The geothermal exploration does involve the search for active geothermal regions with the aim of constructing the geothermal power plants. The exploration methods do involve several techniques ranging from the drilling process to the geochemical analysis.
The geochemical analysis includes the study of relationships between surface fluid properties to geothermal bodies. Geothermometers and other sophisticated instruments are being used to measure the subsurface temperatures. In the geochemical analysis for geothermal exploration, temperature, the ratios of isotopes, elemental ratios (such as mercury and carbon dioxide), etc are some of the major measurements being made.
In the magnetic method for exploration of geothermal energy, identification of the depth of the Curie point or Curie temperature is the most important measurement. Titanomagnetite, which is most commonly found in geothermal regions, has a Curie temperature ranging from about 200 to 600 degrees Celsius.
Most of the geological materials are non-conductors of electricity and thus possess high resistivity but the structural features can enhance their conductivity. Such transformation in conductivity does facilitate the mapping and thus the composition of the subsurface lithology The magnetotellurics measurements facilitate the identification of resistivity anomalies associated with the geothermal structural features such as faults. Such measurements would lead to an assessment of geothermal reservoir temperatures at several depths. This method was successfully applied for the detection of geothermal energy in several countries and especially around the ring of fire.
The resistivity methods are also being widely used to explore the geothermal energy resources. The flowing geothermal waters are the zones of low resistance. The low resistivity zones can also be due to the variation of the composition of the rocks and thus the temperature.
The gravity method is generally used to identify the subsurface density anomalies. Such measurements would be helpful to locate the geothermal regions. The airborne gravitational techniques are more efficient in the collection of data. The gravity data should be corrected for elevation, latitude, etc.
The Geothermal regions within the subsurface are also the regions of intense seismic activity. These regions are generally characterized by low magnitude earthquakes. Hence, further studies in such locations might provide clues to the identification of geothermal energy sites.
The drilling process is one of the most expensive but can provide reliable information related to the subsurface. The geothermal characteristics such as thermal pockets, temperature gradients, etc are obtained by using several types of drilling techniques. The latest developments in remote sensing techniques have also been aiding in the exploration of geothermal energy resources.