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:
Dec. 27, 1988
Filed:
Oct. 30, 1986
Dylan Davies, Tokyo, JP;
Schlumberger Technology Corp., New York, NY (US);
Abstract
Systems, for investigating casings which are fitted into boreholes that traverse earth formations and which are suitable for use in evaluating and/or optimizing the cathodic protection of casings and for finding the location and rate of casing corrosion, generally includes a downhole tool capable of investigating the casing along a measurement control unit located around the surface of the earth formation, and a cable having one end connected to the downhole tool and the other connected to the measurement control unit, with the cable including at least a plurality of first connection lines. The tool invention generally includes at least a first pair of longitudinally spaced electrodes, at least a pair of second connection lines, each of the second connection lines having one end connected to a corresponding one of the electrodes, and relays interposed between the first connection lines and the second connection lines. The relays are arranged such that in a first position, the first connection lines of the cable are short-circuited, and in a second position, the first connection lines are connected to their corresponding second connection lines thereby establishing an electrical connection between the measurement control unit and the electrodes. Accurate corrected high resolution potential difference and casing resistance measurements are so obtained. Likewise, contact resistance measurements can be made and used to perform a quality control screening of the other measurements.