The Coefficient of Isothermal Compressibility of Black Oils

This paper presents a new correlation for the coefficient of isothermal compressibility of black oils at pressures above the bubble point. The correlation is expressed as an empirical function of oil relative density at bubble point pressure, reservoir temperature, bubble point pressure and the reservoir pressure. A total of 3412 data points from 186 laboratory PVT analyses from Middle East fields were used to develop the oil compressibility correlation. The data encompassed a wide range of gas-oil ratios, oil and gas relative densities, reservoir pressure, and reservoir temperature. Multiple linear and nonlinear regressions were used to develop this model. This model is chosen from large number of models tested. The evaluation of the correlation includes comparative studies of the new and existing mathematical models of oil compressibility correlation. The model is validated by using three different data sets from other geographical region of the world not used in the development of the model. The newly developed mathematical model and correlation outperforms the existing mathematical models and correlations for oil compressibility based on low value of average absolute percent relative error and standard deviation.