Abstract: The strings of layered water injection wells in offshore oilfields are structurally complicated.Layered water injection strings are set in sand control strings.The main reasons for the sticking of water injection string are small gap between sand control string and water injection string, long water injection hole section, multiple layers, directional well, long-term scaling of water injection and sand production from broken screen pipe.It is difficult to judge the location of sticking point accurately, and the conventional method takes long operation time and high operation cost.The operation plan was optimized based on the structural characteristics of the double-layer pipe string.According to the optimized plan, water injection string and sand control string are treated separately.Firstly, release the jam and fish the water injection string by using the coiled tubing sand washing, acidizing extrusion and scaling, and overall removal of the jam.Then, treat the sand control string quickly by means of patching, sectional cutting, continuous milling, and integrated cutting and fishing.Through the operation of more than 10 times, a mature and efficient treatment process is summarized.And it can be used as the reference for subsequent wells and other similar wells.