Synthesis and Performance Evaluation of Wetting Regulators in Near-Well Zones

In order to solve the problems of water phase trap failure, working fluid residue, asphaltene colloid deposition, and oil film adhesion in tight sandstone reservoir, a series of new wetting regulators were synthesized by maleic anhydride and fatty alcohol polyoxyethylene ether as raw materials. The surface activity, adsorption performance, viscosity reduction, oil film stripping performance, release phase trapping performance, and reservoir protection performance of the wetting regulator were evaluated. The results showed that the wetting regulator could reduce the interfacial tension of oil and water to 0.11 mN/m–1 and the contact Angle of water droplets from 110.4 to 80.1°. The special symmetric binary structure of the wetting regulator enables it to adjust the oil/hydrophobic rock surface to a weak hydrophilic/oil phobic state through hydrogen bond adsorption between its alcohol hydroxyl group and the crude oil organic matter. The wetting regulator effectively promoted the oil film denudation; the oil phase relative permeability damage rate decreased by 66%, and the liquid phase exclusion rate increased by 51%. The permeability recovery of the reservoir increased by 92%. The wettability of the wettability regulator was enhanced by introducing a special twin structure, which has a strong application prospect in improving water phase capture damage and oil film stripping.