Modelling the influence of two-phase fault rock properties on CO2 storage in faulted saline aquifers.

Global greenhouse gas emissions, due to human activities, have increased since the beginning of the industrial revolution in the mid-19th century, with an increase of 70% the last 40 years. (IPCC 2005). Growth in emissions is linked to the increasing demands for energy services that will keep high the use of fossil fuels to the foreseeable future (IEA 2004). A promising method under increasing consideration for reducing greenhouse gas emissions and mitigating climate change, is capturing CO2 from large stationary sources, such as coal - power plants and refineries, and injecting it at supercritical conditions into deep underground geological formations. Formations considered as potential hosts comprise depleted oil and gas reservoirs, salt domes, non-mineable coal beds, and deep saline aquifers (White et al. 2012). The latter is believed to offer the greatest potential for CO2 storage due to their large storage capacity and wide availability (Bachu 2003; Michael et al. 2010).

Key issue to the successfulness of long term storage in saline aquifers is the hydraulic integrity of the geological formations that bound it. (Eiken et al. 2011). A sealing caprock is the essential geological structure that prevents upward migration of buoyancy-driven CO2. Nevertheless, geological imperfections within the host formation and/or in the caprock may result in CO2 leakage into overlying permeable formations. Therefore, the risk assessment for leakage has emerged as one of the main issues for CO2 capture and storage operations. Faults and fault-rocks are the main naturally occurring imperfections, and are predominant in many sedimentary basins suitable for CO2 storage.

In general faults and fault rocks may act as potential baffles or barrie...

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... Childs, C. & Walsh, J.J. 2010. Faults and fault properties in hydrocarbon flow models. Geofluids, 10, 94-113.

Michael, K., Golab, A., Shukalova, V., Ennis-King, J., Allinson, G., Sharma, S. & Aiken, T. 2010. Geological storage of CO2 in saline aquifers. A review of the experience from existing storage operations. International Journal of Greenhouse Gas Control, 4, 659 - 667.

Tueckmantel, C., Fisher, Q.J., Manzocchi, T., Skachkov, S. & Grattoni, C.A. 2012. Two-phase fluid flow properties on cataclastic fault rocks: Implications for CO2 storage in saline aquifers. Geology, 1, 39-42.

White. C.M., Strasizar, B.R., Granite, E.J., Hoffman, J.S. & Pennline, H.W. 2003. Separation and capture of CO2 from large stationary sources and sequestration in geological formations - coalbeds and deep saline aquifers. Journal of the Air & Waste Management Association, 6, 645 - 715.