Methane drainage in advance of mining using horizontal holes continues to expand. Interpretation of coalbed characteristics and geology in relation to drilling procedures and gas flows will provide additional information for further development of this technique. A study conducted in the Pittsburgh coal-bed at Bethlehem Mines Corp., Marianna mine 58, showed the effect of coalbed discontinuities, such as clay veins and sandstone channels, on drilling of horizontal boreholes and on gas flows. It has shown the need to adapt drilling techniques to the varying degrees of hardness encountered within the same coalbed.

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