Preparation of fluorine-containing nano-emulsion and its application in reservoir wetting reversal
A fluorine-containing nanoemulsion(FPA)to change reservoir wettability and prevent reservoir water lock was prepared from methyl methacrylate,butyl acrylate,γ-methylacryloxy propyl trimethoxy silane and perfluoroalkyl ethyl acrylate(PEA),and then characterized by FTIR,SEM,XRD and Malvern laser particle size analyzer.The effect of FPA-3(mass fraction of PEA was 1.5%)emulsion mass fraction on the core wettability was analyzed by surface tension,discharge rate,capillary imbibition and contact angle.The results showed that PEA was successfully introduced into the polymer chain,and the particle size of the emulsion increased with the increase of PEA mass fraction.The emulsion was stratified when PEA mass fraction was greater than 1.5%and FPA-3 emulsion exhibited the best stability.With the increase of FPA-3 emulsion mass fraction,the surface tension and height of capillary imbibition of FPA-3 solution decreased,while the discharge rate and water contact angle increased.When the emulsion mass fraction was both 2.0%,compared with those of PA aqueous solution,the surface tension of FPA-3 aqueous solution decreased by 50.70%from 46.01 mN/m to 22.68 mN/m,the discharge rate increased by 48.16%from 19.89%to 29.47%,and the surface free energy of the core decreased from 73.2 mN/m to 8.7 mN/m.The core changed from hydrophilicity(θ=69.8°)to hydrophobicity(θ=125.1°).The height of the capillary self-imbibition liquid surface of FPA-3 aqueous solution with mass fraction of 2.0%was reduced from 42 mm(water)to 30 mm.
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