Abstract: In air and mist drilling, annular carries are the typical of gas, liquid and solid multiphase flow, and its mechanism and principles are very complicated. In air and mist drilling practice, the process of drilling does not carry out very well. Generally, the annular carries are not good, and low drilling efficiency, even the borehole held block and its wall collapse, resulting in blocking a drilling tool and causing the explosion under well etc. Obviously, annular carries is the basic theory question that must be solved in air and mist drilling. On the basis of the principles satisfied the engineering precision, experimental research
of annular carries in air-mist drilling was used to verify the one dimension high-load flow model, and the results have an important guidance meaning in air-mist drilling practice.

Key words: air- mist drilling, annular carries, multiphase flow, testing