Prospecting for coalbed methane: preliminary investigation into the possibilities in Spain

• Autor(a) principal: Lemos de Sousa, M. J.
• Data de Publicação: 1996
• Outros Autores: Pinheiro, H. J.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10284/214
• topic: Coal; Coalbed methane; Natural gas; Prospection; Rank

The fundamental objetive of this study resides in investigating the potential suitability of spanish coalfields to prospecting natural gas from coal in-situ (Coalbed Methane-CBM). The study was based not only on a literature survey and supplemented by onsite visits and investigations, but also on inhouse research activities. Tree selecting criteria have been defined: 1.1. Existing resources: a figure of 20MT of coal was estrablished as the minimum in-situ tonnage worth considering. This limit is comprised of the sum of "very probable" and " probable" resources. 1.2. Coal rank: in agreement with the generally accepted principle that the most significant amount of gas produced by coal corresponds to a coalification level of Rr> 1.2% (ca VM (daf) < 30&), only coalfields reporting such values were selected. 1.3 Geological and Structural considerations such as: 1.3.1 Identification of stratigraphic units, their sedimentary conditions including the presence of coal-bearing units with sufficient seams (frequency) with thickness that will potentially permit their in-situ exploration and exploitation for natural gas. 1.3.2 Structural regime compatible with the retention of gas by the coal beds and adjacent host rocks. 2. On the basis of currently available information, and on applying the abovementioned criteria to spanish coalfields, the following ones have been identified as potentially the most suitable for coalbed methane prospecting (in decreasing order of importance): • Ciñera-Matallana and Cerredo-Villablino, considered to have equivalent potential • La Pernía-Barruelo • Central Asturian Coalfield, South region • El Bierzo.