Green, efficient and safe extraction methods of methane-hydrate in Qiongdongnan seabed, China

The green, efficient and safe extraction of natural gas hydrates from the Qiongdongnan seabed, China will play an important role in achieving the China's energy strategy and the goals of carbon peaking and carbon neutrality. However, the traditional depressurization, thermal stimulation and CO₂ replacement methods will face significant challenges when applied to methane-hydrate (MH) bearing clayey silt and silty clay in the Qiongdongnan basin, China. The current research status at home and abroad in recent years is summarized from three aspects: (1) the macroscopic and microscopic mechanical behaviors of hydrates bearing sediments and their relationships under complex multi-field and multi-process conditions together with phase-changes of hydrates; (2) the theoretical and multi-scale numerical analysis methods of simulating the multi-field, multi-phase, multi-process coupling effects in the MH reservoir at all the stages of deep sea energy geotechnical engineering; (3) The green, efficient and safe MH exploitation methods and adaptability evaluation. The existing problems and limitations are explored. It is necessary to employ a new approach combining the depressurization, thermal stimulation, CO₂ replacement/ injection and other measures to increase gas production, carbon sequestration and engineering safety to realize the green, efficient, and all-stages safe exploitation of MH in the Qiongdongnan seabed, China.