Method for the imaging of casing morphology by twice integrating magnetic flux density signals

A method for 360.degree. azimuthal imaging the thickness of conductive casing in which a transducer is utilized to induce a magnetic flux in the casing and to measure variations in flux density caused by the presence of changes in the thickness of said casing, comprising the steps of:

• a) positioning said transducer inside said casing and in close proximity with the inside wall of said casing,
• b) utilizing said transducer to induce a magnetic flux in said casing along a portion of said casing adjacent said transducer,
• c) rotating said transducer about the axis of said casing to produce a 360.degree. azimuthal scan within said casing,
• d) utilizing said transducer to measure variations in the flux density within said casing during rotation,
• e) continuously repositioning said transducer along a selected length of said casing in juxtaposition with the inside wall of said casing and repeating steps b)-d) at each point,
• f) twice integrating said measured variations in flux density as a function of time,
• g) determining a first change in casing thickness from a consistently positive double integral of said measured flux density variations,
• h) determining a second change in casing thickness from a consistently negative double integral of said measured flux density variations, and
• i) recording the measured variations in flux density for each 360.degree. azimuthal image of the thickness of said casing along said selected length.