The effect of weighting agents of different particle sizes on the viscosity of water base drilling fluids

The effect of activated barite with different particle sizes on the viscosity of high density drilling fluids was studied.It was concluded that barite with particle sizes between 0.050~0.065 mm had the greatest effect on the apparent viscosity and plastic viscosity of drilling fluids.The concentration of barite with this particle sizes should be controlled.Barite with particle sizes between 0.040～0.065mm had the minimal effect on apparent viscosity, while barite with particle sizes between 0.040～0.061mm had the minimal effect on plastic viscosity.Addition of the latter two particle sizes in drilling fluids caused little effect on viscosity when added to drilling fluids.