## 5 Conclusions  
Based on the results of analytical studies, the following conclusions can be drawn:  
1. In the Fuxian-Ganquan area of the Ordos Basin, three sets of shales are developed in the Yanchang Formation, but they vary significantly in thickness and distribution. The Chang 7 shale is extensively developed throughout the study area, with a maximum thickness exceeding 100 m, thinning gradually from southwest to northeast. The thickest area of the Chang 8 shale is located in the Zhangjiawan-Zhibuo area of Fuxian, with a maximum thickness of about 30 m, and it is not developed in the northeastern part of the study area. The thickest area of the Chang 9 shale is in the northwest of the study area, in the Xiaishwan-Shimen area of Ganquan, with a maximum thickness of about 25 m, and it is relatively undeveloped in the southwest. 2. The Yanchang Formation shales in the study area have typical geological characteristics of \"high organic content, high clay mineral content, low thermal maturity, low pressure coefficient, and coexisting shale oil and gas\". The average TOC of the Yanchang Formation shales is 4.7%, the average clay mineral content is 46.7%, the vitrinite reflectance ranges from 0.7% to 1.3%, the organic matter type is primarily Type I to II\({}_{1}\), and the average formation pressure coefficient is 0.68. 3. The pore structure of the Yanchang Formation shales is closely related to the lithofacies types, with an average porosity of 2.5% and an average permeability of 0.0133 mD, classifying them as low-porosity and ultra-low-permeability shales. The Yanchang Formation's shale layers exhibit coexisting oil and gas, with multiple fluid types, including liquid hydrocarbons and free, adsorbed, and dissolved shale gas. The average total gas content of the shale is 2.6 m\({}^{3}\)/t, and the average oil saturation index is 86.1 mg/g TOC. 4. According to the geological characteristics of multilayer shales in the Yanchang Formation in the study area, the Chang 7-Chang 9 shale formations were developed using multilayer staged fracturing of vertical wells. Compared with previous single-layer fracturing, the average daily gas production rate significantly increased by 3-fold, with daily oil production of more than 1 ton, achieving the combined exploration and production of shale oil and gas, as well as comprehensive utilization of shale resources. Conceptualization, P.S. and W.Z. ; methodology, P.S. and W.Z. ; validation, P.S., W.Z. and J.Y. ; formal analysis, P.S. and Y.C. ; investigation, P.S. ; resources, J.Z. and Y.C. ; data curation, J.Y. and J.Z. ; writing--original draft preparation, P.S. and W.Z. ; writing--review and editing, W.Z. and P.S. ; visualization, J.Z. and Y.C. ; supervision, W.Z. ; project administration, W.Z. ; funding acquisition, W.Z and P.S. All authors have read and agreed to the published version of the manuscript. This research was funded by the West Light Foundation of the Chinese Academy of Sciences (Grant No. XAB2021 YW03), the Natural Science Foundation of Shaanxi Province of China (Grant No. 2023-JC-YB-368), the National Natural Science Foundation of China (Grant No. 51804036), the Key Research and Development Program of Shaanxi Province (Grant No. 2023-YBGY-308), and Fundamental Research Funds for the Central Universities (Grant No. 300102271205). Not applicable. The data that support the findings of this study are available from the corresponding author, [PERSON], upon reasonable request. **Acknowledgments:** The authors would like to thank the Natural Gas Research Institute of Shaanxi Yanchang Petroleum (Group) Co., Ltd. for its support. **Conflicts of Interest:** Authors [PERSON] and [PERSON] were employed by the company Natural Gas Research Institute of Shaanxi Yanchang Petroleum (Group) Co., Ltd.; Authors [PERSON] and [PERSON] were employed by the company Research Institute of Shaanxi Yanchang Petroleum (Group) Co., Ltd.