Impacts of geological store uncertainties on the design and operation of flexible CCS offshore pipeline infrastructure

Planning for Carbon Capture and Storage (CCS) infrastructure needs to address the impact of store uncertainties and store flow variability on infrastructure costs and availability. Key geological storage properties (pressure, temperature, depth and permeability) can affect injectivity and lead to variations in CO2 flow, which feed back into the pipeline transportation system. In previous storage models, the interface between the reservoir performance and the transportation infrastructure is unclear and the models are unable to provide details for flow and pressure management within a transportation network in response to changes in the operation of storage sites. Variation in storage demand due to daily and seasonal variations of fossil fuels uses and by extension CO2 flow is also likely to influence transportation infrastructure availability and the capacity to deliver. This work examines, at the level of infrastructure planning, the impact of store properties on CCS transportation and injection infrastructure in the context of flow variability. Different off-shore transportation scenarios, relevant to CCS in the UK, are evaluated using rigorous process modelling tools. Considering flow variations of ±50% of a given baseline flow, the results of the analysis indicate that enabling store flexibility is simpler in reservoirs with an initial pressure above 20 MPa. Wellhead conditions are influenced significantly by subsurface conditions. The operational envelope of the storage site is limited by the proximity of wellhead conditions to the CO2 phase equilibrium line and the maximum fluid velocities inside the well. Given reductions in reservoir permeability, the requirements for pressure delivery are strongly dependent on the reservoir temperature. This work provides detailed insight on the expected impacts of store properties on transportation infrastructure design and operation