Research On Rotary Steering Drilling Trajectory Control Technology Of High-level Borehole In Coal Mine

The development of small diameter rotary guide drilling system is of revolutionary significance to the development of directional drilling technology in coal mine,which is conducive to improve the quality of well trajectory control and shorten the drilling construction period.This paper,based on the structure characteristics of small diameter rotary guide drilling tools,studies the trajectory control technology of rotary guide drilling,which provides technical support for the application of small diameter rotary guide drilling system in the construction of directional drilling in coal mines.Firstly,the bending model of the longitudinal and transverse beams and the contact model of the wing rib and the hole wall of the BHA are established according to the structural characteristics of the BHA.The results show that the deviation making ability of drilling tools can be improved by reducing the distance between the wing rib and the bit,the ROP and the WOB.When the Proctor coefficient of the rock on the hole wall is less than 0.4 or the elastic modulus is less than 0.5 GPa,the full force deviation making is not suitable.Secondly,based on the calculation method of the optimal tool orientation angle,four aspects of trajectory deviation calculation,deviation curvature prediction model selection,trajectory correction principle and steering control parameter check and correction are improved to form a steering control parameter calculation method,which can calculate the steering force and steering angle according to the feedback parameters in the actual drilling process.Finally,the indoor experiment shows that the deviation between the output pressure of single rib and the setting value of small diameter rotary steering drilling tool is less than 0.4MPa,the deviation of steering force is less than 0.2MPa,and the deviation of steering angle is less than 0.3 °,It has good control performance.Field application test shows that the average error of Kriging deflection curvature prediction model is 0.02 °/ m? The guidance force and guidance angle calculated by the guidance control parameter calculation method accord with the analysis of trajectory control theory,which verifies the reliability of the calculation method.