Research On Attitude Measurement Method Of Control Shaft For Point-to-the-bit Rotary Steering Drilling Tools

In the process of steering drilling,the downhole tool attitude parameters required for guidance control have the tool rotation speed,the tool inclination,the tool azimuth,etc.Accurate and real-time measurement of these parameters is a prerequisite for guidance control of steering drilling tools and is the key to the feedback control of the dowhole control system to ensure a desire trajectory of the wellbore.In this dissertation,the attitude measurement of the guide shaft is studied for the ground simulation experiment of a new point-to-the-bit rotary steering drilling tool.A set of guide shaft attitude measurement device is developed.Some research results as follows:1^st.The attitude measurement requirements of the guide shaft in the rotation and rocking motion are analyzed.The attitude measurement scheme of the guide shaft based on the gravity accelerometer and the rate gyroscope is designed.The influence of rotational motion on the output signal of gravity acceleration sensor is considered,and an error correction method of attitude measurement is proposed to eliminate the influence of tool rotation.The method of steering axis attitude is established.2^nd.Based on the dsPIC30F4011 single chip microcomputer,a steering shaft attitude collection subsystem which can be installed inside the rotating guide shaft（barrel）is designed according to the ground simulation test of the point-to-the-bit rotary steering drilling tools.The hardware and software are completed.Design and debugging,and experimentally tested the function and performance of the subsystem.After layout optimization and device optimization,the whole subsystem and its power supply and sensor can be encapsulated in a material with a diameter of 58 mm,length of the 120 mm guide shaft in the electronic bin（barrel）.3^rd.The design and debugging of hardware and software such as attitude calculation,digital-to-analogue conversion and single output are completed in the design of the steering axis attitude calculation subsystem which can be installed in the ground simulation experiment console.And test the performance of the subsystem.In view of the ground simulation experiment,it is necessary to transfer the rotation axis attitude measurement information to the static experimental console special request,completed the corresponding wireless transmission hardware and software design.4^th.The performance of the guide shaft attitude measurement system is tested by using CS-3LAS accelerometer and ADXL337 accelerometer respectively.The test results shows that the system performance test of the former can not meet the design requirements because of the sensor failure.The latter’s wireless communication function is stable,the steering angle measurement error is not more than 0.4°,the relative azimuth measurement error does not exceed 4°,to meet the ground simulation experiment on the guidance axis attitude measurement error requirements.The research result of this dissertation has practical application value to the tool,and has been used by the tool’s ground simulation test.