Swiss Norwegian Post-Mortem Analysis of Mont Terri CCS well

One of the major obstacles to storing CO₂ on the Norwegian shelf is all old wells that pose a potential leakage risk. Previous Climit studies for the development of well integrity have outlined new concepts for repair fluids and well monitoring technology. The proposed project is based on a field scale test carried out by SINTEF which was carried out in the underground laboratory at Mont Terri (Switzerland). The field scale test was drilling a borehole through a slate, cementing a casing and simulating a crack on the outside of the pipe

The project will test sealing fluids in-situ in the Mont Terri underground laboratory, where cores consisting of well sections with concentric cement and formation around the well will be drilled. The cores are then tested for mechanical strength and permeability at SINTEF.

Five main activities are planned in the project, each of which is roughly described below.
1. Core extraction of an entire section of well
2. 1m long sections are CT-scanned, if possible; otherwise the sections are cut to length before scanning.
3. Several shorter sections will be sent to Trondheim for further testing at SINTEF.
A larger section is sent to Trondheim, where SINTEF’s logging equipment is tested in the borehole and the result of the log is compared with CT images of the cement on the outside of the casing.
5. An option may be to try SINTEF’s logging equipment in Switzerland on a fresh core section, right after the core extraction operation

The project will alleviate problems associated with old wells. It will help to bring SINTEFS well technology to commercialization and thus enable safe storage on the Norwegian shelf. The technology also has international market potential.

The project has two main objectives:
• Compare the effectiveness of 3 different chemicals in sealing cracks around an injection well with the least disturbance to the well and near well area
• Test SINTEF’s logging method for crack detection behind casings on real samples (field scale).