Characteristics and comprehensive evaluation of Chang 4+5_2 reservoir in Hujianshan Oilfield, Ordos Basin

Based on core observation,cast thin section and intrusive mercury curve, the petrology characteristics,pore throat characteristics and diagenesis of Chang 4+52 reservoir in Hujianshan Oilfield are studied, and the reservoir is comprehensively evaluated. The result shows that the lithologies of Chang 4+52 reservoir are mainly fine arkose and lithic arkose, the reservoir spaces mainly are residual intergranular pore and feldspar dissolved pore, and the lamellar throat and curved lamellar throat are the main seepage channel. The diageneses contain compaction, cementation and dissolution. Chang 4+52 reservoir are mainly of typeⅡ and Ⅲ, belonging to low porosity and extra-low permeability reservoir.