A Field Test and Analytical Study of Intermittent Gas Lift

A series of controlled experiments of intermittent gas lift was carried out in an instrumented well in the Conroe field, Montgomery County, Texas. The well was equipped with 7 pressure transducers over the length of the tubing string so that progress of the lifted slug of liquid could be followed up the tubing. A unique feature of the experimental setup was a surface controlled, bottom-hole hydraulic valve, so that a liquid load could be allowed to enter the tubing and the valve closed, isolating the well from the controlled test. In this manner, individual intermittent slugs could be studied independent of the well performance. A wide range of slug sizes and injection gas volumes was covered in the 52 test runs. Liquid recovery from individual runs did not correlate directly with any of the measured parameters. However, it appears that the amount of the liquid slug which is not produced can be correlated with the average gas velocity below the slug. Since the starting slug size is known, this can be used as a predictive technique for intermittent gas lift design. Comparison of the design method to a field test has been made.