Geophysical exploration methods at European sites
David Bruhn · 2008
Most geophysical exploration methods have been developed for the oil and gas industry, and ever more sophisticated tools and refinements in the different approaches are designed to solve specific problems associated with the detection and characterisation of hydrocarbon reservoirs. The exploration of geothermal resources has profited greatly from these developments, however, the methods cannot always by directly transferred from oil and gas to hot water and/or steam. First of all, physical properties of H2O differ from those of hydrocarbons, resulting in differing responses of physical measurement methods. Secondly, geothermal reservoirs can be found in highly varying geological environments, mostly associated with volcanism, where hydrocarbons are usually not present. Thirdly, the economically most interesting geothermal reservoirs are much hotter than any oil or gas reservoir. At the moderate temperatures comparable to those of hydrocarbons many of the advanced exploration methods are simply cost-prohibitive, as the economic potential of a medium-enthalpy geothermal reservoir is much lower than for an oil or gas well. For these reasons, some of the existing geophysical methods have to be adapted to meet the needs of geothermal exploration or different methods have to be developed and applied.