Abstract: In view of the relatively weak exploration and poor understanding of the exploration potential of the Yanchang Formation in the northern Jiyuan area, the hydrocarbon source rock conditions, reservoir conditions, accumulation mode and reservoir characteristics of the Chang₆-Chang₈ pay zones of Yanchang Formation in the northern Jiyuan area were analyzed and studied with drilling, analysis and laboratory data. It was found in the study that hydrocarbon source rock was developed in the Chang₇ pay zones of Yanchang Formation in the northern Jiyuan area, the dark mudstone at the bottom of Chang₇³ was effective hydrocarbon source rock; the organic carbon content was generally greater than 2%, the average content of chloroform bitumen "A" was 0.189%, the average of hydrocarbon generation potential S₁+S₂ was 13.01 mg/g, the organic matter abundance was high, the organic matter was dominated by Type I with basic source for petroleum generation; the average sand thickness of Chang₆ and Chang₈ pay zones was more than 10m, and the pore-throat combination was mainly small pore + micro-throat, micro pore + micro throat, locally medium pore + medium throat, and the porosity was mainly 8% to 12%; because of the longitudinal and transverse migration of the river channel, favorable reservoir-capping assemblage was formed, constituting lithologic and physical traps; the reservoir distribution was controlled by superposition of hydrocarbon source rock spreading, sand facies distribution and reservoir development. It was generally considered that this area had great oil exploration potential, and Wellblocks Feng 201 and Feng 11 were identified as the most favorable stacked exploration target areas in the area. The study is of guiding significance for the next oilfield exploration and development in the Yanchang Formation, the northern Jiyuan area.

Key words: accumulation conditions, oil reservoir characteristics, exploration potential, Yanchang Formation, northern Jiyuan Area, Ordos Basin