Upscaling studies of diffusion induced convection in homogeneous and heterogeneous aquifers

Lindeberg, Erik; Wessel-Berg, Dag

doi:10.1016/j.egypro.2011.02.331

Cited by 29 publications

(19 citation statements)

References 1 publication

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“…However, natural geological formations typically involve different degrees of heterogeneity in material permeability, and such variations can considerably influence density-driven natural convection (Royer and Flores 1994;Flett et al 2007;Lindeberg and Wessel-Berg 2011). Natural convection influenced by permeability variations has attracted considerable attention (e.g., Riaz et al 2006;Green et al 2009;Farajzadeh et al 2011;Ranganathan et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Effects of Permeability Variations on CO2 Convection in Anisotropic and Heterogeneous Saline Formations

Lin¹,

Lee³

et al. 2016

Terr. Atmos. Ocean. Sci.

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This study simulated the natural convection of dissolved carbon dioxide (CO 2 ) in a small-scale heterogeneous saline formation using the state module ECO2N equation in the TOUGHREACT model. A one-way downscaling approach that involves using a series of sub-models in simulation procedures was proposed to efficiently simulate problems with high-scale discrepancies. This study evaluated the effects of different degrees of small-scale permeability variations on the vertical migration of dissolved CO 2 . The sequential Gaussian simulation model was used to generate unconditional random permeability fields for different natural logarithm of permeability (lnk) variations (i.e., lnk variances and correlations in x and z directions). The results showed an identical transition zone of dissolved CO 2 near the top boundary, where a constant CO 2 gas saturation was specified. The local permeability variations can trigger fingerings and enhance the vertical convection of the dissolved CO 2 . The number of fingerings depends on the variations in permeability near the front interface of the dissolved CO 2 (i.e., the bottom edge of the transition zone for the dissolved CO 2 ). However, the fingering patterns and developments are constrained by the permeability variations along the fingering paths. At the same mean lnk permeability the convection fluxes increase with an increase in lnk variances. However, an increase in lateral correlations (i.e., increase in the correlation lengths in the x direction) can slightly reduce the convection fluxes at the same lnk variance. The highly variable flux rates of the dissolved CO 2 occur early and the variations in the flux rate decrease with time.

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Section: Introductionmentioning

confidence: 99%

Effects of Permeability Variations on CO2 Convection in Anisotropic and Heterogeneous Saline Formations

Lin¹,

Lee³

et al. 2016

Terr. Atmos. Ocean. Sci.

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“…Previous work on simulation of convection mixing phenomena in CO 2 injection into the brine reveals that onset time for convection mixing is higher in numerical simulations comparing to what is predicted by stability analysis (Lindeberg and Wessel-Berg, 2011 process severa at plates separ nts it to leak. Previous work on simulation of convection mixing phenomena in CO 2 injection into the brine reveals that onset time for convection mixing is higher in numerical simulations comparing to what is predicted by stability analysis (Lindeberg and Wessel-Berg, 2011 process severa at plates separ nts it to leak.…”

Section: Pe 15490mentioning

confidence: 77%

Affecting Parameters in Density Driven Convection Mixing in CO2 Storage in Brine

Soroush¹,

Wessel-Berg

Torsæter³

et al. 2012

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After injecting CO2 into subsurface brine for storage, it will be trapped in the reservoir through various mechanisms. In the beginning, the geological trapping mechanism dominates and the CO2 plume is moving upward below a cap rock. Then brine will imbibe the formation and some parts of the CO2 will be trapped in the pore paces. Later on injected CO2 will dissolve in the brine and increases its density. As a result, the heavier brine will move into deeper parts of the reservoir and density driven convection mixing will occur. This is known as the solubility trapping mechanism. Here in this study, density driven phenomena in CO2 storage in brine and the influencing parameters are the prime targets. We find particularly interesting results for this through Hele-Shaw cell experiments and numerical simulations. Hele-Shaw flow is defined to occur between two parallel flat plates separated by a small gap. In each experiment the cell is filled with fresh water and a shim prevents it to leak. Then liquid with higher density is placed on top. Several tests including water of varying salinity at the top of the cell have been conducted, and the results are interpreted separately and compared with the base experiment. More extensive studies and sensitivity analysis is done based on a simulation model constructed on the reservoir properties of a brine formation, with wide range of affecting parameters, including density differences, permeability variations and the effect of diffusion coefficients. It has been also attempted to investigate the effect of anisotropy and heterogeneity on the CO2 state after injection.

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“…The accurate modeling of convection fingers requires very fine grid block sizes. The horizontal grid block size with 1/20 of critical wavelength obtained from linear stability analysis can be a suitable size for simulation of this behaviour (Lindeberg and Wessel-Berg, 2011, Taheri et al, 2012and 2013. Taheri et al (2012 and2013) considered ⌬x ϭ ⌬z in the simulation models, but in this study sensitivity analyses on vertical grid block resolution are performed for selecting the optimum values of vertical grid block sizes.…”

Section: Simulation Modelsmentioning

confidence: 99%

Prediction of the Minimum Onset Time for Convection in a Gravitationally Unstable Diffusive Boundary Layer Using a Finite Difference Pressure Solver

Taheri¹,

Wessel-Berg

Torsæter³

2015

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CO 2 dissolution as one of the most promising mechanisms for trapping of CO 2 free phase into brine causes increased density of the brine and initiation of gravitational instability that eventually leads to densitydriven natural convection in brine aquifers. The gravitational instability of a diffusive boundary layer in porous media has been studied in several papers in recent years and there are several methods in the literature for prediction of the onset time for convection and the related unstable wavelength.In this study we present a numerical solution for prediction of the critical time for the onset of convection and the critical unstable wavelength in semi-infinite anisotropic homogeneous brine aquifer models. A finite difference pressure solver is used for solving this numerical problem. The numerical model is initialized by the recent developed approach and the gravitational instability is triggered by a weak wavy perturbation with dimensionless wavenumber of K. The minimum of the calculated time for onset of instability as a function of wavenumber is called the critical time and the associated wavenumber to this critical time is the critical unstable wavenumber. The results of this analysis shows acceptable agreement with previously published ones derived from other methods. By applying this prediction approach in more complex numerical models, their related critical time for the onset of convection and the critical unstable wavelength can be calculated.

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Upscaling studies of diffusion induced convection in homogeneous and heterogeneous aquifers

Cited by 29 publications

References 1 publication

Effects of Permeability Variations on CO2 Convection in Anisotropic and Heterogeneous Saline Formations

Effects of Permeability Variations on CO2 Convection in Anisotropic and Heterogeneous Saline Formations

Affecting Parameters in Density Driven Convection Mixing in CO2 Storage in Brine

Prediction of the Minimum Onset Time for Convection in a Gravitationally Unstable Diffusive Boundary Layer Using a Finite Difference Pressure Solver

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