Uncertainty analyses of CO2 plume expansion subsequent to wellbore CO2 leakage into aquifers
Hou Z, DH Bacon, DW Engel, G Lin, Y Fang, H Ren, and Z Fang. 2014. "Uncertainty analyses of CO2 plume expansion subsequent to wellbore CO2 leakage into aquifers." International Journal of Greenhouse Gas Control 27:69-80. doi:10.1016/j.ijggc.2014.05.004
In this study, we apply an uncertainty quantification (UQ) framework to CO2 sequestration problems. In one scenario, we look at the risk of wellbore leakage of CO2 into a shallow unconfined aquifer in an urban area; in another scenario, we study the effects of reservoir heterogeneity on CO2 migration. We combine various sampling approaches (quasi-Monte Carlo, probabilistic collocation, and adaptive sampling) in order to reduce the number of forward calculations while trying to fully explore the input parameter space and quantify the input uncertainty. The CO2 migration is simulated using the PNNL-developed simulator STOMP-CO2e (the water-salt-CO2 module). For computationally demanding simulations with 3D heterogeneity fields, we combined the framework with a scalable version module, eSTOMP, as the forward modeling simulator. We built response curves and response surfaces of model outputs with respect to input parameters, to look at the individual and combined effects, and identify and rank the significance of the input parameters.