CCS | CO2 Migration | Reservoir Model Calibration
Carbon Capture and Storage (CCS) is a technique for trapping in underground reservoirs the carbon dioxide (CO2) normally emitted into the air from large point sources such as power plants. The CO2 is compressed and transported to a suitable storage site where it is injected into the ground. CO2 can be stored in geological formations, including depleted oil and gas reservoirs and deep saline caverns. The technique has significant potential to help mitigate climate change, particularly in countries with large fossil-fuel reserves and increasing energy demand.
The In-Salah project in central Algeria represents a world-pioneering, onshore, CCS example: the CO2 from several gas fields is removed from the production stream and transported for storage 1.9 km underground in the carboniferous sandstone of the Krechba field. The performance of the site has been monitored using a wide range of geophysical and geochemical methods to ensure that the CO2 captured remains isolated from the atmosphere. These methods include satellite InSAR data provided by TRE Altamira that shows how the ground surface moves in response to the CO2 injection, offering further, unique insight into the characteristics of the storage site.
InSAR measurements of surface deformation have revealed fluid flow associated with the geological storage of CO2. The analysis of the double-lobed pattern in range change over the injection well KB-502 suggests the opening of a tensile feature. Vertical and horizontal surface displacement values from InSAR have been used to model fault opening, providing a good match between predicted and observed data.
By regularly monitoring displacement with InSAR, site engineers can control injection activities to ensure reservoir pressure distribution and surface uplift remain within safe operational limits.
Reservoir Model Calibration
According to the spatial distribution of deformation, it is possible to infer how CO2 plume propagation is oriented. Satellite displacement measurements incorporated into subsurface models can also be used to calculate reservoir volume and permeability changes.
Active Fault Detection
InSAR maps can highlight rapid changes in the movement rate over large areas, correlating with fault structures, fracture systems and reservoir boundaries. Fault reactivation due to injection can be characterized and monitored through systematic InSAR analyses.
CO2 storage projects require long-term monitoring strategies: InSAR is highly competitive compared to other conventional techniques, providing precise wide-area deformation patterns at a relatively low cost.
For more info, click here to read our co-authored article “Satellite-based measurements of surface deformation reveal fluid flow associated with the geological storage of carbon dioxide”, from Geophysical Research Letters, Vol. 37, Feb. 2010.
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