物理化学学报 >> 2011, Vol. 27 >> Issue (02): 295-301.doi: 10.3866/PKU.WHXB20110204

热力学，动力学和结构化学 上一篇    下一篇

一个考虑沉积物孔径分布特征的水合物相平衡模型

颜荣涛1, 魏厚振1, 吴二林1, 王淑云2, 韦昌富1   

  1. 1. 中国科学院武汉岩土力学研究所, 岩土力学与工程国家重点实验室, 武汉 430071;
    2. 中国科学院力学研究所, 北京 100190
  • 收稿日期:2010-09-17 修回日期:2010-11-29 发布日期:2011-01-25
  • 通讯作者: 韦昌富 E-mail:cfwei@whrsm.ac.cn
  • 基金资助:

    岩土力学与工程国家重点实验室资助课题(Z000801), 中国科学院“百人计划”择优支持项目和中国科学院知识创新工程重要方向项目(KZCX2-YW-JS108)资助

A Phase Equilibrium Model for Gas Hydrates Considering Pore-Size Distribution of Sediments

YAN Rong-Tao1, WEI Hou-Zhen1, WU Er-Lin1, WANG Shu-Yun2, WEI Chang-Fu1   

  1. 1. State Key Laboratory of Geomechanics and Geoengineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, P. R. China;
    2. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, P. R. China
  • Received:2010-09-17 Revised:2010-11-29 Published:2011-01-25
  • Contact: WEI Chang-Fu E-mail:cfwei@whrsm.ac.cn
  • Supported by:

    The project was supported by the Open Research Fund of State Key Laboratory of Geomechanics and Geoengineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences (Z000801), the ‘100 Talents Project’ of Chinese Academy of Sciences, and Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering (KZCX2-YW-JS108).

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摘要：

天然气水合物的相平衡条件一直是水合物相关研究的重点和难点. 本文探讨了沉积物孔隙大小及其分布特征对水合物相平衡条件的影响机理, 提出了有效孔隙半径的概念, 并利用沉积物孔隙大小分布特征, 假设孔径分布呈正态分布, 建立了水合物饱和度和有效孔隙半径之间的定量关系; 与传统的van der Waals-Platteeuw相平衡模型相结合, 提出了一个考虑沉积物孔隙大小及其分布特征的相平衡模型. 相对于传统模型, 本模型所表达的相平衡条件不再是二维平面的p-T曲线, 而是温度、压力以及水合物饱和度之间的三维定量关系. 这一特征使得所建模型既能较为真实地反映水合物形成与分解机理, 又能有效地考虑孔隙大小分布对水合物相平衡条件的影响. 通过与实验数据对比, 证明了所建模型的预测结果优于其他模型. 本模型在温度和压力条件确定的情况下还可以预测沉积物中水合物的饱和度, 因此, 可用于地层中水合物储量计算.

关键词: 天然气水合物, 相平衡, 孔隙大小分布, 水合物饱和度

Abstract:

The phase equilibrium condition for gas hydrates has been an important and difficult subject in gas hydrate-related research. In this paper, the mechanism of the effect of pore-size distribution on the phase equilibrium is first explored and the concept of effective pore radius is proposed. Using information on the pore-size distribution of sediments, a relationship between hydrate saturation and effective pore radius is developed. Combined with the van der Waals-Platteeuw model, this relationship was then used to develop a new phase equilibrium model for gas hydrates in sediments, which can properly account for the effect of pore-size distribution. In contrast to the traditional models, this new model does not represent a curve on the p-T plane but instead addresses the relationship between the temperature, pressure, and hydrate saturation. Such a feature allows the new model to take into account the effect of pore-size distribution on the phase equilibrium while treating the formation and/or dissolution processes of gas hydrates in pores more realistically. The simulated results were compared with the experimental data available in literature showing that the new model gives better results compared with the other traditional models. Given the temperature and the pore pressure, the hydrate saturation can be determined using the proposed model. Therefore, the new model can be used to estimate the amount of hydrate resources in the field.

Key words: Gas hydrate, Phase equilibrium, Pore-size distribution, Hydrate saturation