Data accumulation on the methane potential of the coal beds of Colorado, final report. 25 pages. 5 plates. Digital PDF download. OF-78-02D
From the Abstract:
A two-year project was conducted to gather data that would assist in the evaluation of the methane potential of the coal beds of Colorado. It was found that a number of closed underground coal mines in the State had reported “gassy” conditions or had experienced fires and explosions of varied intensity and frequency. The majority of such occurrences have been in those areas characterized by coals of relatively low (i.e., below 31%) volatile matter (VM) content. The south half of the Raton Mesa coal region (Las Animas County) and the southeastern part of the Uinta region (in Gunnison and Pitkin Counties) contain coals with the lowest percentages of VM, the gassiest producing mines, and the highest grade coking coal in the State. Five active mines in Pitkin County presently are emitting a total of over 8 million cubic feet of methane per day. These mines produce the highest quality metallurgical-grade coal in the western U.S. (high-volatile A and medium-volatile bituminous). The gassy coals in these two regions range from Late Cretaceous to Paleocene in age and usually occur in areas related to igneous activity of late Tertiary age. The VM percentages of Colorado coals can be used, with some caution, to determine their potential methane content. Additional desorption measurements and coal analyses are needed to more accurately predict the effects of rank and depth of occurrence on the methane content of coals in the state.