Bitumen Characterization and Pseudocomponents Determination for Equation of State Modeling

Abstract

The phase behavior and thermodynamic properties of heavy oil and bitumen are of crucial importance for their in situ recovery, pipeline transportation, and upgrading; however, bitumen is a complex mixture of organic compounds whose chemical structures are not well understood. Therefore, bitumen is commonly characterized as a mixture of pseudocomponents derived from experimental data. This manuscript is intended to characterize and define the thermodynamic properties of Alberta bitumens. It has been undertaken three specific objectives: the first is the characterization of the bitumen as a mixture of pseudocomponents. The second objective is calculation of the gas solubility of gas-saturated bitumens by using an equation of state (EOS). The final objective is the selection of a set of pseudocomponents that would be applicable for different types of bitumen; in other words, the pursuit of a universal set of pseudocomponents for an EOS, independent of bitumen type. Varying numbers of pseudocomponents have been tested against the experimental data in the literature for bitumen from different fields (Athabasca, Wabasca, Peace River, and Cold Lake) with four different solvents (CH4, C2H6, CO2, and N2). The results show that the Lee−Kesler correlation (Lee, B. I.; Kesler, M. G. AIChE J. 1975, 21, 510−527) has produced considerably better results than the other correlations; it also appears that the Lee−Kesler correlation is appropriate for bitumen/solvent systems to determine the critical properties of the pseudocomponents.

Prediction of solubility of CH4, C2H6, CO2, N2 and CO in bitumen

“…Experimental data in the vapour-liquid-liquid (VLL) region cannot be represented accurately by the proposed model. However, this inaccuracy has also been reported for other predictive models, such as those of Kariznovi et al [3] and Mehrotra and Svrcek. [2] Experimental solubility data of CO 2 in Cold Lake bitumen for temperatures up to 523.15 K and pressures up to 16 MPa have been reported by Yu et al [14] Experimental solubility data of CO 2 in Peace River bitumen for temperatures up to 473.15 K and pressures up to 10 MPa have been reported by Mehrotra et al [18] Our proposed model showed good accuracy in representing the experimental solubility data of gaseous and super critical CO 2 in bitumen, as illustrated in Figures 5 and 6.…”

“…Therefore, we use the same terminology throughout this article. Letting subscript s and superscript b refer to the solvent and bitumen, respectively, we can write the equality of fugacity for the dissolved gases in the gas and bitumen phase at equilibrium condition as: Mehrotra and Svrcek [19] Proposed model 1.79 287.85-371.35 2.14-10.95 Kariznovi et al [3] 8.89 Eastick et al [5] 6.8 A 3152.545 Mehrotra and Svrcek [2] 1.9 Yu et al [14] Proposed Huang and Radosz [9] 5.675 Huang and Radosz [8] 5.44…”

“…Kariznovi et al [3] 8.77 A 3059.686 Mehrotra et al [6] 9.3 Mehrotra et al [18] Proposed [3] 8.88 v 1 s 69.535-0. 076T Mehrotra et al [7] 5.7…”

“…Mehrotra and Svrcek [24] Proposed model 6.37 284.65-377.65 1.47-6.25 4 Kariznovi et al [3] 19.91 v 1 s 232. 328 Mehrotra et al [7] 17.2 VOLUME 92, MARCH 2014 THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING …”

“…5 Kariznovi et al [3] 3.74 Fu et al [4] Proposed [3] 7.51 v 1 s 58.592 þ 0. 6914T Mehrotra et al [7] 8.6 [19] Proposed model 3.12 296.05-375.85 1.02-10.07 Mehrotra and Svrcek [2] 5.7 A 7101.63 Kariznovi et al [3] 7.64 Fu et al [4] Proposed [3] 6.56 v 1 s 173.64 À 0. 1156T Mehrotra et al [7] 4.1…”