Abstract:

At present, the researches on the heat transfer of the steam cavity edge in the SAGD production process mainly pay attention to the heat conduction between steam and the reservoir, while little attention has been paid to the convective heat transfer and changes of the reservoir physical properties affected by the temperature. However, the influence of both on the heat transfer effect and temperature field distribution cannot be ignored. By the comprehensive consideration of two heat transfer mechanisms of heat conduction and heat convection, as well as the influence of reservoir physical properties changes on heat transfer, a semi-analytical model is established through the conservation of mass, energy and mathematical coordinate transformation, and the temperature distribution at the edge of the steam chamber and the physical property distribution of the reservoir under the influence of temperature are obtained by differential solution. The results show that: ① the model proposed in this paper is more practical, with an accuracy improvement of 34 % and 11 % compared to the Butler's model and the Dong's models, respectively. ② By analyzing the relative relationship between convection and conduction under the change of reservoir physical properties, it is concluded that the proportion of the conduction heat transfer in the crude oil movable area is more than three times higher than that of the conduction heat transfer, the convection heat transfer accounts for the main proportion in the movable area of crude oil, but at the locations far away from the steam cavity, the conduction and convection work together, and it also gives relevant measures to improve heating efficiency.

Key words: change of reservoir physical properties, steam cavity, thermal expansion, heat convection, heat conduction