The Tahe oilfiled is located at the Arkekula salient of the Shaya uplift in the northern Tarim Basin.Its main body is the large scale unconformity-fractured-vuggy reservoir in the Ordovician carbonate.It is superposed by the Carboniferous and Triassic low amplitude anticlinal

lithologic and composite traps

which form secondary reservoirs through connection by faults and unconformities

and show vertically the characteristics of composite play.The Tahe oilfield occurs at the slope of paleo-craton basin and on the edge of large hydrocarbon kitchen. The rich resource rock is the material bases for the formation of large oilfield;the large nose shaped salient with long-term development controls hydrocarbon migration and accumulation;the multi-stage unconformities are effective pathways for lateral hydrocarbon migration;the faulting

fracturing and karstification form the network reservoir consisting of pore

fracture

rug;the favorable reservoir-seal assemblages are important conditions for forming large oilfield.The present complicated hydrocarbon accumulations are caused by long term hydrocarbon generation

multi-stage tectonic movements and multi-phase hydrocarbon charging.