The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 05, 2003
Filed:
Jun. 23, 1999
Richard J. Kostelnicek, Dickinson, TX (US);
Hans-Martin Maurer, Houston, TX (US);
Baker Hughes Incorporated, Houston, TX (US);
Abstract
A method of determining resistivity of an earth formation through a conductive wellbore casing. The resistance of conductors within an armored electrical cable for a wellbore sonde is measured and the sonde is inserted into the wellbore. The sonde has a plurality of electrodes at axially spaced apart locations for electrically contacting the casing. A first electrical current is applied between a first electrode and a surface return electrode and a first current amplitude and phase is measured. A second phase shifted electrical current is applied between a second electrode and the surface return electrode and the second current amplitude and phase is measured. A first voltage amplitude and phase between a first pair of electrodes axially disposed between the first and second electrodes is measured, and a second voltage amplitude and phase between a second pair of electrodes axially disposed between the first and second electrodes is measured. A second difference amplitude and phase between the first and second voltages is also measurable. Formation resistivity is determined by combining the first voltage, the second voltage, the first current measurement, the second current measurement, the second difference of the voltages, and the resistances of the armored electrical cable conductors.