Plunger-Lift Monitoring by Analyzing Wellbore High-Frequency Acoustic Signals and Tubing and Casing Pressures

Abstract

Summary Plunger-lift operations are difficult to optimize owing to a lack of knowledge concerning tubing, casing, and bottomhole pressures; liquid accumulation in the tubing; and the location of the plunger. Monitoring plunger position in the tubing helps the operator understand the operation of the plunger system to optimize the removal of liquids and gas from the well. Plunger position can be tracked from the surface by monitoring the acoustic signals generated as it falls down the tubing. When the plunger passes a tubing collar recess, an acoustic pulse is generated that travels up the gas within the tubing and can be monitored at the surface by a microphone and/or a sensitive pressure transducer. The digitized signal is processed to display plunger depth and velocity and well pressures vs. time. Plunger arrival at the liquid level in and at the bottom of the tubing are identified on the time plots. A field case is presented to show how this information can be applied to optimize plunger-lift operations.