Well Integrity Analysis in a High Temperature Geothermal Well using Distributed Temperature Sensing Behind Casing

Abstract

SUMMARYWithin this study, a fiber optic cable was installed behind the anchor casing of a high temperature geothermal well in Iceland. The aim was to study the integrity of the cemented annulus during load changes, i.e. temperature and pressure changes during fluid production. Fiber optic distributed temperature data were acquired during installation/cementation, flow testing as well as during a subsequent shut-in period. Temperature data from the cementation were used to analyse the cement quality. During the onset of a flow test, measured temperatures in the annulus increased by more than 200°C. From the data a process influencing the well integrity could be identified.

The risk of fluid-injection-induced fault reactivation in carbonate reservoirs: an investigation of a geothermal system in the Ruhr region (Germany)

“…This could imply that (semi-)continuous and realtime temperature field monitoring, complementing seismic monitoring, could be considered as a crucial element of re-risking future geothermal projects. One of the methods, although limited to a narrow area in the close vicinity of a borehole, could include temperature monitoring utilizing fiber optic cable installed in a borehole (Reinsch 2012;Schölderle et al 2021). Another method could include electrical resistivity tomography methods, which enable controlling the temperature distribution within the reservoir and are not limited to a near-borehole area.…”