Revamping, Energy Efficiency, and Exergy Analysis of an Existing Upstream Gas Treatment Facility

Abstract

Surface oil and gas treatment facilities in .service for decades are likely to be oversized due to the natural depletion of their reserx'oirs. Despite these plants might have been designed modularly, meaning they comprise multiple identical units serving the same task, such units operate often in conditions far from the design. This work analyzes the revamping options of an existing upstream gas facility, cho.^en because representative of a wide set of plants. It presents a flexible process simulation model, implemented in the HYSYS environment and dynamically linked to an Excel spreadsheet, which includes the performance maps of all turbomachineries and the main characteristics of the investigated modifications. The model may be used to run simulations for various gas input conditions and to predict the performance over I year of operation and for different possible future scenarios. The first objective is to assess economically the considered options, which shall be applied only if yielding short return times of the investment since the reservoir is mature. Moreover, all options are appreciated adopting a figure of merit, here defined, that compares the overall energy consumption to the one calculated with .•itate-of-the-art technologies. In addition, exergy and environmental analyses are executed.

Thermodynamic Performance Indicators for Offshore Oil and Gas Processing: Application to Four North Sea Facilities

“…Exergy analysis differs from energy analysis, which derives from the first law of thermodynamics only and treats all forms of energy as equivalent (Kotas 1995). Energy accounting does not provide information on the extents and locations of thermodynamic inefficiencies present within the plant, at the contrary of an exergy accounting (Margarone et al 2011).…”

“…These energy-performance indicators provide limited information on the performance of the processes running on the offshore platform, as discussed by Svalheim and King (2003) and similarly by Margarone et al (2011). In addition, they do not address the different qualities of power and heat energy.…”

“…• The field conditions (e.g., initial pressure, temperature, and well-fluid composition) • The specifications of the oil-and gas-processing system (e.g., the export pressures of the oil-pumping, gas-recompression, and treatment sections) • The possible additional processes (e.g., condensate treatment, seawater injection, produced-water treatment, crude-oil heating, gas dehydration, and purification) Margarone et al (2011) suggested evaluating the plant performance of an upstream gas-treatment facility by comparing it against the performance reachable with the BAT. The proposed indicator, called the BAT efficiency (η BAT ), is defined as the ratio of the energy content of the fuel required on-site, with the BAT for compression and pumping, to the energy content of the fuel consumed on-site in the reference case.…”

“…Possible other approaches, applied in similar research fields, are to compare the overall energy use with that used when integrating state-of-the-art technologies (Margarone et al 2011) or during optimal energy management (Svalheim and King 2003). These allow benchmarking of the energy required and assessment of further potentials for energy savings.…”

“…These allow benchmarking of the energy required and assessment of further potentials for energy savings. However, as also emphasized in Margarone et al (2011), energy accounting does not provide information on the extents and locations of the thermodynamic inefficiencies that are present in the overall plant and its subsystems. Such information is given by an exergy analysis (Bejan et al 1996).…”