Water Resources Research

Effect of permeability anisotropy on buoyancy-driven flow for CO2 sequestration in saline aquifers

Authors

  • Philip Cheng,

    1. Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, USA
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  • Michael Bestehorn,

    1. Lehrstuhl für Theoretische Physik II, Brandenburgische Technische Universität Cottbus, Cottbus, Germany
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  • Abbas Firoozabadi

    Corresponding author
    1. Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, USA
    2. Reservoir Engineering Research Institute, Palo Alto, California, USA
      Corresponding author: A. Firoozabadi, Department of Chemical and Environmental Engineering, Yale University, 9 Hillhouse Ave., New Haven, CT 06511, USA. (abbas.firoozabadi@yale.edu)
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Corresponding author: A. Firoozabadi, Department of Chemical and Environmental Engineering, Yale University, 9 Hillhouse Ave., New Haven, CT 06511, USA. (abbas.firoozabadi@yale.edu)

Abstract

[1] Solubility trapping of carbon dioxide (CO2) in deep saline aquifers is considered one of the most effective methods for carbon sequestration. Dissolution of CO2 into the brine may create gravitational instabilities that lead to the onset of convection, which greatly enhances the storage efficiency and reduces the possibilities of leakage. Convection appears in the form of downward traveling fingers of relatively dense, CO2-dissolved fluid. Many natural aquifer formations display considerable permeability anisotropy, where the horizontal permeability kh may be several times greater than the vertical permeability kz. It has been previously found that increasing kh for a fixed kz reduces the critical time tc at which onset occurs and the critical wavelength λc with which the fingers initially form. We extend earlier work by showing how and why this occurs. Our results reveal new insights about λc. We have studied the behavior for times greater than tc using high-resolution numerical simulations. We show that the enhanced dissolution from convection can become significant much earlier in anisotropic media. Furthermore, the effects of anisotropy may be sustained for a long period of time. Our results suggest that permeability anisotropy can allow a wider range of aquifer formations to be considered for effective sequestration.

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