油气藏评价与开发 ›› 2022, Vol. 12 ›› Issue (5): 825-832.doi: 10.13809/j.cnki.cn32-1825/te.2022.05.015

• 综合研究 • 上一篇    

基于分子模拟的气体水合物结构特征及储气特性研究

向雪妮1(),黄亮1(),周文1,邹杰1,张卓雅2   

  1. 1.成都理工大学能源学院,四川 成都610059
    2.中国石油大学(北京)重质油国家重点实验室,北京102249
  • 收稿日期:2021-11-08 出版日期:2022-10-26 发布日期:2022-09-27
  • 通讯作者: 黄亮 E-mail:462092559@qq.com;huangliang@cdut.edu.cn
  • 作者简介:向雪妮(1998—),女,在读硕士研究生,从事流体相态理论及注气提高采收率方向研究。地址:四川省成都市成华区二仙桥东三路1号,邮政编码:610059。E-mail: 462092559@qq.com

Structural characteristics and gas storage properties of gas hydrates based on molecular simulation

XIANG Xueni1(),HUANG Liang1(),ZHOU Wen1,ZOU Jie1,ZHANG Zhuoya2   

  1. 1. College of Energy, Chengdu University of Technology, Chengdu, Sichuan 610059, China
    2. State Key Laboratory of Heavy Oil Processing, China University of Petroleum(Beijing), Beijing 102249, China
  • Received:2021-11-08 Online:2022-10-26 Published:2022-09-27
  • Contact: HUANG Liang E-mail:462092559@qq.com;huangliang@cdut.edu.cn

摘要:

天然气水合物资源丰富,是最具潜力的新能源之一。但目前天然气水合物尚未实现商业开采,其微观结构特征和储气机理亟待明确。基于SI、SII和SH型气体水合物的骨架和客体分子信息,构建并优化了3种典型水合物的分子模型。通过结构表征,明确了水合物的氢键数目、氢键长度、孔隙度、孔隙组成和孔径分布等结构特征,对比分析了3种典型水合物的微观结构差异。基于水合物骨架结构,采用巨正则蒙特卡洛方法研究了甲烷和二氧化碳的吸附行为,结合气体吸附量和吸附热阐明了3种水合物的储气特性及差异。结果表明,SII型水合物中平均氢键长度最大且数量最多,但其孔隙连通性最差;高压有利于提升水合物对气体的储气量,低温可增加水合物中气体吸附的稳定性;二氧化碳储存量虽小于甲烷,但二氧化碳吸附稳定性更强;气体在SII型水合物中的吸附量最大,在SI型水合物中的吸附热最大。

关键词: 气体水合物, 结构特征, 储气特性, 吸附, 分子模拟

Abstract:

Natural gas hydrate are rich, which is one of the most potential new energy resources with abundant resources. However, gas hydrate has not been exploited commercially at present, and its micro-structure characteristics and gas storage mechanism need to be clarified urgently. Based on the framework and guest molecular information of SI, SII and SH type gas hydrates, the molecular models of three typical gas hydrates are constructed and optimized. The hydrogen bonds number, hydrogen bonds length, porosity, pore composition, pore size distribution and other structural characteristics of hydrates are determined by structural characterization, and the micro-structure differences of three typical hydrates are compared and analyzed. Based on the hydrate skeleton structure, the adsorption behavior of methane and carbon dioxide is studied by the grand Canonical Monte Carlo method. Combined with the adsorption capacity and adsorption heat, the gas storage characteristics and differences of the three hydrates are clarified. The results show that the hydrogen bonds in SII hydrate are the longest and the most abundant, but the pore connectivity is the worst. High pressure is conducive to increasing the gas storage capacity of hydrate, while low temperature can increase the stability of gas adsorption in hydrate. Although the amount of carbon dioxide storage is smaller than that of methane, the adsorption stability of carbon dioxide is stronger. The adsorption capacity of gas in SII type hydrate is the largest, and the adsorption heat in SI type hydrate is the largest.

Key words: gas hydrate, structural characteristics, gas storage properties, adsorption, molecular simulation

中图分类号: 

  • TE311