Effect of the number of stages and feed composition on offshore oil and gas separation train

A process analysis of multistage gas-oil separation coupled with gas re-compression was carried out, with reference to offshore oil and gas applications. Two feed types (light oil and gas condensate), different feed conditions (30 bar and 60 bar; 48 °C and 58 °C) and 1 to 4 separation stages were considered. The net profit (oil and gas sales minus operating costs) was mapped as a function of the pressures of the separators with reference to 32 distinct case studies. The maps were generated by means of a brute-force optimization method run by an external routine coupled to Aspen HYSYS. The total number of solved simulation setups was in the order of 10 ⁶. The maps allowed to evaluate the effect of the number of stages and the feed composition on the optimal pressures of the separators, as well as the profit losses caused by sub-optimal operation of single separators in the train.