Review of Influencing Factors and Measurement Methods for the Permeability of Natural Gas Hydrate Reservoirs

The permeability of a natural gas hydrate (NGH) reservoir during production is a core process parameter that dictates the efficiency of mass transfer, heat transfer, and ultimate production. This paper focuses on the critical issues of permeability’s influencing factors and measurement methods, providing a systematic review of the latest research progress in this field. Firstly, it analyzes the dynamic regulation mechanisms of flow channels from a microscopic perspective, considering the physical properties of sediments, pore structure, pore-filling materials, and mechanical conditions. Secondly, it systematically reviews the permeability testing techniques from laboratory to field scales, with a key focus on comparing the advantages and disadvantages of steady-state and unsteady-state methods for measuring low-permeability media. The principles, models, and recent advancements of advanced in-situ detection technologies, such as Formation Pressure Testing (FPT) and Nuclear Magnetic Resonance (NMR), are also elaborated, particularly highlighting the application of intelligent well-logging interpretation methods empowered by machine learning. Based on this review, a future outlook is proposed: future research should prioritize the development of cross-scale numerical simulations that integrate Pore Network Models (PNM), the Discrete Element Method (DEM), and Thermo-Hydro-Mechano-Chemical (THMC) multi-field coupling. Furthermore, it should promote the deep integration of downhole in-situ sensing technology and artificial intelligence, aiming to achieve precise prediction and optimal control of the hydrate production process.