrate resources. Moreover, it will contribute to the technical preparation for the commercial recovery of gas hydrates.

  • 关键词

    南海天然气水合物室内实验导热系数含水饱和度TOUGH+HYDRATE

  • KeyWords

    South China Sea;natural gas hydrate;laboratory experiment;thermal conductivity;water saturation;TOUGH+HYDRATE

  • 基金项目(Foundation)
    中国科学院天然气水合物重点实验室(中国科学院广州能源研究所)开放基金项目(E129kf1701);国家自然科学基金项目(42272363,42072343)
  • DOI
  • 引用格式
    郑明明,周珂锐,吴祖锐,等. 南海水合物地层的孔隙水合物形成机制模拟研究[J]. 煤田地质与勘探,2023,51(5):54−65
  • Citation
    ZHENG Mingming,ZHOU Kerui,WU Zurui,et al. A simulation study on the formation mechanisms of gas hydrates in pores of gas hydrate-bearing sediments in the South China Sea[J]. Coal Geology & Exploration,2023,51(5):54−65
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