Xu Zhanjie ¹

(1 Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China)

Abstract: Accurate prediction of coalbed methane (CBM) enrichment zones remains a major challenge during active production. Here, we developed an isotopic geochemical model to predict CBM enrichment zones in the Carboniferous-Permian Sijiazhuang Block in the Qinshui Basin. While conventional isotopic geochemical applications in CBM research have primarily focused on identifying gas origins and microbial methanogenesis pathways, recent studies demonstrate that stable carbon isotopes in methane undergo kinetic fractionation during production. Because this fractionation is closely linked to desorption, it provides a robust theoretical foundation for predictive modeling. Moving beyond traditional exploration frameworks, this study introduces a novel approach that monitors methane isotopes and total dissolved solids (TDS) in produced water from active production wells. By integrating multiple isotopic geochemical parameters, the resulting model addresses a critical technological gap in predicting CBM enrichment zones during active extraction. This method offers valuable technical support for optimizing development strategies and identifying “sweet spots”, ultimately enhancing the efficient exploitation of CBM resources.

Keywords: CBM; Carbon isotopes; Hydrogen isotopes; Produced water; Sweet spot; Qinshui Basin

Author Profile (first or corresponding author):

Xu Zhanjie, Male, Assistant Professor, PhD, mainly engaged in atmospheric and environmental geochemistry research. E-mail: xuzhanjie@tju.edu.cn.