CO₂-H₂O mixtures in the geologic sequestration of CO₂. I. Assessment and calculation of mutual solubilities from 12 to 100 degrees C and up to 600 bar
Evaluating the feasibility of CO₂ geologic sequestration requires the use of pressure-temperature-composition (P-T-X) data for mixtures of CO₂ and H₂O at moderate pressures and temperatures (typically below 500 bar and below 100°C). For this purpose, published experimental P-T-X data in this temperature and pressure range are reviewed. These data cover the two-phase region where a CO₂-rich phase (generally gas) and an H₂O-rich liquid coexist and are reported as the mutual solubilities of H₂O and CO₂ in the two coexisting phases. For the most part, mutual solubilities reported from various sources are in good agreement. The mixing behavior of H₂O in the compressed gas phase is highly nonideal. A noniterative procedure is presented to calculate the composition of the compressed CO₂ and liquid H₂O phases at equilibrium, based on equating chemical potentials and using the Redlich-Kwong equation of state to express departure from ideal behavior. The procedure is an extension of that used by King et al. (1992), covering a broader range of temperatures and experimental data than those authors, and is readily expandable to a nonideal liquid phase. The calculation method and formulation are kept as simple as possible to avoid degrading the performance of numerical models of water-CO₂ flows for which they are intended. The method is implemented in a computer routine, and inverse modeling is used to determine, simultaneously, new Redlich-Kwong parameters for the H₂O-CO₂ mixture, as well as aqueous solubility constants for gaseous and liquid CO₂ as a function of temperature. In doing so, mutual solubilities of H₂O from 12 to 100°C and CO₂ from 15 to 110°C and up to 600 bar are generally reproduced within a few percent of experimental values. Fugacity coefficients of pure CO₂ are reproduced mostly within one percent of published reference data.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Science. Office of Basic Energy Sciences (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 821638
- Report Number(s):
- LBNL-50991; GCACAK; R&D Project: G30302; TRN: US200411%%321
- Journal Information:
- Geochimica et Cosmochimica Acta, Vol. 67, Issue 16; Other Information: Journal Publication Date: 08/2003; PBD: 29 Jul 2002; ISSN 0016-7037
- Publisher:
- The Geochemical Society; The Meteoritical Society
- Country of Publication:
- United States
- Language:
- English
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