Temperature-dependent rock physics modeling for heavy oil sands

Abstract

Heavy oil is considered an important alternative for traditional fossil fuels. Exploring and developing heavy oil reservoirs require time-lapse seismic data for dynamic monitoring of the reservoir elastic parameters and determining of the temperature field to evaluate the fluidity of the heavy oil. The key is establishing a relationship between the temperature and seismic elastic parameters to convert the elastic field into a temperature field. Therefore, a temperature-dependent rock physics model for heavy oil sand must be established. In this study, we investigated the temperature-dependent elastic wave velocities of natural and artificial heavy oil sands. The modified contact cement theory and the solid Gassmann equation were combined to construct a temperature-dependent rock physics model. The proposed model can predict variations in elastic wave velocities along with temperature changes in both natural and artificial heavy oil sands. Based on the model results, we propose a possible mechanism for the temperature-dependent elastic wave velocity of heavy oil sands, namely, the weakening of heavy oil cementation is the main controlling factor in the elastic wave velocity sensitivity of heavy oil sands. A temperature-dependent rock physics template (TDRPT) is proposed to diagnose the temperature, and the diagnostic results were verified using natural heavy oil sands. Our proposed model and TDRPT are essential tools to guide the thermal production of heavy oil reservoirs.