An empirical model for estimating the saturation pressures of crude oils

Recently, there has been an increasing interest in enhanced oil recovery (EOR) calculations of saturation pressures when various gases contact crude oils. Equations of state are usually used for calculations of saturation pressure at initial condition of discovery or later during EOR design. However, the equations of state results are not reliable unless they are properly tuned using some experimental data of reservoir fluid. The availability of extended analysis of reservoir fluids, characterization of heavy fraction, and number of components are influencing the saturation pressure estimated by equations of state. A simple empirical model to calculate the saturation pressures of crude oil systems was developed. Experimentally measured compositions and saturation pressures of 60 crude oil samples from the Middle East were used to develop the model. Compositions and saturation pressures of 75 crude oil samples from the literature were used to test the accuracy and validity of the model against measured data and simulations by equations of state. The results indicate that the model is accurate, valid, reliable, and eliminates the splitting and characterizing of the heavy fraction, which is necessary for the equations of state. The model is useful for estimating the saturation pressure where experimental data is not available. For EOR processes, the model can be used to calculate the saturation pressure during single contact by hydrocarbon gases. (C) 2003 Elsevier Science B.V. All rights reserved.