低温储层压裂液破胶用酸性微胶囊的制备与性能评价OA

Objective Self-generated heat gas is an effective approach to solving the gel-breaking issue of fracturing fluids in low-temperature reservoirs.However,there is a problem that the acid catalyst in the self-generated heat system is incompatible with the alkaline fracturing fluid,and the addition of a sufficient amount of catalyst during fracturing at once may lead to excessively rapid gel breaking,making it difficult to achieve precise control.Method In this study,a double-emulsion solvent evaporation method was employed to encapsulate the acid catalyst of the self-generated heat gas system,using polyvinyl alcohol(PVA)as a stabilizer and ethyl cellulose(EC)as the shell material,thereby enabling controlled and delayed gel breaking of fracturing fluids under low-temperature conditions.Single-factor analysis and orthogonal experiments were conducted to optimize the gel-breaking microcapsule system.The microstructure and particle size distribution of the microcapsules were characterized using scanning electron microscopy(SEM)and laser particle size analysis,and their gel-breaking performance was evaluated.Result The optimal microcapsule formulation was achieved with 2.5 g EC,4.50%emulsifier,1.0%Tween-60,and 2%PVA stabilizer,resulting in microcapsules with an average particle size of 201.88 μm,a uniform particle size distribution,high sphericity,and an encapsulation efficiency of 46.76%.Conclusion When combined with the self-generated heat gas system,the porous shell structure of the microcapsules facilitates the slow release of hydrogen ions,enabling effective gel breaking of the fracturing fluid within 2 h at 40℃.The microcapsules exhibited remarkable delayed gel-breaking performance.This study is of great significance for ensuring effective gel breaking in low-temperature reservoir fracturing operations and expanding the application scope of microencapsulation technology.