| In this study,based on systematic geochemistry analysis of crude oil samples in Yueman block and its surrounding areas,we conducted research on the oil-oil correlation with multiple molecular parameters of crude oils,and compared with these crude oils from Tahe oilfield.The results show that crude oils from Yueman block and the Tahe oilfield show a high similarity in geochemical characteristics,should belong to the same oil population and originated from Upper Ordovician source rocks.On this basis,using molecular parameters,namely,Ts/(Ts+Tm),benzo [a]carbazole/(benzo[a]carbazole+benzo[c]carbazole)and 4,6-/(1,4+1,6)-DMDBT as tracing indicators,this study traced the orientation and filling pathways of the Ordovician oils inYueman block and showed general direction from south to north.Besides,the charging episode and timing of petroleum accumulation in Yueman block is determined according to the studies of fluid inclusions,hydrocarbon generation history of source rock and vitrinite reflectance.Reconstruction of burial history and thermal history of well Yueman5 shows that the Ordovician reservoir has been charged twice,the relative geological ages are 420Ma~410Ma(namely middle-late Silurian)and 18Ma~6Ma(namely in the middle and late Miocene),respectively.Through the accumulation of oil and gas comprehensive research,the potential hydrocarbon source kitchen for oils in the study area may be located in Manxi Low Uplift.Ordovician carbonate karst reservoir porosity development is a favorable area of oil and gas accumulation.The carbonate karst reservoir with high porosity and permeability in the Ordovician is the favorable area for hydrocarbon accumulation. |
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