Two-Phase Flow Choke Performance in High Rate Gas Condensate Wells

Multiphase flow occurs in almost all producing oil and gas/condensate wells. Wellhead chokes are special equipment that widely used in the petroleum industry to control flow rate, to maintain well allowable, to protect surface equipments, to prevent water and gas coning and to provide the necessary backpressure to reservoir to avoid formation damage from excessive drawdown. Accurate modeling of choke performance and selection of optimum choke size is vitally important for a petroleum engineer in production from reservoirs due to high sensitivity of oil and gas production to choke size. Two main approaches have been proposed for prediction of multiphase flow through chokes can be classified as either analytical or empirical and majority of correlations were developed for critical flow conditions. Although most of the correlations available to petroleum engineers are for critical flow but in lots of high rate gas/condensate wells subcritical flow occurs in large choke sizes.There is no empirical correlation for wellhead choke performance under subcritical condition for high rate gas condensate wells, especially in large choke sizes. The first aim of this paper is to develop a new simple empirical Gilbert type correlation for high rate gas condensate wells under subcritical flow in large choke sizes (40/64 in. to 192/64 in.) using non-linear regression analysis based on 61 field data points of 15 wells from ten different fields. The second is to extend the work of Al-Attar for high rate gas condensate wells flowing through large choke size under subcritical flow conditions and check the applicability and advantages. Finally, statistical comparison between these two approaches is done with different error parameters. Copyright 2011. Society of Petroleum Engineers.