Abstract:This study has tried to improve lubricating properties of water-based drilling fluid with adding nano oxide particles to it. Alumina (Al2O3), titania (TiO2) and silica (SiO2) nanoparticles were selected as modified drilling fluid additives, the study was made on the effects of adding different kinds and concentrations of oxide nanoparticles on lubricating properties and friction reducing of water-based drilling fluid by using the extreme pressure lubrication device and the pin-on-disk friction and wear tester. The results show that the three kinds of spherical nanoparticles all have the effect of lubrication and antifriction, but the drilling fluid containing SiO2 particles has the best properties of lubrication, filtration and antifriction. When the adding amount of SiO2 nanoparticles was 0.4%, the filtration was minimum, the reduction rates of lubricating and friction coefficients were 15.6% and 32.0% respectively with smooth wear scar, the friction reducing effects was the most evident. When the concentration of the nanoparticles was higher than 0.5%, the friction reducing effect decreased with obvious delamination and wear.