Keywords: heavy oil reservoirs, heat accumulation, steam flooding, artificial geothermal energy, energy rate, stored energy, steam injection, simulation
Artificial geothermal energy potential of steam-flooded heavy oil reservoirs
This paper explores the concept of harnessing geothermal energy from heavy oil fields that have undergone steam flooding and so accumulated substantial heat from steam injection. Once the steam flooding process reaches economic cut-off resulting from high water cut and/or high steam-to-oil ratio, the reservoir would be abandoned, leaving behind stored energy in the form of heat. From this point, the reservoir could be regarded as an artificial geothermal system and its intrinsic heat from the steam flooding stage recovered by water circulation. This study shows the results of numerical reservoir simulations to quantify the energy that can be recovered by water injection after steam flooding. The results of the simulations, together with those of a sensitivity analyses on key reservoir parameters, suggest the feasibility of this concept. The results for the synthetic case used in this work show that the average produced energy rate during the water injection phase is approximately 11 MMBTU/day for 3,800 days, after which the operations stop. At that time, a cumulative net energy production of 3.02 × 10
4MMBTU is recovered.