How can you identify geothermal targets using geological maps and satellite images?

1 Geological maps

Geological maps show the distribution, structure, and age of different rock types and formations on the surface or subsurface of an area. They are useful for geothermal exploration because they can reveal the presence of faults, fractures, volcanoes, and hot springs that indicate geothermal activity. By studying geological maps, you can identify areas with high heat flow, fluid circulation, and permeability that are favorable for geothermal development.

3 Geothermal target types

Geothermal targets are areas that have a high probability of hosting a geothermal reservoir that can be exploited for energy production. Different types of geothermal targets exist depending on the source and transfer of heat, the nature and composition of the fluid, and the geological setting. Volcanic geothermal targets are areas where heat is generated by magma chambers or volcanic vents and transferred by convection or conduction to the surface. The fluid is usually water or steam that is heated by contact with hot rocks or magma. Extensional geothermal targets are sites where heat is generated by crustal thinning and stretching due to tectonic forces, allowing heat to rise closer to the surface and create geothermal gradients. The fluid is usually water circulated through faults and fractures. Sedimentary geothermal targets are areas where heat is produced by burial and compaction of organic-rich sediments that generate hydrocarbons, transferring heat by conduction or advection to overlying or adjacent rocks. The fluid is usually water or brine mixed with hydrocarbons or carbon dioxide. These various geothermal targets are often marked by fumaroles, geysers, hot springs, rift zones, basins, grabens, sedimentary basins, oil and gas fields, and coal seams.

4 Geothermal target criteria

Geothermal target criteria are the parameters that define the quality and viability of a geothermal target for energy production. Temperature, depth, flow rate, and permeability are all important factors to consider when assessing a potential geothermal target. Generally, higher temperatures and flow rates mean higher power output and lower costs. The optimal depth for geothermal power generation is usually between 1 and 5 km, while the minimum temperature and flow rate for geothermal power generation is usually around 100°C and 10 liters per second respectively. The minimum permeability for geothermal power generation is usually around 10 millidarcies, but this can vary depending on the pressure and porosity. Ultimately, these criteria will help to determine the feasibility of a potential geothermal target for energy production.

5 Geothermal target evaluation

Geothermal target evaluation is the process of assessing the potential and feasibility of a geothermal target for energy production. This involves data collection, data analysis, and data synthesis. During data collection, you need to gather and integrate geological, geophysical, geochemical, and environmental data from various sources, such as geological maps and satellite images. Data analysis involves interpreting and modeling the data to understand the geothermal system and its characteristics. You can then use various methods and tools, such as geostatistics or geothermometry, to estimate the temperature, depth, flow rate, and permeability of the geothermal reservoir. Data synthesis combines and compares the data analysis results with the geothermal target criteria to evaluate the quality and viability of the geothermal target. Other sources and methods can also be used for refinement and confirmation, such as geophysical surveys or exploration drilling. Geothermal exploration is a complex process that requires skill, experience, and creativity but it can be rewarding and exciting when you discover new ways to harness the Earth's heat for sustainable energy.