Flow Resistance of Gas-oil Mixtures through Vertical Pipes

Abstract

Listen

Translate article

The resistance to flow of mixtures of gas and oil in passing up through theflow tubing of oil wells operated by gas-lift or by natural flow is a factor inoil-recovery technic that has received but little attention. Yet accuratedesign of a tubing installation for a particular set of conditions, whereoperation is by either of these methods, is impossible without quantitativedata on the pressure loss suffered by the oil-gas mixture in its passagethrough the well tubing to the surface. Because of lack of such information, petroleum production technologists have been compelled to approach this problemby "cut-and-try" methods, which, doubtless in many cases, has resultedin the installation and use of tubing too large or too small for most efficientutilization of the expansive force of the gas used in lifting the oil.Impressed with the necessity for information of this character, the authorshave conducted a series of tests with large-scale apparatus in the petroleumengineering laboratories of the University of California, designed to beproductive of data that would.afford a means of attacking the problem offlow-tubing design on a more scientific basis. Mechanics of Expulsion of Gas-Oil Mixtures in Naturally Flowing and Gas-LiftWells When oil is lifted from a well by the expansive force of compressed natural gasor air, the fluids enter the lower end of the eduction tube under elevatedpressure, with the gas partly in solution, but largely distributed in the formof occluded bubbles within the oil mass. As discharged from deep wells, afterreaching the surface, there will normally be at least 60 times as much gas, byvolume, as of oil; and in many cases the ratio of gas volume to that of the oilwill have a value as great as 1000 or more. On entering the lower end of theeduction tube, however, a relatively smaller volume of gas will be found in theoil-gas mixture, on account of compression of the gas in accordance with theelevated pressure necessary.