Slope Stability Analysis during Multi-vertical Well Gas Hydrate Production

Gas hydrate production can lead to reservoir strength degradation and an increase in effective stress, which may induce seabed subsidence and slope failure. This risk is particularly pronounced during multi-well production, where a larger area of the formation is affected, thereby increasing the likelihood of landslides. Considering the thermo–hydro–mechanical (THM) coupling characteristics inherent in gas hydrate exploitation, a slope stability evaluation model was developed by integrating these coupled processes with the finite element strength reduction method. The model was applied to investigate slope stability during multi-vertical well gas hydrate production. The results indicate that, under identical well spacing, a linear well layout parallel to the slope strike enhances slope stability compared with a layout perpendicular to the strike. For the same layout orientation, increasing both the well spacing and production pressure improves slope stability. Conversely, when using a vertical well network, slope stability decreases progressively with increasing well density for a given production duration. Slopes with excessively steep angles exhibit a high risk of failure, whereas reducing the slope angle progressively improves stability. These findings provide a theoretical basis for optimizing development plans for deepwater gas hydrate reservoirs.