Modelling and analysis of offshore energy systems 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, oil and gas export, and power generation. In this paper, a generic model of a North Sea oil and gas platform is described and the most thermodynamically inefficient processes are identified by performing an exergy analysis. Models and simulations are built and run with the tools Aspen Plus R, DNA and Aspen HYSYS R. Results reveal that the total exergy destruction of the system is particularly sensitive to the gas-to-oil ratio and amounts to 55-65 MW, while the total exergy losses amount to 15-20 MW. The gas compression train and the production manifold module are the most exergy-destructive operations of the oil and gas processing system, consuming 4-6 MW and 3-7 MW respectively, while the power generation system alone is responsible for 54-63 MW.