DOWNHOLE TOOL POSITION SENSING SYSTEM

摘要

A downhole tool includes a mandrel, an inner sleeve, and an outer housing. The inner sleeve being rotatable relative to the outer housing and the mandrel being rotatable relative to the inner sleeve and the outer housing. The outer surface of the inner sleeve includes more than one selected position organized in at least one set. At least two of the selected positions include magnets. The downhole tool also includes at least one magnetic sensor to sense at least one of the amplitude and polarity of the magnetic field for the selected positions and to transmit a signal indicative of the sensed magnetic field. The downhole tool also includes an electronics system to process the sensor signal to determine a magnet reference position of the inner sleeve relative to the outer housing.