Effect of polyisobutylenesuccinimide on low-temperature rheology and dispersibility of clay particles in mineral oil

• Low-temperature viscosity of organoclay dispersions can be reduced by PIBSI.
• Low-temperature dispersibility of organoclay was largely improved by PIBSI.
• PIBSI has little impact on the long-term stability of montmorillonite.
• PIBSI adsorbs on the surface of organoclay by hydrogen bonding.
• PIBSI provides steric effect and modifies the Hamaker constant of organoclay.

In the process of deepwater drilling, maintaining proper low-temperature rheological properties of oil-based drilling fluids and controlling the viscosity of clay dispersions in nonpolar solvents are of great importance. In this work, a dichain polyisobutylenesuccinimide with sufficient viscosity lowering performance was synthesized. The effects of polyisobutylenesuccinimide on low-temperature rheology and dispersibility of organoclay particles in mineral oil were investigated by rheological measurements, sedimentation experiments, optical microscopic observation and transmission electron microscopy. The results indicate that the polyisobutylenesuccinimide is an effective rheological modifier and dispersant at low temperatures in nonpolar solvents. The dispersion mechanism was investigated by Fourier transform infrared spectroscopy, adsorption measurements and X-ray diffraction. The results suggest that the polyisobutylenesuccinimide molecules adsorb on the surface of organoclay particles by hydrogen bonding interactions. The combination of steric stabilization and modification of the Hamaker constant of the particles leads to stable organoclay dispersions. In contrast, polyisobutylenesuccinimide has no significant impact on the long-term dispersibility of unmodified montmorillonite in mineral oil, because of the lower surface coverage.

Polyisobutylenesuccinimide (PIBSI) can significantly reduce the viscosity and improve dispersibility of organoclay dispersions in mineral oil at low temperatures. In contrast, PIBSI has no significant effect on long-term stability of montmorillonite. In these figures, OM represents organoclay and MMT indicates montmorillonite.Figure optionsDownload as PowerPoint slide