CCS Technologies, Storage and Monitoring
Technologies used for carbon capture and storage have been in use for decades
The natural gas industry already uses technologies to capture extra CO2 from natural gas production. The first commercial-scale carbon capture and storage project in the world was started in 1996 by Statoil. Sleipner is an offshore natural gas processing facility located in the North Sea off Norway. The CO2 produced during the natural gas processing is captured and injected into a deep saline reservoir 2600 – 3300 feet below the sea floor.
Oil and gas producers have decades of experience injecting CO2 into oil fields for enhanced oil recovery.
- The first CO2- enhanced oil recovery projects were started in the 1970s.
- There are about 15 active commercial-scale CO2- enhanced oil recovery projects operating worldwide.
Storage formation types
Depleted oil and gas reservoirs are natural storage formations for CO2. After all, that is where the oil or natural gas was safely stored for millions of years before being brought to the surface. The injected CO2 fills the tiny pores in the rock that were previously filled by oil or natural gas.
Deep underground saline formations are large, porous rock formations that contain water unusable because of it is extremely high salt and/or mineral content. Deep saline formations have an extremely high potential to store CO2 because over time, some of the gas would dissolve right into the salty water. In Alberta, CO2 storage in underground saline formations must be at least 1km from the surface. These storage formations are contained due to a layer of cap rock located above the formations that prevents any CO2 from escaping.
Monitoring, measuring, and verification
Storage sites are analysed and monitored before, during, and after large-scale CO2 storage projects to ensure the area surrounding the site is unaffected and the CO2 is safely contained in the storage site.
Monitoring and measurement are the surveillance activities necessary for ensuring the safe and reliable operation of a CO2 storage project. Verification refers to the comparison of measured and predicted performance.
Types of monitoring, measurement, and verification:
- Subsurface: monitors the movement of the CO2 in the storage site and the stability of the cap rock.
- Near surface: monitors soil, well water, and ground water to ensure CO2 is not leaking.
- Atmospheric: monitors CO2 levels in the air around the site.
- Pre-operational monitoring: establishes baseline conditions such as groundwater and soil conditions prior to injection.
- Operational monitoring: ensures safety with all injection procedures, including measurement of CO2 concentrations in soil, groundwater and air, continuous monitoring of CO2 injection rate, and tracking of injected CO2 volumes.
- Closure monitoring: assess whether the storage site is performing as expected.
- Post-closure monitoring: monitors the site to ensure it is performing as expected. This type of monitoring continues for decades.