Patent ID: 9360581
Filing Date: 2016-06-07
CPC Classification: E21B,G01V

Claim Text:
1. A method comprising: applying a current across a drill collar that surrounds an internal magnetometer, wherein the current travels across the drill collar and along one or more other current paths to return to the drill collar; measuring magnetic fields due to the current across the drill collar and the current across the one or more other current paths using the internal magnetometer, while the drill collar is disposed at a first angle of rotation; rotating the drill collar to a second angle of rotation; measuring the magnetic fields using the internal magnetometer while the drill collar is disposed at the second angle of rotation; and determining a relationship between the current across the drill collar and a portion of the magnetic fields due to the current across the drill collar measurable by the internal magnetometer, wherein determining the relationship comprises determining a calibration angle relating a scribe line of the drill collar and a vector direction of the measurable portion of the magnetic field.