[PERSON]  
1 Shale Gas Research Institute of Petroleum Southwest Oil & Gas Field Company, Chengdu 610051, China; [EMAIL_ADDRESS] (X.S. ); [EMAIL_ADDRESS] (L.L. ); [EMAIL_ADDRESS] (Y.Z. ); [EMAIL_ADDRESS] (L.X. ); [EMAIL_ADDRESS] (Y.X.Z. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (C.L. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (C.Y. ); [EMAIL_ADDRESS] (C.W. ); [EMAIL_ADDRESS] (L.H.) [PERSON]  
1 Shale Gas Research Institute of Petroleum Southwest Oil & Gas Field Company, Chengdu 610051, China; [EMAIL_ADDRESS] (X.S. ); [EMAIL_ADDRESS] (L.L. ); [EMAIL_ADDRESS] (Y.Z. ); [EMAIL_ADDRESS] (L.X. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (C.L. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (C.Y. ); [EMAIL_ADDRESS] (C.W. ); [EMAIL_ADDRESS] (L.H.) [PERSON]  
1 Shale Gas Research Institute of Petroleum Southwest Oil & Gas Field Company, Chengdu 610051, China; [EMAIL_ADDRESS] (X.S. ); [EMAIL_ADDRESS] (L.L. ); [EMAIL_ADDRESS] (Y.Z. ); [EMAIL_ADDRESS] (L.X. ); [EMAIL_ADDRESS] (Y.X. ); [EMAIL_ADDRESS] (C.L. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (C.Y. ); [EMAIL_ADDRESS] (C.W. ); [EMAIL_ADDRESS] (L.H.) [PERSON]  
1 Shale Gas Research Institute of Petroleum Southwest Oil & Gas Field Company, Chengdu 6 sag, exhibits high thermal maturation and significant burial depth [6]. The enrichment of organic matter in these shales is typically controlled by factors such as the redox conditions of the sedimentary environment, productivity levels, terrigenous input, and paleoproductivity [7,8]. However, exploration of the Qiongzhusi formation in the Sichuan Basin is still in its early stages, and the role of the sedimentary environment in controlling organic matter enrichment within the intracratonic sag of the Sichuan Basin remains unclear. To clarify the reservoir characteristics and organic matter enrichment mechanisms of the Qiongzhusi formation shale, this study takes well Z201 in the Zizhong area of the Sichuan Basin as an example. It analyzes the mineralogical characteristics, organic geochemical features, and key trace element characteristics of the Qiongzhusi formation shale. The study reconstructs the sedimentary environment during the deposition of the Qiongzhusi formation shale within the extensional basin, revealing the mechanisms of organic matter enrichment. This provides geological foundations for the next phase of shale gas exploration and development in the Sichuan Basin. The maturity of organic matter in shale samples is commonly assessed using the vitrinite reflectance (R\({}_{\text{o}}\)). R\({}_{\text{o}}\) is a measure of the reflectance of vitrinite, a component of organic matter, under a microscope. It provides an indication of the thermal maturity of the organic matter, which is crucial for evaluating the potential for hydrocarbon generation. In this study, the organic geochemical characteristics of the shale samples are described using several parameters. S\({}_{\text{0}}\) refers to the initial organic carbon content of the shale, representing the total amount of organic carbon present in the rock (measured in mg/g). S\({}_{\text{1}}\) represents amount of free hydrocarbons released from the sample upon heating, which provides an indication of the volume of hydrocarbons that are readily extractable (measured in mg/g). S\({}_{\text{2}}\) denotes the potential hydrocarbon generation capacity of the sample, calculated as the difference between the total hydrocarbons produced upon heating and the free hydrocarbons measured as S\({}_{\text{1}}\) (measured in mg/g). S\({}_{\text{2}}\) reflects the remaining organic matter's potential to generate hydrocarbons upon further maturation.