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CLIMIT-Forskning, utvikling og demo av CO2-håndtering

XMAS - Excitation method for continuous non-invasive monitoring of CO2 well integrity

Alternative title: XMAS - Metoder for kontinuerlig fjernovervåking av integriteten til CO2 brønner

Awarded: NOK 3.0 mill.

Enabling carbon capture and storage (CCS) is important for reducing the problem of global warming due to man-made CO2 emissions. Storage is achieved by injecting CO2 through wells in suitable geological formations. A prerequisite is that the storage site is safe, implying that the injected gas stays in the sub-surface and does not leak back to the atmosphere. The Norwegian Continental Shelf is a promising candidate for large scale CO2 storage. However, the area has many wells that are plugged and abandoned, since they are no longer used for oil and gas production. These wells are potential leakage points and their integrity is therefore essential for storage safety. Due to a lack of affordable methods for assessing their integrity, such wells are all treated as "high risk" when evaluating possible storage locations. This leads operators to discard drilled regions from CO2 storage ? despite the wealth of subsurface information available there. To optimally exploit available storage capacity on the Norwegian Continental Shelf, it is therefore necessary to find a cost-efficient way of reliably assessing the integrity of wells without having to enter them. Such a remote monitoring option would be a game changer for CO2 storage, as it would not only increase storage options by allowing leakage risk assessment of plugged wells, but would also allow continuous well integrity monitoring during operations ? thereby ensuring targeted remediation and condition-based well intervention schemes. A first step towards this goal is to study the transmission of various signals along well construction materials (casing and cement), and how they can be emitted, detected and interpreted to create a well integrity report. This project combines numerical studies, experiments, and engineering work to determine which excitation methods and signals are most promising for remote well integrity assessment, and it will study how future wells can be constructed to facilitate remote monitoring. Work during 2020: The evaluation of various acquisition configurations has continued using both seismic and electromagnetic modelling. With the improved modelling capabilities achieved in H1, significantly more realistic cases have been considered with the help of a commercial modelling software.

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Wells are the "gate keepers" of stored CO2, and their integrity dictate to a large degree the overall storage safety. Some wells penetrating prospective CO2 storage sites are plugged and abandoned, and their wellhead and upper casing pipes are severed several meters below seafloor. Due to a lack of methods for assessing their integrity, such wells are all treated as "high risk" when evaluating possible storage locations. This leads operators to discard heavily drilled regions from CO2 storage - despite the wealth of information available on the subsurface here. To optimally exploit available storage capacity on the Norwegian Continental Shelf, it is therefore necessary to find a way of reliably assessing the integrity of wells without having to enter them with logging tools. Such a remote (non-invasive) monitoring option would be a game changer for CO2 storage, as it would not only increase storage options by allowing leakage risk assessment of plugged wells, it would also allow continuous well integrity monitoring during operations - and thereby ensure targeted remediation and condition-based well intervention schemes. A first step for reaching this goal is to study the transmission of various signals along well construction materials (casing and cement), and how they can be imposed, detected and interpreted to draw up a well integrity report. This is the goal in the current project, which combines numerical studies, experiments and engineering work. It will determine which excitation methods and signals are most promising for remote well integrity assessment, and it will study ways future wells can be constructed (with different materials) to optimize remote monitoring possibilities.

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CLIMIT-Forskning, utvikling og demo av CO2-håndtering