Estimation of Salinity of Salty Crude Oil Using Arrhenius-type Asymptotic Exponential Function and Vandermonde Matrix

Abstract

Abstract Production of wet crude due to increase in oil-water contact in many oil fields has been a growing field problem and it has affected the quality of crudes. In almost all cases, the salt is found dissolved in the water that is dispersed in the crude oil and its separation is not an easy task because desalting is considered a critical operation due to the importance of meeting the specifications of the acceptable quantities of salt and water in the treated oil. For these reasons, measurements of salt and water content in crude oils are very important in all oil industry operations including crude oil production, processing, transportation and refining. In this paper, an attempt has been made to formulate a simple-to-use method which is easier than existing approaches, less complicated and with fewer computations for accurate and rapid estimation of crude oil salinity as a function of brine quantity that remains in the oil, its salinity (in vol% of sodium chloride concentration) and temperature using an Arrhenius-type asymptotic exponential function and Vandermonde matrix. The proposed method predicts the Salinity of Salty Crude Oil for temperatures up to 373 K and sodium chloride concentrations up to 250,000 ppm (25% by volume). Estimations from the proposed correlation are found to be in excellent agreement with the reported data in the literature with average absolute deviation being 0.3%. The proposed method is superior owing to its accuracy and clear numerical background based on Vandermonde matrix, wherein the relevant coefficients can be retuned quickly for various cases. The tool developed in this study can be of immense practical value for the engineers to have a quick check on the salt content in the crude oil at various conditions without opting for any experimental measurements. In particular, petroleum and field engineers would find the approach to be user-friendly with transparent calculations involving no complex expressions.