The Research Of Marine Shale Gas Preservation In Xiuwu Basin,northwestern Jiangxi Province

Preservation condition plays a significant role in the exploration of marine shale gas in South China.To further explain the mechanism of factors' control on marine shale gas preservation,clarify the shale gas preservation in Xiuwu Basin and optimize the favorable areas,this research analyzed plays in Sichuan Basin and its periphery and Xiuwu Basin to summarize patterns and evaluation standards,which were subsequently applied in Xiuwu Basin.Based on geological settings,logs and previous studies,along with experiments including overburden permeability tests,spontaneous imbibition and triaxial unloading,this research discussed from three aspects: shale and its roof and floor,structural style,fracture and denudation zone.The results show sealing of roof and floor comes from shale's migration ability in different directions,as well as the physical difference between roof,floor and shale.Shale' self-sealing have effects on shale gas reservoir along with roof and floor.As for structural style,its influence presents in burial depth and tectonic deformation.The favorable areas likely lie in the core of syncline with weak tectonic deformation and moderate burial depth,and the top of anticline with effective sealing system.Fracture and denudation zone lead to changes of shale's pore size,geo-temperature and pressure possibly resulting in the alteration of shale gas migration.After evaluation,the favorable interval in Xiuwu Basin is Guanyintang—Wangyinpu Formation,and the favorable areas are mainly in the basin center with moderate depth and small tectonic deforamtion.