Eric Mackay

Heriot-Watt University

CO2 migration in dipping structures

CO2 injection in saline aquifers is used to store CO2. The CO2 plume may migrate for millennia due to buoyancy. Demonstrating that the CO2 will remain within the storage complex over such timeframes is crucial to meet license stipulations. Structural, residual, dissolution and mineral trapping contribute to retarding CO2 migration; each mechanism dominates over different timescales. Understanding the post-injection subsurface migration and trapping of the plume is important in calculating the storage capacity as well as demonstrating storage security. Most aquifers are in tilted strata, and may be subject to groundwater flow, which may accelerate or decelerate the plume migration, as well as impacting residual trapping of CO2 and rate of dissolution in brine.  We use GEM to study the impact of direction and magnitude of groundwater flow on the early post-injection plume migration in a dipping aquifer, drawing conclusions that are counterintuitive about the role of groundwater flow.