Helping De-Risk the Exploration for Suitable Geothermal Drill Targets

Exploration for Geothermal Resources shares many of the same risks as exploring for minerals or oil. As such, the geothermal industry is also seeing the adoption of technologies developed in the oil exploration industry. De-risking the early phase of exploration for suitable geothermal sites requires the early adoption of new technology. While drilling offers a direct way of measuring properties (e.g. temperature) at depth, it also shares extremely high financial and environmental risk. Indirect, geophysical methods such as seismic velocity or electromagnetics are the most cost-effective, environmentally friendly and technically feasible methods for exploring. Accordingly, surface-based, low- to no-impact geophysical techniques present a much more sustainable option for exploring and, in some cases monitoring, when compared with target testing using slow and expensive drilling. Adrok have the capability to achieve two potentially key requirements of the geothermal industry. Firstly, to detect water at depth by using waters high natural dielectric permittivity (Ɛᵣ = 80) relative the typically low dielectric permittivity of host rocks (Ɛᵣ <15), particularly granites for example. Secondly, information acquired from a single scan can be used to infer relative temperature at depth, a technique used and tested by Adrok in the oil industry. After years of testing in the oil industry against well/bore holes with direct temperature measurements, it was discovered that subtle variations in the return energy signal is a good indicator of temperature variability. This discovery can be adopted by the geothermal industry to help de-risk targeting and ensure high temperature zones at a well-defined depth are drilled in the correct location without the need for costly trial/exploratory bore holes. Adrok present a description of the methodologies used and an explanation of how the technology can fit into an exploration and/or monitoring workflow.