Research On Testing Methods And Engineering Device Of Metal Loss In Casing

Oil pipeline is a metal pipe that supports the wall of oil well,which is extensively used in the process of oil exploration to ensure the normal operation of the drilling process and oil production through the well after drilling.However,the metal of oil pipeline is susceptible to wear and tear due to the influence of work environment and other factors,which has caused significant economic losses.Therefore,the detection of metal loss of oil pipeline has become the focus of oil exploration and equipment maintenance.The thesis focuses on Multi-frequency Eddy Current Pipeline Loss Inspection Tool research,aming to design an engineering device that is capable of qualitatively and quantitatively detecting the damage state of the wall of oil pipeline by exploring detection methods of the metal loss of oil pipeline.Meanwhile,the device should work normally underground without comprising detection efficiency and accuracy.First,this thesis compared several current domestic and foreign advanced metal loss detection principles and analyzed the reasons for the use of Remote-Field Eddy Current(RFEC)detection.Then,according to the principle of RFEC detection,the variation regularity of eddy current generated in the Remote-field excitation in the casing wall was analyzed,and the relationship between the signal and the metal casing damage was established.Secondly,the relationship between the excitation signal frequency and the detection range of metal loss of oil pipeline was established by using the pipeline magnetic line simulation model of finite element simulation software(ANSYS).According to the downhole work process of casing metal loss detector,the problems of noise processing,weak signal detection and detection accuracy were analyzed.In order to satisfy the requirements of pipeline phase measurement analysis accuracy,two typical methods of phase measurement: threshold detection method and digital phase sensitive detection method were explained in detail.In the process of metal loss detector circuit design,the incentive module circuit according to the command of the master control to generate the modular SPWM signal,the SPWM signal controls the inverter circuit to send high voltage into the excitation coil to generate RFEC signal.Eddy current is received by the remote field detection coil in the form of induced voltage after two electromagnetic conversions through thetube wall,and is sent to the detection module circuit.The signal processing circuit of the detection module adjusts and calculates the induced voltage signal which carries the metal loss information to obtain the specific loss information.In the end of this thesis,the casing metal loss detection system was debugged and analyzed.And the work of each module circuit,data processing results,as well as the experimental casing metal loss detection were tested and analyzed.It was confirmed that the metal detector of casing metal loss could detect the damage of metal tube wall.And the feasiblilty of method analysis and circuit designin this theis were verified as well.