Factors affecting the attitude accuracy of wireless electromagnetic wave MWD system

In broken soft coal seams of coal mine where hydraulic driving directional drilling is used, hole collapse and hole wall instability are easy to occur. Electromagnetic wave measurement while drilling system is suitable for gas driving drilling, so it is widely used in broken soft coal seams. The accuracy of drilling trajectory is the key to gas drainage effect in broken soft coal seams. In the use of electromagnetic wave measurement while drilling system, the phenomenon of insufficient accuracy and large error of trajectory measurement appears irregularly. In order to solve this problem, this paper analyzes all the factors that affect the attitude accuracy of wireless electromagnetic wave MWD system from design to application, lists the influence sources and treatment schemes one by one, and focuses on the accuracy problems of electromagnetic wave MWD system in drilling field. By collecting data and analyzing the trend of the curves, the causes of the problems are determined, and the self calibration method and process requirements are designed. At the same time, two calibration methods of look-up table compensation method and fitting function method are given, and the principle, method selection and related parameter calculation of the two methods are explained. Finally, the fitting function method is used to calibrate and correct the measured data, and the accuracy of the corrected attitude data was better than 0.2°, which solved the problem of poor attitude accuracy of the wireless electromagnetic wave MWD system and met the requirements of the measurement accuracy of gas extraction trajectory in broken soft coal seams.