Analyzing and Troubleshooting Plunger-Lifted Wells

摘要

Development of a new portable monitoring system has taken the guesswork out of plunger lift analysis, troubleshooting and optimization. During one or more plunger lift cycles at high sampling speeds this system acquires data from the tubing acoustic signals plus pressure recordings from both the tubing and casing. The plunger generates an acoustic pulse as it falls through each tubing collar recess when the well is shut-in. Each acoustic pulse travels through the gas in the tubing and detected at the surface. The pulses are converted to an electrical signal by a microphone and pressure transducer. The signals are digitized, stored and processed in a computer to determine plunger position, plunger fall velocity, and plunger arrival at the liquid level in the tubing. By analyzing the collected data the operator can ensure that the plunger reaches the bottom of the tubing before the end of the shut-in time period. Setting the well's controller to have the shortest possible shut-in time period can maximize oil and gas production from the plunger lift installation. Example data collected from various plunger lifted wells are presented in this paper to show how to identify operational problems such as holes in the tubing, stuck plungers and plungers not getting to bottom. The problem of not knowing the plunger location during the operation cycle has been overcome with this new technology by allowing the operator to see the plunger location at any time during the cycle. Having a detailed analysis of the operation of the well makes optimization of plunger lift production achievable with a minimum of effort and avoids the usual waste of time due to trial and error procedures. Knowing the plunger's location is equally important for timer-based as well as intelligent controllers, since in both cases it is necessary to make initial estimates of the appropriate shut-in time, plunger arrival time and plunger fall time. The capability to calculate the volumes of liquid and gas produced during the cycle and determining the well's inflow performance gives valuable information to determinethe opportunity for increased production. Determining the position and velocity of the plunger throughout the cycle can aid in maximizing oil and gas production of a plunger lift installation.