Error Correction Algorithms Research And Realization For Deep Well High Temperature MWD Systems

In the drilling process,describing the well trajectory accurately is critical to drilling operations.The wireless MWD(MWD,Measurement While Drilling)system can obtain the current drilling attitude of the instrument by measuring the parameter of inclination,tool face and azimuth,and transmit these data to the ground through wireless transmission,which describes the trajectory of the wellbore.With the scarcity of oil and gas resources,oil and gas drilling depth is deeper and deeper,and the underground temperature is getting higher and higher.The 125 ? nominal MWD instrument gradually cannot meet the exploration needs.Therefore,this paper studies the high-accuracy MWD system which can meet the high temperature of 175 ?,which are of great practical value to improve the measurement accuracy of high te mperature MWD instrument.Firstly,this paper expounds the research background and significance of studying on high temperature MWD instrument,summarizes the research status of high temperature MWD instruments and error correction algorithms of MWD system,and analyzes the main factors which lead to the errors of high temperature MWD instrument.Meanwhile,some effective correction algorithms in the orientation measurement module and in signal processing system are proposed.Finally,the system design and experimental verification are completed.The main works are as follows: from the perspective of designing high temperature MWD instrument,the overall design block diagram of the instrument is presented and the design of the azimuth measurement module in the underground measurement system is completed;the signal transmission system is also analyzed.Based on the analysis of MWD measurement principle,the key measurement parameters are modeled mathematically and the main sources of instrument measurement error are analyzed in terms of sensor measurement,environment and signal transmission.Aiming at the key factors influencing the measurement accuracy of high temperature MWD instrument,the correction algorithms of sensor geometric correction,temperature correction and magnetic correction are studied and realized.On the basis of fully analyzing the mud pulse signal,the LMS adaptive noise canceller and the adaptive notch filter are used to eliminate the pump noise,which achieve a good result.Finally,the instrument is tested systematically.The instrument measurement accuracy experiment and the high temperature experiment are finished.The key results of the instrument measurement precision and temperature drift are obtained,and the accurate measurement of the high temperature MWD instrument is realized.The experimental results show that the error correction algorithm s of high temperature MWD system can correct the measurement data effectively and the MWD system can maintain a good measurement accuracy in 175 ? high temperature environment: the accuracy of the tool face is within ± 1.5 °;inclination angle accuracy is within ± 0.2 °;azimuth accuracy is within ± 1.5 °,which highly meet the instrument measurement requirements of high temperature,high accuracy and high reliability.