Green, Efficient, and Safe Extraction Methods of methane-hydrate in the Qiongdongnan seabed, China

Green, efficient, and safe extraction of natural gas hydrates from 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, traditional depressurization, thermal stimulation, and CO2 replacement methods will face significant challenges when applied to methane-hydrate (MH) bearing clayey silty sand and sandy clay in Qiongdongnan basin, China. This article summarizes the current research status at home and abroad in recent years 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. 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. green, efficient, and safe MH exploitation methods and adaptability evaluation. Problems and limitations of existing have been 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.