Hydrochemical Signature of Formation Waters Associated to Unconventional Gas Resources. Application to Central Coal Basin (Spain)

The concept of hydrochemical signature is applied to the research of unconventional gas resources (coalbed methane) in the Asturian Central Coal Basin, in northern Spain. The geochemical processes inherent to the forming conditions of coalbed methane deposits (CBM) tend to modify the quality of groundwater, then, formation water associated to coalbed methane deposits can be easily recognizable by its ”hydrochemical signature”. The knowledge of this standard geochemical signature should have a primary use in the exploration of coalbed methane, as well as in the phases of essay and development. The hydrochemical signature of groundwater associated to the coalbed methane extraction processes can be a useful criterion in a preliminary evaluation of the interest of the unconventional gas deposits when there are enough data