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Link back to DTU Orbit Citation (APA):Nguyen, T-V., Jacyno, T., Breuhaus, P., Voldsund, M., & Elmegaard, B. (2014). Thermodynamic analysis of an upstream petroleum plant operated on a mature field. Energy, 68, 454-469. DOI: 10.1016/j.energy.2014 Thermodynamic analysis of an upstream petroleum plant operated on a mature field AbstractOil and gas processing on offshore platforms operates under changing boundary conditions over a field lifespan, as the hydrocarbon production declines and the water extraction increases. In this paper, the processing plant of the Draugen platform is evaluated by performing an energy and exergy analysis. This facility exploits an end-life oilfield and runs at conditions deviating significantly from its optimal operating specifications. Two different operating modes were assessed, and process models were developed using the simulation tools Aspen Plus R and Aspen HYSYS R , based on measured and reconciliated process data. The total energy demand is moderately sensitive to daily and monthly variations: it ranges between 22 and 30 MW, of which 18-26 MW and about 3-4 MW are in electrical and thermal energy forms. The greatest exergy destruction takes place in the gas treatment (51%), recompression (12%) and production manifold (10%) modules. The separation work performed on this platform is greater than in similar facilities because of higher propane and water fractions of the well-streams. These findings emphasise the differences between peak and end-life productions: they suggest (i) to set focus on processes including gas expansion and compression, (ii) to investigate possibilities for an improved energy integration, and (iii) to consider and evaluate alternative system designs.

Document Version Peer reviewed versionLink back to DTU Orbit Citation (APA): Nguyen, T-V., Voldsund, M., Breuhaus, P., & Elmegaard, B. (2016). Energy efficiency measures for offshore oil and gas platforms. Energy, 117(2), 325-340. https://doi. AbstractOil and gas platforms are energy-intensive systems -each facility uses from a few to several hundreds MW of energy, depending on the petroleum properties, export specifications and field lifetime. Several technologies for increasing the energy efficiency of these plants are investigated in this work. They include: (i) the installation of multiple pressure levels in production manifolds, (ii) the implementation of multiphase expanders, (iii) the promotion of energy and process integration, (iv) the limitation of gas recirculation around the compressors, (v) the exploitation of low-temperature heat from the gas cooling steps, (vi) the downsizing or replacement of the existing gas turbines, and (vii) the use of the waste heat from the power plant. The present study builds on four actual cases located in the North and Norwegian Seas, which differ by the type of oil processed, operating conditions and strategies. The benefits and practical limitations of each measure are discussed based on thermodynamic, economic and environmental factors. Significant energy savings and reductions in CO 2 -emissions are depicted, reaching up to 15-20 %. However, they strongly differ from one facility to another, which suggests that generic improvements can hardly be proposed, and that thorough techno-economic analyses should be conducted for each plant.