Non-destructive Testing Method And Instrument Of Logging Cables

For a long time, in the operations of logging in drilling, logging cables fracture as a result of logging accidents occurs frequently. The procedure of handling the accidents is very complex, and it would easily lead to other subsequent failures, including the damage of the well, causing great losses. The reasons were mainly the lack of the real-time understanding of logging cables'health, the lack of efficient and reliable testing methods of cable defects.Through a full investigation of cables'structure, production and use, according to the actual situation and defects of logging cables, the Magnetic Flux Leakage Testing and the Magnetic Bridge Circuit Testing have been adopted to analyze the broken wires and corrosion in logging cables respectively, and a logging cable testing system has been developed.In the broken wire testing field, through the testing experiments on parallel wires, the factors influencing the leak magnetic field are analyzed. Combining with the testing of the broken wires in logging cables, the quantitative evaluation method of broken wires based on experimental model has been developed, and the influence of the quantity of broken wires in standard samples to the stability and precision of the model. In the corrosion testing field, various testing methods were compared and the Magnetic Bridge Circuit Testing has been adopted. The experimental platform for testing system has been erected and the relationship between signal and the volume's change of cross-sectional area has been achieved through experiment. Further more, the measuring range and precision have been analyzed. Based on above, broken wires and corrosion in logging cables integrated testing system was designed, the quantitative analysis software was compiled, a standard sample with defection was made and a research on it was carried on.Practical testing indicates that the system has high-efficient, high-reliability, a simple structure, and can be used widely.