The effect of low temperature oxidation on the viscosity of Athabasca bitumen was investigated over the temperature range 320 to 370K, and to extents of oxidation as high as 41.7 × 10−3 kg‐O2/kg‐bitumen. Even at this relatively low extent of oxidation, the viscosity was observed to be more than two orders of magnitude higher than that of unoxidized bitumen. It was found that the Andrade viscosity model could adequately characterize the temperature dependence of the viscosity at all extents of oxidation. However, the pre‐exponential constant in the model was observed to be a strong function of extent of oxidation.
Heavy oils contain significantly more acidic components than conventional crude oils. Upon contact with aqueous alkaline solutions, water‐soluble surfactants are formed in‐situ at the interface. These surfactants have the ability to reduce the oil/water interfacial tension to ultra‐low values. This work studies the significant effects of time and temperature on the interfacial tension between alkaline solutions and two Canadian heavy oils (Lloydminster and Cold Lake). The results obtained indicate that the time period during which interfacial tension remains ultra‐low is just as important as the magnitude of the minimum attainable interfacial tension in determining the potential success of an alkaline flooding process in the field.
The kinetics of low temperature oxidation in the Athabasca oil sands were investigated over the temperature range 373 K to 459 K. Oxidation experiments, in which the sand‐free bitumen was vigorously stirred to obtain a homogeneous oxygen concentration throughout the bitumen, were carried out. It was concluded that the oxidation reaction is governed by three different kinetic expressions depending on temperature and past oxidation history. These are: (i) a high rate first order regime which is obeyed at low extents of oxidation and at temperatures below approximately 423 K; (ii) a second order regime, obeyed at low extents of oxidation and at temperatures greater than 423 K; and (iii) a low rate first order regime, obeyed for extents of oxidation greater than 1.7 moles O2/kg bitumen over the entire temperature range investigated.
The partial molar enthalpy of low temperature oxidation was also evaluated, and was found to be constant over the range of oxidation extents studied.
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