Progress of lithology identification technology while drilling

Lithology identification while in drilling is a convenient and efficient technology to obtain information about formation. It has the advantages of instant, accurate, environmental protection and energy saving. It can be applied to field of engineering such as rock bound aries determination, support parameter design, blast parameter design, and regional formation strength parameter identification. And it has always been the focus of research by scholars in domestic and foreign. This paper systematically analyzes the research status and development trend of lithology identification while in drilling technology, combined with the application of lithology identification while drilling technology in recent years, discusses the technology of lithology identification while drilling as a new method and new theory of intelligent detection. First, the development history of key technologies for lithology identification while drilling in domestic and foreign is summarized. Secondly, it focuses on the research status, including the technical principle and system composition, and compares and evaluates some typical lithology identification systemsin domestic and foreign. Thirdly, the response relationship between the drilling parameters and the rock during the drilling process is summarized, and the established drilling index and evaluation system, and the factors affecting the lithology identification while drilling is discussed according to the two drilling methods of rotary cutting and rotary cutting-impact. Finally, according to the development trend of the research field of lithology identification while drilling technology, the problems existing in the engineering application at this stage are summarized, and the future research of lithology identification while drilling technology is prospected.