The Menefee Formation of the Upper Cretaceous Mesaverde Group in the San Juan Basin of Colorado and New Mexico contains abundant coal beds with a substantial coalbed methane resource. Stratigraphically lower than the actively targeted coal beds of the Fruitland Formation, the Menefee Formation coal beds have until recently been overlooked as a potential gas production zone. The total coal resource of the Menefee Formation, including determination of coal rank and coal bed thickness variability, was estimated using extensive subsurface geologic data. Estimates of coal gas content were extrapolated for the Menefee Formation coal beds from a previous study of the overlying Fruitland Formation coal beds. The combination of coal resource and gas content information resulted in a preliminary in-place coalbed methane resource estimate of 38 trillion cubic feet of gas contained in 145 billion tons of coal. As part of the development of the gas in-place estimates, regional cross-sections and isopach, structure and coal quality (rank) maps were produced which illustrate the regional nature and variability of the Menefee Formation coal beds in the San Juan Basin. Because of the variable thickness of the Menefee Formation and the lenticular nature of the contained coal beds, this study delineated regional areas where the potential for the development of the coalbed methane resource is more favorable. Having identified a potential area, an in-depth geologic and reservoir evaluation on a much smaller scale would be required prior to production drilling.

You can access this article if you purchase or spend a download.