METHOD FOR DESALTING CRUDE OIL

摘要

The salt content of crude oil is reduced by washing it with at least 1% by volume of wash water of lower salinity than the water present in the crude oil and separating the resulting mixture of oil and water into a layer of crude oil of reduced salt content and a layer of saline water containing some oil. The latter is passed through a cross-flow membrane separator and the oil-free permeate is removed from the separator as effluent. The oil retentate is recycled from the separator to the washing stage and a quantity of lower salinity than the water associated initially with the crude oil is added to the washing stage. The quantity of added water corresponds at least to the volume of permeate removed from the cross-flow membrane separator. Since the oil is recycled, the need for oil recovery plant for treating desalter effluent is removed.