Analysis of CO2 Leakage through 'Low-Permeability' Faults from Natural Reservoirs in the Colorado Plateau, East-Central Utah
Contribution to Book
Geological Storage of Carbon Dioxide
SJ Baines & RH Worden
Geological Society of London
The numerous CO2 reservoirs in the Colorado Plateau region of the United States are natural analogues for potential geological CO2 sequestration repositories. To understand better the risk of leakage from reservoirs used for long-term underground CO2 storage, we examine evidence for CO2 migration along two normal faults that cut a reservoir in east-central Utah. CO2-charged springs, geysers, and a hydrocarbon seep are localized along these faults. These include natural springs that have been active for long periods of time, and springs that were induced by recent drilling. The CO2-charged spring waters have deposited travertine mounds and carbonate veins. The faults cut siltstones, shales, and sandstones and the fault rocks are fine-grained, clay-rich gouge, generally thought to be barriers to fluid flow. the geological and geochemical data are consistent with these faults being conduits for CO2 moving to the surface. Consequently, the injection of CO2 into faulted geological reservoirs, including faults with clay gouge, must be carefully designed and monitored to avoid slow seepage for fast rupture to the biosphere.
Shipton, Z. K., Evans, J. P., Kirchner, D., Heath, J., and Williams, A. P., 2004, Analysis of CO2 Leakage through 'Low-Permeability' Faults from Natural Reservoirs in the Colorado Plateau, East-Central Utah, Geological Society of London Special Publication 233, S. J. Baines and R. H. Worden, eds., Geological Storage of Carbon Dioxide, p. 43-58.