Variation of Contact Angles in Brine/CO₂/Mica System considering Short-Term Geological CO₂ Sequestration Condition

Abstract

Geological CO2 sequestration has been proposed as an effective solution to mitigate excessive human-emitted CO2 in atmosphere. Knowledge of immiscible two-phase flow of CO2-water/brine is necessary to evaluate the efficiency and safety of geological storage sites. Among forces dominating fluid flow, capillary pressure is highly important because of high uncertainty in measurement due to ambiguous wettability behavior of geomaterials. In particular, time-dependent wettability of geomaterials is of interest for predicting short-term performance of the storage site. After injection of CO2 into an aquifer, both the CO2 and water/brine in rocks pores are unsaturated and tend to dissolve into each other. Present study investigates the variation of contact angle on mica sheet using a captive bubble method at a wide range of pressures and salinities under unsaturated condition. Our results showed a general increase of contact angle with time. Comparison of unsaturated contact angle with previous results in the literature showed a wide span of wettability behavior, ranging from receding to advancing contact angle values reported in the literature. The observed decrease in wettability by time due to heterogeneity and pinning effect of triple line can jeopardize the safety of geological carbon sequestration projects in short-term after injection of CO2.

Derivation of a pH Dependent Solid-Liquid Interfacial Tension and Theoretical Interpretation of the Physicochemistry of Dewetting in the CO2-Brine-Silica System

“…The fractional error is calculated as the difference between the value calculated using our model and that calculated using Carre et al, (2003) model. Table 3 shows values of pH and contact angle deduced from pressure versus solubility data based on the work of Jafari et al (2018). As pressure increases at a given temperature and salinity, the concentration of dissolved species of carbon dioxide must also increase and this holds true in Table 3.…”

“…Based on this equation, hydrogen ion concentration at a given pressure and temperature can be calculated. Jafari et al (2018), studied contact angle on mica surface for the system brine-CO 2 -mica and plotted contact angle versus pressure for one mole of sodium chloride solution at 318 K. To validate our model (Eq. (36)) the solubility of carbon dioxide in one molar solution of sodium chloride at 318 K as a function of pressure is necessary.…”

“…(36)) must be seen in the case of contact angle plot versus pressure for a mineral surface. In this regard, Appendix 6 (Jafari & Jung, 2018) shows plots of contact angle versus pressure, with quadratic trends.…”

“…11, No. 2; Appendix 5: Surface charge density versus pH as a function of salinity (Sverjensky, 2005) Appendix: 6: Final contact angle plots versus pressure for mica surface showing parabolic trends (Jafari & Jung, 2018) http://ijc.ccsenet.org Vol. 11, No.…”

Modeling of Contact Angle versus pH and Derivation of Contact Angle versus Pressure in Deep Saline Aquifers under Geological Carbon Storage

“…We chose 3 different concentrations of aqueous sodium chloride solution. They are 1 M, 0 M, 2 M and 4 M. Concentrations of 1 to 4 M can be found in formation brines (Jafari & Jung, 2020 25for pH calculation, the temperature and salinity dependent first ionization constant was calculated using Eq. (12) with the help of Excel.…”