水合物沉积物力学性质的研究现状

ADVANCES OF RESEARCH ON MECHANICAL PROPERTIES OF GAS HYDRATE DEPOSITS

天然气水合物(简称水合物)是一些具有相对较低分子质量的气体如甲烷,二氧化碳、氮气等在一定温度和压力条件下与水形成的内含笼形孔隙的冰状晶体.天然气水合物沉积物(简称水合物沉积物)是指蕴含水合物的砂、黏土以及混和土等土质的沉积物质.主要从现场调查、室内试验和理论模型分析3个方面对甲烷水合物沉积物力学性质的研究现状做了介绍.在现场调查方面着重介绍水合物沉积物原位和调查船上的物性试验,并对原位带孔压测量的圆锥静力触探试验在水合物沉积物力学性质现场调查中的应用前景进行了阐述;在室内试验方面主要介绍了原状和人工合成的水合物沉积物的三轴试验结果,测定弹性参数的声波测试试验结果,天然气和水的含量及沉积物特性对水合物沉积物强度影响的试验结果,以及与水合物开采有关的水合物分解对水合物沉积物强度影响的室内试验和结果;在理论模型方面着重介绍了目前经常采用的几个模型的特点及应用范围.最后提出了今后在水合物沉积物力学性质研究方面应开展的工作重点及发展方向.

Gas hydrates （GH） are defined as the crystalline solid, or clathrate hydrates, which are formed by some types of low mass molecular gases, such as methane, carbon dioxide, and hydronitrogen et al, with water under relatively high pressure and low temperature conditions. Gas hydrate deposits （GHD） are some sand, clay and mixture soil sediments which contains gas hydrates. Advances of the research on the mechanical properties of the gas hydrate deposit are summarized in the aspects of in-situ investigation, laboratory test and theoretical model. Firstly, the in-situ investigations, including the in-situ tests （such as downhole test） and the physical properties tests on board, are summarized and the application of pizo-cone penetration test in the GHD geotechnical investigation and the study of mechanical properties of GHD are discussed. Secondly, some recent research advances in the laboratory test are presented, including mainly the tri-axial compression tests on the natural and synthesized GHD samples, the acoustic tests for measuring the elastic coefficients and the tests for studying the effects of the main factors such as the gas and water contents and the soil type on the strength of GHD. Some laboratory tests are also summarized regarding the hydrate dissociation influences on the strength of hydrate deposit during gas hydrate exploitation. Thirdly, several theoretical models for estimating the mechanical properties of GHD are introduced, and their main characteristics and application ranges are discussed. Based on the above summary, emphases and tendency in the future research on mechanical properties of GHD are finally discussed.