Abstract: An exploration well of Ningbo 11-1 has been designed with a drilling depth of 4638 m. However, sticking occurs when the drilling depth of 12-1/4 inch hole reaches 4100 m and the bottom hole assembly (BHA) needs to be changed. Through the preliminary analysis of the reasons, the sticking is considered resulting from hole shrinkage or wall collapse. Various methods are adopted to solve the problem, including reverse drilling tools, large tonnage lifting and lowering, as well as pumping releasing agent, drilling fluid and sea water to match large tonnage movable drilling tools. In the absence of a loop path, new treatment measures such as annulus pressure suppression and micro fracture formation are attempted. In the end, the problem is not resolved and explosion has to be performed. Through the detailed introduction to the above technical measures and processes, countermeasures in theory and practical operation are given for such sticking accidents.