Description and Analysis of an Efficient Continuous-Flow Gas-Lift Installation

A series of gas-lift tests was made which verified conclusions reached fromprevious studies and which showed that gas-lift performance could be calculatedif reasonably accurate data on the producing characteristics of the well areavailable. The test installation is described. Its essential features consistedof a rate-of-flow controller to regulate the input gas and an auxiliary stringof small diameter tubing to conduct the input gas to the point of injection inthe eductor tubing. In general, it was shown that for continuous gas-liftoperation, injection should be as deep as possible consistent with availablegas pressure and rate of production desired. Calculated curves are presentedwhich completely characterize the gas-lift performance of the well tested. Introduction A correlation based on field data from a large number of flowing andgas-lift wells, covering a wide range of operating conditions, was developedwhich permitted the logical design and prediction of the performance ofcontinuous gas-lift installations. The procedure made it possible to calculatethe depth, pressure, rate at which to inject gas, horsepower requirements, andthe effect of production rate and tubing size on these quantities. As a resultof these calculations certain significant facts were brought to light orre-emphasized. The presence of efficient ranges of operation and an optimuminjection depth for a given rate of production were shown to exist as well asthe fact that the lower the tubing pressure the less the horsepowerrequirements to lift the reservoir fluids. The fact that the gas-liftperformance can be predicted by calculation does not mean that any giveninstallation will perform over the entire range predicted. Many of theconventional continuous gas-lift installations will not permit operation overthe entire range predicted by calculation (particularly in the efficient rangeof operation) because of the performance characteristics of the installation.Consequently, field tests were initiated for the purpose of investigating andarriving at a simple continuous gas-lift installation which would operate underall conditions predicted by calculation. T.P. 3694