Highlights

• First fiber-optic monitoring of a reverse cementing operation
• Assessment of annular fluid displacement and slurry density
• Structural health monitoring of the well for already half a decade

A fiber optic cable was installed down to 832 m behind the production casing in well RN-15/DEEPEGS/IDDP-2 in the Reykjanes geothermal field, south-west Iceland. Due to extreme temperatures at depth, a high-temperature resistant fiber-optic cable was selected which is designed to operate at temperatures up to 300 °C.
Our job included the preparation of the cable on site, consulting and supporting in the downhole installation, setting up the surface monitoring layout, acquiring, analyzing, interpreting and reporting of the data.
Several campaign based monitoring jobs were conducted since the cable installation in 09/2016. The initial monitoring campaign focused on to the reverse cementing operation of the production casing using distributed temperature sensing (DTS). In 09/2018, we conducted a monitoring campaign during a cold-water injection period with DTS and DAS. From 10/2019-04/2020, a well stimulation period was monitored at DTS and DAS.

Funding

This research project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654662 (Project GeoWell) and grant agreement No 690771 (DEEPEGS). This project also has received funding from the European Union's Seventh Programme for research, technological development and demonstration under grant agreement No: 608553.

References

Lipus, M. P., Reinsch, T., Weisenberger, T., Kragset, S., Stefánsson, A. (2021): Monitoring of a reverse cement job in a high temperature geothermal environment. - Geothermal Energy, 9, 5 (open access link)

Data availability

The acquired fiber optic DTS data is freely available under the Creative Commons Attribution International 4.0 Licence (CC BY 4.0) by GFZ Data Services (Lipus and Reinsch 2020). Data from the temperature and pressure gauges are also freely available (Eggertsson and Stefánsson 2020).