Abstract In-situ combustion (ISC) has a huge potential in recovering heavy oil resources with a low environmental footprint. At the end of the ISC operation, a huge amount of thermal energy is left in the reservoir. By appropriately recovering the thermal energy in the depleted reservoirs after ISC operation, it could extend the economic life of the heavy oil reservoirs. This work investigated the potential of extracting heat using the cold water and CO 2 as the working fluids to advance the knowledge base regarding the thermal energy recovery and CO 2 storage in depleted ISC reservoirs. The extracted fluids are fed to the surface binary cycle for power generation or district heating. Simulation of ISC was performed to estimate the temperature, energy, and fluids distributions after 20 years of the oil production. An assessment of the energy remaining in the reservoir is performed. It is estimated that a total of 3 × 10 14 J thermal energy was left underground after ISC operation in the typical five-spot well pattern. Subsequently, an examination of the potentially recoverable energy from the post ISC operation is performed. Cold water and CO 2 are recirculated into the reservoir for energy recovery. The results indicates that the heavy oil reservoir after ISC operation can be regarded as an artificial geothermal system for subsurface thermal energy extraction. As the water circulation rate increases from 200 m 3 /day and to 400 m 3 /day and 600 m 3 /day, the average reservoir temperature is declined to 95 ℃, 79 ℃, and 71 ℃, respectively. Meanwhile, the corresponding thermal energy recovery factors are 48%, 63%, and 77%, respectively. Larger water circulation rate can generate high energy output and high energy recovery in the post ISC operation. The thermal energy recovery could prolong the energy production to 15 to 20 years in a depleted reservoir. Except for thermal energy extraction, a total of 6100 tons of CO 2 can be sequestrated underground by using the CO 2 as the working fluids in the five spot well pattern. The numerical investigation in this study indicate that huge energy extraction potential and CO 2 storage can be achieved at the full field scale. Utilization of subsurface thermal energy after the ISC operation is a beneficial choice to offset the operating costs, reduce the CO 2 emission and extend the economic life of reservoir.
Yang et al. (Sat,) studied this question.