The "Visco-skin" effect in heavy oil reservoirs

Date
1989
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Abstract
The concept and description of the visco-skin, and it's effect on heavy oil productivity is introduced here. A numerical simulation study was conducted to quantify the visco-skin that develops in the near wellbore region for a typical heavy oil reservoir in Alberta, Canada. The simulator was also used to predict the effect of visco-skin on heavy oil production rate, inflow performance relationship (IPR) curves, the presence of gas on oil relative permeability and well productivity as a function of the visco-skin parameters. Two analytical models are developed. The first model can be used to calculate the flow rate from a reservoir if the visco-skin parameters are known and the second model can be used to calculate the visco-skin factor. The analytical models were compared to numerical simulation and found suitably accurate for first approximation calculations. The numerical simulator was finally used to study the effect of well productivity when the visco-skin was melted away using an electromagnetic heating technique. It was found that the visco-skin depends primarily on two parameters, the live oil viscosity at the bubble point, and the dead oil viscosity, for a given reservoir. Both of these parameters are measurable in the lab. It was also found that the visco-skin develops within one meter of the near wellbore region in a short period of time and does not progress further into the reservoir, even after one year of primary production. Results from the simulation studies indicate that the viscoskin can decrease well productivity by a factor of two for the heavy oil reservoir used in this study. Also that the use of heat produced by electromagnetic stimulation, to melt the visco-skin, results in immediate enhancement of oil productivity by a factor equivalent to the visco-skin. The simulation results for electromagnetic stimulations are verified by actual field data.
Description
Bibliography: p. 87-90.
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Citation
McGee, B. C. (1989). The "Visco-skin" effect in heavy oil reservoirs (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/19788
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