Rapid porosity and permeability changes of calcareous sandstone due to CO 2 ‐enriched brine injection

• Published in: Geophysical research letters Vol. 41; no. 2; pp. 399 - 406
• Main Authors: Lamy‐Chappuis, Benoit, Angus, Doug, Fisher, Quentin, Grattoni, Carlos, Yardley, Bruce W. D.
• Format: Journal Article
• Language: English
• Published: 28.01.2014
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2013GL058534

Abstract Reservoir injectivity and storage capacity are the main constraints for geologic CO 2 sequestration, subject to safety and economic considerations. Brine acidification following CO 2 dissolution leads to fluid‐rock interactions that alter porosity and permeability, thereby affecting reservoir storage capacity and injectivity. Thus, we determined how efficiently CO 2 ‐enriched brines could dissolve calcite in sandstone cores and how this affects the petrophysical properties. During computerized tomography monitored flow‐through reactor experiments, calcite dissolved at a rate largely determined by the rate of acid supply, even at high flow velocities which would be typical near an injection well. The porosity increase was accompanied by a significant increase in rock permeability, larger than that predicted using classical porosity‐permeability models. This chemically driven petrophysical change might be optimized using injection parameters to maximize injectivity and storage. Key Points CO 2 ‐saturated brine is effective at dissolving calcite from sandstone Dissolution of isolated calcite grains markedly increases permeability