Reservoir Forming Pattern of Complicate Reservoirs in Tahe Oilfield

It was obvious that regional structural motions were controlled by hydrocarbon accumulation of Tahe Oilfield, the accumulation process can be divided into four stages: late Caledonian-early Hercynian epoch is the first accumulation stage, effective hydrocarbon reservoir is not formed for lack caprocks; late Hercynian epoch is the second accumulation stage, Ordovician paleo-karst belt is the most advanced hydrocarbon accumulation area, late Yanshanian-mid Himalayan epoch is the third stage, in this period, the main hydrocarbon accumulation is Ordovician hydrocarbon transported to the top formation through transport system, and accumulated in Carboniferous and Triassic systems; Late Himalayan epoch is the fouth stage, hydrocarbon distribution is adjusted, while the high-southern and low-northern structure is formed. Through accumulation condition and process research, it is indicated that Ordovician advanced exploration area is the karst belt in paleo-uplift and Triassic exploration area is the lithologic oil pool in the north of Tahe Oilfield.