Water contact angles on quartz surfaces under supercritical CO2 sequestration conditions: Experimental and molecular dynamics simulation studies

Abstract

The ambiguity of contact angle experimental measurements due to surface chemistry changes resulted from sample contamination and/or the degrees of reaction with supercritical CO 2 has resulted great difficulties to precisely understand the wetting behavior of CO 2 under the geological carbon sequestration (GCS) conditions. In this study, water contact angles on quartz surface under GCS conditions were investigated through the combined experimental and molecular dynamics simulation (MDS) methods. The experimental results show that water contact angles increases as ionic strength increases. The effects of pressure and temperature are very weak. The dependence of ionic strength, pressure and temperature is same for monovalent and divalent ions solutions. In the MDS, a hydroxylated quartz surface was used as the base point. A good agreement between the MDS and experimental results were obtained. Using the MDS method, a clean mineral surface with a desired surface chemistry can be constructed, which is difficult in experiments. So by comparing MDS and experimental results, the mechanisms of the reservoir wettability can be better understood. Further investigation can be made on quartz surface with different functional groups to better understand wettability alteration caused by contamination and/or CO 2 reaction.

Influence of CO2‐wettability on CO2 migration and trapping capacity in deep saline aquifers

“…[3][4][5][6][7][8] Among all these types of CO 2 storage sites, deep saline aquifers are considered more suitable, because they have the largest CO 2 storage capacity and the widest geographical spread. 13,27,[29][30][31][32][33][34][35][36][37][38][39] Wettability, as has been previously shown in laboratory experiments (at the mm to cm scale), has a significant effect on residual trapping 15,[40][41][42] and structural trapping. Indeed, water contact angles between 0°(strongly water-wet) and 170°(strongly CO 2 -wet) have been measured, where CO 2 -wettability mainly depends on the surface chemistry, and to a lesser extent on temperature, pressure, and brine composition.…”

“…Indeed, water contact angles between 0°(strongly water-wet) and 170°(strongly CO 2 -wet) have been measured, where CO 2 -wettability mainly depends on the surface chemistry, and to a lesser extent on temperature, pressure, and brine composition. 13,27,[29][30][31][32][33][34][35][36][37][38][39] Wettability, as has been previously shown in laboratory experiments (at the mm to cm scale), has a significant effect on residual trapping 15,[40][41][42] and structural trapping. 12,13 However, despite this laboratory-scale evidence, the effect of wettability on reservoir-scale processes and associated storage capacity and containment security predictions has received little attention 27 and generally, though the wettability is incorporated in the pilot projects modeling via relative permeability curves and multiphase flow, the values are poorly constrained.…”

“…31,32,35,36,53 Thus, to perform hectometer-scale reservoir simulations, an upscaling mechanism is required. 31,32,35,36,53 Thus, to perform hectometer-scale reservoir simulations, an upscaling mechanism is required.…”

“…CO 2 -wettability is an atomistic phenomenon as it is determined by intermolecular forces between CO 2 , brine, and rock. 31,32,35,36,53 Thus, to perform hectometer-scale reservoir simulations, an upscaling mechanism is required. Here, we directly implemented the effect of wettability into the relative permeability and capillary pressure curves.…”

Dependence of quartz wettability on fluid density

“…However, there is a large uncertainty associated with such contact angle data reported in the literature [Mahadevan, 2012;Bikkina, 2012;Iglauer et al, 2014;Palamara et al, 2015], and such experiments are generally expensive and difficult to perform. Theoretical predictions based on molecular dynamics computations are also laden with uncertainty and the difficulty to mimic the solid surface in a representative way [Liu et al, 2010;Iglauer et al, 2012;McCaughan et al, 2013;Javanbakht et al, 2015;Chen et al, 2015]. It is therefore highly desirable to well constrain θ to make reliable reservoir flow predictions and related economic and safety risk assessments.…”