Compact Electrostatic Treaters for Floating Offshore Production Facilities

Abstract

Abstract Floating production facilities are very sensitive to equipment weight and footprint. New electrostatic technologies have enhanced the dehydration and desalting process for crude oils by improving treater hydraulics and increasing the electrostatic field strength of the treaters. Efficient vessel hydraulics is essential for achieving maximum dehydration performance and efficient utilization of the treater vessel volume. Not only is the oil distribution critical but oil collection is equally important to maintaining treater dehydration and desalting performance. A new distributor can increase the treater utilization from low 50% to 95% allowing for the use of smaller and light weigt treaters for crude oil dehydration and desalting. The crude oil dehydration and desalting performance also decreases as the crude oil conductivity increases, whether this is caused by an increase of heavy solids, asphaltenes or polar organic components, the electrostatic field strength can be reduced significantly. One method for maintaining the electrostatic field strength is to utilize high frequency electrostatic field to quickly replenish the effective voltage and reduce its decay. Modulating the voltage amplitude has also proven to be effective for increased dehydration performance. Another treater improvement is the use of composite electrodes, which increases the water tolerance of the treater and also improves the treater dehydration performance. This paper describes compact (light weight and reduced foot print) electrostatic treaters and how these technologies can provide lower CAPEX as well as lower OPEX for offshore crude oil treating facilities. The role of vessel hydraulics, electrode materials and electrostatic field strength to maintaining efficient dehydration and desalting performance will also be discussed. Introduction Floating production platforms are used for production facilities installed in deep waters. The Cameron Dual Polarity® and Dual Frequency® technologies have been around for more than one decade and have rapidly developed a solid installed base for crude oil dehydration and desalting on floating production facilities such as FPSOs, SPARs, semi submersibles and other floating production facilities. The higher electrostatic field strength of the Dual Polarity and Dual Frequency type electrostatic treaters allows the use of smaller treaters which provides both weight and space savings. The ElectroDynamic Desalters® also provide an opportunity for use of a single desalter in lieu of two stage desalter arrangement. The Dual Frequency technology combines higher electrostatic field strength with a higher coalescing power and thus allow for the use of drastically smaller treaters.