Reservoir Characterization of Chang 6 Member in Jiyuan Area, Ordos Basin

The Chang 6 section in Jiyuan area of Ordos Basin is a key formation for exploration of low permeability sandstone lithology reservoirs. In this study, the reservoir characteristics and low permeability genesis were systematically revealed by means of core analysis, thin section identification and mercury pressure experiment. The results show that the reservoir is dominated by feldspathic sandstone with low porosity and extra low permeability; the pores are dominated by primary intergranular pores and the pore throat structure is poor. The main causes of low permeability include: (1) fine-grained sedimentary background with dual sources; (2) sharp reduction of pore space due to strong compaction and multi-phase cementation; and (3) limited pore enlargement by dissolution. Sedimentation-rock formation coupling analysis shows that the main sand zone of the submerged diversion channel is a favorable reservoir zone, and future exploration should focus on the weak rock formation zone. This study provides geological basis for the efficient development of Chang 6 reservoir in Jiyuan area.