Seismic reflection characteristics and genesis of goafs and underlying coal seams

Coal is an important energy and industrial resource. Coal mining-resulted goafs and subsequently developed caving zones exhibit strong heterogeneity and instability, which can severely restricts the exploration and development of deep coal seams. Focusing on a coal mine in eastern China, this study relied on 2D migrated seismic profiles, and seismic simulating and imaging on a model to systematically investigate the seismic reflection characteristics and its genesis of goafs, caving zones, and their underlying strata. The results indicate that the bottom of goafs presents strong seismic reflections, caving zones generate intense seismic scattering, and reflections from the underlying coal seams exhibit three diagnostic features: namely energy attenuation, phase anomalies, and reduced continuity. Energy attenuation stems from the superimposed effects of strong reflection at the goaf bottom and intense scattering in caving zones. Phase anomalies are dominated by the low-velocity property of goafs and caving zones. Poor continuity is mainly controlled by the scattering in caving zones. The proposed correlation between the attributes of goaf-caving zones and the reflection responses of underlying strata can be used to evaluate the occurrence state of goafs and provide support for the exploration and development of deep coal resources.