Numerical simulation of gas hydrate migration-accumulation system and trial mining optimization of orebodies in the Shenhu area

Based on seismic profile data of natural gas hydrate exploration in Shenhu area in the north of South China Sea, combined with geological conditions of regional accumulation, the 2D geological models for the W17 and W18 orebodies in the exploration area were constructed respectively to further understand the gas hydrate accumulation system in Shenhu exploration area of the northern continental slope of South China Sea.A systematic simulation was carried out to test gas hydrate stability zone, gas source formation, migration and accumulation.The results show that: a.the Shenhu exploration area is rich in gas sources, and both the shallow biogenic gas and the deep thermogenic gas can be used as gas sources for hydrate accumulation; b.the Shenhu exploration area has excellent transport system where the deep fault can be used as source fault to connect the deep source rocks and serves as the main channel connecting the deep thermal gas, and the shallow regulatory fracture and permeable sandstone serve as transverse and vertical transportation; c.the areas with relatively good sealing property of fault blocks and relatively high permeability are favorable reservoirs for gas hydrate accumulation.According to the comprehensive analysis, the orebody W17 has more advantages than the orebody W18 in gas source, migration and reservoir characteristics, so it should be considered as a priority for trial mining.