Abstract:

In order to improve the accuracy of well trajectory calculation in measurement while drilling, a segmented well trajectory calculation method based on magnetic inertia measurement is proposed in this study. When the drill bit is stopped, the tool face angle model recognition method is used to identify the borehole trajectory model of the test section, and the sub-measurement points of the test section under the constraints of the model are generated according to the depth change in the real-time measurement data. Then, the magnetic inertia measurement data is used to correct the measured points, and the corrected points are identified by piecewise trajectory model. Finally, the corresponding models are calculated by piecewise model. The experimental results show that the absolute error of the coordinate increment is reduced from 0.840 m of the single model algorithm to 0.146 m after adopting the new method, which shows that compared with the single model of the well trajectory calculation method, the error of the segmented well trajectory calculation method is smaller and the wellbore trajectory calculation method can improve the accuracy of the borehole trajectory calculation.

Key words: measurement while drilling, magnetic/inertia combination, wellbore trajectory model, model identification, sub point correction, adaptive segmentation, segmented computation, Kalman filter