Theoretical And Experimental Investigation Of Dynamic Measurements Of The Inclination

The main meaning of the dynamic measurements of the inclination, which is mainly used in automatic measurements and controls of the inclination in automatic vertical drilling and is one of the key techniques of it, is how to pick up information of the inclination and the corresponding direction of well deflection.The paper includes such details as follows: The approach to measure the inclination with accelerarometer sensors dynamically during drilling is introduced, as well as the operation principle of accelerarometer sensors and the arithmetic to measure the inclination are expatiated in the paper. The factors to distort the inclination measurement data seriously are analyzed theorietically, such as noises, the viberation and random rotation of drilling tools. Generally speaking, the noises and viberations can be eliminated from the inclination measures by using low-pass filter, but the centrifugal force caused by drilling tool rotation, which will distort the accelerateometer outputs can be reviesd owing to the rotation speed compensation and the like. The Butterworth filter with certain exponent numbers and transition frequency can be selected as low-pass filter, and the calibration of accelerometers beforehand is needed for error compensation of accelerometer outputs. On the basis of theoretical analysis above, particular experimental equipment which is composed of a two-dimension numerical control rotary table and a vertical vibration experiment table is established, and kinetic control programmes of numeracal control rotary table are compiled in Delphi, and some operation conditions with existence of noises, vibrations and rotations at the same time are simulated effectively. Then the reliability and feasibility of the approaches introduced above to measure the inclinations and process signals are verified by means of the particular experiments mentioned above.Both theoretical and practical researches have demonstrated that :1.Higher precision could be reached when the inclination (equivalent to the rake angle of the rotary table) is caculated by measuring rake angles in X and Y axes indirectly.2.The experiments have indicated that the Butterworth low-pass filter works well when viberation signals superimposing in signals output by accelerateometers should be filtered ,while the distortion of signals outlet by sensors ,which is cauzed by the movements of guide sleeve ,could be revised by the calibration of accelerometers beforehand as well.