Microencapsulation of the Enzyme Breaker by Double- Layer Embedding Method

An effective fracturing fluid should have sufficient viscosity to fracture the oil- bearing layer at the initial stage and should be removed smoothly at a later stage by controlling the release rate of the enzyme. Therefore, the gel- breaking speed of an enzyme breaker in the fracturing fluid is an important factor in enhancing the production of tight formations. Microencapsulation is an efficient technology to improve the embedding rate and stability of the core material. In this study, double- layer microcapsules were successfully prepared by spray drying; porous starch (PS) was used as the core material carrier to adsorb the enzyme; and gum arabic was used as the wall material. The morphology of the microcapsules was detected via fluorescence microscopy and scanning electron microscopy. Furthermore, application testing of the double- layer microcapsules showed that the prepared microcapsules can protect the activity of the enzyme breaker, provide a certain sustained- release performance, and increase the gel- breaking time to 40 minutes. The double- layer microcapsule breaker can be further applied to field activities involving fracturing technology. Therefore, this method can be used to develop a platform for the slow release of various enzymes in industries.