▎ 摘　　要

This study has examined the potential improvement of the lubricating properties of drilling fluid by adding graphene and graphene oxide (GO). The effects of different concentrations of graphene and GO addition on lubricating properties and friction reduction of drilling fluid have been studied by using an extreme pressure lubrication device and a pin-on-disk tester. In pin-on-disk tests, the pin material was AISI316 steel (casing material) and the disk material was 7075 aluminum alloy (drill pipe material). The pin-on-disk friction and wear tests were carried out under the condition that the pin and disk are immerged in drilling fluid. Results indicated that the lubricating properties of drilling fluid significantly improved by adding appropriate amount of GO materials, while, on the other hand, addition of graphene had limited effect on the lubricating properties of drilling fluid. The lubricating factor of drilling fluid dropped 12.6% by an addition of 0.075 wt% GO. The coefficient of friction between the friction pairs dropped 19.8% by an addition of 0.075 wt% GO. Moreover, the wear volume (WV) of aluminum alloy disc decreased to the minimum value of 0.32 mm(3) by an addition of 0.075 wt% GO. On the basis of experimental results, 0.075 wt% GO was added to the oil-based drilling fluids used in an SK-II well, a scientific continental drilling project in the Cretaceous Songliao Basin of Northeast China. Results showed that the lubricating factor of the drilling fluid was reduced by 15.6%, the friction coefficient reduction rate was increased by 24.3% and the aluminum disc wear volume decreased by 20.5%.