Research on the Calibration Method of MWD Under the Cooperation of Multiple Models

The accurate calculation of the attitude angle of the down-hole bit is the key technology to realize the automation and intelligence in the field of oil drilling. Therefore, in recent years, Measurement while drilling (MWD) has been widely recognized and rapidly developed in the field of precise target drilling. In order to solve the problem of azimuth error caused by the interference of the flux gate sensor by the fixed magnetic field and the induced magnetic field in the process of solving the attitude angle of the inclinometer, this paper proposes a calibration method of the inclinometer while drilling under the cooperation of multiple models. Firstly, the error analysis is carried out for the interference magnetic field of flux gate sensor. Secondly, the error compensation is carried out for the fixed magnetic field and the induced magnetic field respectively by using the ellipsoid fitting algorithm under the proposed limited conditions and the Newton iterative model under the magnetic shielding coefficient solution. Thirdly, the magnetic field environment during drilling is simulated by building an experimental platform composed of calibration frame and inclinometer carry out experimental verification. Finally, the experimental results show that compared with the accuracy of azimuth before error compensation, the maximum error of azimuth is reduced to 0.486° and the accuracy is increased to 98.58%. Thus, the interference of a fixed magnetic field and induced magnetic field on inclinometer is effectively suppressed, and the correctness and feasibility of the method proposed in this paper are verified.