The Research Of Characteristics Of Acoustic Transmission Channel In Special Drill

The technique of bidirectional data link between the bottom and the ground while drilling played an increasingly important role in modern drilling technology.The transmission of information underground has become the focus of the industry.The method of MWD information mainly include Mud pulse,electromagnetic,intelligent drill pipe and acoustic telemetry.These methods have their own characteristics,and adapt to different scenarios.Acoustic wave transmission belongs to the model of wireless transmission of information for drilling which based on acoustic signal as the carrier,the dill string as information transmission channel.The acoustic transmission is a hotspot of downhole information due to its simple equipment,low cost,spread fast,long distance transmission through the relay technology and less interference than the other way around and so on.So the study of acoustic transmission become the center of this paper.Acoustic transmission is spread through the tubing string.Many factors cause the channel characteristics change significantly,making the sound transmission performance dropped and restricting the transmission of acoustic signals,such as the combinations of structural and physical parameters,cross-sectional area,the length of the drill pipe and threaded coupling assembly,etc.This paper uses acoustic reflectionless transfer models,building periodic and non-periodic channel model to analyze the effects of acoustic channel characteristics of different drilling parameters and BHA.At the same time,build the GUI to analyze its channel characteristics,which facilitate the user to select parameters of the drillstring.According to the simulation model,build a short section in the lab to teste characteristics of acoustic channel characteristics.It provides a testing and inspection platform for the research and experiment of sonic transmission instrument.