Experimental investigation of hydrate formation in water-dominated pipeline and its influential factors

• Published in: China Geology Vol. 5; no. 2; pp. 310 - 321
• Main Authors: Huang, Li, Kang, Jia-le, Shen, Xiao-dong, Sun, Jian-ye, Meng, Qing-guo, Chen, Qiang, Hu, Gao-wei, Liu, Chang-ling, Wu, Neng-you
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2022; KeAi Communications Co., Ltd
• Subjects: Circulation; Flowrate; Formation morphology; Gas concentration; Gas hydrate; NGHs exploration trial engineering; Oil and gas exploration engineering; Pipeline; Shenhu Area; South China Sea; Water production; Gas hydrate; Flowrate; South China Sea; Gas concentration; Water production; Oil and gas exploration engineering; Formation morphology; Shenhu Area; Circulation; NGHs exploration trial engineering; Pipeline
• DOI: 10.31035/cg2022015
• ISSN: 2096-5192; 2589-9430

Blockage in water-dominated flow pipelines due to hydrate reformation has been suggested as a potential safety issue during the hydrate production. In this work, flow velocity-dependent hydrate formation features are investigated in a fluid circulation system with a total length of 39 m. A 9-m section pipe is transparent consisted of two complete rectangular loops. By means of pressurization with gas-saturated water, the system can gradually reach the equilibrium conditions. The result shows that the hydrates are delayed to appear as floccules or thin films covering the methane bubbles. When the circulation velocity is below 750 rpm, hydrate is finally deposited as a “hydrate bed” at upmost of inner wall, narrowing the flow channel of the pipeline. Nevertheless, no plugging is observed during all the experimental runs. The five stages of hydrate deposition are proposed based on the experimental results. It is also revealed that a higher driving pressure is needed at a lower flow rate. The driving force of hydrate formation from gas and water obtained by melting hydrate is higher than that from fresh water with no previous hydrate history. The authors hope that this work will be beneficial for the flow assurance of the following oceanic field hydrate recovery trials. ©2022 China Geology Editorial Office.