An assessment of the produced water handling facilities has been determined on three offshore platforms, under different operational modes. Specific drawbacks have been defined for the oil removal equipment, caused by the methods, by which the produced water, drain water and fluids from the drilling operation are separated and processed offshore.
An integrated part in the handling problem of produced water in the North Sea, is the difficulty in characterisation of the water and determining the long term water production profile, in the early phase of the field development. By underestimating the handling aspects and volume of produced water, as well as the lack of understanding of the water chemistry, the processing of produced water will be the bottle neck in maintaining the oil production. This is caused by the difficulty in meeting the capacity demand and oil content in the discharged water. However, this problem may easily be overcome by establishing good understanding of fluid chemistry.
This paper will address issues related to improvements in the design criteria of handling produced water and in the selection of suitable equipment in treating produced water on platforms in the North Sea or elsewhere.
In addition, issues regarding the environmental and toxicity aspects of produced water have been assessed, as part of a long term evaluation programme of produced water. It was determined, that although certain chemicals are added to the produced fluid in order to control scale and corrosion, the toxicity of produced water is not necessarily influenced significantly by such chemicals.
As part of the long term environmental objectives in handling produced water, the re-injection of produced water has been assessed. The advantages and disadvantages of such an approach will be addressed.