Wettability alteration of oil-wet carbonate rocks by chitosan derivatives for application in enhanced oil recovery

The increasing demand for oil and the fast decline of crude oil production from mature fields encourages the development of new enhanced oil recovery (EOR) technologies. In this work, trimethyl chitosan (TMC) and trimethyl chitosan hydrophobized with myristoyl chloride (TMC-C14) are synthesized, and their wettability modification capacity of oil-wet carbonate rocks is evaluated through contact angle measurements, atomic force microscopy, and Raman spectroscopy. Their interaction with asphaltene molecules was evaluated through UV-Vis spectroscopy. Transport behavior and oil displacement capacity were investigated in an unconsolidated porous medium. Results show that they can modify the wettability of oil-wet carbonate rocks, turning them water-wet, promoting oil displacement increases by 25% for TMC, and 16% for TMC-C14.TMC shows a better performance for wettability alteration than TMC-C14, confirming the hypothesis that the higher the positive charge density on the polymeric surfactant structure, the more efficient will be the system as a wettability modifier and as an EOR agent.