With the continuous increase of offshore oil and gas exploitation activities, the subsea pipelines is becoming larger and larger, which leads to the frequent occurrence of subsea pipeline accidents. The long-term safe operation of subsea pipeline can be ensured by regular defect detection. The premise of locating and disposing defects is to accurately measure the geographic coordinates of subsea pipelines. Our research group has put forward a kind of pipeline spherical internal detector, which has the advantages of convenient implementation, not easy to jam and rich detection parameters. For this internal detector, this paper has carried out research on the key technology of precise measurement of submarine pipeline geographic coordinates. The main work is as follows:(1) The calibration algorithm of magnetometer array has been studied and the magnetometer array has been designed for the sake of the magnetic field’s precision in the pipeline. Which surveyed by the existing spherical inner detector. Through the finite element simulation analysis, it is proved that the magnetic tensor invariant calibration method is feasible when used to calibrate the magnetic array error; by comparing different solving algorithms, it is concluded that the L-M algorithm is optimal in solving the parameters, taking into account the efficiency and accuracy; Through the field calibration experiment, it is proved that the magnetic tensor invariant calibration method has good robustness and can be eliminated under different background magnetic fields in addition to the interference of background magnetic field.(2) In order to improve the measurement accuracy of submarine pipeline pitch angle, and then improve the measurement accuracy of submarine pipeline geographic coordinates, a new method of measuring pipeline pitch angle is proposed. The emulation and field test have been carried out for the purpose of proving that the proposed measurement scheme is reasonable and superior. Under the experimental condition of using AC servo motor to drive the sensor to rotate instead of the Spherical inner detector, the pitch angle measurement error is less than 0.2° and mostly less than 0.15°.(3) In order to meet the needs of precise measurement of geographic coordinates for submarine pipelines, the dynamic design and structure optimization of spherical inner detector are carried out. Two kinds of spherical inner detector are designed, and the characteristics of spiral weld and buckling pipeline are used as new mark points to measure the geographic coordinates of submarine pipelines, are proposed, and the measurement experiment of mark points with the designed spherical inner detector is carried out. The results show that the optimized spherical inner detector can realize fixed-axis rolling, and can successfully measure and identify spiral welds and buckling pipeline.&nbsp;

Research on Key Technologies of Precise Measurement of Geographical Coordinates for Subsea Pipelines

Paper Proceedings: https://asmedigitalcollection.asme.org/qnde/QNDE2021/volume/85529

ASME 2021 48th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE2021)

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