Estimation Of The Lower Segment Reservior’s Feature Of Yanchang Oil Layer In Yanchi-Dingbian Area, Ordos Basin

Used contemporary theories of sedimentology;petroleum geology;structural geology;and logging geology,through field geologic survey and indoor comprehensive analysis,this papar systematically classified and compared the6th,7th,8th and9th member of the lower segment of Yanchang Formation in Yanchi-Dingbian area. Analysed precipitation facies types and characteristic of individual well and it’s distribution and evolutional history, further research the petrologic feature of reservoir;diagenesis of reservoir sand; physical property and pore texture features of reservoir. Then classified and evaluated the reservoir. By the research of key elements of oil field and petroleum concentrated rule of Yanchang oil layer, we can acquire the types of the hydrocarbon reservoir traps and the controlling factors of petroleum partition,then speculated the prospective area of the researched block.Through the research we can know that the6th,8th and9th oil layer developed coastal lake, braided river delta and meandering river delta depositional system. The main rock types are lithic arkose and feldspathic litharenite. Lithology features are low compositional maturity, fine grain-size to mesograin, grain well selected, subangular, line contact, honeycombed cement; The apertures mainly are intergranular pore, arcosic corroded hollow; both of the vertical overlay of the reservoir sandbody and the areal connectedness are preferable, So the6th;8th and9th oil layer are high quality reservoirsof the researched area. Based on the conditions of sedimentary microfacies, physical property of reservoir and regional structure,25promising areas are predicted in the researched area.