Vision System - A New Way to Track Stem Travel for Gas-Lift Valves

Abstract A method for tracking and accurately measuring the stem position of a nitrogen-charged gas-lift valve has been developed. To achieve this goal, a new measuring approach was created for recording and processing stem movement, with no valve intrusion. Stem behavior was recorded for comparison to state-of-the-art stem tracing measuring methods. Differences of less than 5% between the developed Vision System and a linear variable differential transformer (LVDT) were observed. The final apparatus was validated as a reliable tool for the determination of the stem position during load rate tests, becoming a powerful asset for the determination of gas lift valves performance. Compared to API procedures, the Vision System is a considerably simpler and faster alternative, that also enables further understanding of the valve behavior during tests, with direct implications to their use in the field.