Accurate prediction of the behavior of multi-phase flow through wellhead chokes is required for modern production design and optimization of oil well performance.
This study presents the development of an empirical correlation that predicts the performance of simultaneous flow of oil, gas and water mixture through wellhead chokes. The correlation was derived on the basis of actual production data. The newly developed correlation predicts liquid flow rates as a function of flowing wellhead pressure, gas/liquid ratio and surface wellhead choke size.
The study involves a comparison between the available choke correlations based on 200 field tests from twenty wells. The correlations used in this study are those of Gilbert, Al-Attar, Ros, Baxendall, Achonge, and Secen. The Absolute average percent difference is computed for each correlation. Secen correlation has the lowest error compared to the other examined correlations. However, none of the tested correlations is found to be accurate in all ranges of wellhead pressure, gas/ liquid ratio and choke size. The validity of each of these correlations is limited to a specific operational condition for which the correlations are determined. As a result the strength of those correlations for predicting the actual flow rate is restricted.
Due to discrepancy of results obtained by the included correlations, multiple regression analysis using the statistical technique using the Doolittle method is used to create correlation that best fit the measured data. The proposed correlation is similar to the Gilbert-type empirical correlation.
The new correlation was examined against other correlations using another 110 well test data. The results are found to be statistically very good compared to those predicted by other published correlations considered in this work.