摘要
天然气水合物储量巨大且富含甲烷,被视为21世纪最重要的潜在新型清洁能源之一。天然气水合物大多赋存在海底沉积物的孔隙介质中(少部分赋存于永久冻土层中),对其相变过程受孔隙介质影响规律的系统梳理和总结对未来的勘探开发具有重要意义。本文综合分析前人研究成果,将孔隙介质中天然气水合物的相变过程概化为水合物形成分解时的温压平衡条件变化、速率、稳定性、转化效率以及生长形态、分布状态等;将影响因素分为孔隙介质特性如孔径及粒径、润湿性、导热性能,以及孔隙介质中的物理化学因素如温压和水气条件,并总结了其影响规律和影响机理:(1)孔径及粒径能影响水合物温压平衡条件,较小粒径还能加快水合物相变速率,降低其转化效率。(2)润湿性能够决定水合物的微观生长形态及其与孔隙介质间的接触形式,亲水性强的介质表面能加快水合物的相变速率。(3)孔隙介质导热性能越强,水合物的相变速率越大。(4)温压条件控制下的温压驱动力越大,水合物的相变速率越大,但这种趋势不适用于温压驱动力过大的情形。(5)水气条件影响着水合物相变过程的温压平衡条件、相变速率、稳定性及分布状态。另外,本文分析了目前研究中的不足,并给出了未来的重点研究方向。
Natural gas hydrate(NGH)is regarded as one of the most important clean energy in the 21 stcentury.It is found that NGH is mostly stored in the porous media of submarine sediments,and some in permafrost zone.Safe and efficient utilization of NGH is important for solving current energy crisis.However,the NGH production is a complex process with many impact factors,especially the phase transition in porous media during exploitation.By comprehensively analyzing previous research results,we generalized the phase transition process of NGH into the change of equilibrium temperature and pressure,transition rate,transition stability,transformation efficiency and distribution pattern,which are significantly influenced by the characteristics of porous media.These influencing factors can be divided into pore diameter and particle size,wettability,thermal conductivity,temperature and pressure,water and gas conditions in porous media.We summarized the influence and its mechanisms as follows:1)The pore diameter and particle size control the equilibrium temperature and pressure,the small particle size can accelerate the hydrate formation rate and decrease the transformation efficiency.2)Wettability can determine the contact form between the hydrate and the porous media.The surface of the medium with strong hydrophilicity can speed up the formation rate of NGH.3)The rate of NGH phase transition increases with the enhancement of the thermal conductivity.4)The rate of NGH phase transition is positively related to the driving force of pressure and temperature,but this trend has not seen when the driving force of temperature and pressure is too large.5)The water and gas conditions influence the equilibrium temperature and pressure,transition rate,transition stability and distribution pattern.With extensive literatures reviewed,this paper points out several key problems in current researches,gives some potential research methods and comes up with promising research directions,which is important for the extraction and exploration of NG
作者
肖罗坤
董艳辉
李守定
王礼恒
段瑞琪
符韵梅
XIAO Luokun;DONG Yanhui;LI Shouding;WANG Liheng;DUAN Ruiqi;FU Yunmei(Key Laboratory of Shale Gas and Geo-engineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Institution of Earth Science,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《工程地质学报》
CSCD
北大核心
2021年第1期183-196,共14页
Journal of Engineering Geology
基金
中国科学院地质与地球物理研究所重点部署项目(资助号:IGGCAS-201903)
广东省基础与应用基础研究重大项目(资助号:2020B0301030003)。
关键词
天然气水合物
孔隙介质
相变过程
影响因素
Natural gas hydrate
Porous media
Phase transition process
Influencing factors
