By Rick Schrynemeeckers, EVP & CTO of Low Carbon Services
A primary mode of Carbon Capture and Sequestration (CCS) is geologic sequestration in which carbon dioxide (CO2) is injected into underground geologic sinks. Critical to the success of geologic sequestration is the need to ensure that underground storage sinks have an effective seal and do not leak to pose a potential threat to human health and the environment. For offshore applications the question becomes, what is the best method for monitoring potential CO2 leakage?
Current offshore CO2 detection and monitoring falls into two primary categories: seismic methods and CO2 testing methods associated with existing wells. 2D and 3D seismic methods are excellent for identifying potential structural spill points and mapping CO2 plume movement but are not sensitive enough to determine if leakage occurs. Additionally, there are numerous CO2 measurement methods that operate at monitoring or observation wells. However, these techniques are constrained to well locations which is problematic when well density is sparse and the closest CO2 monitoring wells may be >10 km away from potential spill points (Figure 1).
An alternative technology is ultrasensitive passive geochemical monitoring. Passive geochemical surveys have been used in sequestration and CO2 monitoring for 20 years. Amplified Geochemical Imaging’s (AGI) passive samplers contain specially engineered adsorbents encased in a microporous membrane (Figure 2). Membrane pore size is small enough to prevent soil particles and water from entering, but large enough to allow CO2 to pass through and concentrate on the adsorbents within.certification and/or employment goals.
Passive geochemical surveys have several unique advantages:
- Sensitivity – the method detects CO2 at parts per billion (ppb) levels. This allows the detection of CO2 before leaks may become catastrophic.
- Mobility – modules are deployed on the seafloor using divers in shallow waters, and Ocean Bottom Seismic (OBS) nodes in deeper waters. This allows modules to be deployed at potential spill points such as leaking faults, around plugged and abandoned wells, or around injection wells where CO2 may leak up the well bore (Figure 3).
- Time integrated sampling – modules are left in place for ~21 days to allow CO2 to adsorb onto encased adsorbents. The adsorbed CO2 comes into equilibrium with concentrations in the sediment column. The result is a stable and reproducible measurement.
Conclusion: AGI’s 20 years of CCS experience provides the impetus to develop advancements in offshore CO2 monitoring. The key to successful CO2 monitoring is the combination of ultrasensitive passive geochemical CO2 monitoring and high-resolution seismic, which when integrated gives the ability to evaluate faults, natural fractures, structural changes and CO2 leakage data to a high degree of accuracy not previously available.
Mr. Schrynemeeckers holds a Bachelor of Science in biochemistry from Texas A&M University and a Master of Science in chemistry from the University of North Texas. He began his career working for Sun Oil Company in Dallas in Enhanced Oil Recovery. He then spent many years in the environmental arena. He returned to the oil industry working for Baseline Resolution developing international satellite geochemistry laboratories in Venezuela, Brazil, Argentina, and Egypt. He is now the Executive Vice President and CTO of Low Carbon Services for Amplified Geochemical Imaging. He may be reached at Schrynemeeckers@AGIsurveys.net.
Rick participated in an Ocean Exchange webcast in March, 2023, on the topic of Carbon. View the recording here.