2007 GSA Denver Annual Meeting (28–31 October 2007)

Paper No. 5
Presentation Time: 1:30 PM-5:30 PM

EXPERIMENTAL STUDIES USING SUPERCRITICAL CO2 TO CHALLENGE BRINE AQUIFER ROCKS


HANSEN, Logan C., SKIDMORE, Mark, BOWEN, David, GARDNER, Michael and BROX, Tim, Earth Sciences, Montana State University, 200 Traphagen Hall, Bozeman, MT 59717, hansenl@montana.edu

Geologic storage of CO2 by injection into deep brine aquifers is currently viewed as a promising avenue for sequestering CO2 due to large potential storage space, general proximity to significant point sources of CO2, and mean porosities and permeabilities favorable to injection. However, commonly utilized geochemical models may not accurately represent the relevant subsurface conditions and rock-water -supercritical CO2 reactions. Experimental testing of reservoir rock cores to supercritical CO2 challenge under controlled laboratory conditions provides baseline data for determining likely subsurface geochemical reactions and reaction rates.

In this study, we analyze the effects of injecting supercritical CO2 into rock cores prepared from Madison Formation outcrop. The Madison Formation represents a deep brine aquifer system in the Powder River Basin, WY, that has been suggested as an important target for CO2 sequestration. We have developed a flow-through core reactor in which rock cores from the Madison Formation are flooded with supercritical CO2 and reproduced formation water under typical reservoir conditions to simulate the near-well effects of CO2 injection. We report on the physical effects, including changes in crush strength, porosity, and permeability, as well as brine chemistry evolution as a result of injecting CO2 into Madison Formation cores. Preliminary data demonstrate that supercritical CO2 injection can cause significant changes in Madison Formation core permeability and compressional fracture strength without comparable change in porosity.