State Of The Art: Geophysical Methods Applicable To Coal

The application of geophysical technology relative to the exploration, planning, and operation of coal mines is expanding. This is due to the trend of the industry to increase the size of operations, use of mechanized equipment and mining of more difficult coals, where unforeseen conditions can affect mine profitability. Coal is a good geophysical target because of its lower density, higher electrical resistivity, lower seismic wave velocity, and lower magnetic susceptibility in comparison to typical country rock. The more important techniques are well logging, high resolution seismic reflection, seam wave velocity, and radar. These methods can be used to map coal horizons, determine the physical properties of the coal, and identify mining hazards. The methods are not a pancrea however. Their use should be based on a careful assessment of their expected success and cost benefit analysis in comparison with conventional technology, primarily drilling, which none of the techniques presented should entirely replace. In general, the level of technology developed for geophysics surpasses their current level of application to coal problems. In some cases, identifying hazards in advance of mining using seam wave seismic in particular, the state of the art has been developed in Europe and is awaiting fruitful application in the United States.