METHOD AND APPARATUS FOR ELECTRICALLY DETERMINING PIPE INSIDE DIAMETER

摘要

A method and apparatus is disclosed for electrically measuring the inside diameter of a metallic pipe such as oil or gas well casing. The transimpedance of two coaxial coils within the pipe is determined and then resolved into its inphase and quadrature components. The magnitudes of these two components are used to generate a corrected measurement output. A signal representative of the inside diameter of the pipe is generated in response to the corrected measurement output and may be recorded as a function of travel distance in the pipe. The generation of the corrected measurement output may also comprise the simultaneous solution of two non-linear equations which express the magnitudes of the inphase and quadrature components as functions of a1, the inside radius of the pipe, and tau , a factor proportional to the ratio of the permeability to the conductivity of the pipe.