Importance

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Abstract

A well apparatus for detecting the position of a moving element in a well. Downhole well tools normally comprise a magnetically permeable material which forms a Faraday Shield to interrupt the flux of a magnet positioned within the well tool. The invention attaches a magnet to a moving element surrounded by a magnetically permeable second element, and a magnetic sensor is positioned within a recess in the second element. The magnetic sensor detects the proximate position of the magnet and generates a signal. The signal can be transmitted to a surface controller for display or for generating a command signal to displace the moving element within the second element. A single wire can transmit signals from multiple sensors in a sensor array, and the absolute position and movement rate of the moving element can be identified by the sensor array. The magnet can comprise a permanent magnet or can comprise an electromagnet. The signal from the magnetic source can be modulated to communicate the signal through the second element.

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First Claim