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. 07, 1992
Filed:
Feb. 27, 1990
Anthony W Russell, Drachlaw, Turriff, Abedeenshire AB5 7JB, GB;
Michael K Russell, Prestbury, Cheltenham, Gloucester GL52 3AU, GB;
Other;
Abstract
Borehole surveying methods and apparatus for surveying the true longitudinal magnetic field within a substantially non-magnetic drill collar. A plurality of longitudinal magnetic field measurements are made to provide a longitudinal-position-dependent series of magnetic field measurements BZ(z) which enable the true magnitude of the terrestial magnetic field BZe in the direction of the longitudinal axis of the borehole to be calculated on the basis that BZ(z)=BZe+E(z), where E(z) is the longitudinal-position-dependent longitudinal magnetic field error induced by the magnetism of the drill string and the bottom-hole assembly. Several different methods of calculation are described, including polar and non-polar magnetic error function models. The methods can be extended to a full survey of the borehole heading by contemporaneous measurements of two further magnetic fields in each of two mutually orthogonal axes each also orthogonal to the longitudinal axis, along with contemporaneous gravity vector component measurements in each of these three axes.