Theoretical analysis and comparison with experimentation of the molecular and thermal diffusion coefficients for a ternary hydrocarbon mixture

Abstract

The thermal diusion phenomena, also known as the Soret eect, is important for the study of compositional variation in hydrocarbon reservoirs. Several theoretical models have been developed over the years to predict the thermodiusion coefficient of an organic mixture. Firoozabadi et al. [1] developed an analytical relationship between the thermal, molecular, and pressure diusion coefficients based on the approach of Dougherty and Drickamer [2]. The distinctive feature of Firoozabadi's model is its ability to be used not only for binary mixtures but also for multicomponent mixtures. The verification of Firoozabadi's model by numerical simulations was limited to binary mixtures only because of a lack of experimental data on thermodiusion coefficients in multicomponent hydrocarbon mixtures. However, Platten et al. [3] were able to measure the thermodiusion coefficients of a ternary hydrocarbon mixture experimentally by utilizing the thermogravitational column technique, hence making it possible to verify the theoretical model. This paper will compare the density, thermodiusion, and molecular diusion coefficients obtained with the Fontainebleau benchmark values for binary mixtures of n-dodecane, isobutylbenzene, and tetrahydronaphtalene. The accuracy of the numerical results from the Firoozabadi's model for ternary hydrocarbon mixtures is investigated. Results reveal a positive agreement between experimental and numerical data. © Copyright 2005 Walter de Gruyter.