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Refractive‐Light‐Transmission Technique Applied to Density‐Driven Convective Mixing in Porous Media With Implications for Geological CO 2 Storage
Author(s) -
Rasmusson M.,
Fagerlund F.,
Rasmusson K.,
Tsang Y.,
Niemi A.
Publication year - 2017
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2017wr020730
Subject(s) - convection , porous medium , convective mixing , scaling , mixing (physics) , mechanics , solubility , materials science , aquifer , flow (mathematics) , thermodynamics , porosity , mineralogy , geology , chemistry , physics , geotechnical engineering , groundwater , geometry , mathematics , organic chemistry , quantum mechanics , composite material
Density‐driven convection has been identified to accelerate the rate of CO 2 solubility trapping during geological CO 2 storage in deep saline aquifers. In this paper, we present an experimental method using the refractive properties of fluids (their impact on light transmission), and an analogous system design, which enables the study of transport mechanisms in saturated porous media. The method is used to investigate solutally induced density‐driven convective mixing under conditions relevant to geological CO 2 storage. The analogous system design allows us by choice of initial solute concentration and bead size to duplicate a wide range of conditions ( R a ‐values), making it possible to study the convective process in general, and as a laboratory analogue for systems found in the field. We show that the method accurately determines the solute concentration in the system with high spatial and temporal resolution. The onset time of convection ( t c ), mass flux ( F ), and flow dynamics are quantified and compared with experimental and numerical findings in the literature. Our data yield a scaling law fort cwhich gives new insight into its dependence on R a , indicatingt cto be more sensitive to large R a than previously thought. Furthermore, our data show and explain why F is described equally well by a R a ‐dependent or a R a ‐independent scaling law. These findings improve the understanding of the physical process of convective mixing in saturated porous media in general and help to assess the CO 2 solubility trapping rate under certain field conditions.