Rock physics modelling of acoustic velocities for heavy oil sand

The rock physics models for the acoustic velocities of the heavy oil sand with different oil distributions are proposed in this paper. The heavy oil distributions are classified into three primary types, based on which the corresponding acoustic velocity models are given. For the first type, the heavy oil is detached from the sand grains, for which the Hertz-Mindlin- Hashin-Shtrikman (HMHS) model can be used. In the second type, a continuous matrix is formed by the heavy oil and the sand grains float inside the matrix. The Hashin- Shtrikman (HS) lower bound gives good estimation results under this condition. For the third type, the heavy oil cements the sand grains at the grain contacts. The modified Contact Cement Theory (CCT) can describe this cementation effect well. To validate the proposed models, we analyzed the heavy oil sand data from Xinjiang Oil Field of China. The heavy oil distribution is obtained and the corresponding model is selected to estimate the acoustic velocities. The results show that it can predict the measured data well. Furthermore, we also compare the responses of the acoustic velocities for the heavy oil sand with different oil distributions. It reveals that different heavy oil distribution results in different acoustic velocities responses. The heavy oil distribution can thus be obtained by matching the measured data with the results estimated by the models. The model that match the data best implies the primary oil distribution. Many properties of the sand can then be estimated from the heavy oil distribution, such as the strength and permeability of the sand.