Optimization of Main Functional Groups of High Efficiency Hydration Inhibitors in Shale Based on Quantum Mechanical Simulation

The hydration of clay minerals in shale is one of the main causes of borewall instability. Efficient shale hydration inhibitors require strong interactions between the inhibitor and the mineral surface, such as van der Waals forces, static electricity, hydrogen bonds, and even the formation of chemical bonds, which can significantly reduce the crystal layer spacing of clay minerals. The selection of main functional group of inhibitor plays a decisive role in the performance of inhibitor. The density functional theory method based on quantum mechanics can simulate and calculate the interaction between inhibitor and montmorillonite (001) plane, and study its electronic structure and properties at the atomic level. The adsorption of C₂H₅–NH₂, C₂H₅–OH, C₂H₅–OCH₃, C₂H₅–CHO and C₂H₅–COCH₃ on Montmorillonite (001) was calculated by density functional simulation. The adsorption of inhibitor functional groups on montmorillonite (001) layer was studied comprehensively from the aspects of adsorption configuration, adsorption energy, charge population, frontier orbit and differential electron density distribution. According to this study, the primary amine group is suitable as the main functional group of hydration inhibitor. Meanwhile, this paper provides theoretical support for the development of efficient surface hydration inhibitors..