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.