Zou Jiaqi, Chen Shuangquan, Li Yuanji, Yu Tingting
National Key Laboratory of Petroleum Resources and Engineering, CNPC Key Laboratory of Geophysical Exploration, China University of Petroleum (Beijing), Beijing, 102249, China.
Department of Safety Engineering, Heilongjiang University of Science and Technology, Harbin, 150022, China.
Sci Rep. 2025 Jul 18;15(1):26029. doi: 10.1038/s41598-025-09650-3.
Understanding the correlation between coal resistivity and methane content is critical for optimizing coalbed methane (CBM) recovery and ensuring mining safety. Existing studies mainly rely on empirical trend fitting, leaving a gap in model-driven analyses of resistivity dynamics during methane adsorption and desorption. This study develops a dual-coefficient electrical rock physics model integrating inorganic mineral composition, organic resistivity, methane adsorption-desorption behavior, and pore inclusion structures. Correction coefficients (0.2 for methane and 0.4 for organic resistivity) were introduced to address adsorption heterogeneity and structural complexity. Experimental validation on coal samples (density: 1.45 g/cm, porosity: 5.5%) showed strong agreement between simulated and measured resistivity during adsorption (0.8882-3.6973 m/t) and desorption (3.3974-2.1773 m/t), with high correlation (R = 0.9815 adsorption, 0.9956 desorption; P-values = 0.9861, 0.9763). Sensitivity analysis revealed that mineral composition (e.g., quartz, clay) and inclusion aspect ratios (0-1) notably affect resistivity. Flattened inclusions (low aspect ratios) reduce resistivity more than spherical ones, especially at methane volumes lower than 0.15 m/t. Organic content inversely correlates with resistivity; when the volume fraction exceeds 0.92, pore structure effects diminish. This work links microscopic adsorption mechanisms to macroscopic electrical properties, providing a predictive framework for CBM resource evaluation, CO storage monitoring, and coal mine hazard mitigation. The model adapts to diverse coal types and structural conditions, demonstrating broad applicability in research and industry.
了解煤电阻率与甲烷含量之间的相关性对于优化煤层气（CBM）开采和确保采矿安全至关重要。现有研究主要依赖经验趋势拟合，在甲烷吸附和解吸过程中电阻率动态的模型驱动分析方面存在空白。本研究开发了一种双系数电岩石物理模型，该模型整合了无机矿物成分、有机电阻率、甲烷吸附-解吸行为和孔隙包裹体结构。引入了校正系数（甲烷为0.2，有机电阻率为0.4）以解决吸附非均质性和结构复杂性问题。对煤样（密度：1.45 g/cm，孔隙率：5.5%）的实验验证表明，在吸附（0.8882 - 3.6973 m/t）和解吸（3.3974 - 2.1773 m/t）过程中，模拟电阻率与测量电阻率之间具有很强的一致性，相关性很高（吸附时R = 0.9815，解吸时R = 0.9956；P值 = 0.9861，0.9763）。敏感性分析表明，矿物成分（如石英、粘土）和包裹体纵横比（0 - 1）对电阻率有显著影响。扁平包裹体（低纵横比）比球形包裹体更能降低电阻率，尤其是在甲烷体积低于0.15 m/t时。有机含量与电阻率呈负相关；当体积分数超过0.92时，孔隙结构效应减弱。这项工作将微观吸附机制与宏观电学性质联系起来，为煤层气资源评估、二氧化碳封存监测和煤矿灾害缓解提供了一个预测框架。该模型适用于多种煤种和结构条件，在研究和工业中具有广泛的适用性。
