engleski

A contribution to predicting the properties of petroleum fluids

Petroleum fluids (crude oil, gas condensate, and their derivatives) are highly complex natural mixtures in the sense that they contain too many components to be identified and analyzed. This is why they are difficult to represent thermodynamically. Nevertheless, such mixtures can be characterized after splitting them into fractions and after determining the properties of each fraction (e.g., molecular weight, boiling point, density, viscosity, etc.). Phase equilibria in such mixtures are usually computed by standard tools such as the pseudo-component method, which assumes that each fraction is a mixture of predefined pure components. The sheer number of components and/or their poorly defined structure require simplifications, which are more or less justified for fractions of a molecular weight higher than 100. Phase equilibrium calculation is therefore simplified by substituting these fractions with corresponding mixtures of well-defined model components, in order to evaluate averaged characteristic parameters. Based on our previous research, here we present a simplified method for characterizing heavy petroleum fractions and for predicting vapor–liquid equilibria. The required input data include complete TBP analysis, PNA analysis, and density data, preferably for each sub-fraction. Known thermodynamic procedures are used to estimate the critical data, acentric factor, and molecular weight for the model compounds. The calculated thermodynamic properties are in a very good agreement with the corresponding experimental values for light to medium crude oil fractions. Additional experimental data are needed to obtain more reliable results for fractions with a TBP above 600 K.

petroleum fluids; VLE; prediction

http://www.omicsgroup.com/conferences/petrochemistry-chemical-engineering-2013/scientific-programme.php?day=2&sid=132&date=2013-11-19