Demulsifiers - Chemicals Services
During the production process, the fluids experience significant shearing in different locations, including the perforated zone, the downhole pump and the wellhead. Emulsifying agents naturally present in the crude oil, such as asphaltenes and the soaps of linear and aromatic organic acids, along with solids such as clays, sand and scale, stabilize the crude oil water interface and make the emulsions difficult or slow to separate. In most oilfield applications, the initial crude is an oil-continuous emulsion that, upon treatment, can invert to become water continuous, requiring the use of deoilers, which are covered separately.
Due to the high throughput requirement of most oilfield separation systems, gravity separation of the emulsions is insufficient, particularly if the relative gravitational difference between hydrocarbons and water is negligible - e.g., steam-assisted gravity drainage (SAG-D). Therefore, assistance is required to achieve satisfactory throughput.
To achieve optimized demulsification, natural gas needs to be removed from the fluids to encourage quiescent coalescence of the emulsion. This is Physically aided through heating of the oil and/or the emulsion pad. This helps melt waxes and reduces the crude oil's viscosity, allowing the water droplets to settle out more quickly. However, by far the most common treatment to help break the emulsion is the addition of formulated chemical demulsifies. These chemical additives are usually injected at the wellhead to achieve adequate mixing prior to the separator so that the demulsifier
During the production of crude oil, a multi-phase fluid is produced.Co-produced with the oil are natural gas and an amount of water, usually saline, which as the reservoir is depleted, can be present in quite large proportions, an reach the target interface and function effectively.
To reach the surface of the emulsified water droplets, the Demulsifier blend must have the right Solubility. The chemical Demulsifier is attracted to the emulsifying agent through differences in polarity. Once at the target, it neutralizes the effect of the emulsifying agent, allowing the finely dis parsed Water droplets to coalesce upon contact. As the Water droplets increase in size, they tend to settle, separating the water from the oil. The stability of an emulsion is unique to each reservoir, and may vary from well to well.
As such, it is necessary to develop demulsifier blends specifically targeted at fluids produced. Our Demulsifier products should be considered as concentrated raw materials, or intermediates, for the preparation and/ or formulation of oilfield demulsifies and dehydrating chemicals. Field demulsifies are usually blends of two or more intermediates, Selected on the basis of their performance in bottle tests and centrifuge tests, the methods of which can be found in separate publications. These tests help identify the products that produce the maximum amount of water and the cleanest oil. The samples should be examined for fastest water drop, sledging, quality of the interface, and quality of the water.
The best-performing candidates should have bottle tests repeated using different combinations and concentrations until eventually the best performance blend is found.
Relative Solubility Number
Another useful guide in formulation is the relative solubility number (RSN), which helps eliminate some of the trial-and-error involved in formulating demulsifies blends. The value assigned to each product indicates its relative solubility in water.
As the numerical value increases, water solubility increases. Generally, products with a solubility number below 13 are insoluble in water. Products with solubility between 13 and 17 are dispersible in water at low concentrations and form gels at high concentrations. Products with values of 17 and above are completely water-soluble.
The following are general guidelines for the RSN system:
For crude oil emulsions, a demulsifies formulation should have an RSN between 8 and 15. The RSN values combine algebraically. For example, a 50-50 blend of a product with an RSN of 10 and a product with an RSN of 20 will yield a blend RSN of 15.
In general, synergistic action between intermediates makes demulsifies blends better than single-component formulations.
Demulsifies with either very low or very high RSN values are seldom used individually; their properties can be best utilized by blending.
Due to synergism, blends of intermediates from different chemical groups make better demulsifies than blends using intermediates from the same family of compounds. Some demulsifier bases have special properties that give them very good blending characteristics.
This is the case with highly oil-soluble (low RSN) polglycols.When blended with ox alkylated resins, some Combinations include ox alkylated resins blended with polyols, dioxides or polyacrylate-based intermediates. To dehydrate crude oil to a sufficient level to achieve export quality, a combination of water droppers and oil dryers need to be used in the final demulsifier blend. While the droppers may work very quickly due to flocculation of large droplets, usually the base sediment and water (BS+W) will be greater than 1 percent - not sufficient to complete the job.
Drying demulsifies help reduce the water content further via coalescence of the fine emulsion droplets, but this function usually takes longer. A balanced formulation of droppers and driers is usually required to achieve target. Typical dropper/drying characteristics of individual demulsifies are given.
Desalting
Another important demulsifier application occurs at the refinery and is referred to as desalting. The imported crude oil arriving at the refinery contains up to 1 percent water, which will contain significant amounts of dissolved salts. The refining process relies heavily on catalysts that will be poisoned if they are contacted by such salts, so the import crude is mixed with freshwater to remove these salts. The coalescence of the resulting emulsion is encouraged using an electrostatic grid and specialty desalting demulsifies that yield crude suitable for refining.
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