The petroliferous studied block (Zhen 11 block, Zhenwu oilfield, Gaoyou sag) is situated in the North Jiangsu basin, China. The studied Sanduo formation is the target zone with two members. The main objective of the studied formation is to evaluate the reservoir characteristics of the Sanduo formation. To accomplish the aims, the core data, logging data, mercury injection capillary pressure (MICP), Cathodoluminescence (CL), X-ray diffraction (XRD), and Petrographic thin sections analysis of more than 10 wells have been analyzed. The reservoir rock types are felspathic litharenite and lithic arkoses. The grain rounding and sorting are deprived, with low texture maturity with moderate to good reservoir characteristics (10% to 30% porosity and 0.4 × 10− 3µm2 to 8000 × 10− 3µm2 permeability). Mechanical compaction, quartz and calcite cement, feldspar dissolution, and alteration of clay minerals are the main diagenetic processes. Thick-bedded coarse-grained sandstones have been deposited in a channel, where primary pores are common and the rock has strong compaction resistance, resulting in better reservoir quality. In the channel bay and estuary sedimentary environment, fine-grained and thin-layer sandstones are deposited, which represent weak anti-compressive capacity and rapid attenuation of pores during burial, indicating low reservoir characteristics. Carbonate cements block pores that significantly reduce the reservoir properties. Type I and type II zones are favorable reservoirs that are primarily developed in the superimposed development positions of meandering channel, side beach, braided channel, and underwater distributary channel at the front of the delta. The sandstone deposited in these environments has a high content of quartz and feldspar with good sorting. The rock has strong anti-compaction ability during burial and compaction, and the original intergranular pores are well preserved, which permits the acidic fluids migration into the reservoir. Due to that, dissolution can create secondary pores that enhance the reservoir characteristics.
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