Research Development in the Traditional Methods and Water Flow Erosion for Natural Gas Hydrate Production: A Review

Natural gas hydrates are considered a possible sustainable energy source. Various methods have been proposed and developed in the past few decades to exploit hydrate. The purpose of this paper is to review the research advances, application potential, and limitations of hydrate production methods, including four traditional methods (depressurization, thermal stimulation, inhibitor injection, and CO2 replacement), and novel water flow erosion. For the four traditional methods, there still exist many bottlenecks to achieve commercial hydrate production owing to a series of problems such as vast sand production, ice generation, hydrate reformation, lower energy efficiency, and huge water production. For the water flow erosion method, it can be a novel strategy to promote hydrate decomposition by introducing the chemical potential difference and accelerating mass transfer. Significantly, if the traditional methods assist with water flow erosion, the problems such as insufficient decomposition driving force and ice generation are prevented. However, there is always a gap between the experimental results and the practical application of the water flow erosion method. Therefore, future work should be undertaken to investigate the selection criteria of suitable water flow rates for different reservoirs and the ecological security of the hydrate reservoir during the water flow erosion process.