If your separator sends wet crude to the tank, choose your demulsifier for crude oil emulsion with a bottle test on your own fluid. Do not choose it from a catalogue. A bottle test on a fresh sample from your station shows which crude oil demulsifier drops the water fastest, gives a sharp interface and meets your BS&W target, and at what ppm. We supply Demulsifier Premium from Barka, and we recommend a bottle test before any field trial.
What a demulsifier for crude oil emulsion does
Crude from the well carries produced water as fine droplets held in the oil. This is a water-in-oil emulsion. Natural stabilisers in the crude, mainly asphaltenes and resins, sit at the oil-water interface and form an interfacial film that stops the droplets from merging. A demulsifier, also called an emulsion breaker, is a specialty surfactant blend. It moves to that interface, pushes the natural stabilisers aside and lets the water droplets coalesce.
Larger droplets settle faster, and that settling is how crude oil dehydration works in a separator, a free water knockout or a desalter. Settling follows Stokes' Law: the speed rises with droplet size and with the density difference between water and oil, and falls as oil viscosity rises. This is why heavy, viscous crude is harder to treat.
Products in this class are usually blends of alkoxylated (EO/PO) resins, epoxy compounds and high molecular weight polyols in an aromatic solvent. Published heavy-oil work found two things. Mixed EO:PO alkoxylates did better than single alkoxylates, and blends of high and low molecular weight materials worked best in the field. Our Demulsifier Premium (RXSOL-16-2064-210) is listed in our rig and oilfield range.
Oil soluble demulsifier or reverse emulsion breaker
Most oilfield emulsions are water-in-oil, with oil as the continuous phase. They need an oil soluble demulsifier, usually carried in xylene or heavy aromatic naphtha and dosed into the oil stream. This is the primary emulsion breaker on a production station.
A reverse emulsion breaker is a water soluble demulsifier for the opposite problem: oil droplets held in produced water. It goes into the water phase, usually in a carrier such as methanol or ethanol, and you dose it separately from the primary product. Your separator may meet BS&W on the oil side while the water leg still carries oil to the skim tank. In that case you need both products, each with its own pump and injection point.
Why Oman crudes need a bottle test first
Asphaltene and paraffin wax content differ from field to field, and both stabilise the interface. A demulsifier that suits one crude can leave a thick rag layer on another. Crude composition and temperature decide which product works.
Southern Oman adds its own conditions. Marmul produces heavy, viscous crude under polymer injection, and polymer in the produced fluids makes the water more viscous and harder to treat. Water cut rises as a field ages, and the emulsion changes with it. Desert heat means a separator runs much warmer in July than in January, so a dose that works in summer can fall short in winter. Test on your own fluid at your own separator temperature, and test again when the season or the water cut changes.
Demulsifier bottle test, step by step
There is no single standard bottle test method, and procedures vary between operators. Whichever method you use, it has to be realistic, reliable and reproducible. Before you fill a bottle, do the groundwork on site:
- Record every chemical injection point on the station and measure the current injection rates.
- Check the system flow and choose a sample point that gives representative fluid. A manifold without a composite sample point gives you one well's emulsion, not the mix the separator sees. Sample upstream of the separator inlet, or sample the individual wells and combine them in proportion.
- Check how the treating vessels perform today: water in the oil outlet, oil in the water outlet, and the interface level.
- Take fresh samples from the producing wells, including any wells known for difficult emulsions.
A published field evaluation used this laboratory set-up:
- Fill 100 ml graduated screw-top bottles to 100 ml with emulsion. Screw caps stop light ends from escaping. Losing them would change the viscosity and spoil repeatability.
- Bring the bottles to field temperature in a water bath. The published range is 30 to 50 °C, and you should match your own separator temperature.
- Dilute each candidate demulsifier 10% in xylene so that small doses can be measured accurately. Add it by pipette at 30 to 200 ppm on total fluids.
- Shake each bottle 100 to 200 times by hand to mix in the chemical.
- Return the bottles to the bath and record water drop against time, for up to 6 hours.
- Give coalescence shakes during the test to imitate conditions in the separator, then record interface and water quality.
Reading the results: water drop, interface and BS&W
The water drop readings show how fast each product separates. The residence time of your separator sets how fast is fast enough, so compare the bottles at the time that matches your vessel. Then check three more things:
- Interface: a sharp line between oil and water is the goal. A ragged or thick layer is residual emulsion that will build up in the vessel.
- Water clarity: clear water means little oil is carried into the water leg. Cloudy or oily water shows oil carry-under, which may need a reverse emulsion breaker.
- Residual emulsion top cut: take oil from the 80% or 60% level into a 12.5 ml centrifuge tube half-filled with solvent. Heat to 50 °C, centrifuge for 10 min, and record emulsion and water as BS&W. Add a knock-out drop, centrifuge again and record total water. The mixed-cut test repeats this on the whole oil after you drain the free water.
Slow water drop and a high top-cut BS&W mean the crude is undertreated. Adding more chemical does not always help. In one published bottle test on a stable crude, efficiency passed 95% at 200 ppm. Doubling the dose to 400 ppm added only about 4 to 5% efficiency and used far more chemical. Choose the lowest dose that meets your pipeline specification.
From bottle test ppm to field injection rate
The typical treat rate for an oil soluble demulsifier is about 50 to 200 ppm. The figure depends on crude type and viscosity, water cut, temperature and how stable the emulsion is. In published field trials, doses ranged from about 5 to 100 ppm, and in one field the existing product treated crude at 36 to 45 ppm. Desalters usually need less, about 3 to 30 ppm. Your bottle test gives the figure for your own fluid.
To turn ppm into a pump setting, calculate on total fluid volume and on neat product, not on the 10% xylene dilution used in the bottles. The formula is: litres per day = ppm × total fluid litres per day ÷ 1,000,000. A station handling 2,000 m³ of total fluid a day (2,000,000 litres) at 50 ppm needs 100 litres of demulsifier a day. Start the field trial at the bottle test dose, then adjust it against measured BS&W.
A continuous injection pump can dose at the wellhead, at a pipeline dosing point or upstream of the separator inlet, which gives the chemical time to mix before the vessel. Batch treatment and storage tank treatment suit tank dehydration. Before a field trial, test the candidate in the lab with the other production chemicals on your station, such as corrosion inhibitor, scale inhibitor and H2S scavenger, to confirm they are compatible.
Storage, packing and where to buy demulsifier in Muscat
Solvent-based demulsifiers use a flammable aromatic carrier. Store drums in a cool, dry, ventilated area away from direct sunlight and heat. In an Omani summer that means shade and airflow, not an open yard. Keep containers tightly closed, and wear gloves and safety goggles when you decant. Typical shelf life for this class of product is about 24 months.
| Item | Detail |
|---|---|
| Part number | RXSOL-16-2064-210 (Demulsifier Premium), RXSOL-34-2064-200 (Demulsifier Premium, drilling fluids range), RXSOL-16-2064-025 (Demulsifier Emulsion Breaker) |
| Application | Breaking water-in-oil emulsions at wellheads and production separators, free water knockouts, pipelines, desalters, electrostatic dehydrators, tank dehydration, polymer-flood produced fluids and heavy crude (typical for this product class) |
| Typical dosage | About 50 to 200 ppm for oil soluble types. Confirm the dose with a bottle test on your own fluid. |
| Typical properties | Yellow to brown liquid, mild aromatic odour, density about 0.85 to 0.98 g/cm3, flash point above 60 °C, pH 5 to 10, active content 50 to 80% (typical of the class, varies by formulation) |
| Packing | Products in this class are commonly supplied in 200 L HDPE drums or 1000 L IBC tanks. We confirm your pack size in the quote. |
Oman Chem (Muscat & Barka for Business Trading) is based in Barka Industrial Area, Sultanate of Oman. Call +968 77333599, message us on WhatsApp or email muscatchem@gmail.com, and tell us about your bottle test requirement. Our rig and oilfield chemicals range also lists Demulsifier Premium RXSOL-34-2064-200 for drilling fluid work and the general Demulsifier Emulsion Breaker RXSOL-16-2064-025.
The same emulsion breaker is also listed on Sohar Chemical and on Muscat Chemical.
To request a quote, message us on WhatsApp at +968 77333599 or use our quote request form. Send your crude type, water cut, separator temperature and daily total fluid volume with the request.
Frequently asked questions
What dosage of demulsifier is needed in ppm?
The typical treat rate for an oil soluble demulsifier is about 50 to 200 ppm, depending on crude type and viscosity, water cut, temperature and emulsion stability. Published field trials ranged from about 5 to 100 ppm, and desalters usually run lower, at about 3 to 30 ppm. A bottle test on your own crude gives the right figure. Choose the lowest dose that meets your BS&W specification.
At what temperature should a demulsifier bottle test be run?
Run the test at your field or separator temperature. A published method used a water bath at 30 to 50 °C, and desalter testing is typically done at about 180 °F (82 °C). In Oman, separator temperatures differ between summer and winter, so repeat the test when the season changes.
What is the difference between an oil soluble demulsifier and a reverse emulsion breaker?
An oil soluble demulsifier is the primary emulsion breaker. It is dosed into the oil phase to remove water from a water-in-oil emulsion. A reverse emulsion breaker is water soluble and is dosed into the water phase to remove oil from produced water. The two products are dosed separately.
Why does a demulsifier that works on one crude fail on another?
Asphaltenes, resins and paraffin waxes stabilise the oil-water interface, and their amounts differ from crude to crude. Temperature, viscosity, water cut and polymer in the produced fluids also change how the emulsion behaves. For these reasons, test each crude by bottle test before a field trial.
Who supplies demulsifier in drums or IBCs in Oman?
Oman Chem supplies Demulsifier Premium (RXSOL-16-2064-210) and related emulsion breakers from Barka Industrial Area. Products in this class are commonly supplied in 200 L HDPE drums or 1000 L IBC tanks, and we confirm your pack size in the quote. Call or message +968 77333599.
