Minerales Monclova S.A. De C.V. (MIMOSA) operates five underground longwall mines in the Gassy Los Olmos Coals of the Sabinas Basin in the state of Coahuila in Northern Mexico. Because of high in-situ gas contents and high cleat and natural fracture permeability, MIMOSA has had to incorporate a system of methane drainage in advance of mining in order to safely and cost effectively exploit their reserves. In the early 1990s Resource Enterprises (REI) conducted reservoir characterization tests, numerical simulations, and Coal Mine Methane (CMM) production tests at a nearby mine property in the same basin. Using this information REI approached MIMOSA and recommended the mine-wide implementation of a degasification system that involves long in-seam directionally drilled boreholes. REI was contracted to conduct the drilling, and to date has drilled over 26,000 m (85,000 ft) of in-seam borehole in advance of mining developments, reducing gas contents significantly below in-situ values. This paper discusses the basis for the degasification program recommended at the MIMOSA mines, and presents the impact of its mine-wide application on MIMOSA\u27s mining operations over the last six years. The paper focuses on the degasification system\u27s impacts on methane emissions into mine workings, coal production, and ventilation demands. It also presents lessons learned by the degasification planners in implementing in-seam methane drainage. The paper presents actual CMM production data, measurements of methane emissions and advance rates at development sections, and mine methane liberations
