Acoustic pressure wave gas lift diagnostics

A method of identifying and diagnosing open gas lift valves in a gas lift production well, the gas lift production well including a production tubular having a plurality of mechanical gas lift valves spaced along at least a portion thereof, each of the plurality of mechanical gas lift valves set to a selected minimum design opening pressure, and a casing surrounding at least a portion of the tubular to form an annulus, the annulus in fluid communication with the interior of the tubular upon the opening of one or more of the mechanical gas lift valves, the method comprising:

• reducing injection pressure below the minimum design opening pressure of each of the plurality of mechanical gas lift valves to close each of the plurality of mechanical gas lift valves;
• incrementally increasing injection pressure to the design opening pressure to open one of the plurality of mechanical gas lift valves;
• measuring at least one of pressure, amplitude, frequency and wave patterns, and combinations thereof, produced by the opening of the one of the mechanical gas lift valves;
• incrementally further increasing injection pressure to the design opening pressure to open another of the plurality of mechanical gas lift valves;
• measuring another of at least one of pressure, amplitude, frequency and wave patterns and combinations thereof, produced by the opening of the another of the mechanical gas lift valves;
• determining the location of the one mechanical gas lift valve and the location of the another of the plurality of mechanical gas lift valves, from the measured at least one of the and the another at least one of, pressure, amplitude, frequency and wave patterns, and combinations thereof, wherein the location of the one mechanical gas lift valve and the location of the another of the plurality of mechanical gas lift valves are determined based on travel times of the at least one of pressure, amplitude, frequency and wave patterns that travel in both directions from the one mechanical gas lift valve and the another of the mechanical gas lift valves;
• and
• determining whether at least one of the one mechanical gas lift valve and the another mechanical gas lift valves are operating according to the selected minimum design operating pressure.