Review of natural gas hydrate dissociation effects on seabed stability

As a high-energy clean energy substance, natural gas hydrate (NGH) has a high value of development and utilization. However, NGH is extremely easy to decompose during its exploitations, thereby leading to the destruction of seabed stability. In this paper, the distribution and significance of NGH, the mechanism of decomposition and formation, the effect of seabed stability, and the influencing factors are studied and analyzed. Studies show that NGH reserves are large, and they are easy to decompose. The dissociation of NGH is the main factor of seabed instability. During the decomposition of NGH, the strength parameters (cohesion and friction angle) of seabed soil are reduced, and the pore water pressure of seabed increases. The seabed structure exhibits soft sliding surface and large deep cracks, leading to the instability of sediments and serious seabed landslide. The factors affecting the decomposition of NGH include environmental change, human activities, structure difference in seabed itself, and sea solute difference. This paper aims to better understand the decomposition mechanism of NGH for analyzing the influencing mechanism of seabed stability and for providing a direction for the study of marine geological hazards.