(334d) A Practical Molecular Thermodynamic Model for Asphaltene Aggregation | AIChE

(334d) A Practical Molecular Thermodynamic Model for Asphaltene Aggregation


Chen, C. C. - Presenter, Texas Tech University

One of the most challenging properties of petroleum fluids is crude oil compatibility. Asphaltene molecules precipitate or aggregate when one blends “incompatible” crude oils (Shen, 2002). Such crude oil “incompatibility” often results in significant negative economic impact. Therefore it is highly desirable to advance theoretical understanding of crude oil compatibility and develop robust thermodynamic models to describe and predict crude oil compatibility.

Recent advances in molecular characterization of petroleum fluids make it possible to derive optimal chemical compositions of representative hydrocarbon constituent molecules for crude oils and petroleum fractions from correlating readily available petroleum assay data. From such chemical compositions one could then estimate and predict wide ranges of physical and chemical properties of petroleum fluids rigorously and consistently.

In this work we present a novel and practical molecular thermodynamic framework for modeling crude oil compatibility. Chemical compositions of representative hydrocarbon constituent molecules, including asphaltene molecules and their compositions, are first identified from readily available assay data for crude oils of interest. Aggregation of asphaltene molecules is described with the Yen-Mullins molecular model (Mullins, 2010). Liquid phase nonideality of molecular species in petroleum fluids is modeled with the NRTL-SAC conceptual segment activity coefficient model of Chen and Song (2004). Model parameters including asphaltene aggregation constant and conceptual segment numbers for asphaltene molecules are then derived from appropriate literature data.

Shen, E.Y., Petroleum Asphaltene-Properties, Characterization, and Issues, Energy & Fuels, 2002, 16, 74-82

Mullins, O.C., The Modified Yen Model, Energy & Fuels, 2010, 24, 2179-2207

Chen, C.-C. and Song, Y., Solubility Modeling with a Nonrandom Two-Liquid Segment Activity Coefficient Model, Ind. Eng. Chem. Res. 2004, 43, 8354-8362