Seismic signatures of the bitumen-bearing sand reservoir are critically affected by the change in petrophysical parameters during steam-assisted gravity drainage production. We investigate the temperature evolution of the steam chamber in a bitumen-bearing sand reservoir from 4D time-lapse seismic logging by merging geologic characterizations, laboratory measurements, and temperature observation wells focusing on a bitumen sand reservoir (McMurray Formation) in Alberta, Canada. We characterize the ultrasonic P- and S-wave velocities of heavy oil sand rocks and bitumen from the McMurray Formation. The VP and VS of oil sands vary with temperatures ranging from 10°C to 175°C. Overall, VP gradually decreases as temperature increases for different slopes with decreased slopes. Meanwhile, bitumen saturation, burial depth, and clay content mutually control the elastic characteristics of heavy oil sands. In addition, the viscosity and moduli of heavy oil behave differently at varying temperature ranges, leading to ultrasonic velocities that vary from temperature dependency. A frequency-dependent impedance-temperature relation bridges the ultrasonic P-wave impedance and the petrophysical temperature parameter through 4D time-lapse seismic. It allows us to estimate the temperature distribution of the steam chamber in the bitumen sand reservoir, ultimately optimizing the steam injection strategy during oil production. The field test results demonstrate that the temperature is the highest near the steam injection well within the steam injection zone. Then the hot steam (e.g., >200°C) gradually diffuses toward the surrounding cool (e.g., 8°C) bitumen-cemented formation, which, consequently, is warmed up, and bitumen becomes movable. In addition, because of the heterogeneity of oil sand reservoirs, the temperature map is distributed heterogeneously. More important, comparing temperature mapping in the first and second monitoring lines shows that hot steam spreads in the reservoir with a similar path at different steam injection stages, reminding us that the optimized steam injection strategy plays a substantial role in improving bitumen production.

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.