Desorption-diffusion specificity of deep coalbed methane under high-temperature effects: Implications for development

Abstract

China’s deep coalbed methane (CBM) resources demonstrate immense potential with extensive developmental prospects. However, the coupling relationship between the negative adsorption effect and the positive desorption-promotion effect under high-temperature conditions remains unclear. In this study, a self-built high-temperature adsorption-desorption system was used to investigate the coupled effects of temperature and coal rank on methane adsorption-desorption behavior in deep CBM. The results show that elevated temperatures significantly reduce methane adsorption capacity, with high-rank coals exhibiting greater sensitivity. Conversely, high-temperature conditions significantly enhance methane desorption and diffusion behavior, accelerating initial desorption rates, enabling rapid gas release in a short period, and thus improving desorption efficiency. The desorption volume and desorption-diffusion rate exhibited an asymmetric U-shaped variation with coal rank. By coupling the positive and negative effects of temperature and defining the desorption ratio, it was found that a 10 K increase in temperature raised the desorption ratio by 3.78%-8.05%. Finally, an effective gas content prediction model is proposed, and the key regulatory role of temperature in the resource potential and gas production characteristics of deep CBM is clarified. These findings can provide theoretical guidance for the subsequent optimization of deep CBM exploration and development strategies.

Keywords

Deep coalbed methane / Desorption-diffusion characteristics / High-temperature effect / Effective gas content / Development significance

Acknowledgments

This work was supported by the National Natural Science Fund of China (No. 42272195); the National Natural Science Fund of China (No. 42130802); the Fundamental Research Funds for the Central Universities (No. 2025ZDPY10); the China National Petro-leum Co., Ltd.. Research applied science and technology special (No. 2023ZZ18); and the PetroChina Changqing oilfield science and technology major project (No. 2023DZZ01).

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