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Abstract
Compared with cement stone, epoxy resin has a higher compressive strength, lower elastic modulus, and better seepage capacity in repairing cement sheath or cementing in special formations. The viscosity of epoxy resin is significantly affected by temperature, which causes a serious decrease in the settlement stability. In this study, the effects of the diluent, solid epoxy resin and rheological agents on the slurry viscosity, and settlement stability were evaluated. The results indicate that fumed silica and organic bentonite have a good effect on improving the settlement stability, but have negative effects on pumpability. Therefore, a method to improve the settlement stability of epoxy resin-based cementing slurry was developed. Fumed silica and organic bentonite were compounded to increase the settlement stability and lower dosage (fumed silica less than 3 wt.%) can avoid too much negative effect on pumpability. Viscosity tests showed that diluent work more effectively at low temperatures while solid ER and Xanthan gum are more effective at high temperatures. When they use together, the viscosity at 90 °C is increased by 33% while decrease by 86% at 25 °C. When the temperature increases downhole, the viscosity of diluent is closed to ER, and tackifying materials dominate, increasing the viscosity at high temperatures. Based on the method proposed in this paper, the epoxy resin-based cementing slurry can increase the settlement stability to less than 0.01 g/cm3 when the slurry density is less than 1.3 g/cm3 and a settlement stability of less than g/cm3 when slurry density is less than 1.59 g/cm3 .
Graphical Abstract
