Well integrity monitoring using distributed fiber optic sensing

Abstract

New concepts are required to accelerate the global development of high-temperature geothermal resources in a cost effective and environmentally safe way. Keeping the geothermal system in operation for several decades is challenging - yet key to economic success. Real-time monitoring of temperature and strain along the well bore is a powerful tool to evaluate the performance and integrity of installed subsurface components. A fiber optic cable was installed behind the casing of a high temperature geothermal well in Iceland (IDDP2). A second cable was installed in a low temperature well in Germany. During cementation, distributed strain data (Rayleigh backscatter) as well as distributed temperature sensing data (Raman backscatter) was acquired. In a subsequent measurement campaign, data shall be acquired in these wells during load changes (production/injection). In combination with concurrent laboratory investigations and conventional borehole logging data, this study will identify processes influencing the long-term integrity of casing and cement in high-temperature geothermal environments.