Fn-0-C800 is a nano multifunctional drilling fluid additive, which is applicable to water-based, oil-based and synthetic based drilling fluid. lts main functions include: effectively blocking formation micro fractures orpores, reducing the invasion of drilling fluid filtrate into the formation, weakening the destructive effect of hydraulic wedging effect on wellbore shale and improve wellbore stability; Reduce the high temperature and high pressure filtration of drilling fluid; Reduce friction torque; Increase the fracture pressure of sandstone and shale.