An investigation into the pore-scale mechanisms of capillary trapping : application to geologic CO₂ sequestration

Graduation date: 2015Geologic CO₂ sequestration is a climate change mitigation strategy that prevents CO₂ emissions to the atmosphere by capturing CO₂ gasses from large point source emissions streams and then pressurizing and pumping the supercritical-state CO₂ into underground geologic storage reservoirs. Once underground, CO₂ is prevented from buoyant migration to the surface by various trapping mechanisms, one of which is capillary trapping. Capillary trapping is a secure trapping mechanism that immobilizes CO₂ on relatively short timescales; accurate prediction and optimization of capillary trapping of CO₂ is crucial to ensure the safety and success of a sequestration operation. The research comprising this dissertation utilizes x-ray computed microtomography (x-ray CMT) to allow for three-dimensional (3D) investigation of the main factors influencing nonwetting phase capillary trapping from a pore-scale in-situ perspective. Results from ambient- and supercritical-condition experiments are presented that provide insight as to the controls on capillary trapping during multiphase flow in porous media. The presented findings may be used to help design injection strategies that optimize capillary trapping of CO₂ during sequestration operations and to help develop more accurate predictive transport models