HR: 15:15h
AN: NS33A-05    [Abstracts]
TI: Ground Penetrating Radar Response Over Coal Seam Discontinuities
AU: * Verma, S
EM: listen2sumit@yahoo.com
AF: Dept. of Applied Geophysics, Indian School of Mines , Dhanbad, Dhanbad, 826004, India
AU: Srivastava, S
EM: svismagp@yahoo.co.in
AF: Dept. of Applied Geophysics, Indian School of Mines , Dhanbad, Dhanbad, 826004, India
AU: Bhattacharya, B B
EM: bimalendu@bose.res.in
AF: SN Bose National Centre for Basic Science, Sec-III , Block-JD, Salt Lake, Kolkata, 700098, India
AB: Coal is one of the most important sources of energy. There are a number of problems associated with the mining of coal; one of them is the detection of unknown structural features encountered in coal measures. The commonly occurring structural features include fault, wedge out, seam splitting, dykes, cavities both water and air filled. The geophysical techniques, which are extensively used by the coal mining industry, are surface reflection seismic, dipole-dipole resistivity and geophysical borehole logging. The resolution of GPR for the shallow subsurface features is higher and the survey is easier to carry out in comparison of other methods. In this paper we map the coal seam discontinuities with the help of GPR data. GPR response over coal seam discontinuities viz., fault, wedge out, seam splitting, dykes, cavities both water and air filled, prevailing in Raniganj and Jharia coalfields has been obtained using GPRMAX (ver 1.5) software. The source pulse is a Ricker wavelet of frequency 50 MHz and sampling interval is 0.23587 nanosec. Here we use the relative permittivity values as 3.0 for dry sandstone, 6.0 for coal, 10.0 for shale and 80.0 for water whereas the relative permeability is assumed to be 1.0 for all the media. The conductivity values are taken as 0.000010 S/m for dry sandstone, 0.001S/m for coal, 0.01 S/m for shale and 0.1 S/m for water. The obtained response is contaminated with diffraction noise. Time migration has been carried out with help of MATLAB tools, to overcome the diffraction noise present in the radargram. The obtained GPR response after time migration helps in identifying these coal seam discontinuities prevalent in Raniganj and Jharia coalfields of India.
DE: 0545 Modeling (4255)
DE: 0639 Nonlinear electromagnetics
DE: 0689 Wave propagation (2487, 3285, 4275, 4455, 6934)
DE: 0694 Instruments and techniques
SC: Near-Surface Geophysics [NS]
MN: 2007 Joint Assembly