Scheme design of recoverable bottom hole assembly in casing drilling

Casing drilling means the combination of drilling with casing. The design of recoverable bottom hole assembly is to replace the drilling bit with the downhole tool when no conventional trip is conducted. In this paper, the current state of casing drilling techniques used by domestic and foreign companies is introduced. The working principle of the recoverable bottom hole assembly and the main idea of some bottom hole assemblies are discussed. It presents the scheme design of wellhead equipment, the cementing tool string, and the drilling tool string. Field simulating test is conducted on some assemblies. It is shown that the recoverable bottom hole assembly is qualified in design and it can be studied further in the future.