Overview of Gas Recovery from Natural Hydrate Reservoirs by Depressurization: Current Status, Challenges, and Key Issues

Natural gas hydrates (NGHs) are among the most promising clean alternative energy sources to replace fossil fuels in the post-petroleum era. Over the past decade, extensive research on NGHs has made remarkable progress, advancing from the resource exploration stage to trial production. Field production tests have demonstrated that depressurization is one of the most effective and promising methods for the commercial exploitation of NGHs. In this paper, we systematically summarized the current advances in experimental simulations, numerical simulations, and field production tests of NGHs exploitation by depressurization. The problems and limitations of laboratory simulations and field tests were discussed, and related technical and environmental issues that may arise in commercial production were analyzed. Key scientific challenges involved during production were put forward. Enhancing production efficiency and ensuring the stability of sediment layers are critical to achieving commercial-scale exploitation of NGHs reservoirs.