Kinetics of methane gas hydrate formation with microscale sand in an autoclav...

葛成红66

【文件名】 Kinetics of methane gas hydrate formation with microscale sand in anautoclave with windows
【文件格式】 PDF
【页数】 11
【内容介绍】 During the exploitation of subsea natural gas hydrate (NGH) deposits, the muddy silt from marine sedimentis carried by the fluid inside the wellbore. Furthermore, NGH is readily formed inside the wellborewhen the fluid is in a hydrate formation area. Once NGH has formed inside the wellbore, the exploitationoperation will be hindered, or shut down, due to the blockage. Understanding the kinetic characteristicsand morphology of NGH formation is important to prevent its occurrence. To this end, a high-pressureautoclave system was designed and constructed in this work. Experiments were conducted to determinethe mechanism of sand aggregation, the effect of sand on the kinetic characteristics and the morphologyof hydrate formation. Additionally, models of hydrate particle formation with sand and sand aggregation,and structure of wall-attached hydrate layer growth were proposed. The results showed that sand couldpromote the growth of hydrate and the wall-attached hydrate layer. Additionally, it was observed thathydrate particles were formed with and without sand, and that the wall-attached hydrate layer presenteda sandwich structure. The rolling and colliding implantations of hydrate particles were also observedexperimentally. Sand aggregation was caused by hydrate particle implantation and the carrying sandeffect. Hydrate particle formation with sand can be divided into four stages: nucleation, surface growth,shell formation, and shell growth. The sand aggregation process can also be divided into four stages:hydrate film formation, rupture of hydrate film, particle aggregation, and hydrate layer sintering. Forstructure of wall-attached hydrate layer growth, the growth front of the hydrate layer was concaveupward.
Keywords:Gas hydrate; Hydrate morphology ;Growth mechanism ;Sand aggregation ;Growth characteristic
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