Experimental determination of CO2 diffusion coefficient in aqueous solutions under pressure at room temperature via Raman spectroscopy: impact of salinity (NaCl). (25th June 2015)

• Record Type: Journal Article
• Authors: Belgodere, Clément; Dubessy, Jean; Vautrin, Denis; Caumon, Marie‐Camille; Sterpenich, Jérôme; Pironon, Jacques; Robert, Pascal; Randi, Aurélien; Birat, Jean‐Pierre; Marshall, Craig P.
• Is Part Of: Journal of Raman spectroscopy. Volume 46:Number 10(2015:Oct.)
• Page Start: 1025
• Page End: 1032
• Publication Date: 2015-06-25
• Subjects: Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.4742
• Languages: English
• ISSNs: 0377-0486

Abstract

<abstract abstract-type="main" id="jrs4742-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="jrs4742-para-0001">The accurate determination of the diffusion coefficient of dissolved CO<sub>2</sub> in aqueous solutions is a key parameter to predict the transport of the dissolved gas in the aqueous solution of porous aquifers and caprocks in the context of the mitigation of greenhouse gases emissions. A better understanding of the diffusion kinetics of dissolved CO<sub>2</sub> as a function of subsurface conditions is essential to ensure the integrity of CO<sub>2</sub> storage in saline aquifers. Experimental data are available to predict the CO<sub>2</sub> diffusion kinetics as a function of temperature and pressure. However, the impact of salinity on CO<sub>2</sub> diffusivity is still poorly documented. In this work, the diffusion coefficients of dissolved CO<sub>2</sub> were determined using <italic>in situ</italic> Raman microspectrometry in Fused Silica Capillaries in a range of salinity from 0.0 to 6.0 mol<sub>NaCl</sub> kg<sup>−1</sup><sub>H2O</sub>. The diffusion coefficient of CO<sub>2</sub> dissolved in pure water at 21 ± 1 °C and 40 bar is 1.71 × 10<sup>−9</sup> ± 0.06 m<sup>2</sup> s<sup>−1</sup>. In the same conditions of pressure and temperature, the diffusion coefficient of dissolved CO<sub>2</sub> decreases with salinity increase: from 0.0 to 6.0 mol<sub>NaCl</sub> kg<sup>−1</sup><sub>H2O</sub> (the diffusion kinetics of dissolved CO<sub>2</sub> is divided by two). Consequently, the impact of salinity on the diffusion coefficient of dissolved CO<sub>2</sub> must be taken into account to evaluate the transport of dissolved gases in the brine of the reservoir and caprock. Copyright © 2015 John Wiley & Sons, Ltd.</p> </abstract>