Geothermal exploration

Geothermal exploration is the exploration of the subsurface in search of viable active geothermal regions with the goal of building a geothermal power plant, where hot fluids drive turbines to create electricity. Exploration methods include a broad range of disciplines including geology, geophysics, geochemistry and engineering.

Geothermal regions with adequate heat flow to fuel power plants are found in rift zones, subduction zones and mantle plumes. Hot spots are characterized by four geothermal elements. An active region will have:

Exploration involves not only identifying hot geothermal bodies, but also low-density, cost effective regions to drill and already constituted plumbing systems inherent within the subsurface. This information allows for higher success rates in geothermal plant production as well as lower drilling costs.

As much as 42% of all expenses associated with geothermal energy production can be attributed to exploration. These costs are mostly from drilling operations necessary to confirm or deny viable geothermal regions. Some geothermal experts have gone to say that developments in exploration techniques and technologies have the potential to bring the greatest advancements within the industry.

Drilling provides the most accurate information in the exploration process, but is also the most costly exploration method.

Thermal gradient holes (TGH), exploration wells (slim holes), and full-scale production wells (wildcats) provide the most reliable information on the subsurface. Temperature gradients, thermal pockets and other geothermal characteristics can be measured directly after drilling, providing valuable information.

Geothermal exploration wells rarely exceed 4 km in depth. Subsurface materials associated with geothermal fields range from limestone to shale, volcanic rocks and granite. Most drilled geothermal exploration wells, up to the production well, are still considered to be within the exploration phase. Most consultants and engineers consider exploration to continue until one production well is completed successfully.

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