دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a device used to detem1ine direction and angle at which a wellbore is drifting off the vertical. Unlike magnetic surveying instruments, a gyroscopic instrument reads true direction and is not affected by magnetic irregularities that may be caused by casing or other ferrous metals. See directional drilling, directional survey.

n: a kind of inclinometer used to measure the angle of inclination ,angle of orientation using the orientation-keeping ability of the top

n: a device used to determine the direction and drift angle of a deviated wellbore. It uses a magnetic compass to measure magnetic direction, which differs from true direction by the amount of local declination.

n: the apparatus that measures drift azimuth and deviation angle.

n: term used for a non-magnetic drill collar made from specially treated alloys so that it does not affect magnetic surveying instruments.