Research On Attitude Measurement Method Of Rotary Steerable Drilling Tool Based On Kalman Filter

Accurate measurement of inclination and toolface is the premise of accurate control of steerable drilling tool.The dynamic measurement method of inclination and toolface near the bit is studied based on Kalman filter algorithm,which takes the prototype of dynamic pointthe-bit rotary steerable drilling tool(DPRSDT)as the research object.The main contents are as follows:Firstly,the principle,advantages and disadvantages of common attitude sensors are analyzed,and the vibration state of downhole drilling tool and its influence on measuring signals of accelerometer and gyroscope are analyzed,so as to provide theoretical support for the design of measurement scheme,simulation and experimental test.Secondly,the stability of Kalman filter and the selection method of filter parameters are analyzed,and the toolface measurement method which make use of accelerometer and gyroscope based on Kalman filter algorithm is designed.The effects of downhole vibration intensity,inclination and drilling condition on the measurement of toolface are simulated and analyzed.The simulation results show that the Unscented Kalman filter has better performance than the extended Kalman filter.The experimental results on DPRSDT prototype show that the filtering method has good performance under different vibration intensity.Thirdly,regarding the situation that the accelerometer is used alone to measure the inclination,the method of filtering the accelerometer measurement with low-pass filter and adaptive line enhancer is adopted at first,and then Kalman filter method is proposed.The influence of toolface,axial and transverse vibration on measurement accuracy is analyzed.Finally,the two methods are compared by numerical simulation and experiment,and the results show that the Kalman filter method is more effective.Finally,the possible downhole attitude sensor faults are analyzed,and according to different sensor faults,the corresponding toolface measurement method is designed.The simulation and experimental results show that the measurement accuracy of which combining single accelerometer and single gyroscope is almost the same as that of combining double accelerometer and single gyroscope,and the two triaxial accelerometers in the prototype can be redundant to each other.In addition,when the gyroscope fails,the measurement error of the toolface angle will be greatly increased.In order to improve the performance of the measurement system,a redundant gyroscope is suggested.