Abstract
Asphaltene precipitation remains a major challenge in heavy crude oil production and processing due to its adverse effects on flow assurance and operational efficiency.In this study, quaternary ammonium salt-based deep eutectic solvents (DESs) were investigated as inhibitors for asphaltene precipitation in heavy crude oil from the Karazhanbas oil field.Four DES formulations were synthesized using choline chloride and betaine as hydrogen bond acceptors combined with ethylene glycol, urea, lactic acid, and propylene glycol as hydrogen bond donors.The synthesized DESs were characterized using fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to evaluate their structural features, intermolecular interactions, and thermal stability.Results confirmed successful DES formation through strong hydrogen-bonding interactions.Thermal analysis showed that choline chloride:ethylene glycol and betaine:lactic acid exhibited superior thermal stability.The inhibition performance was evaluated using UV-vis spectroscopy and dynamic light scattering (DLS).UV-vis results showed that choline chloride:urea exhibited the strongest intermolecular interactions.DLS analysis revealed significant reduction in asphaltene aggregate size from 9-11 nm in the inhibitor-free system to 0.7-3.0nm after DES treatment.Among the investigated systems, choline chloride:urea and choline chloride:ethylene glycol demonstrated the highest inhibition efficiency.These findings demonstrate that DESs, particularly choline chloride-based systems, are promising and environmentally friendly alternatives for effective asphaltene stabilization in heavy crude oil systems.