Modern CMM drainage strategies

摘要

Numerous advances have been made in directional drilling equipment over the last five years. This paper will review specific improvements in this technology and present how this impacts CMM drainage strategies for underground coal mines. Long in-seam boreholes can be placed in the working seam far in advance of mining to significantly reduce in-situ gas contents of virgin reserves and commercially recover CMM. Directionally drilled boreholes can also be drilled into overlying strata to reduce the in-situ gas content of gas bearing strata in advance of mining (this gas would otherwise contribute to gob gas make), and subsequently recover gob gas liberated during under-mining (reduce emissions of CMM into mine workings). Precision placement, ultra-long boreholes, and higher capacity boreholes enable mine operators to more effectively recover the "total resource" (coal and CMM), reduce CMM emissions during mining, and improve mine safety.