New multiphase choke correlations for a high flow rate Iranian oil field

Abstract

<jats:p>Abstract. The multiphase flow through wellhead restrictions of an offshore oil field in Iran is investigated and two sets of new correlations are presented for high flow rate and water cut conditions. The both correlations are developed by using 748 actual data points, corresponding to critical flow conditions of gas-liquid mixtures through wellhead chokes. The first set of correlations is a modified Gilbert equation and predicts liquid flow rates as a function of flowing wellhead pressure, gas-liquid ratio and surface wellhead choke size. To minimize error in such condition, in the second correlation, free water, sediment and emulsion (BS &amp;amp; W) is also considered as an effective parameter. The predicted oil flow rates by the new sets of correlations are in the excellent agreement with the measured ones. These results are found to be statistically superior to those predicted by other relevant published correlations. The both proposed correlations exhibit more accuracy (only 2.95% and 2.0% average error, respectively) than the existent correlations. These results should encourage the production engineer which works at such condition to utilize the proposed correlations for future practical answers when a lack of available information, time, and calculation capabilities arises.</jats:p>

Predicting liquid flow-rate performance through wellhead chokes with genetic and solver optimizers: an oil field case study

“…8)]. The correlations derived by Baxendell (1958), Ros (1960), Achong (1961), Beiranvand et al (2012), and Mirzaei-Paiaman and Salavati (2013) involve different values for the coefficients A, B, and C applied to the following equation (Table 3): where Gilbert (1954) Table 3 reveals the significant superiority of our proposed Eq. (8), in terms of accuracy, compared to the other liquid flow-rate prediction formulas evaluated.…”

“…Oil flow rate through a wellhead choke is a function of: (a) choke size; (b) wellhead pressure; (c) percentage of water produced (expressed as BS&W); and (d) gas-liquid ratio (Beiranvand et al 2012), which are shown in the following equations:…”

“…(6) include orders of magnitude of error in relation to Q L(measured) . Although the Gilbert (1954), Baxendell (1958), Ros (1960), Achong (1961), Beiranvand et al (2012), and Mirzaei-Paiaman and Salavati (2013) formulas also significantly outperform Eq. (6) in terms of accuracy, their levels of accuracy (i.e., APD, AAPD, SD, MSE, and RMSE values) they are much inferior in accuracy to those achieved by our proposed Eq.…”

“…If the ratio of downstream pressure to upstream pressure is greater than 0.588, sub-critical flow conditions prevail (Beiranvand et al 2012). When critical flow conditions prevail, the flow rate is primarily a function of upstream pressure, gas oil ratio (GOR), and the choke aperture diameter.…”

“…Using 97 well-test datasets and with choke diameters ranging from 24/64 to 128/64 in., Al-Attar (2008) developed an equation that predicts choke performance for subcritical conditions. Beiranvand et al (2012) proposed two formulas for estimating the liquid critical flow rate, based on 748 experimental data records including measured data for the input parameters of wellhead pressure, gas-liquid ratio, surface wellhead choke size, and the percentage of water, sediment, and emulsion. Mirzaei-Paiaman and Salavati (2013) investigated the effect of gas-specific gravity and oil-specific gravity on liquid flow rate.…”