New methodology for heavy oil desalination

Abstract

The salts present in petroleum interfere in the characterization of its physicochemical properties, and from the measurements of these properties is established the price of crude oil. Therefore the water and salt need to be removed before these analyses. A new desalting apparatus was developed for heavy crude oils desalination by using demulsifier with water. The desalination process is accomplished in several washing steps and the extracted oil salts are monitored by ionic conductivity. Operational conditions were studied before and after the desalting process and the following parameters were evaluated: density, kinematic viscosity, total salinity index, total sulfur, total acid number and ionic conductivity. Using the proposed process it was possible to reduce the chloride content in the crude oil to values lower than 43mgkg−1 of sodium chloride in petroleum with extraction efficiency about 99.87%. After the desalination process it was not observed significant changes in the intrinsic oil properties, and after the fourth wash of the oil there was a reduction of approximately 33% of total sulfur and total acid number content. These results indicate an improvement in oil quality, once the presence of sulfur compounds in the oil is undesirable because it increases the polarity of the oil, thereby increasing the polarity of the emulsions. These compounds are also responsible for the corrosivity of the petroleum products and produce harmful gases during combustion. Variations about 2% in API gravity and 3% in kinematic viscosity were not significant, indicating no change in the physical properties of the oils. The proposed procedure is faster (about 80min) than the salt extraction method given by ASTM D6470 (about 140min) for four washing cycles and it was possible to obtain a suitable condition for salt removal from heavy crude oil emulsions without toxic reagents.