Background Oilfield preparation of hydrocarbons is one of the most urgent tasks in the development of oil fields. The depth of dehydration and desalination of oil significantly depends on the temperature of the emulsion, the process of interaction of the demulsifier and the result of their mixing. Aims and Objectives The aim of the work is to conduct experiments on the selection of demulsifiers for oils of Eastern Siberia. The research involved oils from the Danilovskoye and Ichedinskoye fields and demulsifiers: SNPKh 4802, DIN 4E. Metods Using sedimentation in cylinders (Bottle test), the indicators of the dehydration process of oil-water emulsions were analyzed. To maintain the temperature regime, the obtained oil-water emulsions were poured into cylinders with a volume of 100 ml and placed in a thermostat. Every 15 min, readings were recorded for the amount of settled water. The investigated physical and chemical parameters of demulsifiers contributed to the identification of the most effective for each field. The experiments were continued on the Lumifuge instrument, where the results were confirmed. The obtained graphs of the Danilovskaya and Ichyodinskaya emulsions with the addition of demulsifiers indicate that the separation of water has occurred and two phases have formed: oil - water. Results An analysis of the effect of demulsifiers on dehydration processes using the example of oils from Eastern Siberia showed that with the addition of a demulsifier, the completion time of the process is reduced by 2 times, and almost complete separation of water is observed. The choice of the optimal parameters of the demulsification process of the studied oils is substantiated: the consumption of the demulsifier, the temperature, the intensity of mixing.