An investigation into the mechanisms of heavy oil recovery by alkali-surfactant flooding

Date
2008
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Abstract
A considerable portion of the heavy oil and bitumen resource in Canada is found in relatively small and thin reservoirs, and cannot be produced using thermal enhanced oil recovery options. As a result, less energy-intensive non-thermal enhanced oil recovery techniques need to be developed. At the conclusion of primary production, there are still significant volumes of continuous oil in place, which can be immiscibly displaced to production wells through the injection of fluids such as water, despite the adverse mobility ratio between the injected fluid and the oil. Previous experience has shown that the injection of alkali and/or surfactant solutions can lead to improved oil recovery, compared to that of waterflooding. This work examines the mechanisms by which heavy oil is recovered by alkali-surfactant (AS) flooding. In heavy oil systems, the main recovery mechanism from chemical flooding appears to be that of the formation of in-situ emulsions, which effectively plug off the pre-formed water fingers and lead to overall improvements in the sweep efficiency of the flood. In this manner, chemical flooding leads to an acceleration of the oil recovery through improvements in the macroscopic sweep efficiency. This is in contrast to actual reductions in the residual oil saturation, which are expected in conventional oil chemical floods. Both oil-continuous (O/W) and water-continuous (W /0) emulsions can lead to this improved recovery, and emulsification may be accompanied by changes in the rock wettability to more oil wet conditions. The efficiency of the chemical floods is related to the injection rate, or the degree of shear applied, and under controlled conditions significant oil may be recovered at the conclusion of a waterflood. The results of this study demonstrate that alkali-surfactant flooding has considerable potential for application in heavy oil reservoirs.
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Bibliography: p. 349-366
Some pages are in colour.
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Citation
Bryan, J. (2008). An investigation into the mechanisms of heavy oil recovery by alkali-surfactant flooding (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/1868
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