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:
Apr. 11, 1989
Filed:
Jan. 20, 1987
Anthony W Russell, Turriff, GB;
NL Sperry-Sun, Inc., Houston, TX (US);
Abstract
For the purposes of determining the orientation of a surveying instrument in a borehole, while compensating for the effects of perturbing magnetic fields associated with magnetized sections of the drill string both above and below the instrument, the inclination angle .theta. and the highside angle .phi. of the instrument are determined, together with two transverse components Bx and By of the local magnetic field as measured at the instrument in the borehole. Additionally either a single component of, or the magnetide of, the true earth's magnetic field at the location of the borehole is ascertained from a look-up table or directly by measurement away from the influence of the drill string. A value .PSI.a for the azimuth angle of the instrument is then determined from the inclination and highside angles, the measured component(s) of the local magnetic field, and only the single component of, or the magnitude of, the true earth's magnetic field.