SCAL model for CCS – Insights from the first commercial CO2 project on the Norwegian Continental Shelf, Northern Lights

Relative permeability and capillary pressure are multi-phase flow properties characterized by a SCAL-model that determine the reservoir fluid dynamics for the fields in production and for the new field developments. For Carbon Capture and Storage projects (CCS), multi-phase flow properties are equally important. Interpretation of SCAL experiments and implementation of the SCAL-model for full-field simulations will be shared to highlight the impact of the SCAL model uncertainty on the estimation of the carbon dioxide (CO2) storage resource assessment and plume migration for the Northern Lights project - the world’s first open-source CO2 transport and storage infrastructure.
In case of CO2 storage in the saline aquifer like in the Northern Lights project, the flow process is inverse to the hydrocarbons production as water saturation decreases from unity saturation toward a residual water saturation when the CO2-plume propagates though the formation. Therefore, there is a need to provide the SCAL-model for the process and system applicable for CCS, i.e., primary drainage type when the CO2 plume develops and residual trapped CO2 when the aquifer later imbibes into the stored CO2.
Nitrogen (N2) has frequently been used by the industry at ambient conditions as proper analogue fluid to CO2 to achieve fluid flow properties without the need for SCAL experiments at the resource-demanding reservoir conditions with supercritical CO2. For the SCAL-model presented her, we have also included experiments with supercritical CO2 at reservoir conditions. Several multi-phase flow experiments have been performed, and comprehensive interpretation work has been performed using the core flow simulations tool Sendra. The experiments cover steady state for relative permeabilities, multi speed centrifuge and porous plate for capillary pressure and residual water saturation, as well as unsteady state trapped gas experiments to provide data for determination of residual trapped CO2.