Improved Estimation of Bubble Point Pressure of Crude Oils: Modelling by Regression Analysis

Abstract

Abstract The Bubble Point Pressure of crude oil is a critically important property for the description of reservoir fluid behaviour. Accurate estimation of such properties is required for important reservoir and production engineering calculations such as reserve estimation, production forecasting and design of Enhanced Oil Recovery (EOR) projects. A comprehensive literature review was carried out to understand and analyze the limitations of currently available methods for estimation of bubble point pressure. A large database consisting of the compositional analysis, temperature and measured bubble point pressure of more than 140 crude oil samples of varying geographical origins was compiled. The parametric form of the model was constructed based on the analysis of trends from collected experimental data and theoretical inputs. The model was then calibrated, using non-linear regression techniques, to a major portion of the data set. The remaining data was used to validate the calibrated model and verify its conformity to physical processes. The performance of the model was then compared and found to be more accurate than existing methods such as Equations of State (EOS). The various applications of this new model to the simulation of Liquid-Vapour phase boundary were explored. Laboratory experiments such as the swelling test were simulated using this model and the predictive performance was found to be better than that of an EOS. These laboratory tests, especially swelling tests, are integral for the design of miscible flooding EOR projects. Other applications and modifications of this model were also such explored in the latter portion of this work. It is concluded that the performance of this new model is better than other current methods when operating in a purely predictive mode and that the model could be manipulated as a powerful tool for applications which require identification and simulation of the Liquid-Vapour phase boundary.