Trenchless Detection of Gathering and Transportation Pipeline Corrosion Based on Magnetic Dipole Model

Abstract

Aiming at the problem of corrosion detection of buried gathering and transportation pipeline under trenchless conditions，a selfleakage magnetic field model for corrosion defects of buried gathering and transportation pipeline was established based on the magnetic dipole model and considering the magnetic charge distribution of corrosion defects.The waveform characteristics of magnetic induction intensity of corrosion defects and the effects of different height off the ground and size of corrosion defects on the magnetic induction intensity were studied by numerical simulation.Results showed that at the corrosion defect，Bx and Bz presented extreme value characteristics and the direction was opposite，By had the feature of passing zero and the peak value changed the direction；the height off the ground was inversely proportional to the extreme values of Bx and Bz and the peak values of By；the size of corrosion defect was proportional to the extreme values of Bx and Bz and the peak value of By.According to the oilfield field testing data，14 excavation points were selected to verify the distribution characteristics of magnetic induction intensity of corrosion defects，and 3 excavation points were selected to verify the relationship between the height off ground and the size of corrosion defects and magnetic induction intensity.

Keywords

• buried gathering and transportation pipeline|trenchless detection|corrosion defects|self-leakage magnetic field|magnetic induction intensity