Calibration structure for assisting rotary tensor instrument in well in monitoring magnetic gradient tensor for long time

The utility model relates to a calibration structure for assisting a rotary tensor instrument in a well to monitor magnetic gradient tensor for a long time, which is composed of the rotary tensor instrument and a pair of Maxwell coils, and the rotary tensor instrument and the Maxwell coils are fixed through a shell; according to the utility model, the Maxwell coil is adopted to re-calibrate the tensor instrument at set intervals, so that the error problem caused by time drift and temperature drift of a fluxgate sensor in the tensor instrument is effectively avoided, and the accuracy of long-term monitoring of the magnetic gradient tensor in a well is improved. The Maxwell coil and the shell of the tensor instrument are directly fixed through screws for drilling, and it is guaranteed that the rotating center of the tensor instrument is consistent with the center point of the Maxwell coil. And the relative positions of the two are ensured not to be changed in the calibration process. 本实用新型涉及一种辅助井中旋转张量仪长期监测磁梯度张量