Circulating preheating model of full-length horizontal wellbore in heavy oil reservoirs with multiple thermal fluid injection

Heavy oil reservoirs are rich in resources and have broad prospects for exploration and development. Wellbore heat transfer is one of the important areas of heavy oil research. However, the current research on the preheating of multi-element thermal fluid circulation in the wellbore is still insufficient. Based on thermodynamic equations and fluid dynamics equations, this paper establishes a cyclic preheating model of multi-element thermal fluid in the wellbore. The model considers the mixing characteristics of superheated steam and non-condensed gas, and is applicable to both vertical and horizontal wellbores. Results show that the temperature curve can be divided into four parts: the temperature of the inner tube in the vertical section of the wellbore, the temperature of the inner tube in the horizontal section of the wellbore, the temperature of the annular space in the horizontal section of the wellbore, and the temperature of the annular space in the vertical section of the wellbore; In the horizontal section of the wellbore, the multi-element thermal fluid in the inner tube releases heat energy into the annular space, and there is a large temperature difference at the heel end and a small temperature difference at the toe end.