CO2 Storage in Complex Gas Fields
Tracer technology enhances CO2 management in the pioneering onshore CCS project
In Salah field is a joint venture between Sonatrach and BP and it presents the world’s pioneering onshore CO2 capture and storage project. It is a complex conventional gas field containing large reserves with an estimated economic limit in 2063. It processes natural gas from three gas fields in the area. Captured CO2 is separated and injected underground in the 1.9 kilometers deep Carboniferous sandstone unit at the Krechba field.
In Salah is a complex, multiple gas field development. The client’s goal was to reduce uncertainty in gas volumes and deliverability, prove additional reserves, demonstrate commerciality of the development and achieve their greenhouse gas emission goals. Various uncertainties were identified and ranked by quantitative assessment of alternative appraisal options and their impact on project value (Value of Data analysis).
The CO2 storage performance has been monitored using diverse geophysical and geochemical methods including seismic, micro-seismic, CO2 gas tracers, down-hole logging and core analysis, surface gas monitoring, groundwater aquifer monitoring and satellite InSAR data. Tracer technology was used with other methods for enhanced reservoir modelling. Tracers enable real-time monitoring of CO2 movement, providing early warning signs of anomalies or unexpected behavior. Tracers were also utilized to identify the source of CO2 leaks in the legacy well.
Routines and procedures for collecting and interpreting multiple datasets have been developed, offering valuable insights into Monitoring, Modelling and Verification (MMV) approaches for CO2 storage. Between 2004 when the injection commenced and 2011, over 3.8Mt of CO2 was stored in the subsurface. Tracer technology helped to successfully monitor CO2 movement from the aquifer into the hydrocarbon gas field, identify preferential flow paths, verify injection strategies and identify sources of leaks to the surface through the legacy well.
The In Salah CCS project is a world pioneering onshore CO2 capture and storage project which has helped to build up a wealth of relevant experience for CCS projects worldwide. It presents an important case study for knowledge transfer to other major CCS projects, highlighting the importance of diagnostic accuracy for successful CO2 management. Tracer technology is instrumental in optimizing and ensuring the success of CCS projects, providing a valuable tool for monitoring, analyzing and mitigating risks associated with the injection, storage and recovery of CO2 in subsurface.