Preparation and application of a fluoropolymer emulsion as novel wettability reversal agent

A polymer emulsion with multi-fluoromethyl structure was synthesized by emulsion polymerization and its structure and properties were characterized. As a wettability reversal agent, the polymer emulsion has strong dispersibility and adsorption. The particle size of polymer particles in polymer emulsion is at micron level, in which the larger particle sizes are less than 2μm. After the treatment of 2.0 wt.% product, the core surface contact angles with water and n-hexadecane changed from 27.8° to 130.1° and from 0° to 66.8°, for which the core surface changed from amphiphilicity to hydrophobicity and to poor lipophilicity. It can also significantly reduce the surface energy of the core surface. When the concentration was at 2.0 wt.%, the surface free energy changed from 65.68 mN/m to 3.90 mN/m. The product can maintain good performance after long term storage. After 60 days storage, the contact angle of core (treated with 2.0 wt.% product) with water and n-hexadecane can still keep at 128.4° and 65.3°. After injection of the polymer emulsion, the permeability of cores with different permeability has been improved to varying degrees, for which the higher the water permeability is, the more the core permeability improves. Finally, the polymer emulsion used as wetting reversal agent tested through visual displacement experiments. The results show that the displacement efficiency can be effectively improved, and the oil recovery efficiency is increased more than 13 % on the basic polymer displacement.