Numerical Modeling of CO2 Sequestration in Geologic Formations -Recent Results and Open Challenges
Rising atmospheric concentrations of CO2, and their role inglobal warming, have prompted efforts to reduce emissions of CO2 fromburning of fossil fuels. An attractive mitigation option underconsideration in many countries is the injection of CO2 from stationarysources, such as fossil-fueled power plants, into deep, stable geologicformations, where it would be stored and kept out of the atmosphere fortime periods of hundreds to thousands of years or more. Potentialgeologic storage reservoirs include depleted or depleting oil and gasreservoirs, unmineable coal seams, and saline formations. While oil andgas reservoirs may provide some attractive early targets for CO2 storage,estimates for geographic regions worldwide have suggested that onlysaline formations would provide sufficient storage capacity tosubstantially impact atmospheric releases. This paper will focus on CO2storage in saline formations.Injection of CO2 into a saline aquifer willgive rise to immiscible displacement of brine by the advancing CO2. Thelower viscosity of CO2 relative to aqueous fluids provides a potentialfor hydrodynamic instabilities during the displacement process. Attypical subsurface conditions of temperature and pressure, CO2 is lessdense than aqueous fluids and is subject to upward buoyancy force inenvironments where pressures are controlled by an ambient aqueous phase.Thus CO2 would tend to rise towards the top of a permeable formation andaccumulate beneath the caprock. Some CO2 will also dissolve in theaqueous phase, while the CO2-rich phase may dissolve some formationwaters, which would tend to dry out the vicinity of the injection wells.CO2 will make formation waters more acidic, and will induce chemicalrections that may precipitate and dissolve mineral phases (Xu et al.,2004). As a consequence of CO2 injection, significant pressurization offormation fluids would occur over large areas. These pressurizationeffects will change effective stresses, and may cause movement alongfaults with associated seismicity and increases in permeability thatcould lead to leakage from the storage reservoir (Rutqvist and Tsang,2005).
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE. Assistant Secretary for Fossil Energy.Coal
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 919767
- Report Number(s):
- LBNL-59888; R&D Project: G22401; BnR: AA1505000; TRN: US200822%%531
- Resource Relation:
- Conference: Computational Methods in Water Resources (CMWRXVI), Copenhagen, Denmark, 18-22 June 2006
- Country of Publication:
- United States
- Language:
- English
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