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Gas Lift Logs


Gas Lift uses a high-pressure source to inject gas down the annulus into the tubing. The gas is injected at prescribed depths downward to the lowest point possible. As the gas flows to the surface, it expands, reducing the density and column weight of the fluid. By reducing the flowing tubing pressure, differential pressure between the reservoir and the well bore is created, allowing the well to flow

Convention gas lift designs usually have several gas lift valves which are designed to sequentially open and close as gas is injected at high pressure into the casing-tubing annulus.  Ultimately, all the gas lift valves should be closed with gas only entering the tubing at the bottom orifice.

Cardinal's gas lift log shows the actual performance of the orifice and valves by temperature and pressure data.  An active valve will normally show up by cooling from gas expansion on the temperature log.  The pressure gradient, derived from the pressure data, shows the density indicating fluid or gas.  Generally, a low value for the pressure gradient indicates that the system is sweeping the tubing clean and lifting fluid.

Sometimes it is advantageous to also run a spinner velocity log (not shown.)

Example gas lift log (click on image for PDF log):
Note collar log can detect gas lift valves, and temperature
log shows active valves!)

 

Example gradient stops (above and below each gas lift valve:

(Click on image for pdf file)

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