Evaluation of Bitumen-Solvent Properties Using Low Field NMR

Yang, Wen; Bryan, J.; Kantzas, Apostolos

doi:10.2118/2003-031

Cited by 3 publications

(2 citation statements)

References 9 publications

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“…A single model could be used to predict the mixture density of Cold Lake bitumen with pentane, hexane, and naphtha, as shown in Figure . This density model is expressed as eq 2: The same correlations between the density ρ and AI and T 2gm were observed for the mixtures of Edam oil with kerosene, hexane, heptane, and naphtha . These results show that NMR can be a useful tool to predict density changes as the solvents mix with heavy oil or bitumen.…”

Section: Solvent Content Prediction With Nmrsupporting

confidence: 55%

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Monitoring Bitumen−Solvent Interactions with Low-Field Nuclear Magnetic Resonance and X-ray Computer-Assisted Tomography

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Kantzas

2005

Energy Fuels

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This work involves the detection and monitoring of solvent interactions with heavy oil and bitumen. Two nondestructive methodslow-field nuclear magnetic resonance (NMR) and X-ray computer-assisted tomography (CAT)were used. It is shown that low-field NMR can be a very useful tool in understanding the relationship of viscosity, density, and asphaltene precipitation in bitumen−solvent mixtures. Such mixtures are present in solvent-related heavy oil and bitumen recovery processes, such as vapor extraction (VAPEX). As a solvent comes into contact with a heavy oil or bitumen sample, the mobility of hydrogen-bearing molecules of both solvent and oil changes. These changes are detectable through changes in the NMR relaxation characteristics of both the solvent and the oil and can be correlated to mass flux and concentration changes. Based on Fick's second law, diffusion coefficients were calculated for combinations of three oils and six solvents. X-ray CAT scanning was also used in parallel for analysis of solvent diffusion into the bitumen. As the solvent was diffusing into the bitumen, a concentration gradient was obtained. Concentration values at certain times were used to calculate diffusion coefficients, which were compared with results obtained from NMR data, using both an analytical method and a numerical method. The diffusion coefficients were considered either as constants or as functions of solvent concentration in two models that have been developed during this research. The overall diffusion coefficients calculated for several pairs of oils and solvents at different ratios, both by NMR data and X-ray tomography, were on the order of 10-6 cm2/s.

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Section: Solvent Content Prediction With Nmrsupporting

confidence: 55%

“…The images showed a homogeneous profile in the horizontal direction; thus, a one-dimensional diffusion process was considered in this experiment. An average computed tomography (CT) number in each horizontal direction was calculated, and then the changes in the average CT number, , relative to vertical distance, were obtained.…”

Section: Methodsmentioning

confidence: 99%

Monitoring Bitumen−Solvent Interactions with Low-Field Nuclear Magnetic Resonance and X-ray Computer-Assisted Tomography

and

Kantzas

2005

Energy Fuels

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Diffusion Coefficient of n-alkanes in Heavy Oil

2008

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The use of hydrocarbon solvents in the recovery of heavy oil has been increased because of the advantages they have over the thermal methods under some reservoir conditions. The injection of a miscible solvent in the reservoir implies a mass transfer process which is governed by a diffusion coefficient. Consequently the measurement of the diffusion coefficient is extremely important. This, however, presents a significant amount of challenges in the laboratory and in the data analysis, mainly because of the viscous and opaque nature of the heavy oil and the dependence on concentration of the diffusion coefficient. The MatanoBoltzmann method has been used in the past to obtain the concentration dependency of the diffusion coefficient of solvents in heavy oil. Although the method successfully shows that such dependency exists, the results exhibit abnormal trends.In this work the concentration profiles of three n-alkanes in heavy oil were obtained in the laboratory using Computed Assisted Tomography (CAT), and the "Slopes and Intercepts" analytical technique was used to calculate the concentrationdependent diffusion coefficients. The results are in good agreement with the theory of diffusion in binary mixtures. In addition a comparison is presented with the Matano-Boltzmann method. Finally the Vignes model was successfully used to also perform predictions on the studied systems.

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Measurement and Evaluation of Bitumen/Toluene-Mixture Properties at Temperatures Up to 190?°C and Pressures Up to 10 MPa

2016

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Summary The viscosity of bitumen and heavy oil is extremely high at both reservoir and surface conditions, on the order of 1 million cp. Therefore, viscosity reduction is necessary for production from the reservoir, pipeline transportation, and oil processing. The aim of this study is to evaluate the effect of different parameters (temperature, pressure, and solvent-weight fraction) on the density and viscosity of bitumen-containing mixtures. Thus, the density and viscosity of mixtures are measured for a sample of Athabasca bitumen diluted with different fractions of toluene at pressures from 0.1 to 10 MPa and at temperatures from 22 to 190 °C. The mixture densities show a linear decrease with temperature, pressure, and solvent concentration. The viscosity of the mixtures indicates a curvilinear trend with respect to the solvent-weight fraction and temperature. The effect of pressure on the mixture viscosity is more pronounced at lower-solvent-weight fractions. The mixture-density data are evaluated with two different methods: no volume change upon mixing and excess volume. The excess-volume method predicts the mixture-density data with an overall average absolute relative deviation (AARD) of 0.34%. The viscosity data for mixtures are compared with different models: Arrhenius (1987), Cragoe (1933), Shu (1984), Lobe (1973), double-log (Yarranton et al. 2013), Lederer (1933), power-law (Kendall and Monroe 1917), and Bij (Yarranton et al. 2013). The Bij model (Yarranton et al. 2013) produces the most-reliable results for mixture viscosities, with 5.5% AARD.

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Evaluation of Bitumen-Solvent Properties Using Low Field NMR

Cited by 3 publications

References 9 publications

Monitoring Bitumen−Solvent Interactions with Low-Field Nuclear Magnetic Resonance and X-ray Computer-Assisted Tomography

Monitoring Bitumen−Solvent Interactions with Low-Field Nuclear Magnetic Resonance and X-ray Computer-Assisted Tomography

Diffusion Coefficient of n-alkanes in Heavy Oil

Measurement and Evaluation of Bitumen/Toluene-Mixture Properties at Temperatures Up to 190?°C and Pressures Up to 10 MPa

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