Error Analysis And Improvement Of Wellbore Trajectory Fitting

Accurate measurement of borehole trajectory is a very important problem in the development of oil fields and coal mines.Firstly,it can reflect the deviation from the preset trajectory,and secondly,it can provide the direction of drilling control.At present,the calculation method of borehole trajectory is mainly based on the well inclination Angle,azimuth Angle and well depth(the basic parameters of trajectory fitting)calculated by the measuring unit,and through some assumed mode.However,in order to avoid obstacles and other factors during the drilling process,the well trajectory can not be drilled in a single mode,so following only one model can lead to significant errors,which will affect the accuracy of trajectory fitting.Moreover,the trajectory model shape has been determined,the trajectory model can not accurately reflect the local information of the actual drilling test section in trajectory fitting.Therefore,in order to improve the accuracy of trajectory fitting,based on the research at home and abroad,the error of survey calculation method is analyzed,and an improved method is proposed.The main research contents of this paper are as follows:1、Based on the establishment of the trajectory reference curve,the errors caused by various models are analyzed,and the influence of the length of the measured section on the trajectory fitting is analyzed.Through analysis,it is found that the error increasing trend of different selection models is different,and the accuracy of trajectory fitting can be improved by selecting the appropriate model,and the shorter the selection of the test section,the closer the trajectory fitting is to the reference trajectory.2、According to the basic parameter characteristics of various models,the trajectory model evaluation and segmentation index are established,and segmentation and pattern recognition are carried out for the actual drilling trajectory.3、Using the measurement data while drilling,the local coordinates under the primary trajectory fitting were corrected by the spherical model,and the corrected coordinates were fitted by the cubic B-spline.