Investigation of mechanisms involved in generation of foamy oil flow

Date
2007
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Abstract
Some heavy oil reservoirs in Western Canada and Venezuela under solution-gasdrive show anomalous primary performance: high oil recovery and low production GOR. This anomalous oil production behaviour under solution gas drive has been observed since the 1980's and one of the factors responsible for such behaviour is thought to be foamy oil flow, i.e. flow of gas in the form of dispersed gas bubbles. However, the mechanisms behind the formation of gas dispersion under foamy oil flow conditions remain unclear. There are two contradictory theories to explain the formation of a dispersion: explosive nucleation theory and dispersion due to dynamic equilibrium between the processes of break-up and coalescence. The objective of this work was to further examine the basic mechanisms behind the formation of dispersed gas bubbles and infer which one of the theories of foamy oil flow is consistent with the experiments. The study included a series of sand pack and fluid property measurements, and three series of depletion experiments. Based on the results from these depletion tests, it was concluded that the hypothesis of "explosive nucleation" may not be correct. The mechanism involved in the formation of gas dispersion under solution gas drive appears to be that of the break-up of mobilized gas ganglia. The bubble size distribution is maintained by a dynamic equilibrium between the processes of break-up and coalescence. Some other notable observations were that the capillary number fluctuation corresponded with the fluctuation of simultaneous gas production rate and that the apparent critical gas saturation was 1 % to 16%, increasing with increasing depletion rate.
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Bibliography: p. 119-123
Some pages are in colour.
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Citation
Xu, S. (2007). Investigation of mechanisms involved in generation of foamy oil flow (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/1035
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