Experimental Evaluation of Geo-mechanical properties of Coal using Sonic Wave Velocity

Abstract

India is the third largest coals producing country in the world. Estimation indicates the coal reserve is about 522 BT and CBM magnitude is of 4.6 TCM. CBM is one of the proved clean energy resources with heating value of approximately 8500 KCal/kg. CBM is future hope for energy demand in India and worldwide. But successful exploitation of coal bed methane needs advance knowledge of the coal and its behavior at varying condition. Estimation and evaluation of geo-mechanical properties of the coal and coal matrix has a direct relationship with CBM production. It is related to the in situ stress, lateral strain, axial strain, Poisson’s ratio, young’s modulus, bulk modulus, shear modulus etc. The measurement of geo-mechanical parameters using laboratory experiments are expensive and quite time taking. The coal from deep mines contains higher percentage of carbon and hence fragile in nature. Many a times, it is very tough to get sample of desire size to test for specific properties. This is why the ultrasonic testing is frequently employed to resolve and characterize the dynamic properties of coal. The P-wave velocity is closely related to the intact coal. Present paper discussed about dynamic properties and petrographic analysis of some coal samples from Jharia coalfield India. Correlation of geo-mechanical parameters with P- wave velocity and petrographic analysis results was also discussed due to its greater applicability in CBM evaluation and production. Statistical technique was employed to analyze the results for the credibly of the findings.