Experimental studies on the P-T stability conditions and influencing factors of gas hydrate in different systems  

作　　者：LIU ChangLing YE YuGuang SUN ShiCai CHEN Qiang MENG QingGuo HU GaoWei 

机构地区：[1]Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology, Ministry of Land and Resources [2]Qingdao Institute of Marine Geology [3]College of Civil Engineering and Architecture, Shandong University of Science and Technology

出　　处：《Science China Earth Sciences》2013年第4期594-600,共7页中国科学（地球科学英文版）

基　　金：financially supported by the National Basic Research Program of China (Grant No. 2009CB219503);the National Natural Science Foundation of China (Grant No. 41072037)

摘　　要：The P-T stability conditions of gas hydrate in different systems （i.e., solution, silica sand, and marine sediment） were studied using multi-step decomposition method with our experimental equipment. The effects of different ions with various concentra- tions and sediment grains on the P-T stability conditions of gas hydrate were investigated. The results show that different ions have different influences on the phase equilibrium of gas hydrate. However, the influence of ions is in a similar trend： the larg- er the concentration, the bigger the P-T curve shifts to the left. For the silica sand, the influence of pore capillarity of coarse particles （〉 460 ~tm） can be negligible. The P-T curve measured in coarse silica is in agreement with that in pure water. How- ever, the influence of pore capillarity of fine particles （〈 35 μm） is significant. The maximum reduction value of temperature is 1.5 K for methane hydrate under stable state. The sediment from the South China Sea significantly affects the P-T stability conditions of methane hydrate, with an average reduction value of 1.9 K within the experimental conditions. This is mainly the result of both the pore water salinity and the pore capillarity of sediment. Because the pore water salinity is keeping diluted by the fresh water released from hydrate dissociation, the measured P-T stability points fall on different P-T curves with the de- creasing salinity.The P-T stability conditions of gas hydrate in different systems (i.e., solution, silica sand, and marine sediment) were studied using multi-step decomposition method with our experimental equipment. The effects of different ions with various concentrations and sediment grains on the P-T stability conditions of gas hydrate were investigated. The results show that different ions have different influences on the phase equilibrium of gas hydrate. However, the influence of ions is in a similar trend: the larger the concentration, the bigger the P-T curve shifts to the left. For the silica sand, the influence of pore capillarity of coarse particles (> 460 μm) can be negligible. The P-T curve measured in coarse silica is in agreement with that in pure water. However, the influence of pore capillarity of fine particles (< 35 μm) is significant. The maximum reduction value of temperature is 1.5 K for methane hydrate under stable state. The sediment from the South China Sea significantly affects the P-T stability conditions of methane hydrate, with an average reduction value of 1.9 K within the experimental conditions. This is mainly the result of both the pore water salinity and the pore capillarity of sediment. Because the pore water salinity is keeping diluted by the fresh water released from hydrate dissociation, the measured P-T stability points fall on different P-T curves with the decreasing salinity.

关 键 词：pore water silica sand methane hydrate sediment from South China Sea P-T stability conditions 

分 类 号：P744.4[天文地球—海洋科学] O241.82[理学—计算数学]