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Title: Study on gas-water-sand-hydrate foam flow and discharge in the wellbore during hydrate depressurisation production

Authors: Haitao Li; Xuefei Zhang; Na Wei; Jianyong Feng; Zhaolong Ge; Shuning Yi; Liehui Zhang; Bjørn Kvamme; Richard Banks Coffin

Addresses: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Road No. 8, Chengdu 610500, China; State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China ' State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Road No. 8, Chengdu 610500, China ' State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Road No. 8, Chengdu 610500, China ' State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Road No. 8, Chengdu 610500, China ' State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China ' State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Road No. 8, Chengdu 610500, China ' State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Road No. 8, Chengdu 610500, China ' State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Road No. 8, Chengdu 610500, China; Department Physics and Technology, University of Bergen, Allegaten 55, Bergen, N-5007, Norway ' State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Road No. 8, Chengdu 610500, China; Department of Physical and Environmental Science, Texas A&M University – Corpus Christi, Corpus Christi, TX, 78412, USA

Abstract: To address sand and water production in hydrate reservoirs that affect the production efficiency, this study innovatively considers the application of foam drainage to hydrate production scenarios. Using a multi-physics field coupling approach, a numerical model of continuous foam drainage in wellbores based on the liquid- and solid-carrying models and other models is developed, and its evaluation accuracy was verified to be up to 95% by comparing with the indoor experimental data. Correlation factor analysis showed that increasing nitrogen injection rate, gas production rate and gas-liquid ratio enhanced liquid and solid transport efficiency. However, both excessive foam viscosity and overly low viscosity adversely affect system performance. Under South China Sea hydrate trial conditions, the study employed model predictions and multi-factor analysis to determine optimal foam injection rates for varying water/sand production levels. The findings provide theoretical guidance for optimising continuous foam drainage technology in hydrate wells, aiding in productivity enhancement. [Received: May 18, 2025; Accepted: July 8, 2025]

Keywords: foam drainage; wellbore fluid accumulation; reservoir sand production; natural gas hydrate; numerical simulation.

DOI: 10.1504/IJOGCT.2026.152625

International Journal of Oil, Gas and Coal Technology, 2026 Vol.39 No.5, pp.1 - 29

Received: 06 May 2025
Accepted: 08 Jul 2025
Published online: 31 Mar 2026 *