The similitude and discrepancies in the results of these studies suggest that differences in the design setup and in the field conditions may affect the locations and extents of the thermodynamic
irreversibilities of the overall system. The literature appears to contain no systematic comparison of the sources of energy destruction for oil and gas platforms. Therefore, in this work, the
platform analysed by Voldsund et al. [9] is compared with three other North Sea offshore platforms, which have not been studied in this manner before. The variations of the reservoir fluid composition over the life cycle of each field are not investigated, but it is worth emphasising that the four platforms operate at a different production period of an oilfield (peak and end-life). The work was carried out in three main steps: