Empirical Equations for Estimating ADE of Crude Oils

Abstract

There has been an increasing interest in the construction of asphaltene deposition envelope (ADE) to determine a safe zone of operation during oil production. Equations of state are usually used for calculations of ADE; however, the method requires tuning some experimental Pressure Volume Temperature (PVT) data of the reservoir fluid. The objective of this study is to develop a simple, accurate, and reliable empirical equation for estimating the ADE by determining the upper and lower onset pressures as well as the saturation pressures. Three simple empirical equations are developed to calculate these onset pressures of several crude oils. Experimentally measured compositions, saturation, and onset pressures of 33 crude oil samples, primarily from the Middle East, at different temperatures were used to develop the equations. Another set of compositions and upper saturation and lower onset pressures of different crude oil samples from the literature were used to test the accuracy of the empirical equations. The results were also compared with equations of state predictions. The results indicate that the method is accurate, valid, reliable, and eliminates the splitting and characterizing of the heavy fraction, which is necessary for the equations of state predictions. The method is useful for estimating the ADE of crude oils where experimental data is not available.