Evaluating the Effect of Gravity on CO2 Plume Behavior in Deep Confined Saline Aquifers
Abstract
Previous modeling studies of CO2 injection into deep saline aquifers have often neglected to account for gravity. Here, we assess the conditions under which this simplification may be valid. We considered the injection of CO2 at a constant rate into a confined, homogeneous, isotropic saline aquifer via a single vertical well. We employed the TOUGH2/ECO2N software package to conduct numerical simulations of CO2 injection. We conducted two sets of simulations, one in which gravity is included, and the other in which gravity is neglected. Other factors varied in the simulations include the relationship between relative permeability and brine saturation. Predicted pressures and vertically-averaged brine saturation profiles are used as bases of comparison between the two sets of simulations. The effect of gravity on the predicted pressures was found to be significant when relative permeability (kr) varies non-linearly with brine saturation (Sw). However, if the relationship between kr and Sw is linear or quasi-linear, gravity was found to have a small effect on model predictions of pressure in the formation. Results of vertically-integrated brine saturation profiles show slight increases in CO2 plume extent when gravity is included, with a concomitant reduction in CO2 storage efficiency. Results from this study suggest that gravity must be included in simulations of CO2 sequestration if kr varies non-linearly with Sw.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.H23D1010O
- Keywords:
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- 1899 General or miscellaneous;
- 9810 New fields (not classifiable under other headings)