Abstract
Mature crude oil fields most often contain higher water cuts and higher content of fines. The combination of a large population of water droplets and fines form very stable crude oil emulsions that are difficult to break.
The higher water cuts provide higher crude oil emulsion viscosity because of the larger population of small water droplets, often leading to a need for higher operating temperatures, frequent production upsets and high demulsifier dosage.
Another challenge is arcing between electrodes as a result of the higher water cuts. Typically older crude oil dehydration and desalting treaters use AC type electrostatic technology, which are less effective in treating crude oils with higher water cuts.
The use of combined AC / DC electrostatic technology provides a two prong approach where bulk water is removed in a weaker AC field and remaining smaller water droplets are removed in a stronger DC field. Further improvements to the AC/DC treaters include use of composite electrode plates, modulated electrostatic fields as well as improved fluid distribution inside the treaters.
AC / DC treaters provide an attractive opportunity for retrofitting existing AC treaters in mature fields and make the treaters more suitable for dehydrating the crude oil emulsions from these fields.
This paper describes new enhanced electrostatic dehydration technologies suitable for treating higher water cut crudes from mature fields, efficient test methods for optimized usage of production chemicals and selection of electrostatic technologies, including case studies.
