含氟纳米乳液的制备及在储层润湿逆转中的应用

Preparation of fluorine-containing nano-emulsion and its application in reservoir wetting reversal

摘要:

以甲基丙烯酸甲酯、丙烯酸丁酯、γ－甲基丙烯酰氧基丙基三甲氧基硅烷、全氟烷基乙基丙烯酸酯(PEA)为原料，制备了一种可改变储层润湿性、防止储层水锁的含氟纳米乳液（FPA）。采用FT-IR、SEM、XRD、粒径对FPA乳液的结构及稳定性进行了表征，结果表明，PEA成功引入到聚合物链上，随着PEA质量分数增加，乳液粒径增大，当PEA质量分数大于1.5 %时，乳液出现分层， PEA质量分数为1.5 %时（FPA-3），乳液稳定性最好。采用表面张力、排出率、毛细管自吸、接触角等测试方法，考察了FPA-3溶液质量分数对改变岩心润湿性的影响，结果表明，随着FPA-3溶液质量分数增大，FPA-3水溶液表面张力减小，排出率增大，毛细管自吸高度减小， 与水的接触角增大。当FPA-3乳液质量分数为2.0 %时，其表面张力由46.01 mN/m减小至22.68 mN/m，表面张力减少了50.7 %；排出率由19.89 %提高至29.47 %，排出率提高了48.16 %；毛细管自吸高度由42 mm减小至30 mm，毛细管自吸高度减少了28.6 %；岩心的表面自由能由73.2 mN/m减小至8.7 mN/m，岩心的表面自由能减少了88.11 %；使岩心由亲水性（θ=69.8 °）转变为疏水性（θ=125.1 °）。因此，含氟纳米乳液可作为润湿反转剂改变储层润湿性，提高气井采收率。

Abstract:

A fluorine-containing nanoemulsion (FPA) was prepared with methyl methacrylate, butyl acrylate, γ-methylacryloxy propyl trimethoxy silane and perfluoroalkyl ethyl acrylate (PEA) as raw materials, which can change reservoir wettability and prevent reservoir water lock. The structure and stability of FPA emulsion were characterized by FT-IR, SEM, XRD and particle size. 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. When PEA mass fraction was greater than 1.5 %, the emulsion was stratified. When the mass fraction of PEA was 1.5 % (FPA-3), the emulsion stability was the best. The influence of FPA-3 solution mass fraction on core wettability was investigated by surface tension, discharge rate, capillary imbibition and contact Angle. The results show that with the increase of FPA-3 solution mass fraction, the surface tension of FPA-3 solution decreases, the discharge rate increases, the capillary imbibition height decreases, and the contact Angle with water increases. When the mass fraction of FPA-3 emulsion is 2.0 %, the surface tension decreases from 46.01 mN/m to 22.68 mN/m, and the surface tension decreases by 50.7 %. The discharge rate increased from 19.89 % to 29.47 %, and the discharge rate increased by 48.16 %; The capillary imbibition height decreased from 42 mm to 30 mm, and the capillary imbibition height decreased by 28.6 %. The surface free energy of core decreases from 73.2 mN/m to 8.7 mN/m, and the surface free energy of core decreases by 88.11 %. Change the core from hydrophilic (θ=69.8 °) to hydrophobic (θ=125.1 °). Therefore, nano-emulsion containing fluorine can be used as wetting inversion agent to change reservoir wettability and improve gas well recovery.