CASING INSPECTION WITH MAGNETIC PERMEABILITY CORRECTION

An electromagnetic thickness tool is disclosed to produce a measurement of the wall-thickness of a ferromagnetic casing corrected for the effects of casing permeability. First apparatus provides an uncorrected thickness signal proportional to the thickness of the casing uncorrected for the effects o...

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Bibliographische Detailangaben
1. Verfasser:	GLEN S SMITH
Format:	Patent
Sprache:	eng
Schlagworte:	EARTH DRILLING EARTH DRILLING, e.g. DEEP DRILLING FIXED CONSTRUCTIONS MINING OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS
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Beschreibung
Zusammenfassung:	An electromagnetic thickness tool is disclosed to produce a measurement of the wall-thickness of a ferromagnetic casing corrected for the effects of casing permeability. First apparatus provides an uncorrected thickness signal proportional to the thickness of the casing uncorrected for the effects of casing permeability. A second apparatus provides a permeability signal representative of the permeability of the casing. A signal processor uses the mathematical square root of the permeability signal as a correction factor for the uncorrected thickness signal for generating the corrected value. The second apparatus, responsive to a signal proportional to the magnitude of the inside diameter of the casing, corrects the permeability signal for the effects of casing inside diameter.