The Fault Sealing Ability Research Of Kuche Depression In Talimu Basin And Its Controlling Effect On Fluid Migration

Through the research on the development character of overthrust fault, we analyzed its sealing mechanism. We also established evaluation standard and method of fault sealing ability through the experiment on the quantitative relationship between property of fracture zone filler, fault obliquity, shale percent and fault sealing ability. Based on these work, we evaluated sealing ability of overthrust faults on several typical structure in Kuche depression. The result is that most current faults are sealed. This is the main condition for natural gas and abnormal pore pressure to preserve in Kuche depression. We have also studied fracture formation and moving period by means of growth triangle zone and equilibrium section technology. The result is that fracture formation period in different structure zone are very different. The basic law is that from the north to the south, the fracture formation period is later and later. But the main fracture moving period is Kuche - Quaternary. Based on these research, we recovered the evolution history of overthrust fault's vertical sealing ability and considered that there always have fracture activity ever since Jidike formation deposition period. But this kind of activity is not always continuous. During moving period, fault is open. During static period, fault is closed. We analyzed the effect of fracture in the gas deposit formation and hold that different kinds of fracture have different effect:: hydrocarbon dissipation and relief effect of crossing salt bed faults that run through source rock, reservoir, and caprock; filling effect of under salt bed faults that run through source rock and reservoir; slippage faults that did not connect source rock have no effect to hydrocarbon accumulation and dissipation; adjusting faults in reservoir have effect of adjusting formations for hydrocarbon distribution.