Stability of a fluid in a horizontal saturated porous layer: effect of non-linear concentration profile, initial, and boundary conditions |
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Authors: | H Hassanzadeh M Pooladi-Darvish D W Keith |
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Institution: | (1) Department of Chemical and Petroleum Engineering, University of Calgary, 2500, University Drive, NW, Calgary, AB, Canada, T2N 1N4 |
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Abstract: | Carbon dioxide injected into saline aquifers dissolves in the resident brines increasing their density, which might lead to
convective mixing. Understanding the factors that drive convection in aquifers is important for assessing geological CO2 storage sites. A hydrodynamic stability analysis is performed for non-linear, transient concentration fields in a saturated,
homogenous, porous medium under various boundary conditions. The onset of convection is predicted using linear stability analysis
based on the amplification of the initial perturbations. The difficulty with such stability analysis is the choice of the
initial conditions used to define the imposed perturbations. We use different noises to find the fastest growing noise as
initial conditions for the stability analysis. The stability equations are solved using a Galerkin technique. The resulting
coupled ordinary differential equations are integrated numerically using a fourth-order Runge–Kutta method. The upper and
lower bounds of convection instabilities are obtained. We find that at high Rayleigh numbers, based on the fastest growing
noise for all boundary conditions, both the instability time and the initial wavelength of the convective instabilities are
independent of the porous layer thickness. The current analysis provides approximations that help in screening suitable candidates
for homogenous geological CO2 sequestration sites. |
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Keywords: | Stability analysis Convection Geological CO2 storage Saline aquifers Geological sequestration |
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