摘要
采用硫酸铵盐水溶液中分散聚合法制备了粒径为1~3 μm的交联聚合物微球，确定了最佳合成条件。在60℃下，以丙烯酰胺（AM）、2-丙烯酰胺基-2-甲基丙磺酸（AMPS）、丙烯酸钠（SAA）为主要单体，分散稳定剂选择相对分子质量为35万的聚乙烯吡咯烷酮PVP K60，交联剂与总单体摩尔比0.5%~0.75%，AM、SAA、AMPS单体摩尔比15:2:3，硫酸铵质量分数14.5%。实验结果表明，所制备的微米颗粒为球形，形貌规则，粒径分布均匀，干粉粒径为1~3 μm，熟化后体系中微球粒径达8~10 μm。微球分散体系抗剪切、耐温抗盐。30℃下，随剪切速率的增大，交联聚合物微球分散体系（400 mg/kg）的黏度逐渐降低，100 r/min下的黏度仍高达9.3 Pa·s。当温度由30℃增至90℃时，交联聚合物微球分散体系的黏度保留率由100%降至53.58%；当矿化度由0增至10 g/L，黏度保留率由98.13%降至53.74%。室内封堵实验结果表明，交联聚合物微球在中高温条件下具有一定的封堵性、良好的变形性和逐级深部调剖效果。交联聚合物微球在25℃保温溶胀时，对微孔滤膜的封堵时间随天数的增加而延长，溶胀4 d后的封堵时间可达8.2 h；75℃保温溶胀时，封堵时间随天数的增加呈降低趋势，溶胀3 d后的封堵时间为3 h。随聚合物微球浓度的增大，岩心初始注入压力降低，在渗透率为0.5 μm2的人造岩心中的最佳注入量为400 mg/L。
Abstract
Water-soluble crosslinked polymer microspheres were prepared by dispersion polymerization in ammonium sulfate solution (AS), polymerized by acrylamide (AM), 2-acrylamide-2-methyl propane sulfonic acid (AMPS) and sodium acrylate (SAA). The optimum synthesis condition was obtained as follows: dispersion stabilizer of polyvinylpyrrolidone K60 with 350000 molecular weight, 0.5%~0.75% mole ratio of crosslinking agent to main monomers, 15:2:3 monomer mole ratio of AM/SAA/AMPS, and 14.5% AS. The results showed that the crosslinked polymer microsphere had a morphology of regular and homogeneous spheric and particle size of 1—3 μm in powder but 8—10 μm in slaking dispersed system. The crosslinked polymer microsphere dispersed system had the characteristics of shear resistance, heat resistance and salt tolerance. At 30℃, with increasing shear rate, the viscosity of crosslinked polymer microsphere dispersed system (400 mg/kg) decreased, which was 9.3 Pa·s at 100 r/min. The viscosity retention rate of dispersed system decreased from 100% to 53.58% when temperature increased from 30℃ to 90℃. And that decreased from 98.13% to 53.74% when the salinity increased from 0 to 10 g/L. Plugging experiment results indicated that the crosslinked polymer microspheres had a favorable property of plugging, deformability and effect of deep profile control step by step. At 25℃, the plugging time of microporous membrane increased with the growth of swelling number of days which was 8.2 h after 4 days. At 75℃, the blocking time of microporous membrane reduced with the growth of swelling number of days which was 3 h after 3 days. With increasing concentration of polymer microspheres, the initial injection pressure of core reduced. The optimum injection concentration was 400 mg/L in artificial core with permeability of 0.5 μm2.
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