Emulsification during in-situ thermal recovery of heavy oil
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AbstractThe formation of water in oil emulsion during the Steam Assisted Gravity Drainage Process is discussed. The effects of wettability of the reservoir, orientation of the injection well, steam pressure and steam quality are considered. From theoretical considerations it should be easier to form water in oil (w/o) emulsion in an oil-wet system than in a water-wet one. This prediction is supported by the experimental results. It is found that more extensive emulsification occurs during the upward growth of the steam chamber than during its growth sideways or downwards. Lower emulsified water oil ratio (EWOR) is associated with higher steam saturation temperature, with wet steam and also with the steam injected at the top of the reservoir. During much of the process w/o emulsification is undesirable because the viscosity of emulsion increases greatly. There is a two fold increase for only 19% concentration of the dispersed water. This increase in viscosity impedes oil flow substantially. The w/o emulsification also increases the volume of the draining oil stream. The overall effect of emulsification of water into the bitumen is the decrease in net oil production rate. However, it may also reduce the net quantity of residual oil which remains in the depleted steam chamber.
Bibliography: p. 96-101.