A possible strategy to reduce cost of Carbon Capture and Storage (CCS) is to re-use old wells for the storage of CO2 in the subsurface. There are several oil & gas wells with the potential for re-used as CO2 injection wells for permanent storage in the subsurface. The objective of REX-CO2 project is to investigate tools and methods for assessing the suitability of existing wells for CO2 injection. A considerable part of the project work is experimental laboratory studies, with emphasis on understanding well integrity and barriers before and after re-use as CO2 injector.
The ongoing REX-CO2 prosjektet is part of the ACT2 initiative, with the research partners TNO (coordinator), BGS, IFP-EN and Los Alamos National Laboratory. SINTEF is the main Norwegian partner, and the other Norwegian partners are Equinor and ReStone. The research content deals with cement-casing interactions and how to understand, minimize failures and to possibly remediate failures. Regular meetings and workshops between all research partners and the industry have been arranged in order to discuss findings and plan future activity.
Existing oil and gas industry installations which cover large parts of the
potential CCS chain are already in place, and an increasing number
of reservoirs have come to the end of their production lifetime and are
earmarked as major targets for initiating large-scale CCUS operations
(DOE, 2017). The existing wells in these assets present both opportunity
and challenges. Substantial savings could be realized by re-using these
wells as CO2 injectors, monitoring wells, or for water production (pressure
management). On the other hand, the existing well infrastructure poses
a risk as a potential CO2 or brine leakage pathway (Watson and Bachu,
2009). In this proposal, we take a fresh look at this problem and provide a
novel solution. The re-use of wells is the inverse of the problem of identifying
defective wells. The process of certifying well integrity can also be used
to identify wells suitable for continued use in a CO2-rich environment. We
develop a qualification process that will simultaneously save CO2 storage
projects money and time by identifying existing infrastructure that is safe
to re-use, while determining which wells must be remediated to ensure
Re-use can benefit projects in all geological settings but may be particularly
crucial for off-shore environments, such as the North Sea or the Gulf of
Mexico, where well development costs could otherwise be prohibitive.
Developing a procedure and tools for evaluating the reuse potential of
existing hydrocarbon fields and wells will require a dedicated investigation
encompassing the interrelated technical, environmental, economic and social
aspects. Currently no such publicly available tool exists. For this project, we
conduct the necessary research to develop a dedicated well-screening tool
for Reusing EXisting Wells for CO2 storage operations (REX-CO2).