Wireline Distributed Temperature Measurements and Permanent Installations Behind Casing

Abstract

Quasi-continuous temperature profiles can be measured in boreholes deploying fibre-optic distributed temperature sensing technology. In this paper, two different experimental designs using this technology are presented within case studies. For temporary installations, the sensor cable is lowered into the borehole, and after data acquisition the sensor cable is again retrieved. In the In-situ Geothermal Lab Gro? Schˆnebeck a wireline DTS installation has been performed up to a depth of 4265 m and temperature of 143 ?C. For long-term monitoring, or in cases when full access to the interior of the borehole is needed, the sensor cables are installed behind the borehole casing. The deployment of distributed temperature sensing technology proved to be successful for temperature monitoring in boreholes under a wide range of conditions, and it favors the observation of dynamic subsurface processes involving temperature changes. With wireline DTS installations, the open-hole and cased-hole sections of a borehole can be measured and multiple deployments can be performed with a single sensor cable. With the permanent installation behind casing, even abandoned and sealed wells can be monitored, which makes this method especially suitable for long-term thermal monitoring.