Microscopic experimental study on the effects of NaCl concentration on the self-preservation effect of methane hydrates under 268.15 K  

作　　者：Yu-Jie Zhu Yu-Zhou Chen Yan Xie Jin-Rong Zhong Xiao-Hui Wang Peng Xiao Yi-Fei Sun Chang-Yu Sun Guang-Jin Chen 

机构地区：[1]State Key Laboratory of Heavy Oil Processing,China University of Petroleum,Beijing 102249,China [2]Research Centre of Ecology&Environment for Coastal Area and Deep Sea,Guangdong University of Technology,Guangzhou 510006,China [3]School of Chemistry and Food Engineering,Changsha University of Science and Technology,Changsha 410114,China

出　　处：《Chinese Journal of Chemical Engineering》2024年第9期1-14,共14页中国化学工程学报（英文版）

基　　金：financial support received from the Basic Research Program of Qinghai Province(2023-ZJ-703);the National Natural Science Foundation of China(22178379,42206223);the National Key Research and Development Programof China(2021YFC2800902)is gratefully acknowledged.

摘　　要：It is known that salt ions are abundant in the natural environment where natural gas hydrates are located;thus,it is essential to investigate the self-preservation effect of salt ions on methane hydrates.The dissociation behaviors of gas hydrates formed from various NaCl concentration solutions in a quartz sand system at 268.15 K were investigated to reveal the microscopic mechanism of the self-preservation effect under different salt concentrations.Results showed that as the salt concentration rises,the initial rate of hydrate decomposition quickens.Methane hydrate hardly shows self-preservation ability in the 3.35%(mass)NaCl and seawater systems at 268.15 K.Combined the morphology of hydrate observed by the confocal microscope with results obtained from in situ Raman spectroscopy,it was found that during the initial decomposition stage of gas hydrate below the ice point,gas hydrate firstly converts into liquid water and gas molecules,then turns from water to solid ice rather than directly transforming into solid ice and gas molecules.The presence of salt ions interferes with the ability of liquid water to condense into solid ice.The results of this study provide an important guide for the mechanism and application of the self-preservation effect on the storage and transport of gas and the exploitation of natural gas hydrates.

关 键 词：Gas hydrate SELF-PRESERVATION SALINITY In situ Raman spectroscopy Endothermic behavior DISSOCIATION 

分 类 号：TE31[石油与天然气工程—油气田开发工程]