Critical Factors in Oil Field Exploration and Development: Reservoir Characteristics and Controlling Factors

Elucidating reservoir characteristics and main controlling factors has guiding significance for identifying favorable target areas for oil and gas exploration and development. Based on core observation, casting thin section, scanning electron microscope, mercury intrusion curve, physical property analysis, etc., the characteristics and controlling factors of Chang 8 reservoir in Wanggoumen area of Ordos Basin were studied and analyzed. The results show that feldspar sandstone and lithic feldspar sandstone are the primary rocks in the Chang 8 reservoir, and the composition of cuttings and interstitials is higher. Intergranular pores, feldspar, or lithic dissolution pores are the main pore types of Chang 8, with an average surface porosity of about 2.41%. The porosity of Chang 8–1 and Chang 8–2 sublayers is 8.77 and 8.64%, respectively, and the permeability is 0.39 and 0.32 MD, respectively, which belong to the ultra-low porosity and ultra-low permeability reservoirs. High-quality reservoirs are distributed in underwater distributary channel microfacies. The destructive diagenesis affecting the reservoir quality is mainly compaction, followed by cementation, and the constructive diagenesis is dissolution.