Natural gas hydrate formation induced by the leakage of methane was observed in field investigation. The appearance of cold seep might be an indication of natural gas hydrate reservoir. In this study, CH4 hydrate formation in porous media with continuous gas flow was firstly investigated using magnetic resonance imaging. Three flow rates (0.2, 0.4, 0.6 mL/min) were experimentally conducted and the results indicated that the gas flow rate plays a crucial role in the hydrate formation. A high flow rate could reduce the CH4 displacement and hydrate formation time, however, more water was brought out from the sediment during displacement process, finally leading to a low hydrate saturation. It is suggested that for cold seep where gas bubble gushes violently, the hydrate reservoir may not be abundant. Our work can provide some insights of the mechanism of hydrate formation induced by cold seep, making contributions to future cold seep field investigation.
Keywords Cold seep; Methane hydrate formation; Gas flow; Porous media