For a long time, coalbed gas has brought about various problems to the safety of coal mine production. In addition, the mining of gas and coalbed methane (CBM) has attracted much attention. The occurrence and migration of CBM are believed to be closely related to the micro-surface properties of coal. To further explore the characteristics of CBM occurrence and migration, in this study, the micro-surface topography, adhesion, and elastic modulus of five metamorphic coals were measured by atomic force microscopy (AFM). The results show that the microtopography of coal fluctuates around 40 nm, reaching a maximum of 66.5 nm and the roughness of the surface decreases with the increase of metamorphism. The elastic modulus of coal micro-surface varies from 95.40 to 9626.41 MPa, while the adhesion varies from 15.08 to 436.22 nN, and they both exhibit a trend of “M” shape with the increase of metamorphism. Furthermore, a high correlation exists between adhesion and microtopography fluctuation. In most cases, the adhesion is larger in the concavity area and smaller in the convexity area. The research results may provide a new method for revealing the occurrence and migration of CBM and ensure efficient and safe CBM exploitation.

长期以来，煤层气给煤矿安全生产带来了各种问题。此外，天然气和煤层气（CBM）的开采也引起了人们的极大关注。据信煤层气的发生和迁移与煤的微观表面特性密切相关。为了进一步探讨煤层气发生和运移的特征，本研究通过原子力显微镜（AFM）测量了五种变质煤的微观表面形貌，黏附力和弹性模量。结果表明，煤的微观形貌在40 nm附近波动，最大达到66.5 nm，表面粗糙度随着变质作用的增加而减小。煤微表面的弹性模量在95.40到9626.41 MPa之间变化，而附着力在15.08到436.22 nN之间变化，随着变质作用的增加，它们都呈现出“ M”形的趋势。此外，在附着力和微形貌波动之间存在高度相关性。在大多数情况下，在凹处的粘附力较大，而在凸处的粘附力较小。研究结果可能为揭示煤层气的发生和迁移提供新的方法，并确保煤层气的开采安全有效。