دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

unit of magnetic survey map. 1 gamma = 1 nanotesla or 1 gamma = 10-5 gauss.

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: an exploration method in which an instrument that measures the intensity of the natural magnetic forces existing in the earths subsurface is passed over the surface or through the water. The instrumentation detects deviations in magnetic forces, and such deviations may indicate the existence of underground formations that favour the entrapment of hydrocarbons.

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.

the units in which magnetic survey maps are contoured. 1 nanotesla = 10-9 tesla. 1 nanotesla = 10-9 weber/m2. 1 nanotesla = 10-1 lines/m2. 1 nanotesla = 10-5 lines/cm2. 1 nanotesla = 10-5 gauss, 1 nanotesla = 1 gamma.