Review on Water Lock Phenomenon of Natural Gas Hydrate and Mitigation Technology of Chemical Reagents

Natural gas hydrate is a promising clean and efficient energy resource with vast global reserves, making its development crucial for optimizing the future energy structure. However, during production, free water and hydrate dissociation water can accumulate in pore throats under capillary forces, leading to the formation of water lock. This phenomenon can reduce reservoir permeability and in severe cases, interrupt production, thereby severely limiting recovery efficiency and long-term productivity. Chemical mitigation using functional reagents has emerged as a core approach to address this challenge owing to its operational simplicity, strong specificity, and rapid effectiveness. This paper systematically reviews the formation mechanisms and influencing factors of the water lock phenomenon in natural gas hydrate reservoirs. The mitigation mechanisms, performance characteristics, and application outcomes of representative chemical agents—including surfactants, alcohols, and salts—are summarized and analyzed. Furthermore, the existing technical bottlenecks are identified, and future research directions are proposed to provide theoretical guidance and technical support for the efficient and sustainable exploitation of natural gas hydrate resources.