Unified model of heat transfer in the multiphase flow in Steam Assisted Gravity Drainage process

Steam assisted gravity drainage (SAGD) is an effective method for bitumen and heavy oil reservoirs. In SAGD process, steam is injected into the reservoir with a high pressure from the upper horizontal well, and the injected steam will heat the surrounding oil sands through a conduction and convection heat transfer process. In this paper, a novel unified model is developed to investigate the heat transfer mechanism in SAGD process. Typically, the multiphase flow assumption at the edge of steam chamber is introduced in our model. And the effect of both the conduction and convection heat transfer in steam chamber are considered. Especially, in this model, the convective heat transfer process caused by pressure difference and gravity is studied. Then the simulation results are compared against the UTF field data to confirm the accuracy of our model. Results indicate that our model can match the UTF field data very well, and it can be used to investigate the heat transfer process in SAGD process. It is found that the oil production rate decreases as the interface velocity increases. The optimal interface velocity is about 1.5-2.5 cm/d. In this range, the oil production rate is about 0.4 m3/(m·d) and oil cut is approximately 31%. The variations of condensate liquid mobility and density lead to that oil production will decrease as the pressure difference increases. Finally, it can be concluded that a suitable injection pressure should be chosen to guarantee the optimal interface velocity in SAGD process. This new model will benefit to understanding the convective heat transfer mechanism and guiding the field production behavior in SAGD process.