Temperature-Dependent Wave Velocities of Heavy Oil-Saturated Rocks

Understanding the dependence of the rock properties on temperature is essential when dealing with heavy oil reservoirs. Reported rock physics models can hardly capture the effect of temperature on wave velocities. We propose a dual-porosity temperature-dependent model based on the coherent potential approximation, combining temperature- and frequency-dependent empirical equations for pore fluids with the David-Zimmerman model. The Maxwell model is adopted to obtain the complex shear modulus as a function of temperature and frequency. To verify the validity of the model, a glycerol-saturated tight sandstone and three heavy oil sand samples are considered. The comparison between the predicted and measured wave velocities shows that the model can quantitatively describe the behavior as a function of temperature. We find that there is a viscosity threshold (liquid point), where the P- and S-wave velocity variation trends change, while the porosity has no effect.

Automated summary

Understanding the dependence of rock properties on temperature is crucial for heavy oil reservoirs. A dual-porosity temperature-dependent model has been proposed, combining empirical equations for pore fluids with the David-Zimmerman model, to quantitatively describe wave velocities behavior with temperature variation. The study also reveals a change in trends of P- and S-wave velocities when reaching a viscosity threshold.