Magnetic Azimuth Compensation Method Based on Dual - Triaxial Flux Gate Sensors

Conventional drill-following measurement systems pass the downhole instrument bus through the drill hole in the drill collar. The effect of magnetic field generated by bus current on measuring magnetic azimuth is avoided, but it destroys the structure of the drill collar. In order not to damage the structure of drill collar and eliminate the influence of bus current,a magnetic azimuth compensation method based on dual- triaxial flux gate sensor is proposed in this paper. Based on the measurement of magnetic azimuth by a single flux gate, the magnetic field distribution of the bus current and its influence on the three-axis flux gate are investigated, and the method based on the dual-three-axis flux gate sensor is designed. Through simulation, we know that the current only affects the single axis. In this method, two groups of three-axis fluxgate components are measured by two fluxgate sensors, and the unaffected three-axis fluxgate components are analyzed and used to calculate the magnetic azimuth. The experimental results show that the method can effectively improve the accuracy of magnetic azimuth measurement and provide reliable and safe data for downhole drilling.