石油学报 ›› 2014, Vol. 35 ›› Issue (5): 941-951.DOI: 10.7623/syxb201405015

• 油田开发 • 上一篇    下一篇

天然气水合物分解区演化数值分析

刘乐乐1,2,3, 鲁晓兵3, 张旭辉3   

  1. 1. 国土资源部天然气水合物重点实验室 山东青岛 266071;
    2. 青岛海洋地质研究所 山东青岛 266071;
    3. 中国科学院力学研究所 北京 100190
  • 收稿日期:2013-11-15 修回日期:2014-02-18 出版日期:2014-09-25 发布日期:2014-08-05
  • 通讯作者: 刘乐乐,男,1986年3月生,2008年获清华大学学士学位,2013年获中国科学院力学研究所博士学位,现为青岛海洋地质研究所助理研究员,主要从事天然气水合物开采涉及力学问题研究。Email:liulele_leo@163.com
  • 作者简介:刘乐乐,男,1986年3月生,2008年获清华大学学士学位,2013年获中国科学院力学研究所博士学位,现为青岛海洋地质研究所助理研究员,主要从事天然气水合物开采涉及力学问题研究。Email:liulele_leo@163.com
  • 基金资助:

    国家自然科学基金项目(No.11102209)、国家自然科学基金青年基金项目(No.11272314、No.41104086)和中国科学院仪器设备创新性功能开发项目资助。

Numerical analysis on evolution of natural gas hydrate decomposition region in hydrate-bearing sediment

Liu Lele1,2,3, Lu Xiaobing3, Zhang Xuhui3   

  1. 1. Key Laboratory of Gas Hydrate, Ministry of Land and Resources, Shandong Qingdao 266071, China;
    2. Qingdao Institute of Marine Geology, Shandong Qingdao 266071, China;
    3. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2013-11-15 Revised:2014-02-18 Online:2014-09-25 Published:2014-08-05

摘要:

为了分析水合物试开采效率与水合物分解区时空演化过程的内在联系,对水合物沉积物中水合物降压—加热分解区演化过程进行了数值分析,获得了水合物分解区的时空演化规律和控制参数,找到了水合物分解效率的制约因素,提出了水合物分解过程的解耦分析方法。研究结果表明:水合物降压分解相变阵面和加热分解相变阵面的传播距离均与时间平方根成正比;气体渗流和热传导两者特征时间的比值为水合物分解区演化过程的控制参数;水合物分解区分为降压分解区和加热分解区,降压分解区扩展速度快,最大厚度大于水合物分解区最大厚度的90%,加热分解区扩展速度慢,最大厚度小于水合物分解区最大厚度的3%;水合物分解效率由热传导效应控制,由开采方式决定的传热效率低下是提高水合物分解效率的制约因素;砂土类等渗透性良好的沉积物中,水合物分解过程解耦分析可简化求解流程,提高计算精度。

关键词: 天然气水合物, 水合物沉积物, 水合物分解区, 降压法, 加热法

Abstract:

Efficiency of Natural gas hydrate (NGH) test exploitation and spatial-temporal evolution of NGH dissociation region are analyzed through numerical analysis on the evolution of NGH dissociation region in hydrate-bearing sediments. The laws of spatial-temporal evolution and the control parameter of NGH dissociation region are obtained, and the limiting factor of NGH dissociation efficiency is identified. Further, a decoupling method for analysis of NGH dissociation by depressurization and heating is developed. Results show that: (1)Propagation distances of NGH dissociation by both depressurization and heating are proportional to the square root of time. (2)The ratio of characteristic time between gas flow and heat conduction is the key parameter controlling evolution of NGH dissociation region. (3)NGH dissociation region can be divided into depressurization-and heating-dissociation regions. Propagation of depressurization-dissociation region is of higher velocity and its maximum thickness is greater than 90 % of that of NGH dissociation region, whereas propagation of heating-dissociation region is of low velocity and its maximum thickness is less than 3 % of that of NGH dissociation region. (4)NGH dissociation efficiency is controlled by heat conduction. Low efficiency of heat conduction determined by the mining method constrains the improvement of NGH dissociation efficiency. (5)For analysis of NGH dissociation in permeable sandy sediments, the proposed decoupling method can simplify the solving process and improve the computational accuracy.

Key words: natural gas hydrate, hydrate-bearing sediment, hydrate decomposition region, depressurization, heating

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