Coalbed methane resources assessment in Asturias (Spain)

The Asturian Central Coal Basin, located in Northern Spain, is the most important coal basin in the Iberian Peninsula and some antecedents for coalbed methane exploration on this basin go back to the beginning of the 90's, when two deep wells were drilled in selected areas of the basin. This paper contains the results of preliminary studies, accomplished from 2003 to 2006, that focused on the potential of the Asturian Central Coal Basin for the development of coalbed methane projects. According to these studies, the gas content in coal beds approximately ranges from 3.88 to 10.81 m3/t (ash free), and coalbed methane resources in the coal basin has been estimated in a minimum value of 25 100 Mm3. Despite the fact that the gas content in the entire coal basin is modest, it appears to be adequate for a commercial coalbed methane development, although it is limited by the size of the basin. The option for implementation of coalbed methane projects in this basin is associated to the application of a non-traditional programme for coalbed methane development, including the use of directional drilling from a limited number of well sites. Carbon dioxide sequestration could be associated with the recuperation of methane from the unexploited coal beds.