Significance of Conceptual Model Uncertainty in Simulating Carbon Sequestration in a Deep Inclined Saline Aquifer

Abstract

AbstractIn modeling geologic carbon sequestration in a deep inclined aquifer in Wyoming, the impact of geologic, engineering, and environmental uncertainty factors on parameter importance and prediction uncertainty is evaluated. Given site characterization data, a suite of geologic model families were built to represent aquifer permeability heterogeneity at increasing complexity. With each family, the same CO2 experiment was simulated. Over a period of 50 years, 17 million tons of CO2 is injected into the aquifer at an approximate depth of 3,750 m. Postinjection simulation is then carried out for a total simulation time of 2,000 years. Based on the design of the experiment, a screening sensitivity analysis was first conducted for all families, systematically varying uncertain input parameters. Parameters with first-order impact on CO2 performance metrics (i.e., trapped gas, dissolved gas, brine leakage, storage ratio) are identified, which vary with time and modeling choice. When the model is of low compl...