System and Method for Monitoring Rod Rotation and Position Using RF Signal Characteristics

Abstract

Methods and systems for monitoring rotation and position of a rod-string in a pumpjack by monitoring RF signal characteristics of wireless transmissions. A wireless device, such as a wireless load cell, is positioned to move relative to a stationary receiver during pumpjack operation. As the wireless device moves (through rotation above a rod rotator and / or linear motion during pumping strokes), RF signal characteristics vary predictably. Monitored characteristics may include signal strength, link quality, attenuation, RSSI, SNR, bit error rate, packet error rate, packet loss rate, communication interruption rate, and other RF parameters. The rod-string acts as an RF obstruction, creating periodic variations when the wireless device rotates. Rotational status, rate, and direction are determined from variation patterns. Position within the stroke cycle may also be determined. Rotator failure is detected through absence of expected variation patterns. The invention enables rotation and position monitoring without dedicated sensors, using existing wireless equipment.

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