基于多测点分析法的水平井高精度磁方位校正方法

High precision magnetic azimuth correction of horizontal well by multi-station analysis

随着水平井、多分支井等技术的出现,随钻测量技术对磁方位精度的要求越来越高.常规单测点磁方位校正法误差较大,无法满足复杂结构对磁方位精度的需求.近年来,国外围绕Brooks多测点分析法的基本公式,建立了一系列优化后的多测点分析法来提高磁方位的精度.本文以多测点分析法的公式为基础,结合常规单测点磁方位校正法,推导出一套收敛的改进多测点分析法.并通过实验来验证改进后的多测点分析法的效果.用改进后的多测点分析法得到的方位角精度在0.2°以内,达到或接近国际先进水平.通过进一步开展数据处理和分析,该套算法可以应用于水平井、多分支井等大斜度钻井工程中的精确定位和导向.

MWD (Measurement While Drilling) technology require greater precision for the high precision of magnetic azimuth with the emergence of horizontal wells and multi-branch wells. The normal correction for magnetic azimuth have a relatively big error that cannot meet the request of horizontal wells and multi-branch wells. In recent years,many people has derived a series of algorithm to improve multi-station analysis based on the multi-station analysis of Brooks in foreign countries. But,there is no such high precision magnetic azimuth correction algorithm in China. This paper deduced an improved multi-point analysis algorithm based on the multi-station analysis method and a single point analysis method,and the algorithm is convergence. Then we make an experiment to verify the effect of the improved multi-station analysis method in the laboratory. The azimuth that is corrected by improved multi-point analysis algorithm very close to real azimuth,and its accuracy is within in 0.2°. The results show that the improved multi-station analysis can improve the precision of the magnetic azimuth and reach or approach advanced international standards,which is suitable for the drilling process of the larger slope. This algorithm meet the demand of a high precision magnetic azimuth correction in China.