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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. [ABSTRACT FROM AUTHOR]

Natural gas hydrate-bearing sediment permeability, which influences the flow behavior of fluids, is a key physical parameter used to determine the exploitation efficiency of hydrate. However, no comprehensive overview of existing research related to its measurement and application development has been conducted to date. In this review, the related advances in sediment permeability are systematically summarized in terms of experiments, models, numerical simulations, and its influence on hydrate exploitation. The sediment permeability measurement and their influencing factors have been comprehensively analyzed. In particular, the effects of hydrate phase transition on sediment permeability are discussed in detail. In addition, the normalized models of sediment permeability and numerical simulations of sediment structure are investigated. However, no universal normalized models of sediment permeability and numerical simulation of hydrate phase transition are available. The mechanism by which sediment permeability magnitude and anisotropy influence the hydrate exploitation efficiency has also been discussed. Finally, future efforts should focus on dynamic evolution, high-precision measurement, multifactor coupling effect, generalization of models, and optimization of numerical simulations, which are beneficial to improve guidance for the commercial exploitation of hydrate. • The influence of permeability on hydrate exploitation from experiments, models, numerical simulations are reviewed. • The sediment permeability measurement and its influencing factors have been comprehensively analyzed. • The normalized models of sediment permeability and numerical simulations of sediment structure are investigated. • The effect mechanism of sediment permeability magnitude /anisotropy on hydrate exploitation efficiency has been discussed. • The challenges of current research and future research prospects are discussed. [ABSTRACT FROM AUTHOR]

Natural gas hydrate-bearing sediment permeability, which influences the flow behavior of fluids, is a key physical parameter used to determine the exploitation efficiency of hydrate. However, no comprehensive overview of existing research related to its measurement and application development has been conducted to date. In this review, the related advances in sediment permeability are systematically summarized in terms of experiments, models, numerical simulations, and its influence on hydrate exploitation. The sediment permeability measurement and their influencing factors have been comprehensively analyzed. In particular, the effects of hydrate phase transition on sediment permeability are discussed in detail. In addition, the normalized models of sediment permeability and numerical simulations of sediment structure are investigated. However, no universal normalized models of sediment permeability and numerical simulation of hydrate phase transition are available. The mechanism by which sediment permeability magnitude and anisotropy influence the hydrate exploitation efficiency has also been discussed. Finally, future efforts should focus on dynamic evolution, high-precision measurement, multifactor coupling effect, generalization of models, and optimization of numerical simulations, which are beneficial to improve guidance for the commercial exploitation of hydrate. • The influence of permeability on hydrate exploitation from experiments, models, numerical simulations are reviewed. • The sediment permeability measurement and its influencing factors have been comprehensively analyzed. • The normalized models of sediment permeability and numerical simulations of sediment structure are investigated. • The effect mechanism of sediment permeability magnitude /anisotropy on hydrate exploitation efficiency has been discussed. • The challenges of current research and future research prospects are discussed. [ABSTRACT FROM AUTHOR]