Jiafang Xu , Lingfeng Kong , Jie Chen , Justine Kiiza , Shi Yuan
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引用次数: 0
Abstract
The hydration swelling of clay minerals during oil and gas production can severely compromise wellbore stability, particularly under deep, high-temperature, and high-pressure conditions, where the thermal limitations of drilling fluids exacerbate downhole accidents. This study employs molecular dynamics (MD) simulations to investigate the interactions between water molecules, clay, and polyethyleneimine (PEI) under high-temperature and high-pressure conditions. Key parameters, including dynamic parameters, hydration characteristics, adsorption conformations of water, Na+, and PEI, and intermolecular interaction energies, were analyzed to elucidate how PEI molecules inhibit montmorillonite surface hydration. The results reveal that PEI primarily hinders hydration through Coulombic interactions and hydrogen bonding with the Na-montmorillonite surface, with inhibition significantly declining above 473 K. Functional groups like -NH2 and -OH enhance PEI adsorption at high-temperature, while -SO3− and -COO− groups improve both the hydration resistance of PEI and its disruption of the montmorillonite hydration layer at high-temperature. These findings provide a theoretical basis for the design of shale inhibitors in high-temperature drilling fluids and offer insights into the underlying mechanisms. The research has significant implications for developing drilling fluids capable of maintaining stability under high-temperature conditions.
期刊介绍:
Chemical Physics publishes experimental and theoretical papers on all aspects of chemical physics. In this journal, experiments are related to theory, and in turn theoretical papers are related to present or future experiments. Subjects covered include: spectroscopy and molecular structure, interacting systems, relaxation phenomena, biological systems, materials, fundamental problems in molecular reactivity, molecular quantum theory and statistical mechanics. Computational chemistry studies of routine character are not appropriate for this journal.