Quantitative Prediction And Main Controlling Factor Analysis Of Litho-stratigraphic Reservoirs In The Third Shahejie Formation Of Dongpu Depression

The Shahejie Formation of Paleogene in the Dongpu Depression is the most aboundant in oil and gas.So far most reservoirs founded are the stratigraphic reservoirs,but the litho-stratigraphic reservoirs are very few,and the exploration degree is relatively low.At the same time,the exploration method only depends on the trap characterization and reservoir prediction results to deploy wells.In this paper,two typical litho-stratigraphic reservoirs in Huzhuangji Oilfield and Baimiao gas field are selected for dissection,and their basic petroleum geologic characteristics and main controlling factors are analyzed.The results show that the litho-stratigraphic reservoirs in the third member of Shahejie Formation in Dongpu Depression have good near-source rock conditions(S),favorable sedimentary and accumulate facies(D),low interfacial potential(P),high quality of the area caprock condition(C).The expulsion intensity of the source rock controlls the sources of the litho-stratigraphic reservoirs,and 85% of the litho-stratigraphic reservoirs distribute in the range of hydrocarbon expulsion;reservoir conditions control the properties of litho-stratigraphic reservoirs,most of the reservoirs are located in the shallow lakes and the outer front of the delta;The low boundary potentials control the dynamic conditions of litho-stratigraphic reservoirs,most of them are distributed in relatively low interfacial potentials.The regional caprock controls the preservation conditions of litho-stratigraphic reservoirs and 90% of the cover layer thickness is more than 50 m.On the basis of the above analysis,the Model of Functional Elements Combination(“T-CDPS”)in the main reservoir formation period is established,and the reservoir formation probability of lithologic reservoirs in the upper,middle and lower sections of the Dongpu depression is predicted.85% of the lithologic stratigraphic reservoirs are distributed in the range of the probability of accumulation of 0.75-1.0,which provides a certain direction for the exploration of lithologic traps in Dongpu Depression.