MIXING RULES FOR PREDICTING THE VISCOSITY OF BITUMENS SATURATED WITH PURE GASES

Mixing rules are developed and evaluated for predicting the viscosity of Alberta bitumens saturated with each of N2, CO, CH4, CO2 and C2H6. The viscosity-temperature variation for all bitumens and gases is expressed as [log(mu + 0.8) = +/- 10b1 T(b)2]. A linear cross-correlation between parameters b1 and b2 in the above relationship is identified and used subsequently to derive a one-parameter viscosity equation: [log(mu + 0.8) = THETA(PHI-T)b], where THETA = 160, PHI = 0.008 for all bitumens and THETA = -0.1, PHI = 0.015 for all gases. The two mixing rules examined in this study are: log(mu-BAR + 0.8) = SIGMA-upsilon(i) log(mu(i) + 0.8) and log(mu-BAR + 0.8) = SIGMA-upsilon(i) log(mu(i) + 0.8) + SIGMA-SIGMA upsilon(i) upsilon(j) B(ij), where upsilon represents the geometric mean of mass and mole fractions and B(ij) is a binary viscous interaction term. Predictions for the viscosity of gas-saturated bitumens are validated with over 400 experimental data points for five Alberta bitumens at temperatures from 12 to 120-degrees-C and pressures up to 10 MPa.