Study on the Factors Affecting Gas Production and Sedimentation Ratios in the Extraction Process of Marine Methane Hydrate

In response to the risk benefit assessment of formation settlement and gas production induced by depressurization extraction of natural gas hydrates in the sea area, based on the coupling numerical simulation of multiphase seepage heat transfer mechanics, the evolution of mechanical parameters of shallow seabed strata with depth was considered, and the effects of extraction pressure difference and well spacing on the formation gas production settlement ratio were analyzed. The research results indicate that increasing the production pressure difference can effectively increase the gas production of the mining well, but its settlement also increases, and the gas production settlement ratio shows a decreasing trend with the increase of the bottom hole pressure difference; Increasing the spacing between the branch well and the main wellbore can effectively increase gas production, reduce formation settlement, and gradually increase the gas production settlement ratio. The research results can provide theoretical reference for the design of mining schemes in the process of shallow depressurization of natural gas extraction in the sea area.