Shea Province, Apache Corp.
Carrie Anne Taylor and Lynn Rowlan, Echometer Company
The Dual Shot Acoustic Technique is used to troubleshoot Gas-lift Wells by looking for pressure communication between tubing and casing. One gas gun is fired, sending a pressure wave down the tubing. Simultaneously, a second gas gun listens to the casing. Both microphones are attached to the same input to record the acoustic signal. The tubing microphone is disconnected immediately after creating the traveling pressure wave at the surface of the tubing, and the microphone on the casing detects signals that pass through defective valves or checks or holes in the tubing. The acoustic signal is created in the tubing, then holes and malfunctioning check and gas-lift valves pass the pressure wave into the casing. To account for the pressure wave traveling down the tubing and up the casing, the average acoustic velocity of just prior tubing and casing shots is used for accurate depth determination to the detected communication.