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Effect of water chemistry on Cold Lake and Athabasca bitumen
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- Author / Creator
- Penaloza, Isabel
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Unconventional oil reserves are taking an increasing importance globally due to the decrease of conventional sources of hydrocarbons. Oil sands industry plays an important role in the production of unconventional bitumen, through proven technologies such as surface mining and in situ extraction processes.
Water use is an important part of both the surface mining and in situ production methods. The separation of the bitumen from the sand is assisted using water at different temperatures (75oC for surface mining and 200oC for in situ process). Therefore, it is expected that the water chemistry influences the bitumen separation during these processes.
The objective of this study was to investigate the effect of pH, salt concentration and equilibrium separation stages on some bitumen properties, by washing the bitumen while manipulating these variables. Also, it was of interest to determine and quantify the removed ions through this washing. A first phase of experimental work was performed by an one-step washing at room temperature Cold Lake bitumen with deionized water and 0.03M HCl, while increasing the concentration of dissolved NaCl from 0 to 1000 mg/L in both the deionized water and the acid solution. Three phases were obtained: aqueous, emulsion and organic (recovered bitumen) phase. Analyses of the recovered aqueous phase included: cation determination by Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES), anion determination by High Performance Liquid Chromatography (HPLC), pH and conductivity. Viscosity and water content of the raw and the recovered bitumen was measured, and the remaining solvent content of the recovered bitumen was determined by Fourier Transform Infrared Spectroscopy and the viscosity was corrected for residual solvent content. The emulsion phase was not analyzed.
It was found that the increase of salt concentration in neutral aqueous solutions increased the viscosity of the bitumen after being washed, while the opposite effect was observed when washing the bitumen with acid solutions, where the increase of salt concentration led to the decrease of the viscosity. On the other hand, the one-step washing of Cold Lake bitumen resulted in the removal of mainly Cl- (over 11000 µg/g bitumen vs 7000 µg/g bitumen initially added) and cations of Na (around 503 µg/g bitumen vs 90 µg/g bitumen initially added). Lesser quantities of HPO42- (up to 40 µg/g bitumen approximately) and CO32- (over 100 µg/g bitumen) were quantified. The removal of CO32- was favored in the bitumen washing with 0.03 M HCl, while the higher removal of HPO42- was obtained from the bitumen washing with deionized water. The increase of NaCl concentration decreased the removal of these anions.
A second phase of the experimental work consisted of the washing of Cold Lake bitumen. A four-step washing procedure at 75oC was developed, by removing the free water after each washing step and adding fresh water for the subsequent step. Two phases were obtained: aqueous phase and organic emulsion. The same analyses of the one-step washing procedure were performed on the aqueous phase samples. In the organic emulsion the cation content, asphaltenes, water and remaining solvent content were determined, as well as simulated distillation was performed.
Removal of ions of Cl (996 ± 227 µg/g bitumen) and Na (415 ± 65 µg/g bitumen) resulted from the four-step washing of Cold Lake bitumen. Cations of Ca, K were also removed. CO32- and cations of elements such Ca and K were detected in lower concentrations. The ion removal could be explained to come from the connate water; however, it was found that the experimental concentrations obtained after each washing step were lower than those calculated from dilution of the connate water, indicating that the salts were retained in some way by the organic phase.
A third phase of experimental work was performed, with the goal to determine if the use of a low-water content bitumen could lead to differences in the ion removal, and if the removed ions could be linked to the bitumen. Washing of Athabasca bitumen under the same conditions of the second phase of experimental work was developed. The removal of ions after the washing of Athabasca bitumen was linked to the bitumen, with a higher removal of SO42- (up to 62 µg/g bitumen) and CO32- (up to 63 µg/g bitumen). Cations of elements such as Al and Fe were also removed in lower concentrations. Ions of Na and Cl were removed in lower concentrations compared to the quantities removed by washing the Cold Lake bitumen (16 ± 1 µg/g bitumen for cations of Na, and 4 ± 1 µg/g bitumen for Cl-).
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- Subjects / Keywords
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- Graduation date
- Fall 2018
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.