Downhole tool for measuring angular position

A downhole tool for measuring angular positions at a location within a subterranean borehole. The tool is rotatable around the longitudinal direction of the borehole. The tool includes two or more magnetometers which measure the Earth's magnetic field along respective magnetometer axes. Each ma...

Ausführliche Beschreibung

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Bibliographische Detailangaben
1. Verfasser:	Jeffryes, Benjamin Peter
Format:	Patent
Sprache:	eng
Schlagworte:	DETECTING MASSES OR OBJECTS EARTH DRILLING EARTH DRILLING, e.g. DEEP DRILLING FIXED CONSTRUCTIONS GEOPHYSICS GRAVITATIONAL MEASUREMENTS MEASURING MINING OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS PHYSICS TESTING
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Beschreibung
Zusammenfassung:	A downhole tool for measuring angular positions at a location within a subterranean borehole. The tool is rotatable around the longitudinal direction of the borehole. The tool includes two or more magnetometers which measure the Earth's magnetic field along respective magnetometer axes. Each magnetometer is arranged such that its measurement includes a component of the Earth's magnetic field normal to the longitudinal direction of the borehole. The magnetometers are further arranged such that these normal components are at an angle to each other around the longitudinal direction. The tool further includes a device which measures the rotational speed of the tool or the time derivative thereof. The tool includes a processor unit that calculates angular positions of the downhole tool around the longitudinal direction relative to the direction of the Earth's magnetic field from the measurements of the Earth's magnetic field and the tool rotational speed or time derivative thereof.