The Effect of Liquid Viscosity in Two-Phase Vertical Flow

Abstract

Continuous, two phase flow tests have been conducted during which four liquids of widely differing viscosities were produced by means of air-lift through 1¥.! -in. tubing in a 1,500-ft. ex- perimental well. The purpose of these tests was to determine the effect of li- quid viscosity on two-phase flowing pressure gradients. The experimental test well was equipped with two gas-lift valves and four Maihak electronic pressure trans- mitters as well as instruments to accu- rately measure the liquid production, air injection rate, temperatures, and surface pressures. The tests were conducted for liquid flow rates ranging from 30 to 1,680 B/D at gas-liquid ratios from 0 to 3,- 270 scfl bbl. From these data, accurate pressure-depth traverses have been constructed for a wide range of test conditions. As a result of these tests, it is con- cluded that viscous effects are negligi- ble for liquid viscosities less than 12 cp, but must be taken into account when the liquid viscosity is greater than this value. A correlation based on the method proposed by Poettmann and Carpenter and extended by Fan- cher and Brown has been developed for 1¥.! -in. tubing, which accounts for the effects of liquid viscosity where these effects are important.