Prediction of Salinity of Salty Crude Oil Using Arrhenius-Type Asymptotic Exponential Function and Vandermonde Matrix

Abstract

Summary Production of wet crude because of a rise in the 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, salt is dissolved in the water that is dispersed in the crude oil and its separation is not simple because desalting is a critical operation because of the importance of meeting the specifications of 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, and transportation and refining. In this paper, we attempt to formulate a method that is easier than existing approaches, that is less complicated and requires fewer computations for accurate and rapid estimation of crude-oil salinity as a function of the quantity of brine 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 the 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 engineers, providing a quick check on the salt content in the crude oil at various conditions without the necessity of any experimental measurements. In particular, petroleum and field engineers would find the proposed approach to be user friendly, with transparent calculations involving no complex expressions.