Impact of relative permeability hysteresis on geological CO2 storage
Article first published online: 23 DEC 2006
Copyright 2006 by the American Geophysical Union.
Water Resources Research
Volume 42, Issue 12, December 2006
How to Cite
2006), Impact of relative permeability hysteresis on geological CO2 storage, Water Resour. Res., 42, W12418, doi:10.1029/2005WR004806., , , and (
- Issue published online: 23 DEC 2006
- Article first published online: 23 DEC 2006
- Manuscript Accepted: 21 AUG 2006
- Manuscript Revised: 28 JUL 2006
- Manuscript Received: 13 DEC 2005
- carbon sequestration;
- multiphase flow;
- porous media;
 Relative permeabilities are the key descriptors in classical formulations of multiphase flow in porous media. Experimental evidence and an analysis of pore-scale physics demonstrate conclusively that relative permeabilities are not single functions of fluid saturations and that they display strong hysteresis effects. In this paper, we evaluate the relevance of relative permeability hysteresis when modeling geological CO2 sequestration processes. Here we concentrate on CO2 injection in saline aquifers. In this setting the CO2 is the nonwetting phase, and capillary trapping of the CO2 is an essential mechanism after the injection phase during the lateral and upward migration of the CO2 plume. We demonstrate the importance of accounting for CO2 trapping in the relative permeability model for predicting the distribution and mobility of CO2 in the formation. We conclude that modeling of relative permeability hysteresis is required to assess accurately the amount of CO2 that is immobilized by capillary trapping and therefore is not available to leak. We also demonstrate how the mechanism of capillary trapping can be exploited (e.g., by controlling the injection rate or alternating water and CO2 injection) to improve the overall effectiveness of the injection project.