A number of empirical correlations and mechanistic models have been developed for predicting pressure drop and other fluid flow characteristics during multiphase flow in vertical wellbore. At any particular time, engineers are often faced with the difficulty of which particular empirical correlation or mechanistic model should be used to evaluate multiphase flow in vertical wellbore. This is because; a particular correlation or model may be developed under some certain assumptions or for a particular region which may not be applicable to other regions or under a new set of conditions.
This paper presents a study that was conducted to evaluate the predictive performance of both mechanistically based models and empirical correlations in calculating pressure drop and other flow characteristics in vertical multiphase flow. Using 414 real field data points covering pipe sizes of 2.375 in. to 7.0. in, oil flow rate of 280B/D to 23,200B/D, water cut up to 95%, gas-oil ratio up 927SCF/STB from the Middle East, the correlations and models are used to predict pressure drop in vertical multiphase phase flow for several wells. The predicted performance is then compared with actual measured well pressure drop data.
The empirical correlations evaluated are those conventional correlations of Hagerdon and Brown, Duns and Ros, Orkiszewski, and Beggs and Brill. While mechanistic models of Ansari et al, Aziz et al, Chokshi et al are also evaluated. The variations between the predicted and the measured are analyzed using statistical error analysis.
Based on the results from the analysis, mechanistic model of Ansari et al. out-perform all the conventional empirical correlations evaluated in this study for vertical multiphase flow for the Middle East region.