Harpreet Singh Evgeniy M. Myshakin Angela L. Goodman Robert M. Dilmore Timothy C. Grant David Morgan Grant Bromhal Peter D. Warwick Sean T. Brennan Philip A. Freeman C. Ozgen Karacan Charles Gorecki Wesley Peck Matthew Burton-Kelly Neil Dotzenrod Scott Frailey Rajesh Pawar Sean Sanguinito 2020 <p><span>Residual oil zones (ROZs) are increasingly gaining interest as potential reservoirs for carbon dioxide (CO</span>₂<span>) storage. Here, we present a national- and regional-scale methodology for estimating prospective CO</span>₂<span>&nbsp;storage resources in residual oil zones. This methodology uses a volumetric equation that accounts for CO</span>₂<span>&nbsp;storage as a free phase in pore space and as a dissolved phase in oil and does not assume any oil production associated with CO</span>₂<span>&nbsp;storage. Reservoir modeling and the CO</span>₂<span>-SCREEN tool are used to demonstrate that CO</span>₂<span>&nbsp;storage in residual oil zones will predominantly take place in the free phase (approximately 92–97%) with some storage as dissolution in oil (approximately 3–8 %). Based on this preliminary demonstration, the CO</span>₂<span>&nbsp;storage efficiency for ROZs using this national- and regional-scale method ranges from 0.61 to 7.1 %. This range indicates ROZs have a similar efficiency potential for storing CO</span>₂<span>&nbsp;as deep saline formations (0.51–5.4 %).</span></p> application/pdf 10.1016/j.ijggc.2020.103006 en Elsevier Methodology for estimating the prospective CO2 storage resource of residual oil zones at the national and regional scale article