无线电磁波随钻测量系统姿态精度的影响因素分析

煤矿井下采用水力钻进方式进行碎软煤层瓦斯抽采时，容易出现塌孔、孔壁失稳，电磁波随钻测量系统适用于气体钻进，在碎软煤层瓦斯抽采中逐步得到应用。钻孔轨迹的准确性是影响碎软煤层瓦斯抽采效果的关键，电磁波随钻测量系统使用中，出现轨迹测量精度不够、误差大的现象。为解决这一问题，分析测量系统从设计到应用全过程中影响姿态精度的因素，列举因素产生的原因及解决方案，重点针对钻进现场出现的电磁波系统精度问题进行分析。通过现场采集数据、分析曲线趋势规律，确定造成误差大的原因为测量短节与外无磁钻杆不同轴，设计现场自校准方法和流程要求。提出查表补偿法和拟合函数法2种校准方式，对2种方法的原理、方法选择以及相关参数计算给出了说明。最后采用拟合函数法对实测数据进行了校准修正，修正后的姿态数据精度达到0.2°，解决了无线电磁波随钻测量系统在使用中的姿态精度不高问题，满足碎软煤层瓦斯抽采轨迹测量精度要求。 

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.