Characteristics and Comprehensive Evaluation of the Shanxi Formation Tight Sandstone Reservoir in the Wuzhong Area of the Western Ordos Basin

In order to clarify the reservoir characteristics of the Upper Paleozoic tight sandstone in Wuzhong area of Ordos Basin and evaluate it reasonably, the rock types, pore types, diagenesis and physical properties of the reservoir were studied by means of casting thin sections, scanning electron microscopy and high pressure mercury injection test. The impact of the reservoir class on oil productivity is analyzed by dividing the reservoir class and combining it with oil testing. The results show that the compact sandstone reservoirs of the Shanxi Formation in the study area developed in the underwater sedimentary of the tidal delta front, and mainly developed lithic quartz sandstone and lithic sandstone. Pore types are mainly dissolved intergranular pores, dissolved intraparticle pores, intercrystalline micropores and microfractures. Compaction, cementation, metasomatism, and dissolution are common, and diagenesis occurs mainly in the C period of the stage of over-mature late diagenesis. The tight sandstone reservoirs of Shanxi Formation in the study area can be divided into four types, among which the class I reservoirs with the highest exploration potential are concentrated in the main part of the underwater distributary channel, and the gas production of a single well exceeds 10,000 m3.