Berlin 2012 – wissenschaftliches Programm
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AKE: Arbeitskreis Energie
AKE 7: Erneuerbare Energie: Geothermie
AKE 7.2: Vortrag
Montag, 26. März 2012, 16:30–16:45, A 151
Structural wellbore integrity monitoring in a hot geothermal well using fiber optic distributed temperature measurements behind casing — •Thomas Reinsch1, Jan Henninges1, and Ragnar Ásmundsson2 — 1Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany — 2ÍSOR - Iceland GeoSurvey, Reykjavík, Iceland
Structural wellbore integrity is an important issue for a sustainable provision of geothermal energy. Raman based fiber optic distributed temperature sensing (DTS) can help to monitor the status of a well and therefore help to optimize expensive work-over activities. This study reports on temperature logging data that has been acquired in the hot geothermal well HE-53 within the Hellisheidi geothermal field, SW Iceland. In spring 2009, a fiber optic cable has been installed in the cemented annulus behind the anchor casing and temperature measurements were performed during cementation of that casing in May and during the onset of a production test in summer 2009.
During the onset of the production of hot geothermal fluid, the wellhead temperature was constantly increasing up to 240°C and maximum temperatures of 230°C were measured within the annulus. Although the fluid temperature within the well was increasing, a temperature decrease within the annulus was observed locally.
This temperature anomaly can be explained by the evolution of fractures within the cemented annulus. Subsequent to the fracture evolution, trapped fluid within the cement evaporated, absorbing latent heat. The structural wellbore integrity is reduced by these fractures.