US Patent 10139371 Casing defect determination using eddy current techniques

A system comprises one or more electromagnetic coils configured to generate and direct excitation signals toward a plurality of casings in a wellbore and receive response signals based on the excitation signals. The system further comprises one or more processors configured to receive a first response signal from the one or more electromagnetic coils and determine one or more characteristics of a first defect in the plurality of casings using the first response signal and small defect information.