Cross-linked polystyrene microspheres as density-reducing agent in drilling fluid

Cross-linked polystyrene (CPS) microspheres are synthesized by modified boiling soap-free emulsion polymerization. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) are employed to investigate the structure and morphology of the CPS. The density of the Xanthan Gum solution used to simulate drilling fluid is also measured under different factors including CPS content, rolling time, temperature, and pH value. The results show that the density of the Xanthan Gum solution is decreased at 100 °C in a basic environment by using CPS microspheres as a density-reducing agent. The density increases slightly when the temperature is increased and the rolling time becomes longer due to the reduced apertures between the microsphere aggregates. CPS is potential useful as a density-reducing agent in drilling fluid.

► Cross-linked polystyrene microspheres with higher Tg are prepared.
► The density of Xanthan Gum solution varies at different CPS content and rolling time.
► The density variation is due to water entering into the aggregates of microspheres.