Selection and types of crude oil demulsifiers are introduced

Chemical demulsifiers can be divided into ionic and non-ionic demulsifiers according to their molecular structure. When the demulsifier soluble in water, who can ionize the formation of ions, called Ionic demulsifier; where in the water solution can not be ionized, called non-ionic demulsifier. IONIC demulsifiers can be divided into anions, cations and amphoteric ions according to their ionic electrical properties, which have surface activity in aqueous solutions. Sodium alkylsulfonate and sodium alkylbenzene sulfonate used in the early stage are anionic demulsifiers which have good dehydration effect on crude oil.

Non-ionic chemical demulsifiers are synthesized from Oxirane, 1,2-epoxypropane and other basic organic synthetic materials by following a certain procedure in the presence of catalyst and initiated by an active hydrogen initiator. The ratio of raw materials, operating conditions, molecular weight and other parameters can be artificially controlled in the synthesis. The molecular weight is above 50000, has the high activity and the good dehydration effect.

Compared with ionic chemical demulsifiers, nonionic chemical demulsifiers have the following advantages: 

(1) less dosage. The dosage was about 20 ~ 50 MG/L,

 (2) no precipitation was produced. Generally not with the oil-water mixture of salts and acids from the chemical reaction, in the pipeline and equipment to produce precipitation; 

(3) less oil in the dewatering. Non-ionic chemical demulsifiers only destroy w/o emulsions, which do not produce o/w emulsions during demulsification. The water is clear and contains less oil. 

(4) the dehydrating cost is low. Although the unit price of non-ionic demulsifier is higher, the dosage is only a few tens of the IONIC demulsifier, so the dehydrating cost of crude oil is reduced. 

Because of the advantages of non-ionic demulsifier, it has replaced Anionic demulsifier in crude oil dehydration and plays a very important role. According to the Solubility, non-ionic demulsifiers can be divided into three types: water-soluble, oil-soluble, partially soluble in water and partially soluble in oil. 

(2) the characteristic of oil-soluble demulsifier is that the demulsifier can not be carried away by the dehydrating water, and the concentration of demulsifier in crude oil increases gradually with the dehydrating water, which is beneficial to the continuous decrease of the water cut of purified crude oil. The molecular weight of oil-soluble demulsifier is higher than that of water-soluble demulsifier, and the ability of purifying oil is higher than that of water-soluble demulsifier. 

(3) the demulsifier which is partly soluble in water and partly soluble in oil can increase the flexibility of use.