Geothermal exploration drilling

Temperature gradient, slimhole, and full-size geothermal wells to derisk exploration

Overview

Reduce exploration risk

Geothermal energy is a powerful solution for sustainable power generation. To lower risk and improve project outcomes, developers often take a phased approach to exploration drilling—starting with targeted well types that provide critical data before major investments are made. At SLB, we can help you optimize costs and maximize your operational success by leveraging our extensive geothermal and well construction expertise.

Why a phased drilling strategy matters

Drilling full-size wells without adequate subsurface data can lead to costly failures. A phased approach using temperature (thermal) gradient (TG) wells and slim holes enables developers to reduce exploration risk, optimize drilling investments, build robust geothermal conceptual models, and make final investment decisions with confidence. This strategy is even more important for enhanced geothermal systems (EGS), where advanced techniques such as hydraulic stimulation and horizontal drilling are used to expand resource access.

Mapping the thermal profile

TG wells are shallow, vertical wells, typically 150–1,000 m deep, drilled early in the exploration phase. These wells do not tap into the geothermal reservoir, but instead enable measuring temperature changes with depth to identify thermal anomalies. They are essential for building the initial geothermal resource conceptual model, helping developers identify where deeper drilling is warranted—at a fraction of the cost of drilling full-size wells.

Attach_Money

Low cost (typically USD 100,000–1 million/well)

design_services

Thermal anomaly mapping for early-stage conceptual modeling

Eco

Minimal environmental impact

Drillable with rotary or core rigs, and sometimes with heliportable rigs for remote sites

Attach_Money

Cost-effective geothermal exploration drilling (typically USD 2–4 million/well)

science

Reservoir access for short-term testing and fluid sampling

design_services

Support for numerical modeling and feasibility studies

Slotted liner completion for fluid sampling and basic testing

Drillable with rotary or core rigs and can be converted into monitoring and injection wells

Direct resource characterization

Slim wells, usually with a diameter of <7 in, are drilled to depths of 1,000–2,000 m. They are designed to penetrate the geothermal reservoir and enable collecting data on temperature, pressure, permeability, and fluid composition. These wells are a powerful tool for derisking geothermal exploration, offering valuable insights at half the cost of full-size wells. They can also be repurposed for long-term monitoring or injection support.

Production-scale validation

Full-size geothermal appraisal wells are typically drilled to depths of 1,500–3,500 m and are designed for long-term production or injection. They are usually drilled after TG and slim wells have confirmed the viability of the resource. While more expensive (USD 4–8 million/well), full-size wells are critical for demonstrating project feasibility and securing investment.

science

Enabling comprehensive reservoir testing, including interference tests

assignment

Support for feasibility studies

Architecture

Production-ready infrastructure

Manufacturing

Can be converted to producers or injectors postexploration

Geothermal exploration drilling

Temperature gradient, slimhole, and full-size geothermal wells to derisk exploration

Reduce exploration risk

Why a phased drilling strategy matters

Mapping the thermal profile

Direct resource characterization

Production-scale validation

Ready to derisk your geothermal project?

Related products & services

Geothermal Consulting Services

Geothermal Well Construction