ИСТИНА

Superficial electrical and electromagnetic methods are used worldwide for pipeline characterization. There are two groups of DC electrical and AC electromagnetic methods, in the first group only electrical signals are measured while in the second one both electrical and magnetic field measurements are used. In Mexican Petroleum Institute new technology of pipeline characterization was developed based on the approximation of a metallic pipeline by a heterogeneous transmission line with variable distributed parameters. Field technology and interpretation procedure are based on the theory and quantitative determination of insulation resistance and holiday's rate is possible on both magnetic field and electrical field measurements. These operation have difference velocity (magnetic measurements are 10 times faster) and different resolution to insulation damage, that is why combination of two types of measurements as reconnaissance survey and detailed study of anomalous zones is quite reasonable. Some examples of field studies are presented.