GB503849A - Method and means for determining magnetic polarity - Google Patents

Abstract

503,849. Magnetic tests and measurememts. STANDARD OIL CO. OF CALIFORNIA. Oct. 14, 1937, No. 27975. Convention date, Jan. 25. [Class 37] The magnetic polarity of a core, taken during well drilling, is determined by locating the core in the field of a magnetic system, rotating the core about an axis parallel to the magnetic axis of the system (when undefiected), and measuring the reaction between the core and the system during rotation. The core 31, of cylindrical form, is mounted in a head 33 for rotation about a horizontal axis through reduction gearing 45, 46, 48, 49, 52, 53, 54 by an electric motor 55, the head 33 being vertically adjustable to locate the core in suitable proximity to the magnetic system 12, through a crank 42, and locked in the adjusted position by screw 37. The magnetic system 12 is removably suspended by a flange 14 in a magnetic shield 13 provided with a winding 29 for removing in known manner any magnetic polarity accumulated thereby, and comprises astatically arranged horizontal magnets suspended by a torsion wire from an adjustable head 16 in a non-magnetic casing 15. Light from a lamp 23 is directed by a lens 24 through apertures in the screen 13 and casing 15 on to a mirror carried by the magnetic system and reflected therefrom on to a light sensitive chart 27 driven by a cord 57 in synchronism with the sample 31 whereby the magnetic variations of the sample are recorded and measured by comparison with the record of a standard sample, The original orientation of the core in the earth may then be determined in known manner.