The researches on the mechanism of the emulsified crude oil demulsification

This paper discusses the cause of emulsifying crude oil, the harm of transporting crude oil emulsion are reviewed in this paper. In order to get the better results before the emulsified crude oil transport, demulsification mechanism was proposed.

After the block finished the first produce, we use the method to inject the water or steam to enhance oil recovery efficiency. At this time, the moisture content of the water injection,steam injection well group will rise rapidly, and will produce the emulsion crude oil.

The emulsion crude oil means with crude oil emulsion liquid as a dispersed phase and dispersion medium, W/O emulsified oil is crude oil emulsion of collectively known as dispersion medium, a production and secondary oil recovery of crude oil emulsion is W/O emulsified oil. With crude oil dispersed phase emulsion as O/W type emulsified oil, tertiary recovery of crude oil emulsion is O/W type emulsified crude oil.

Every oil fields will encounter this problem when the oil production into the middle and later. The crude oil emulsion is getting more stable, because the content of colloid and asphaltene in the crude oil increases. In addition, with the development of new technology, a lot of surfactant flooding, make the composition of crude oil is relatively complex, produced oil rate of aqueous salt increased, but most of produced crude oil emulsions are O/W type emulsified crude oil. To the dehydration of crude oil desalting work put forward higher requirements. Because water cut of crude oil emulsion in the process of transportation will corrosion of pipeline, storage tank and pump and other metal objects, a corrosive action on metals, or on the surface of the metal equipment structure. Because the well of the crude oil emulsion, higher viscosity, friction resistance increases, so before the crude oil emulsion are exporting all through professional technology for dehydration of crude oil emulsion. Emulsified crude oil dehydration methods are: heat method, chemical method and electrical method.These three methods generally not used alone, often link up with others, most of them are chemical method. Chemical emulsification of crude oil dehydration hair to use chemical agent, demulsifier is the current our country around the oilfield demulsifier dosage is about 20000 tons.


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The whole process of dehydration of crude oil emulsion is actually use chemicals to make oil/water separation, and the principle of heavy oil by water light, when crude oil through a special device, make water sink, oil and water separate.2.1 W/O emulsified crude oil demulsification mechanism of demulsifier low molecular chemical dehydrating of crude oil is mostly belongs to water-soluble (HLB value > 8), relative to the W/O emulsified oil chemical dehydrating agent, between them is the opposite type of chemicals, W/O emulsified crude oil demulsification principle is through the role of the offset chemical dehydrating of crude oil to achieve the purpose of dehydration. Chemicals are the same with the offset effect and high polymer chemical dehydrating of crude oil in the water soluble chemical dehydrating of crude oil, the oil soluble demulsifier chemical dehydrating of crude oil is also efficient, is it the emulsion breaking principle of actually not by this effect. The original chemical dehydrating dehydrated polymer through the following main functions:

1 completed through the formation of the adsorbed film
Because polymer chemical dehydrating of crude oil is blood adsorption layer on the interface after instead of emulsifier, which is formed by the adsorption film unstable, so it's not tight, that his protection relatively speaking is very poor.

2 Aggregation of water droplets
It was able to gather water droplets because polymer emulsion breaker has a strong adsorption, the adsorption effect of it can be caused by adsorption in a number of water droplets on the interface at the same time, through the adsorption, the droplets have more chance of collision together, together.

Solubilization mechanism
The demulsifier used by one or a few molecules can form micelles, the polymer thread or micellar solubilization emulsifier molecule, so that the emulsified crude oil/water separation.

O/W emulsion breaking principle of emulsifying crude oil dehydration
The dehydration process is mainly through the electrolyte, low molecular alcohol, compound and surface active agent, such as composition of demulsifier is different, the principle of demulsification are also quite different:
(1) also played a large role in the electrolyte, it produced by reducing oil bead surface of negative charge and change the shape of incompatible principle of emulsifier to complete.
(2) molecules with low alcohol is by making the polarity of the increase of crude oil, the polarity of the water, thereby decreasing to the composition of emulsifier to move to the oil content is high, or swam to high water content which have the effect of dehydration.
(3) surface active chemical agents is through chemical reaction with the emulsifying agent, so as to form weak adsorption film and offset function, the cause and demulsification dehydration.
(4) gathered compounds mainly by connection, the principle of the effect of demulsification. Because of demulsifier composition is different, the principle of demulsification are very different, so the use of demulsifier composite configuration.

The conclusion
Is an essential part of today's crude oil dehydration demulsifier additives, with large oil field of our country has entered high water cut period, how to ensure that in the process of demulsifier on the demulsification efficiency and economy is the urgent problems at this stage, because only the problem solved to meet the needs of oilfield development and oil and gas gathering and transferring, to speed up the vigorous development of the oil industry.