Some special features of the desalting of carboniferous crude oils

Conclusions

• 1. Because of the use of nonionic demulsifiers at the oil fields, the dewatered crude oil contains a large quantity of surface-active substances which dissolve in the fresh water during the subsequent desalting. As a consequence of this, the surface activity of the waste waters from the desalination plant is many times greater than that of the water from the dewatering stage.

• 2. The surfactants remaining in the crude oil can be used to the greatest advantage for preventing the formation of stable emulsions during the contact between the dewatered crude oil and the fresh scrubbing water if the scrubbing is carried out immediately after the dewatering.

• 3. These two circumstances, due to the physicochemical properties of the nonionic reagents (being able to be salted out and going over into the oil phase under the influence of the electrolytes in the stratal water and the higher dewatering temperature), indicate the desirability of building petroleum pretreatment plants on the fields, incorporating a desalination stage.

• 4. To improve the desalination of heavy high-sulfur oil on the field and to remove at the same time other harmful acid components (hydrogen sulfide, carbonic acid, petroleum acids, and phenols) it is recommended that fresh water containing a certain quantity of caustic (NaOH or NH₄OH) be used. The consumption of the latter depends on the nature of the oil and the hardness of the water. For Arlansk crude oil, the NaOH consumption does not exceed 50 g/ton.