ChemInform Abstract: Self‐Diffusion in the Compressed Fluid Lower Alkanes: Methane, Ethane, and Propane.

Greiner‐Schmid, A.; Wappmann, S.; Has, Michael; Luêdemann, H.-D.

doi:10.1002/chin.199135042

Cited by 3 publications

(4 citation statements)

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“…Values of the mutual diffusion coefficient for Peace River bitumen þ propane as high as 10 -7 m 2 s -1 have been reported. 6 Such values are larger than the liquid-and gas-phase self-diffusion coefficients for propane under similar experimental conditions [11][12][13] and are clearly too high. Time-dependent mutual diffusion coefficient values have been reported for mixtures of Cold Lake bitumen with heptane.…”

Section: Introductionmentioning

confidence: 88%

Forced and Diffusive Mass Transfer between Pentane and Athabasca Bitumen Fractions

et al. 2011

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Forced and diffusive mass transfer between pentane and Athabasca bitumen fractions was investigated at 297 K. Mutual diffusion coefficients were obtained using a free diffusion technique, where time-dependent composition profiles were jointly fit to obtain composition-dependent values. Because the density difference between pentane and Athabasca bitumen is significant, the density gradient was accounted for explicitly in the data analysis. Forced mass-transfer measurements were made by placing a high shear impeller in the pentane-rich phase adjacent to the pentane-feedstock interface. Mass-transfer coefficients were evaluated independently on the basis of the movement of the interface with time and changes in the bulk composition of the well-mixed pentane-rich phase above the interface. Because bitumen fractions are only partially soluble in pentane, the impact of the asymptotic assumptions, complete miscibility and complete immiscibility, on mass-transfer coefficient values obtained was assessed and found to fall within experimental error. The dependence of mass-transfer coefficients upon the shear rate and impeller-interface distance was also evaluated. Mass-transfer rates are shown to range from the diffusion limit at low shear rates and large impeller-interface distances to values consistent with those obtained from pertinent correlations for forced mass transfer under turbulent conditions at higher shear rates. The results suggest that bitumenpentane mass transfer in reservoirs and surface facilities is likely to be diffusion-limited.

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Section: Introductionmentioning

confidence: 88%

Forced and Diffusive Mass Transfer between Pentane and Athabasca Bitumen Fractions

et al. 2011

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“…In fact, over the entire range, the agreement between hexane and octane is quite remarkable. However, as the density nears 0.75 g/cm 3 , the scaled diffusion coefficients for hexane and octane at elevated pressure start to deviate noticeably from the scaled diffusion coefficient for dodecane at atmospheric pressure, and the difference between them and C 16 looks significant. This is at about 250 MPa for C 6 and 100 MPa for C 8 , so these are already rather high pressures at which our assumptions about the free volume may no longer be valid.…”

Section: Density Dependence Of the Diffusion And Relaxationmentioning

confidence: 95%

“…We note, though, that for extremely large temperature ranges the diffusion coefficients no longer have an Arrhenius temperature dependence, especially for the smallest alkanes. 3 Next, we will consider the temperature dependence of the NMR relaxation times. There is much less data for the relaxation of alkanes and their mixtures than there is for the self-diffusion of alkanes.…”

Section: Temperature Dependencementioning

confidence: 99%

“…Thus, neither of these approaches fully applies to alkanes or other oligomers. Several treatments have addressed the temperature and pressure dependence of the self-diffusion coefficient of alkanes, [3][4][5] while very few have modeled the temperature and pressure dependence of their relaxation times. 6 None of these approaches easily extend to describing mixtures containing a wide range of particles, including ones with no clear distinction between solvent and solute.…”

Section: Introductionmentioning

confidence: 99%

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Temperature and Pressure Dependence of the Diffusion Coefficients and NMR Relaxation Times of Mixtures of Alkanes

Freed

2009

J. Phys. Chem. B

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Recently, it was shown (1, 2) that the diffusion coefficient and nuclear magnetic resonance (NMR) relaxation times of a molecule in a mixture of alkanes follow scaling laws in the chain length of the molecule and the mean chain length of the mixture. These relations can be used to determine the chain length distribution of crude oils from diffusion and relaxation measurements. Oil reservoirs are usually at elevated temperatures and pressures, so it is important to know how these scaling relations depend on temperature and pressure. In this paper, we obtain the relation between the molecular composition of mixtures of alkanes at elevated pressures and temperatures and their diffusion coefficients D(i) and relaxation times T(1i) and T(2i). Using properties of free volume theory and the behavior of the density of alkanes, we show that, for a large range of pressures, the diffusion coefficients and relaxation times depend on pressure and mean chain length of the mixture only through its density. We further show that the pressure effect can be taken into account in the power laws of refs 1 and 2 by a multiplicative prefactor that depends only on temperature and the free volumes of pure alkanes at the pressure of interest and a reference pressure. We also combine the scaling laws for D(i), T(1i), and T(2i) and the Arrhenius dependence on temperature to obtain the temperature dependence of the diffusion coefficients and relaxation times. We obtain good fits between the scaling relations and literature data. These scaling relations can be used to determine the composition of a mixture of alkanes from measurements of diffusion coefficients or relaxation times at elevated pressures and temperatures.

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A Critical Analysis of Crude Oil Flow Through Porous Environments in Tertiary Migration

Dutu,

Stoianovici,

Pelin

et al. 2023

JPGT

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In the process of tertiary migration of crude oil, the phase that occurs after the cessation of primary exploitation of petroleum fluid deposits, the deposit is characterized by a state of maximum discontinuity of microscale phases and their abnormal gravitational positioning. This is precisely why it is necessary to discuss the blocking/unblocking mechanisms of wetting phase and non-wetting phase plugs in/out of capillary microtraps. The article presents for the first time a microfluidic behavior of crude oil through cores, with the analysis of polymer flow through rock pores and their filling with petroleum fluids.

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ChemInform Abstract: Self‐Diffusion in the Compressed Fluid Lower Alkanes: Methane, Ethane, and Propane.

Cited by 3 publications

References 1 publication

Forced and Diffusive Mass Transfer between Pentane and Athabasca Bitumen Fractions

Forced and Diffusive Mass Transfer between Pentane and Athabasca Bitumen Fractions

Temperature and Pressure Dependence of the Diffusion Coefficients and NMR Relaxation Times of Mixtures of Alkanes

A Critical Analysis of Crude Oil Flow Through Porous Environments in Tertiary Migration

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