Performance indicators for evaluation of North Sea oil and gas platforms

Well-defined performance indicators can motivate optimal operation of offshore oil and gas platforms. This paper aims to develop such parameters, indicating possibilities for reducing power consumption and emissions of pollutants. Different platforms have different oilfield conditions and process specifications. Such conditions determine the theoretical minimum work required to operate the platforms, and can have a high impact on the power consumption. We introduce performance indicators based on energy and exergy. The specific energy use and specific exergy consumption evaluate the resources spent to produce the exported petroleum. The best-available-technology efficiency compares the current energy use with the energy use if state-of-the-art components replace current compressors and pumps. Exergetic efficiency compares the actual resources spent in the current process with the minimum resources required under ideal conditions (i.e. reversible operation), and specific exergy destruction illustrates the amount of resources lost due to irreversibilities. We use these indicators to evaluate the oil and gas processing at four different North Sea platforms that differ by the field lifetime, system configuration and reservoir properties. Both the specific energy use and the specific exergy consumption ranged between 20 and 667 MJ/Sm3 o.e. in the four cases. The best-available-technology efficiencies showed that the energy use of the different platforms could be reduced by 17% to 44% if the most efficient technologies existing on the market were used. The exergetic efficiencies were 99.4% – 99.9%, 50% – 84% or 2% - 46%, depending on the interpretation of product exergy and fuel/utilized exergy, while specific exergy destruction ranged from 17 to 162 MJ/Sm3 o.e. The platforms with best performances in specific energy use and exergy consumption did not necessarily have the highest best-available-technology or exergetic efficiencies. This illustrates the importance of considering different types of indicators when evaluating the performance of oil and gas platforms.