A study of residual carbon dioxide trapping in sandstone

The storage of carbon dioxide (CO2) in deep brine-filled geologic strata is largely seen as one of the most important tools for CO2 emissions mitigation on industrial scales. Residual trapping is a major factor in determining the ultimate extent of CO2 migration within the reservoir. At the same time there are few studies that have observed the trapping characteristics for CO2-brine systems in permeable rocks, including the impact of reservoir conditions, and this remains a major uncertainty for geologic CO2 storage. In this experimental study, we take advantage of flow conditions that enhance the capillary end effect so that a large saturation gradient across the core is created during drainage with CO2. We observe residual trapping of CO2 in sandstone rocks across the wide range of conditions representative of subsurface reservoirs suitable for CO2 storage. The observations are made using a reservoir condition core-flooding laboratory that includes high precision pumps, accurate temperature control, the ability to recirculate fluids for weeks at a time and a rotating X-ray CT scanner. Application of residual trapping curves in reservoir scale simulation has also been discussed. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).