Attitude Measurement Method Of Automatic Vertical Steering Drilling Tools Under The Vibration Environment

In the real-time drilling,by controlling the oriented block in a given direction to produce the required guiding force automatic vertical steering drilling tools achieve the purpose of steady or correct direction,so as to control the well trajectory,resulting in vertical wells.Therefore,the downhole control system needs to feedback control according to the guidance of the downhole attitude parameters(i.e.inclination,tool face angle),so as to ensure the dynamic stability of the well trajectory.So the measurement of the downhole attitude in real time is essential,and it is the precondition of realizing the real time control.By analyzing the principle of attitude determination of the Automatic vertical steerable drilling tool,this paper studies the uncertainty and unpredictable problems caused by using gravity accelerometer under the conditions of near-vertical.Aim at above problems,this paper also proposes non-orthogonal measurement method.Through the study of the theory analysis and calculation of typical attitude angle,results show that,compared with conventional methods,the attitude measuring error of the non-orthogonal measurement method is greatly reduced and the improvement is remarkable.All of these meet the requirements of the measuring accuracy of vertical steering drilling.Finally the effectiveness of these methods are verified by Hydraulic driving test.Simultaneously,under the conditions vibration and rotation of vertical steering drilling tool,a great measurement error exists in the dynamic attitude parameters measuring.To this issue,a speed compensation measurement method was put forward for eliminating the measurement error of attitude caused by the rotating of the tool and the LMS adaptive filtering algorithm is proposed,which can effectively filter out near-bit vibration influence on the attitude measurement.The research results show that the measurement error of inclination is less than 0.1°,and the tool face angle error is less than 5°,which effectively improve the dynamic measurement precision of the vertical steering drilling tool.Simulation experiment of real-time measurement data shows that the method is effective and feasible.Under the condition of variable speed rotation of steering tool,the attitude of the tool still exists relatively large measurement error when the speed compensation method and the LMS adaptive filtering method are adopted,for this,analyzing the principle of the attitudemeasurement of the fluxgate and the performance of the attitude dynamic measurement under the drilling condition,and the combination measuring method is put forward,which is the inclination is logged by accelerometer under the “stop drilling” conditions and the tool face angle is logged by fluxgate under the “drilling”.