A time-domain electromagnetic tool is presented that is capable of quantifying four barriers individually and inspecting a fifth barrier qualitatively. The new tool uses time-domain electromagnetic (TEM) or pulsed-eddy-current technology, which has become a recognized technique for individual quantitative tubular-corrosion evaluation in multiannular well systems (multiple concentric tubulars) in recent years. The novelty of the tool is its ability to exploit the information-rich wide-band-pulsed excitation using three sensors that enhance the sensitivity to multiple barriers.
Physics of Time-Domain Measurements
The TEM tool described in this paper belongs to the broad family of electromagnetic induction tools. Induction tools use a transmitter coil to generate a time-varying magnetic field that induces a time-varying electric field (and hence eddy currents) in the surrounding media.
