Exergy analysis of offshore processes on North Sea oil and gas platforms

Offshore processes are associated with significant energy consumption and large CO2 emissions. Conventional North Sea oil and gas facilities include the following operations: crude oil separation, gas compression and purification, wastewater treatment, gas lifting, seawater injection and power generation.

In this paper, the most thermodynamically inefficient processes are identified by performing an exergy analysis, based on models built with the simulation tools Aspen Plus®, DNA and Aspen HYSYS®. Results reveal that the total exergy destruction of the system amounts to 69.4 MW, while the total exergy losses amount to 22.3 MW.

The gas lifting train and the production-separation module are the most exergy-destructive operations of the oil and gas processing system, consuming 8.83 MW and 8.17 MW respectively, while the power generation system alone is responsible for 46.7 MW. The exergetic efficiency of the oil and gas processing is about 39%, while the exergetic efficiency of the utility system is about 21-27%.