Encapsulation of potassium persulfate with ABS via coacervation for delaying the viscosity loss of fracturing fluid

ABSTRACT Encapsulation of persulfates is an important and effective method for sustained release to delay the gel breaking of a fracturing fluid in a high‐temperature reservoir. For a gel breaker with sustained release performance, the coacervation of Acrylonitrile‐Butadiene‐Styrene (ABS) induced by polydimethylsiloxane (PDMS) was conducted to encapsulate potassium persulfate (KPS). Moreover, the composition, KPS loading, morphology, structure, release property, and gel‐breaking performance of the obtained microcapsules were investigated thoroughly. The results show that KPS was successfully encapsulated by the ABS, and the KPS/ABS microcapsules consisted of micron‐sized particles with a porous surface, core/shell structure, and significant sustained release property that were affected by the core/shell mass ratio during the preparation. Moreover, the apparent viscosity of gel fracturing fluid at 70 °C obtained using the KPS/ABS microcapsules as the gel breaker could be maintained above 50 mPa·s for 100 min. Therefore, the encapsulation of KPS by the coacervation of ABS is a feasible method to achieve sustained release property, and it could effectively reduce the rate of viscosity loss of fracturing fluid at a high temperature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47734.