Gas Lift and other lift mechanisms

At some point in the life of the well, the reservoir will no longer be able to flow naturally to the surface at the required rate. At this point in time, artificial lift is required to maintain production. Various lift mechanisms are used in the industry, a few of which are described below.

Gas Lift

Gas lift is either a continuous or intermittent process whereby gas in injected into a well to reduce the density of the produced fluid. This has the effect of reducing the static head in the tubing thereby assisting the flow of fluid from the resevoir through the tubing to the wellhead.

Gas lift is essentially an extension of natural flow, whereby the producing GOR is artificially increased by the injection of gas. The requirement of gas lift is often a result of either an increased watercut or a declining reservoir pressure.

For maximum benefit, the gas should be injected as deep as possible, reducing the density of the fluid column as much as possible. Gas is injected through gas lift valves, a series of which are run in side pocket mandrels together with the tubing string, and so designed that only one valve is open and passing gas at any one time.

To view rest of this section, please login or register..