Sensitivity analysis of sedimentological controls and the effects on simulated CO2 plume behavior during dynamic reservoir modeling

Sedimentology exerts a first-order control on carbon dioxide (CO2) injection performance, plume migration, pressure evolution, and long-term trapping mechanisms for geologic storage. Variations in depositional facies and stratigraphic architecture influence reservoir connectivity, injectivity, and storage efficiency. Often, exerting a stronger influence on plume behavior than structural framework alone. Consequently, an explicit understanding of sedimentary controls is essential for robust predictions of CO2 distribution and containment over the life of an injection program.

At the reservoir scale depositional facies distributions define the spatial porosity and permeability relationships that influences CO2 migration. High-energy depositional environments, such as fluvial channel sands, shoreface deposits, or proximal turbidite lobes, typically exhibit high permeability and strong lateral connectivity. They also support high injectivity and efficient plume propagation but promote rapid lateral migration and elongated plume geometries. In contrast, facies distributions associated with low-energy depositional environments including floodplain, deltaic, and offshore mudstones are characterized by low permeability and high capillary entry pressures. These units act as baffles, barriers, and seals to flow, that restrict vertical migration and force lateral migration of the CO2 plume. Sedimentary architecture also influences the interaction between CO2 plumes and trapping elements. Stratigraphic pinch-outs, facies transitions, and sequence boundaries often create effective stratigraphic traps independent of structural closure. As a result, CO2 plumes often display complex geometries that reflect stratigraphic stacking patterns rather than simple buoyancy-driven ascent. At the pore scale, sediment texture and grain size distribution control capillary forces and residual trapping efficiency. Fine-grained or poorly sorted lithologies exhibit higher capillary entry pressures and restrictive pore throat distributions. Other reservoir quality effects related to sedimentologic features, bedding, or cementation contribute to enhanced residual and solubility trapping by increasing plume surface area and contact with grains and formation brines.

Overall, sedimentary controls fundamentally govern CO2 injection behavior, plume migration pathways, and trapping efficiency. Integrating depositional facies models and stratigraphic frameworks into site characterization, reservoir models, and dynamic numerical simulations is essential for reliable well designs, operation practice, and monitoring of geological carbon storage projects.