| The production efficient of oil and a series of safety often caused by casing damage.Now casing detecting instrument take the mechanical method,but the cost of operation is high and the work efficiency is low.As an excellent method of non-destructive testing,electromagnetic detection is a usual conventional method in the oil industry.Now there aremany kinds of interpretation methods on the data,but the research and its relevant theories are not perfect.At first,the essay start with electromagnetic induction,the solution of eddy current is computed in some hypothesis.The eddy current and its property are discussed then.Bipolar pulse signal transient electromagnetic signal,not only produces a zero interval to eliminate emission source signal's interference,but also wide-band information can be detected for frequency characteristics of pulse signal.Secondly,the model of electromagnetic detection on multi-layer metal tubular is build by finite element method(FEM)with the Comsol multi-physics software.The distribution of magnetic field can be computed.Finally,inverse model of electromagnetic detection on tubular is researched,the data is processing with the damping least square methods,and the test is carried out.Theoretical analysis and simulation modeling is the base of inverse interpretation in this paper.The inversion analysis and test data,they can be ascertained that the electromagnetic flaw detection technology of multi-layer metal tube string can qualitatively inspect the damage of the pipe string,which provides the basis for the damage analysis of tubing and casing in oil industry. |
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