CO2-brine interfacial tension correlation based on the classical orthogonal polynomials: monovalent salts with common anion

Abstract

Accurate estimation of CO2-brine Interfacial Tension (IFT) is of great importance since it is required to model the residual/capillary trapping of CO2 in geological formations. In this paper, a novel correlation is proposed based on the classical orthogonal polynomials to estimate the CO2-brine IFT of monovalent salts with common anion. To do so, CO2-brine IFT samples composed of samples from the literature and experimentally measured values using an in-house high-pressure high-temperature IFT measurement device were collected within a wide range of temperatures, pressures, and salinities. The utilized brines included NaCl and KCl salts. Then, a predictive model was developed based on the Group Method of Data Handling approach as a function of temperature, pressure, and ionic strength. The proposed method was compared with four methods from the literature in terms of average absolute percentage error (AAPE), coefficient of determination R2, histograms of error, and percent error plots. Results showed the superiority of the proposed method over other methods with an AAPE of 9.85 and R2 of 0.719. Also, it was shown that the proposed method did not produce too large errors, contrary to other methods. Therefore, the proposed method can be used reliably as a tool for CO2-brine IFT estimation in CO2 storage projects.