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High Salt Content In Crude Oil Pipeline Metering Station


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#1 Dandy Komboris

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Posted 27 May 2012 - 10:40 PM

Dear Everyone.

I am fresh engineer who is working on Oil & Gas Company in Indonesia.
I have a problem in my Crude Oil. Its salt content is so high above 20 Ptb this week.
Our pipeline length is 265 Km, API is aroun 32-34, Temperature 85 Celcius, BS&W is around 0.3-0.5
Also there are so many leakage in our oil pipeline because local people have been stealing our oil for years.
My question are :
What are factors that can increase Salt content in Crude oil in pipeline, since the salt content from the source is not very high like in the metering station right before the Refinery???
Is the leakage can contribute to the high salt content ?
Is it possible to build mini desalter unit in the metering station ??

I really appreciate any help from you..

#2 Technical Bard

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Posted 29 May 2012 - 12:04 AM

Leaks cannot possibly ADD material to the oil - therefore, all the salt in the oil at the end of the pipeline was in the oil at the beginning of the pipeline. Your oilfield source is not properly treating the oil to remove the produced water (brine) down to an appropriate level. They may need an electrostatic treater/desalter to meet your requirements. Failing that, a desalter will need to be added in the refinery.

#3 Dandy Komboris

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Posted 29 May 2012 - 08:06 PM

Dear Bard.

There are many shippers (oil producer) that use our pipeline to transport the crude oil to Refinery Unit, but none of them have Electrostatic treater/desalter unit. I was thinking membrane Reverse Osmosis or Ultrafiltration can help to reduce the Salt Content in Crude oil. What do you think about that ? Is electrostatic treater/desalter unit only the way to solve my problem ?..
One more, My company handle the Oil Trasportation, you can say we are the Transporter. We do not own the oil, we just send the oil to the Refinery Unit.
Is there any device that can be attached in the oil pipeline that can reduce the Salt Content ?

#4 Technical Bard

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Posted 31 May 2012 - 05:38 PM

Salt in crude oil is usually present not in the oil phase itself, but in the small water droplets suspended in the oil. There are rare cases where crystalline salt has been found in crude oils, which is a much more difficult scenario.

The only technologies I have ever seen used to remove this salt water (brine) from the oil are electrostatic desalters and centrifuges. As you are the transporter, you should not have any responsibility for the oil quality, except to ensure that water is not accumulated in tankage or during tank transfers (i.e. don't pump tank bottoms into product lines prior to draining water). The responsibility for treating the oil must be either the producer or the refiner.

#5 Dandy Komboris

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Posted 01 June 2012 - 03:11 AM

Dear Brad
Indeed you are right. But we do have special case in our Location.
Firstly, many local people rob/steal our oil from the pipeline. Because of the leak, there are so many oil spill. By using Vacuum system we take the oil and then we store it into the Tank (slope Tank).
Secondly, most of producer do not drain the water in Oil Storage Tank before inject the oil into our pipeline..
Could it be one of the factors that causes Salt accumulation in our Oil Pipeline ?
Did you mention Centrifuges ?
Do you mean Centrifuges like Centrifuge System in Water Treatment Plant ??

#6 Technical Bard

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Posted 01 June 2012 - 06:59 PM

The failure of producers to drain water from their tanks is probably the cause of your salt problem. Slop oil picked up off the ground may also be a contributor if you are doing this very near the ocean.

Stacked Disc centrifuges can be used to separate oil and water, but this is an expensive route to do on a large scale. I would prefer an electrostatic desalter.

#7 kkala

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Posted 06 June 2012 - 03:18 PM

Though experience is limited in some PIDs around a refinery desalter, below are some views on the matter.
1. Taking oil out of pipeline does not logically add salts to the transported crude.
2. Since most producers do not dewater the crude (post No 5), preliminary dewatering at vicinity of metering station could alleviate the problem. http://www.cheresources.com/invision/topic/10526-dewatering-of-crude-oil-tanks/. This would result in oily wastewater, which would rather be treated locally, then disposed off.
3. Slope tank content could also undergo dewatering and probably filtration before mixed with the crude for transportation.
4. Crude passing from electrostatic desalter needs heating to reduce its viscosity, http://www.setlaboratories.com/desaltin/tabid/109/Default.aspx. This heating may not be economic far from the refinery. Refinery realizes efficient heating in the first preheating train (complex set of numerous exchangers), then electrostatic desalter is used, then further heating, then introduction to distillation column.
5. Deposits along the pipeline is assumed to occur, which could be probably alleviated by adding hot demineralized water into the crude to be transfered (not having heard of such a method before). Crude will be desalted in the refinery at any case.
6. Such actions and similar can be done by the refinery rather than the transporter, after systematic lab measurements to clarify the situation.

Editing note 8th Jun 12: W L Nelson in "Petroleum Refinery Engineering" (4th ed, McGrawHill 1958), Chapter 9 (Refinery Corrosion and metals), para of "Processing Sour Crudes", point D (desalting) reports "Injection of caustic ahead of settlers to a pH of 8 or 9 helps corrosion and aids settling".

Edited by kkala, 08 June 2012 - 04:23 AM.


#8 sidibouziane

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Posted 13 June 2012 - 09:32 PM

good day.

as stated by the forum members, that the source should be the non drained water in your tanks or whatever you pick up as a slope.

i do recommend to look for the VIEC technolgy to be applied. as you are the shipper and it looks that you are the pipeline owner, why dont you go for an life time investment. you can google the tech and decide.
regards

#9 Dandy Komboris

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Posted 14 June 2012 - 09:42 PM

Dear Kkala

The Oil Producers transport the oil through pipe line directly from production wells. The length of oil pipeline is 265 Km. None of our Booster Station has dewatering system for crude oil. Nevertheless, some of our booster station has Water Pond. I wonder If I drain the water from the slope tank, what would be the best method to assure that water is safe before we send it to the environment or store it into the water pond ? What kind of purification method to do that ?

#10 Dandy Komboris

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Posted 14 June 2012 - 09:48 PM

Dear sidibouziane

VIEC (Vessel Internal Electrostatic Coalescer)...
Is it possible to install this equipment in our pipe line ??

#11 kkala

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Posted 20 June 2012 - 03:22 AM

Referring to post No 9, drain water from refinery tanks is directed to waste water treatment and undergoes following treatment in brief, together with waste water of other sources.
1. Passing from API separator (separated oil / water phase usually returns to slop tank).
2. Air floatation, http://en.wikipedia.org/wiki/Dissolved_air_flotation, where oil and solids are brought to surface by air bubbles, creating a sort of "cream" on the surface, which is collected.
3. Biological treatment, so that developed bugs consume remaining oil. This can be specific, according to remaining oil components and can create sludge as byproduct.
After these stages, waste water can be directed to the receiver, on the condition that dissolved salts are within legal limits (which is usual case for refineries). Resulting sludge, or remaining of floatation cream, may be exported for further treatment.
Above is rough information from others, since Process here has not dealt so far with waste water treatment (it will).

Having asked the opinion of a Petroleum Engineer (specialized in Refineries, not in wells anyway), he said that first stage desalting (even using electrostatic desalters) should have been done close to the wells by the oil producers (not in the "terminal" of your company); and that disposal of waste water from the "close to wells" treatment can have a lot of difficulties.
Waste water from tank stations here are locally pumped to local refinery, being at a distance of about 20 - 30 km.

Edited by kkala, 20 June 2012 - 03:29 AM.





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