Experimental study on the influence of weighting additives on lubricity of water-based drilling fluids

Through the analysis of the particle size distribution, scanning electron microscope, ZETA potential, the friction coefficients of mud cakes are investigated when water-based drilling fluids are added to different densities by three weighting additives of barite, activation barite, activation iron ore powder and their complex combination. The experimental results show that under high density, all the three weighting additives can enhance the lubricity of the drilling fluids. To improve the lubricity of water-based drilling fluids, the critical densities of drilling fluids added by barite, activation barite and activation iron ore powder are 1.6 g/cm3, 1.4 g/cm3 and 1.2 g/cm3, respectively. The lubricity of the drilling fluids will be improved in a certain range beyond the critical density. Complex combination is better than the every single additive.