Understanding Wettability of SiO2-Brine-CO2 System Using Modified DLVO Theory and its Applications in Carbon Geo-Sequestration Processes

Abstract

The reduction of Carbon footprints without hindering the evolution of the fossil fuel industry is the subject of prominent attention and research these days. In multi-phase rock-fluid systems, the wettability characteristics play a substantial role in determining the trustworthiness of underground reservoir formations for holding CO2 in situ for Carbon Geo-sequestration applications. Despite several struggles over the modern years in recognizing the aspects such as the information on the wettability of systems comprising CO2 under supercritical conditions and the zeta potential over the brine- CO2 film interfaces, inferring the wettability of the complete arrangement are crucial uncertainties and voids in our existing knowledge. Again, one needs to deal with the concepts of wettability and capillary pressures to understand the suitability of a formation for carbon sequestration. This study focuses on the sequestration of carbon in deep saline brine reservoirs. Under the intense pressure and temperature situations in these formations, CO2 can exist in a supercritical state and thus have a liquid-like density, enabling efficient utilization of the pore spaces in those formations. In this research, a mathematical model based on the modified DLVO (Derjaguin, Landau, Verwey, and Overbeek) theory is designed to provide a better insight into the wettability of supercritical CO2 systems by utilizing fundamental principles to evaluate contact angles. The base model has been modified in the course of the study to accommodate for the properties of supercritical CO2. This model can also take up the experimental contact angle measurements as an input to anticipate values of critical properties that are presently unfamiliar, as they are challenging to analyze, such as the zeta potential on brine- CO2 interfaces. This model could also predict the suitability of geological reservoirs for carbon sequestration by evaluating the wettability under known conditions.

Correlation between Contact Angle and Water Film Energetics in Carbon Dioxide–Water–Clay Mineral Interfacial Systems: A Molecular Dynamics Study

“…According to the free energy variation determined for a representative CO 2 molecule permeating the water film, the amount of work needed for this molecule to approach the surface increases with increasing negative layer charge. On the basis of these findings, we proposed a novel approach to complement direct contact angle calculations by means of computing the permeation free energy. This method offers a promising approach to investigating the wetting phenomena even on rough surfaces or complex systems, − in which the interfacial profile may not be easily converted to the macroscopic contact angle. Furthermore, the present analysis of the structure and dynamics of the adsorbed water provides us with new insights into the change in the film energetics from an atomic-scale viewpoint, which cannot be gained using the widely used thermodynamic model, namely, the Frumkin–Derjaguin equation. − ,, Therefore, our approach demonstrated in this study would be a valuable framework aimed at enhancing the comprehension of the variation of the water contact angle on hydrophilic mineral surfaces. …”

“…Furthermore, the present analysis of the structure and dynamics of the adsorbed water provides us with new insights into the change in the film energetics from an atomic-scale viewpoint, which cannot be gained using the widely used thermodynamic model, namely, the Frumkin–Derjaguin equation. − ,, Therefore, our approach demonstrated in this study would be a valuable framework aimed at enhancing the comprehension of the variation of the water contact angle on hydrophilic mineral surfaces.…”

“…Frumkin−Derjaguin equation. [11][12][13][14][15][16][17][18]21,22 Therefore, our approach demonstrated in this study would be a valuable framework aimed at enhancing the comprehension of the variation of the water contact angle on hydrophilic mineral surfaces. The present findings have implications for future studies on the mechanism of the wettability changes, which are of great significance in CGS and utilization because it directly affects the injectivity, storage potential, and seal integrity of CO 2 .…”

“…Disjoining pressure is commonly modeled using Derjaguin–Landau–Verwey–Overbeek (DLVO) interactions , such as van der Waals or electro-double-layer forces and non-DLVO interactions such as hydration or structural forces. ,,,, As the DLVO terms are well established, and the physicochemical meanings of the parameters are clear, this model has been widely used to estimate contact angle changes and identify the key factors influencing wettability alteration, particularly in enhanced oil recovery ,,, and CGS. , The non-DLVO terms used in previous studies are, however, not clearly interpretable and have been formulated using a monotonic repulsive force ,,, or fitting curves based on atomic force microscopy (AFM) data . However, the potential energy estimated from the AFM force curves does not account for the interactions of CO 2 , water, and minerals but rather reflects the interactions of the cantilever, water, and minerals.…”