In the process of thermal recovery of heavy oil

hot fluid is injected into oil reservoir through pipe strings made up of thermal insulated tubing. Thermal insulated tubing is the key component to reduce heat loss and to protect tubes in the process of hot fluid injection. Currently the researches on heat loss of thermal insulated tubing by domestic and foreign scholars mainly focus on theoretical analysis and numerical calculation. Thermal insulated tubing consists of interior tube

thermal insulating layer and exterior tube

its thermal insulated effect depends on the apparent heat conductivity of thermal insulating layer. This paper designed and developed ground analogue test device of thermal insulated tubing and actually measured the surface temperature hot fluid distribution with device

then calculated the apparent heat conductivity of new and old thermal insulated layer based on experimental date. The study result shows that: heat bridge existed between the collar and exterior of insulated pipe

and the affected length of insulated pipe is about 0.5 m.Heat flow rate in the normal insulated pipe is less 3 times than that in the heat density of collar. The apparent hot flow

surface temperature and apparent heat conductivity of oldthermal insulated tubing is obviously higher than those of new thermal insulated tubing

and the thermal insulated performance in the old insulated tubing decreases. According with current manufacture technique and structure characteristics of thermal insulated tubing

some suggestions are proposed for improving thermal insulated performance.