A Study On The Reservoir Of Yan'an Formation In South Wangyao Area, Changqing Oilfields

South wangyao region is located in the central and southern ordos basin yishan slope belt, namely the ansai- yan'an area. Research purpose layer of yan'an group is a set of terrigenous clastic sediments, Y 8~10 is the main reservoir. it had lower degree of exploration in this area. To carry on the fine reservoir research, find out the yanan group of sedimentary microfacies and sand body distribution characteristics of relationship, on the basis of predicting reservoir, for the future of the field has important guiding significance to the effective mining.South Wangyao area is located in the middle to south of Yishan slope, Ordos basin, namely Ansai—Yan'an area.Yan'an formation is a set of terrestrial clastical sediments and Y10~Y8 are the main oil reservoirs.The core description for coring wells,casting sections,scanning electronical microscope and X-ray diffraction,well logging curves are used to evaluate the reservoir property of studied area and distribution characteristics. The results of the research show that the rocks of sand-stone reservoirs of Y10-Y8 oil layers are dominated by lithic quartz-sandstone,feldspathic quartz-sandstone. Having undergone compaction,cementation and dissolution processes, the reservoirs are mainly in the diagenesis stage. The maturation of ingredients of rocks is medium or slightly high. The maturation of structures is medium.The grains are well-sorted;the roundness is mainly sub-edge to sub-corner.The pore types are primary intergranular pores and secondary pores. The following factors, namely the property of the original rocks, the sedimentary micro-facies, compaction, the alteration of unstable components, metasomatism,and dissolution,all have important impacts on the characters of the reservoirs. Besides them, compaction and cementation destroyed the structure of the primary pores, while the dissolution and the alteration of unstable components form the secondary pores then improved the pore structure. If the reservoirs in studied area are divided into 4 kinds(?,?,?,?),the sandstone reservoir of Yan'an formation usually are dominated by type?,? reservoir, where the micro-facies are water branch channel,river mouth-bar,underwater branch channel and sheet sand,etc.Qualified petroleum reservoirs distribute in the part where sheet sand or branch channel develops.