Two-dimensional experimental study on stepwise depressurization production characteristics of natural gas hydrate with combined horizontal well and vertical well

Combined multi-well production method has irreplaceable advantages over single well, especially in the future industrialization of natural gas hydrate regarded as a highly efficient and clean potential alternative energy source. Researching the effectiveness of combined multi-well production contributes to optimizing production plans and well designs, thereby improving overall production efficiency. In this study, utilizing a self-developed large-size two-dimensional natural gas hydrate production simulation apparatus to conduct stepwise depressurization production experiments under three types of well, including single horizontal well, single vertical well, and combined horizontal well and vertical well. The investigation focused on the impact of well types on reservoir responses and gas production characteristics at the planar scale during depressurization production. The findings reveal that during the constant pressure stage of dual-well combined production, pressure can be maintained stable, but maintaining stability in temperature is challenging due to the comprehensive impact of factors such as the distribution of hydrates in the reactor, hydrate reformation, and heat transfer efficiency. Throughout the process of dual-well combined production, combined production effect is observed. In the early and middle stages of production, the two wells complement each other, exhibiting a synergistic effect. In the later stages of production, combined production effect manifests as optimization of gas production behavior, whereby the gas production behavior is optimized to be more conducive to further production of hydrate.