收稿日期: 2005-10-13
修回日期: 2006-01-14
网络出版日期: 2006-04-20
基金资助
国家自然科学基金项目(编号：40471024)；中国科学院寒区旱区环境与工程研究所创新项目联合资助.
EXPERIMENTAL RESEARCH OF FORMATION PROCESS OF METHANE HYDRATE IN FREEZING COARSE-GRAIN SAND BY COMPUTERIZED TOMOGRAPHY
Received date: 2005-10-13
Revised date: 2006-01-14
Online published: 2006-04-20
冻土甲烷水合物形成的试验研究对于认识冻结多孔介质中形成、存在天然气水合物的机制和评价多年冻土区的气候变化、环境变化等有极为重要的意义,通过X-射线断层扫描系统对冻结粗砂土中甲烷水合物形成的试验表明:冻结砂土中甲烷水合物形成过程中CT数有所变化,且与甲烷气水合物形成、水分迁移和砂土密度增大均有关,而且通过不同时段CT图像的差值运算可以获得甲烷水合物形成的新信息;同时在甲烷水合物形成过程中具有明显的压力降低阶段,且伴随有相变热产生;尽管CT下砂土较大的吸收系数影响了对甲烷水合物形成的判断,但通过CT扫描定量信息,结合甲烷水合物形成过程中的压力和砂土温度变化,可以较为清楚地判断冻结砂土中甲烷水合物的形成。
关键词： 冻结粗砂土; 甲烷水合物; X-射线断层扫描系统
吴青柏;,蒲毅彬,蒋观利,邢莉莉 . 冻结粗砂土中甲烷水合物形成CT试验研究[J]. 天然气地球科学, 2006 , 17(2) : 239 -244 . DOI: 10.11764/j.issn.1672-1926.2006.02.239
The experimental research of formation process of methane hydrate in frozen soil is very important to comprehend the formation and existing mechanisms of na tural gas hydrate in frozen porous media, and also very meaningful to estimate t he climate change and environment change in permafrost areas. The experimental r esearch of formation process of methane gas hydrate in frozen coarse-grain sand by computerized tomography (CT) is expatiated on in this article. It was proved in the experiment that CT could describe the formation process through the way of CT-value which is closely related to the formation of methane hydrate, moist ure migration and density change. The formation of methane hydrate can be observ ed by computation of CT images in different time, and the pressure would decreas e evidently with the generating of phase transition heat in this process. The es timation of methane hydrate formed could be influenced by the absorption coeffic ient coarse-grain sand because of its high density, but the other information, such as the changes of pressure and temperature, and CT image can be used to hel p to judge clearly the formation of methane hydrate in freezing coarse-grain sand.
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