Effluent water treatment

Produced water which is originated from crude oil or from the treatment plants  is so called effluent water. As most of the processes to treat the crude are to dewater the oil, all this effluent water at such plants contains oil to some degree. Depending what will happen to this water, there are specific requirements to the quality of this water.
If the effluent water is pumped back in the reservoir in order to sustain the pressure in the oilfield it is not so important how much oil is still in this water. Of course all the oil which is going back in the reservoir is oil which can not be sold or processed, so there is an interest to minimize the oil content in this water as well.
Very often the effluent water is dumped in the sea or nearby rivers or lakes.  For doing so there are strict requirements from the government about the quality of this water and the limits about the oil inside. In most countries these limits are 30ppm oil in the water. In some parts of the world, where already bad influence on e.g. coral reefs or the marine life is recognized, the local authorities request even better quality, before dumping the water in the sea.
The oil is removed by a row of mechanical devices and of course there are chemicals so called deoilers added to the water as well, in order to reduce the amount of oil. Essential to the quality of the water which is finally dumped, is the input to the effluent treatment plant.  As the effluent water is originated out of different process steps, such a s free water which separates easy from the crude, effluent water out of separation processes such as 3-phase separators or Emulsion Treatment plants, it is essential that these processes work proper in order to deliver as less as possible oil in the water.

Merus improves the quality of effluent water

If the Merus Rings are already installed in the different separation processes, the effluent water is cleaner, than water coming from untreated separation systems. It has been found the effluent water out of a treated separator has up to 30% less oil in it.
Receiving water with less oil from the beginning makes the job in the effluent treatment plant far easier. It shows as well the efficiency of the deoiler is increased, and delivers better results, with less added chemicals.

The ROI using Merus in effluent water.

Next to the savings of the deoiler, there are parameters which are more difficult to calculate.
If water which is brought back in the reservoir contains only 50ppm of oil instead of 100ppm, this sound on the first look not too much.  But doing the calculations, how much oil can be sold instead of dumped, astonishing figures will come out.  A Crude Oil Terminal receiving 200.000 bbls/day, with a water cut of 50% has to dump a day app. 100.000 barrel of water or app. 17.000 m3 of water a day.  Saving 50ppm per ton of water will result in 5 barrels a day. Again for a big oil company 5 barrels a day are nothing, but considering 5 barrels a day more dumped in the sea, is a very big figure for the environment and the marine live around the plant.



effluent treatment on FPSO




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