To further clarify the reservoir characteristics and controlling factors of Member 1 of the Lower Permian Shanxi Formation in the Qingtan 3–Long 37 well area of the Qingyang Gas Field, located in the southwestern Ordos Basin, techniques such as grain size analysis, thin section identification, mercury intrusion porosimetry, and physical property testing were employed. The study qualitatively and quantitatively analyzes the petrological and physical properties, pore types, reservoir space types, and pore structure characteristics. It also investigates the primary factors affecting reservoir properties from the perspectives of sedimentation and diagenesis. The results show that: (1) Member 1 of the Shanxi Formation in the study area is characterized by meandering river–delta deposits. The reservoir lithology is dominated by lithic quartz sandstone and feldspathic lithic sandstone, with matrix materials primarily composed of clay and calcareous components. Pore cementation is the main cementation type. (2) The reservoirs are ultra-low porosity and ultra-low permeability, primarily consisting of intergranular primary pores, intergranular dissolution pores, and intragranular pores. The capillary pressure curve types are classified into four categories: Type I (low displacement pressure–coarse throat), Type II (relatively low displacement pressure–medium to coarse throat), Type III (high displacement pressure–fine throat), and Type IV (high displacement pressure–micro throat). (3) Reservoir development is mainly controlled by sedimentation and diagenesis. Reservoir quality positively correlates with grain size, and the most favorable depositional microfacies are found at the bottom of riverbeds. (4) Destructive diagenesis is the primary reason for porosity reduction, whereas constructive diagenesis significantly enhances porosity and permeability in sandstones.

Guo Fengwei, Wang Yongqiang, Gao Wei, Xu Yong, Sun Liyong, Liu Pengfei. Characteristics and Controlling Factors of Tight Reservoirs in the Shanxi Formation Member 1 of the Lower Permian in the Southwestern Ordos Basin: A Case Study of the Qingtan 3–Long 37 Well Area in the Qingyang Gas Field. Academic Journal of Architecture and Geotechnical Engineering (2025), Vol. 7, Issue 2: 65-71. https://doi.org/10.25236/AJAGE.2025.070209.

[1] Wang Yongqiang, Wang Yue, Li Chuanhao, Zhang Haoran, Sun Liyong, Liu Pengfei. Sedimentary Characteristics and Sandbody Distribution of Qingyang Gas Field [J]. Petrochemical Industry Technology, 2023, 30(10):144-145, 226.

[2] Liu Pengfei, Gao Wei, Sun Liyong, Zhang Xinyuan. Analysis of Production Construction Area in Block X of Qingyang Gas Field [J]. Petrochemical Industry Application, 2024, 43(2):74-75, 117.

[3] Wang Yongqiang, Li Chuanhao, Ji Yecheng, et al. Structure and Stratigraphic Characteristics of Qingyang Gas Field[J]. China Petroleum and Chemical Standards and Quality,2022, 42(22): 100-101+104.

[4] Duan Zhiqiang, Xia Hui, Wang Long, et al. Reservoir Characteristics and Controlling Factors of Shan 1 Member in Qingyang Gas Field, Ordos Basin[J]. Petroleum Geology,2022, 43(03): 285-293.

[5] Xia Hui, Wang Long, Zhang Daofeng, et al. Sequence architecture, sedimentary evolution and controlling factors of the Permian Shanxi Formation Member 1 in the Qingyang Gas Field, Ordos Basin[J]. Oil & Gas Geology,2022,43(06):1397-1412+1488.

[6] Wang Yongqiang, Liu Yamin, Lu Zhen, et al. Reservoir Evaluation and Prediction of Block Qingtan 1 in Qingyang Gas Field[J]. Petrochemical Industry Technology,2022,29(09):147-149.

[7] Jiang Fujie, Jia Chengzao, Pang Xiongqi, Jiang Lin, Zhang Chunlin, Ma Xingzhi, Qi Zhenguo, Chen Junqing, Pang Hong, Hu Tao, Chen Dongxia. Accumulation characteristics and geological model of natural gas enrichment in the Upper Paleozoic total petroleum system of the Ordos Basin[J]. Petroleum Exploration and Development,2023,50(2):250-261

[8] Yang Hua, Liu Xinshe, Yan Xiaoxiong. Tectonic-sedimentary evolution and tight sandstone gas accumulation in the Ordos Basin since the Late Paleozoic[J]. Earth Science Frontiers,2015,22(3): 174-183

[9] Li Jinbu, Wang Jiping, Wang Long, et al. Paleogeomorphology restoration and its controlling effect on delta-front sedimentary sand bodies: A case study of the 1-3 sub-members of the Permian Shanxi Formation in the Qingyang Gas Field, Ordos Basin[J]. Oil & Gas Geology,2021,42(05): 1136-1145+1158.

[10] Jinhua Fu, Xinshan Wei, Shunshe Luo, Zhifeng Zuo, Hu Zhou, Baoxian Liu, Qing fenKong, Sha Zhan, Junxiang Nan. Discovery and geological understanding of the Qingyang deep coal-derived gas field[J]. Petroleum Exploration and Development,2019,46(6):1047-1061

[11] Sheng Chen, Xinyu Li, Bo Yang, Xuan Li, Yaojun Wang, Yadi Yang, Wenhui Du, Yonggen Li, Xiujiao Wang, Lianqun Zhang,Detailed analysis of seismic reflection characteristics of tight sandstone reservoirs in the upper paleozoic of the ordos basin: A casestudy of block X[J], Unconventional Resources,Volume 4,2024,100085, ISSN 2666-5190,

[12] Citation: Xiao, L.; Yang, L.; Zhang, X.;Guan, X.; Wei, Q. Densification Mechanisms and Pore Evolution Analysis of a Tight Reservoir: A Case Studyof Shan-1 Member ofUpper Paleozoic Shanxi Formation in SWOrdos Basin, China[J]. Minerals 2023,13,960. https://doi.org/10.3390/min13070960

[13] Wang, H.; Zhang, J.; Yong, Z.; Qu, X. The Differential Enrichment Law of Tight Sandstone Gas in the Eighth Member of Shihezi Formation in the North and South of Ordos Basin[J]. Energies 2024,17, 5978. 

[14] He Dengfa, Bao Hongping, Sun Fangyuan, Zhang Caili, Kai Baize, Xu Yanhua, Cheng Xiang, Zhai Yonghe. Geological Structure and Genetic Mechanism of the Central Paleo-Uplift in the Ordos Basin[J]. Chinese Journal of Geology.,2020,55(3):627-656

[15] Li Xiwei, Jiang Shu, Shi Yuanpeng, et al. Characteristics and Controlling Factors of Deep Clastic Rock Reservoirs: A Case Study of Yangwuzhai Area in Raoyang Sag [J/OL]. Earth Science, 1-22[2025-05-25].

[16] Qiu Longwei, Mu Xiangji, Li Hao, et al. Influence of diagenesis on pore developmentin tight sandstone reservoirs of the Lower Shihezi Formation in the Hangjinqi area [J]. Petroleum Geology and Recovery Efficiency,2019,26(2): 42-50