成果归属作者：

陶树

成果归属机构：

能源学院

作者：

Fu, Xinyu ; Chen, Shida ; Yang, Fan ; Tao, Shu ; Ma, Litao ; Liu, Cheng ; Yang, Jianghao ; Cui, Yi ; Jing, Qinghe ; Gao, Wei

单位：

China Univ Geosci Beijing, Sch Energy Resources, Beijing 100083, Peoples R China;PetroChina Res Inst Petr Explorat & Dev, Beijing 100083, Peoples R China;CNOOC EnerTech Drilling & Prod Co, Tianjin 300452, Peoples R China;Zhalainuoer Coal Ind Co Ltd, Hulunbuir 021410, Peoples R China;Guizhou Univ, Coll Resources & Environm Engn, Guiyang 550025, Peoples R China

关键词：

DYNAMIC VARIATION; ADSORPTION; PERMEABILITY; PRESSURE; STRESS; GASES

摘要：

Accurate evaluation of gas content in different occurrence states is crucial for resource assessment and sustainable development of deep coalbed methane (CBM). This study integrates isothermal adsorption experiments with real-time nuclear magnetic resonance (NMR) measurements to quantify multiphase methane under variable temperature and pressure conditions. Results show that adsorbed and free methane exhibit T2 values of 0.01-10 ms and 100-10000 ms in 1D NMR spectra, respectively, with corresponding T1/T2 ratios of 10-1000 and 1-10 in 2D NMR spectra. Free methane content increases linearly with pressure, whereas adsorbed methane content follows a logarithmic growth trend, with adsorption capacity increasing with vitrinite reflectance but decreasing with temperature. Based on the supercritical Dubinin-Radushkevich theory, an integrated prediction model was established to characterize variations in adsorbed and free methane content as a function of temperature, pressure, and pore compressibility. Taking the Linxing-Shenfu block as a case study, the model was applied to determine the critical depth thresholds for gas content. The critical depth for adsorbed gas is approximately 2200-2400 m, beyond which the adsorbed gas content tends to decrease with increasing depth. Based on the measured total gas content and calculated adsorbed gas content, free gas is present at depths greater than 1600 m. Combined with the distribution characteristics of free gas and total gas content, the optimal depth interval for deep CBM exploitation is identified as 1600-2400 m. Due to differences in coal rank, geothermal gradients, pressure gradients, and pore compressibility, the critical depths may vary between regions and require case-by-case analysis.

基金：

National Natural Science Foundation of China [42130802, 42272200]; Guizhou Provincial Science and Technology Plan Project [Qiankehe support-ZK [2025] commonly 062]; Science and Technology Major Project of China National Petroleum Corporation [2023ZZ18-03]; Changqing Oilfield [2023DZZ01]; Technology project of Huaneng Group Headquarters [HNKJ23-H51]

语种：

英文

DOI：

10.1016/j.fuel.2025.136655

来源：

FUEL,2026():.

出版日期：

2026-02-01

提交日期：

2025-09-23

引用参考：

Fu, Xinyu; Chen, Shida; Yang, Fan; Tao, Shu; Ma, Litao; Liu, Cheng; Yang, Jianghao; Cui, Yi; Jing, Qinghe; Gao, Wei. NMR-based quantitative characterization and predictive modeling of adsorbed and free methane in deep coal reservoirs[J]. FUEL,2026():.