胶囊破胶剂的介质分散分相法制备研究

针对压裂施工过程中破胶过早的问题，以过硫酸铵为芯材，选用适宜的聚合物为囊衣材料，采用分散分相法制备胶囊破胶剂。通过比较，确定了聚乙烯醇（PVA）和乙烯醋酸乙烯共聚物（EVA）为较好的囊衣材料，通过正交实验研究了两种胶囊破胶剂的制备工艺。结果表明：搅拌速率、温度、衣材与囊芯的质量比、衣材溶液和分散剂的质量分数对胶囊破胶剂性能有较大影响。制备PVA胶囊破胶剂的最佳条件为:温度25℃，搅拌速率270r/min，衣材与囊芯的质量比2:8，分散剂用量为1%；制备EVA胶囊破胶剂的最佳条件为:温度25℃，搅拌速率300r/min，衣材溶液和分散剂的用量为5%和2%。

PREPARATION OF ENCAPSULATED BREAKER BY MEDIA DISPERSION AND PHASE SEPARATION

To the problem of gel breaking prematurely in fracturing operations，encapsulated breaker is produced with ammonium persulfate as the core and appropriate polymer materials as the coat by media dispersion and phase separation.Polyvinyl alcohol （PVA） and ethylene vinyl acetate copolymer （EVA） is selected as the coat materials by experimentation and comparing.The preparation technology is studied by orthogonal experiment.The result shows that the performance of encapsulated breaker can be influenced by the stirring rate，temperature，mass ratio of coat and core materials，mass fraction of coat materials in solution and dispersant mass fraction.For the encapsulated breaker with coat materials of PVA，the optimal preparation conditions are the temperature is at 25℃，the stirring rate at 270r/min，the mass ratio of coat and core material at 2∶8，and the dispersing agent mass fraction at 1%.For the encapsulated breaker with coat materials of EVA，the optimal preparation conditions are the temperature is at 25℃，the stirring rate at 300r/min，the mass fraction of coat materials in solution at 5%，and the dispersing agent at 2%.