During crude oil production, a significant amount of water is co-produced. This produced water is the largest volume waste stream in oil production, with an estimated 670 million tons of produced water generated worldwide during 2002(1). Typically, a new operational field produces relatively minor amounts of water, i.e. 0-20%, of the total production. As the field ages, the water volume can increase to over 90% of the production. The offshore production facilities primarily treat oil/water mixtures by adding chemical agents to assist the mechanical separation of the fluids. The produced water is usually discharged after separation of as much of the oil and other organics as possible with current technology. At the point of discharge, typical produced waters contain oil & grease contributors at 10-40 ppm. The organic contaminants in the produced water are of increasing concern throughout the world due to their potential harmful effects on the environment.

The conventional mechanical separation devices used on the oil producing platforms can be placed in two groupings. The first grouping is high centrifugal force separators and typical examples are hydrocyclones and centrifuges. The primary advantage of this grouping is that these devices can separate large amounts of oil from water. The primary disadvantages are that these devices have difficulty with changing flowrates, changing oil in water concentration, and create small micron oil droplets by their shear forces. The second grouping is composed of polishing units and examples are horizontal dissolved gas floatation. The primary advantages of this grouping are the ability to obtain very low ppm oil in water discharge. The primary disadvantages of the horizontal dissolved gas floatation devices are the footprint requirements, changing oil concentration influent, and susceptibility to wave motion. Secondary disadvantages include the frequent requirement for routine and continuous additional chemical injection, usually water clarifiers/deoilers presenting extra operational cost and potential for increased environmental impact.

In order to overcome the disadvantages to the traditional mechanical separation devices currently utilized on oil and gas producing platforms, CETCO has developed a new vertical cyclonic separator, trademarked CrudeSep® that combines the best attributes of cyclonic separation and induced gas floatation to generate a small footprint and efficient oil and water separation. This paper will discuss the separator design and give examples of how this CrudeSep® separator can replace conventional centrifuges, hydro cyclones, horizontal dissolved gas floatation devices and degassers.

You can access this article if you purchase or spend a download.