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Well logging Prediction of Total Organic Carbon Content in Shale Gas Reservoirs of the Long 11 Submember in Southern Sichuan —Taking the Z205 Well Area as an Example

Environment and Resource / 2025,7(2):  / 2025-12-02 32 17

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• Authors: Xin Gong¹² Jing Li¹ Ang Luo¹² Jia He¹² Xing Liu¹² Wen Cao¹² Haizhou Su¹² Xiaohai Ren³ Zhaona Yang¹
• Information:

  1. Institute of Geological Exploration and Development of CNPC Chuanqing Drilling Engineering Company Limited, Chengdu;
  2. Sichuan Yuesheng Energy Group of CNPC Chuanqing Drilling Engineering Company Limited, Chengdu;
  3.Shale Gas Exploration and Development Department of CNPC Chuanqing Drilling Engineering Company Limited, Chengdu

• Keywords:
  Long 11 Submember; Shale Gas; Well Logging Prediction; TOC; Stepwise regression method
  Long 11 Submember; Shale Gas; Well Logging Prediction; TOC; Stepwise regression method
• Abstract: Total organic carbon (TOC) is not only an important indicator for evaluating the hydrocarbon generation capacity of shale gas reservoirs, but also a crucial parameter for the evaluation of shale gas reservoirs and the selection of platinum target areas. The existing TOC content prediction methods either have low prediction accuracy or require a large number of samples. This article takes the Long 11 submember in the Z205 well area of southern Sichuan as the research object. Based on the measured TOC data from the core samples, it was clearly determined that the logging responses of the four microlayers in the Long 11 submember in the well area were all different. By combining the “layered fine prediction” and “stepwise regression” methods, a TOC prediction model for each of the four microlayers in the Long 11 submember of the well area was established. In the past, the study area always regarded the Long 11 submember as a single entity. The TOC was predicted using the “input method” in the “multiple regression method”, without considering the actual logging response characteristics of each layer. This led to numerous “false fitting” occurrences. This study selects the optimal logging parameters for different layers. By using the “stepwise regression method”, the occurrence of “false fitting” is avoided, thereby improving the interpretation accuracy. The study reveals that the TOC development occurs in the Long 11 submember of the Z205 well area, and the variation patterns of TOC in different layers are quite distinct. Total organic carbon (TOC) is not only an important indicator for evaluating the hydrocarbon generation capacity of shale gas reservoirs, but also a crucial parameter for the evaluation of shale gas reservoirs and the selection of platinum target areas. The existing TOC content prediction methods either have low prediction accuracy or require a large number of samples. This article takes the Long 11 submember in the Z205 well area of southern Sichuan as the research object. Based on the measured TOC data from the core samples, it was clearly determined that the logging responses of the four microlayers in the Long 11 submember in the well area were all different. By combining the “layered fine prediction” and “stepwise regression” methods, a TOC prediction model for each of the four microlayers in the Long 11 submember of the well area was established. In the past, the study area always regarded the Long 11 submember as a single entity. The TOC was predicted using the “input method” in the “multiple regression method”, without considering the actual logging response characteristics of each layer. This led to numerous “false fitting” occurrences. This study selects the optimal logging parameters for different layers. By using the “stepwise regression method”, the occurrence of “false fitting” is avoided, thereby improving the interpretation accuracy. The study reveals that the TOC development occurs in the Long 11 submember of the Z205 well area, and the variation patterns of TOC in different layers are quite distinct.
• DOI: (DOI application in progress)
• Cite: Gong, X., Li, J., Luo, A., He, J., Liu, X., Cao, W., Su, H. Z. Ren,X.H, Yang,Z.N. (2025). Well logging prediction of total organic carbon content in shale gas reservoirs of the Long 11 submember in southern Sichuan — Taking the Z205 Well Area as an Example. Environment and Resource, 7(2)