The influence of fluorochemical-modified graphene oxide on the gas-wetting alteration of reservoir cores

Abstract Gas condensate reservoir plays an indispensable role in the supply of fossil fuels to alleviate energy shortages. However, liquid condensate near the wellbore can lead to a decrease in gas well deliverability during development. In this work, the strong gas-wetting graphene oxide is prepared by functional modification and characterized by FTIR and XPS. Thermodynamic analysis shows that surface modification can improve the temperature resistance of graphene oxide. To investigate the influence of gas-wetting alteration on the core, the contact angle of the droplets on the core surface is measured and the results exhibit that the contact angles of water and n-hexadecane increase from 23° and 0° to 140° and 132°, respectively. Meanwhile, the surface free energy is sharply reduced from 67.97 mN/m to 1.15 mN/m after treatment. These results are further verified by imbibition. Core flooding illustrates that the required pressure for water and n-hexadecane injection into the core is reduced by 57.06% and 54.08%, respectively, and the permeability of different cores is improved after the gas-wetting alteration. Also, the analyses of the 3D morphology and elements demonstrate that the gas-wetting adsorption layer has been formed on the core surface. These results indicate that the liquid is easier to peel from the core surface to improve the ability of transportation and distribution. Besides, this work also reveals the mechanism of gas-wetting alteration so that it can be better applied to other oil fields and engineering fields.