Study On Heat Transfer And Its Influencing Factors Of Insulated Tubing

The vacuum insulated tubing is one of the main facilities that are exploited in heavy oil by the injection of steam. Its heat insulation function has direct impact on the effect of heat-exploitation. At present, a lot of scholars of home and abroad had not accurately calculate the heat loss of the coupling when they studied wellbore heat transfer, the heat loss of the coupling is calculated relying on experience proportion. This method might cause some error. So the calculation of the heat loss of the coupling requires more thorough analysis and study. Moreover, so far there is few is a fat lot research on inside of thermofin, which brings insufficiency theory support in the procedure of production of insulated tubing. Thus it can be seen, It is necessary to study the heat transfer about inside of thermofin and analyze the effects of various process variables on hest losses during the injection of steam into a well. so that computation model can optimize thermofin structure and improve heat insulation performance of insulated tubing. The paper has three aspects content as follows:1,This paper puts forward the concept of the heat insulation performance of the coupling with apparent heat conductivity, and by combining on-site experiments, fluent simulation and theoretical calculation, we get the apparent heat conductivity of the coupling with bush. In the simulation conditions, we research the apparent heat conductivity of the coupling without bush. And compare with two structures of the apparent heat conductivity of the coupling with or without bush. The result is that the apparent heat conductivity of the coupling without bush is 8~18 times of the coupling with bush.2,On the base of the coupling with apparent heat conductivity, we program the simulation computation of wellbore heat losses with Visual Basic to work out wellbore heat losses and the heat loss of the coupling. The effects of various process variables on wellbore bottom steam parameter and heat losses are investigated3,Effects of layers of thermofin , pressure, aluminium foil emissivity, void ratio of glass silk spreads on heat losses have been analyzed. the result of Calculation analysis indicates: For glass silk spreads and aluminium foil heat insulation structure, layers of thermofin should be 4~6 layers, Do not let glass silk spread diagonal direction accepting a force to ensure that bigger void ratio at the glass cloth winding process; the surface of aluminum foil should be smooth and no corrosion and leveling, aluminum foil emissivity should be 0.01~0.05, In the production process, try to make the glass cloth and aluminum foil to keep dry And maintain a certain vacuum.