Practical Use of Recent Research in Multiphase Vertical and Horizontal Flow

Abstract

ABSTRACT A recent correlation for multiphase vertical flow by Hagedorn and Brown1has been used to examine the effect of numerous variables such as pipe size, gas-liquid ratio, liquid flow rate, liquid viscosity, liquid surface tension, oil API gravity, water cut, etc., on flowing pressure gradients. Most previous correlations were derived by using a form of the generalenergy equation which assumed negligible changes in kinetic energy. Undercertain flow conditions this can lead to serious errors in predicting pressuretraverses. Examples of traverses calculated both with and without the kineticenergy term are included here. The Chew and Connally correlation for calculating change, in viscositywith changing pressure and temperature has been extended so that the effect ofa changing viscosity with depth on pressure gradients can also bepredicted. Examples illustrating the effect of tubing size show the importance ofthis correlation in determining pipe sizes for initial well completions. Limitations on production rates in small pipe sizes from excessive frictionlosses can be predicted with greater accuracy. The combined use of a vertical-flow correlation with a horizontal-flowcorrelation provides a method for determining the maximum flow rate possiblefrom both flowing and gas-lift wells. Examples are included to illustrate application of the combined use ofvertical and horizontal-flow correlations in optimizing production rates andminimizing excessive costs from over injection of gas in gas-liftwells. INTRODUCTION The problems of multiphase vertical and horizontal flow are immediatelyencountered in any producing well. Fig. 11 shows three stages ofproduction: flow in porous medium, vertical flow and horizontal flow. All threestages affect the production rate from a well. If we are confronted with a particular well and consider only the variablesinvolved in the vertical and horizontal stages of Fig. 1, we should be capableof calculating the flowing bottom-hole pressure necessary to produce aparticular flow rate. A change in any of the variables results in a newsolution to the problem. Recent approaches in developing horizontal and vertical-flow correlationshave improved to the extent that the solution can now be obtained with moreconfidence than previously.