Optimizing separator pressures in the multistage crude oil production unit

To achieve good separation between gas and liquid mixture coming out of a crude oil production system and to maximize hydrocarbon liquid recovery, it is necessary to use several separation stages at decreasing pressures and then adapting the pressure set-points to improve product separation and recovery at minimum cost. The aim of this study is to present an accurate methodology for optimizing separator pressures in the crude oil production unit. The new proposed methodology determines the optimum pressures of separators in different stages of separation and consequently optimizes the operating conditions. Using this new method, the optimum separator pressures for a 5724-m³/day oil production unit were determined. As a result, the oil recovery was increased by 6 and 5 m³/day during summer and winter seasons, respectively. In this work, the C₇ + fraction was also treated as one cut and then breakdown of heavy fraction cuts (C₇ + splitting) with respect to the most widely used distribution function (gamma probability function). The results obtained showed that the calculations with C₇ + fraction breakdown is more accurate than definition of feed stream a with single C₇ + fraction.