Well integrity analysis in a high temperature geothermal well using distributed temperature sensing behind casing

Abstract

Within 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.