Abstract:A high-performance water-based drilling fluid system has been developed to solve the technical problems such as borehole cleaning, borehole stability, lubrication, anti-sticking and protection of oil and gas reservoirs in horizontal well construction. By the optimization of inhibitor, coating agent, filtrate reducer and other treatment agents, the high performance water-based drilling fluid formulations are ultimately determined, the performance experiments show that this drilling fluid system has stable performance with strong inhibition, lubricity, anti-pollution and reservoir protection capability, very good construction effects have been achieved in the field application of well Suping-5 of Sudeerte oilfield with stable wall, and no jamming in the tripping.