Geothermal Exploration

Understanding geothermal exploration

Geothermal exploration is the process of using geophysical methods to locate and characterize shallow hydrothermal systems that drive geothermal fields. This includes identifying:

Hydrothermal alteration zones: Near-surface resistivity anomalies caused by ascending geothermal fluids altering the surrounding rock.
Permeability structures: Pathways that allow geothermal fluids to migrate from depth toward the surface.
Up-flow areas: Zones where near-boiling fluids rise close to the ground surface, often showing the strongest resistivity contrasts.
Springs and feeder aquifers: Shallow water systems connected to and fed by geothermal activity.

This process involves:

Measuring variations in ground resistivity, which change with rock alteration, fluid temperature, and permeability.
Using high-density towed TEM (tTEM) surveys to map near-surface (top 100 m) resistivity anomalies with fine spatial resolution.
Using sTEM surveys to extend resistivity mapping to greater depths, supporting characterization of deeper reservoir structures.

With tools like tTEM and sTEM, geothermal exploration becomes faster and less invasive, supporting resource assessment, environmental risk management, and regulatory planning.

Geophysics in geothermal exploration

Discover how geophysical methods improve efficiency in geothermal exploration

Map Alteration and Permeability Structures

Identify hydrothermally altered zones and the fluid pathways that connect them to the surface.

Locate Up-Flow Areas

Pinpoint zones where near-boiling fluids rise closest to the surface - typically the sharpest resistivity contrasts in a geothermal field.

Support Hazard Assessment

Help identify shallow boiling zones that can contribute to hydrothermal explosion risk, supporting community and site safety planning.

Inform Resource and Regulatory Planning

Provide shallow hydrological data to support resource use, resource protection, and policy development around geothermal fields.

Understand Spring-Feeding Aquifers

Trace the shallow aquifer systems that feed geothermal springs, supporting long-term monitoring.

TEMcompany's role in geothermal exploration

See how our instruments enhance precision and efficiency in exploring geothermal fields

Near-Surface Resolution

tTEM is designed to resolve resistivity anomalies in the shallow (top 100 m) subsurface, where geothermal alteration and up-flow signatures are strongest.

Non-Invasive & Fast

High-density towed surveys cover geothermal fields quickly without drilling or ground disturbance.

Distinguishing Fluid Pathways

Contrasts in modelled resistivity are typically stronger over up-flow areas than steam-heated ground, helping identify likely fluid pathways from depth to surface.

Adaptive to various Terrain

tTEM can be deployed across the varied terrain typical of geothermal fields.

Deep Penetration

sTEM extends investigation depth beyond tTEM’s near-surface range, supporting characterization of geothermal reservoirs and structures at greater depth.

Targeting deep structures

Supports identification of deeper faults and permeability zones that may not be visible in shallow surveys alone.

Real-time data

Field crews can assess data quality on-site, reducing survey re-mobilization risk.

Need help choosing the right instrument for a specific application or want to discuss your survey challenges?

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Research Insight - Rotorua and Wairakei-Tauhara Geothermal Fields, New Zealand

A 2023 study published in Geothermics applied high-density tTEM surveys across parts of the Rotorua and Wairakei-Tauhara Geothermal Fields. The surveys mapped near-surface resistivity anomalies linked to hydrothermal alteration, permeability structures, and up-flow zones, including a possible near-surface boiling zone identified just 50 m below ground at one site. The findings support both geothermal resource understanding and hydrothermal explosion hazard management.

Read the research paper

FROM GROUNDWATER TO PERMAFROST: INNOVATIVE INSIGHTS

Explore Applications

Managed Aquifer Recharge

Managed Aquifer Recharge (MAR) is a way of replenishing underground water supplies by intentionally storing water in aquifers. This is done by directing surface water, stormwater, or treated wastewater into the ground.

Fractured Hard Rock

Fractured hard rock refers to rock types like granite or basalt that have cracked or broken due to natural processes such as tectonic movements, weathering, or even drilling.

Saltwater Intrusion

Saltwater intrusion happens when seawater enters freshwater aquifers or coastal groundwater systems. This is caused by over-extraction of groundwater, rising sea levels, and natural changes.

Weathered Bedrock

Weathered bedrock is the layer of rock beneath the soil that has undergone various weathering processes, including chemical, physical, and biological breakdown.

Permafrost Mapping

Permafrost is ground that remains frozen for at least two consecutive years, consisting of soil, rock, and organic material bound by ice. Found in polar and high-altitude regions.