Abstract: Solid-free strongly inhibitive water-based drilling fluid has been developed by optimizing the key processing agents that take in brine in a dispersion phase.This innovative drilling fluid can effectively eliminate problems,and can protect low-permeability reservoirs and reduce the high frequency of drilling troubles in the Liaohe Oilfield.An indoor performance evaluation showed that newly-developed drilling fluid can provide outstanding inhibition performances,with a rolling cutting recovery rate of 98.7%,and which contains drilling cuttings up to 25% and temperature resistant up to 180℃.There are mild damages to the reservoir.The core permeability recovery rates are over 90%,which can effectively plug fractures of 0.1 to 0.3 mm,with high pressure bearing capacity and anti-flowback ability.The drilling fluid was used in the third phase drilling in the Well Tuo-62 in the Liaohe Oilfield,and achieved a regular borehole size without any down-hole trouble.Compared with offset wells,the well has high ROP and oil production,and possesses low skin factors.Research results indicated that the solid-free strongly inhibitive water-based drilling fluid can effectively meet the demands of drilling operations for low-permeability formations in the Liaohe Oilfield,which can be popularized and applied widely in the future.