Reflection Seismic Methods for Deep Geothermal Exploration

Reflection seismic is an essential tool in the search for geothermal reservoirs, particularly where spatial resolution is a critical issue for a successful drilling and/or where the geological complexity and the target depths make it compulsory to obtain reliable images of the subsurface prior to drilling. The need, as always, is to reduce the mining risk. In general, tools and methodologies of reflection seismic employed for geothermal exploration are common to those for hydrocarbon exploration. Quite often, however, a number of issues specific to geothermal exploration, either related to the peculiar geological conditions or to budget limitations, require that methods and techniques be adapted for the specific purposes. This paper illustrates some examples of the application of reflection seismic to geothermal exploration and focuses on the potential and limitations of the methodology and on the work ahead. We split the presentation into two parts. The first delineates the industry standard approaches and results of 2D and 3D seismic from different sites in Italy and in the States. The second part illustrates some more advanced techniques that are still under scrutiny to assess their robustness and applicability to the specific situations and geological settings of the geothermal sites of interest. All the data examples we discuss are taken from Enel Green Power ventures in Italy and abroad.