Evaluation Study of Various Produced-Water Treatment Technologies to Remove Dissolved Aromatic Components

Abstract

Abstract In the frame work of the zero discharge work ongoing in Norway, all oil companies operating on the Norwegian Continental Shelf have been obliged to deliver a field specific strategy to the Norwegian Pollution Control Authority (SFT) in 2003 explaining how to achieve the zero discharge goal in 2005. A high focus within the various presented strategies was given to the implementation of new technology or combination of existing and new technologies, especially for reducing the amount of harmful aromatic components. These components often constitute a considerable contribution to the total environmental risk of produced water. The traditional technologies such as separators, hydrocyclones, etc. in general only remove dispersed oil and the aromatic fraction dissolved in the oil phase. However, fairly new water treatment technologies on the market are also able to remove the aromatic components dissolved in the water phase. These new technologies are usually based on extraction, stripping or adsorption technology. By knowing the amount of aromatic components present in the dispersed oil, the removal of aromatics by traditional treatment techniques can be assessed. The results from such an assessment are presented in this paper for the Ekofisk field and compared to results from other fields, all located in the North Sea. Based on these results and on recent pilot field tests on Ekofisk, various new technologies such as CTour and Cetco units have been evaluated for their possible increased efficiency on the removal of aromatics from the water phase, compared to traditional technologies.