Experimental study of density-driven convection effects on CO2 dissolution rate in formation water for geological storage

Convective carbon dioxide dissolution in a closed porous medium at low pressure

“…Here we show that the pressure drop in the gas can limit CO 2 dissolution long before saturation of the brine becomes a limiting factor. These negative feedbacks in closed systems are common in experiments on CO 2 dissolution (Farajzadeh et al 2009;Moghaddam et al 2012;Mojtaba et al 2014;Shi et al 2017) and in some natural CO 2 reservoirs that serve as analogs for geological CO 2 storage (Akhbari & Hesse 2017). Engineered geological storage sites are typically selected such that CO 2 is supercritical to maximise the storage capacity (Orr 2009).…”

Experimental study of gravitational mixing of supercritical CO2

“…For example, experiments have 83 measured CO 2 mass transfer to water at 25 °C and 1 -5 MPa (Farajzadeh et al, 2009), to water-84 saturated porous media at 25 °C and 2 -6 MPa (Moghaddam et al, 2012), and to water and 85 brine (up to 20 % salinity) saturated porous media at 38 °C and 3.45 MPa (Mojtaba et al, 2014; 86 Moghaddam et al, 2015). Although these experiments are informative to the general behavior of 87 3D density driven mixing, these CO 2 -water experiments were not conducted at relevant reservoir 88 conditions so the CO 2 phase (gas and liquid vs. supercritical), fluid densities, viscosities and the 89 solubility of CO 2 in water are not analogous.…”

Experimental study of CO 2 convective dissolution: The effect of color indicators

“…This latter apparatus is made of two transparent glass or Plexiglas plates (typically a few tens of cm wide) separated by a narrow gap, generally less than 2 mm. CO 2 under subcritical (Okhotsimskii and Hozawa, 1998;Arendt et al, 2004;Song et al, 2005;Pruess, 2010, 2011;Kilpatrick et al, 2011;Wylock et al, 2011Wylock et al, , 2013Wylock et al, , 2014Faisal et al, 2013;Mojtaba et al, 2014;Thomas et al, 2014;Outeda et al, 2014;Kirk et al, 2014) or supercritical (Khosrokhavar et al, 2014) conditions is brought in contact with aqueous solutions, reactive or not, in the quasi two-dimensional space between the glass plates, in order to study the characteristics of the buoyancy-driven instability setting up in the aqueous solution upon CO 2 dissolution. Similar convective dissolution in partially miscible systems have been well characterized experimentally in other two-layer systems (Budroni et al, 2014).…”

“…In some cases however, the presence of acidic dissolved CO 2 is detected with a color indicator sensitive to pH changes which allows to visualize the pattern with a simple camera thanks to a change in color of the fingers Pruess, 2010, 2011;Outeda et al, 2014;Kilpatrick et al, 2011;Faisal et al, 2013;Kirk et al, 2014;Mojtaba et al, 2014). There are some underlying hypotheses in the use of such color indicators for visualization purposes: the pattern revealed by the indicator is supposed to be exactly the same as the convective pattern developing upon CO 2 dissolution and the effect of indicators on the dynamics is assumed to be negligible.…”