Measurement of water phase permeability in the methane hydrate dissociation process using a new method

Abstract

Natural gas hydrates (NGHs) are a new, clean and effective energy source with great potential for exploitation. The permeability of hydrate-bearing sediment is one of the crucial factors for evaluating the efficiency of gas hydrate production. Many researchers have investigated the variation in permeability, but there is still no effective method for identifying the variation in permeability during hydrate dissociation. In this study, a new method was proposed by using a constant step of 0.5 K in the temperature-increasing process to control hydrate dissociation, which achieved a continuous measurement of permeability. Different initial water saturations (0%, 25%, 30%, 40%, 50%, 55%, and 60%) were used to investigate water phase permeability in the porous media during hydrate dissociation. The results showed that there was little MH in the reservoir after 277.65 K under a constant volume in the simulation process of hydrate extraction. Additionally, the distribution of permeability tended to be gradually centralized by dispersal during the increase in temperature under various experimental conditions. There is a variation in the permeability curve from an exponential distribution to a logarithmic distribution with an increase in temperature. The higher the initial water saturation, the lower the initial water phase permeability. Furthermore, in the process of hydrate dissociation, the permeability decreased exponentially with the increase in saturation. But when the hydrate saturation was less than 3%, the exponential correlation is not valid.