A Processing Method Based On Wavelet For Downward Signal In Rotary Steerable Drilling System

In the rotary steerable dirlling system, there is a downward communication channel tosend the guidance control command from the ground monitor to the down-hole steeirng tool.The negative pulse signal of drilling lfuid transmits a downward command word encoded inthe3-dcsccnding and3-ascending mode. A command-sending device on the ground transmitsthe command into lfow rate of drilling fluid which is changing with a certain pulse width ofdrilling fluid. There should be a downward rccciving dcvice in the down-hole steering tool.The data acquisition unit of the device can detect the output voltage or frequency of thedown-hole fluid motor that relfects the pulse flow change of drilling fluid. The data processingand interpretation sotfware based on signal threshold judgment and pulse width identificationcan process the received information. Then a right guiding control command calculated usingthe pulse width and the sequence of the5codes could be obtained. The command recognitionand explanation methods for down-hole tool receiver in rotary steerable dirlling signaldownward system using lfuid negative pulse intervals mode have always been a researchemphasis.On the basis of analyzing of the distinctive features of dirlling fluid flow signal and itsrecognizing, decoding method of the pulse width of the down-hole fluid are studied, decodingsotfware program are designed, instructions are recognized by the pirnciple of similarity, andtesting result has proved the method of research and software is correct and success. Considerwavelet denoising method, denoising method based on Harr ascension wavelet transform isapplied to process the downward command signal recognition, to improve the signalrecognition of reliability and anti-interference ability. And the ifeld testing, ground test,underground expeirment results have proved the validity and feasibility of the method.