Abstract: To solve the decline of production capacity in oil wells penetrated in medium to high porosity and permeability reservoirs due to the leakage of drilling and completion liquids during workover, a new broken down method has been developed, which integrated with organic cleaning, water lock releasing, and inorganic descaling properties. The oil production of well-C in BZ28-2 oilfield increased from 63.6 m³/d to 180.6 m³/d after applying the new broken down technique. For well-D in Wen19-1 oilfield, the daily oil production has increased 37.7 times, reaching 151 m³/d compared to 4 m³/d before applications of the treatment. The success application in five offshore wells indicated that the new method can effectively remove damages caused by the leakage of drilling and completion fluid. The new method may provide good reference for similar offshore oil field with broken down techniques.