Seismic inversion for Geotechnical properties relevant to coal mining

Abstract

The 3D seismic reflection method has an established role in Australia in mapping geological structures, faults and discontinuities that might affect the operation of an underground coal mine. However, successful longwall mining also requires knowledge of geotechnical properties of the roof and floor strata. Most geotechnical information is obtained from core drilling, geophysical logging and underground mapping. In particular, log analysis can now be used to determine geotechnical properties of the strata through the Geophysical Strata Rating (GSR). However such “point” measurements need to be extrapolated into a full three dimensional geotechnical model for longwall mining operations. Geotechnical variability is related to lithological variations that can be inferred from high resolution seismic reflection data. Hence geotechnical variability could be studied directly from seismic data or a particular seismic attribute. Here we investigate a relationship between acoustic impedance derived from seismic data and log-derived GSR values to produce a 3D geotechnical model.