High Temperature Downhole Tools for Enhanced and Supercritical Geothermal Systems

Abstract

Downhole investigations in high temperature geothermal wells are often restricted by tool availability, since most logging instrumentation used in geothermal applications are designed for oil and gas applications. On-going and planned scientific projects in Iceland and New Zealand require downhole gauges tolerating temperatures up to and even beyond 400°C, where only a small selection of specialized instruments are available to the geothermal community. The target for geothermal energy extraction in supercritical geothermal wells is 400-600°C. In the foreseeable future, a larger set of advanced borehole instruments, tolerating temperatures up to 300°C, will be required. Long-term deployment of production monitoring tools at temperatures up to 300°C can also be foreseen, in particular in enhanced geothermal reservoirs engineered for heat extraction from magma sources. Currently, work is on-going to identify the most urgent instruments required by the geothermal community at high temperatures within the ‘International Partnership for Geothermal Technology’ (IPGT)1. Some of these instruments are mentioned here.