微胶囊缓释破胶剂的室内研制

LABORATORY PREPARATION OF MICROENCAPSULATED SLOW RELEASE GEL BREAKER

采用滚动造粒法在过硫酸铵颗粒外包一层高分子粉体，再采用Ｗｕｒｓｔｅｒ流化床法将颗粒包封，制成了微胶囊缓释破胶剂，在室内实验装置上产率达９０％以上。所得微胶囊破胶剂具有良好的延迟释放、延迟破胶性能。有两个样品７０℃时延迟释放时间分别达４８ｍｉｎ和６５ｍｉｎ，释放５０％的时间分别为２０８ｍｉｎ和３１２ｍｉｎ。在冻胶体系中加入其中一个样品，加量０．１４ｇ／ｌ（以所含过硫酸铵计），在７０℃放置９０ｍｉｎ后冻胶体系粘度损失仅８％。

Ammonium persulfate (APS) particles are rolled with a powdered polymer to obtain a powder coated APS particles and the later are encapsulated by using Wurster fluidized bed process on a laboratory installation through spraying the polymer solution in hot air stream. For two of four laboratory samples of different composition, C and D, the release time in distillation water at 70℃ are 48 and 65 min and the 50% release time-208 and 312 min, respectively. A gelled fracturing fluid with sample D introduced in APS concentration 0.14 g/l losses its 8% initial viscosity after maintaing at 70 ℃ over 90 min. It is suggested that the microencapsulated gel breaker would release APS by a way of water diffusion in and dissolving out through micropassages in capsule walls.