The key factors that influence sealing capacity of fault include fault activity

shale smearing factor

lithologic juxtaposition on both sides of fault

and relation between pressure on fault plane and shale stratum ratio. Taking these four key influential factors as appraisal parameters and integrating with tectonic evolution of the basin

the vertical and lateral sealing capacities and sealing history of the faults in Gas fault depression in Qaidam basin are studied. It is shown that the sealing capacities of faults vary largely in time and space in western Qaidam basin and have played different roles in hydrocarbon migration and accumulation. When acting as migration pathways of hydrocarbon

the faults would interconnect source rocks and traps and controlled the horizons and times of vertical migration and accumulation of hydrocarbons

such as the Ⅶ and Ⅺ faults. When acting as barrier beds

they would control the formation of traps for hydrocarbon accumulation

such as Wunan fault. Reactivation of faults would destruct oil and gas reservoirs

leading to the redistribution of oil and gas

such as the faults in Youshashan and Nanyishan areas.