Abstract: An thermal insulation technology has been studied and developed in mid-shallow heavy oil reservoirs with low quality oil. This technology utilizes φ139.7mm casing to complete well and use the conventional tubing with annular gas to insulate heat, resolving the problems such as heat loss during the steam injection through blank tubing in the new block's steam soak , which can influence the development effects, and result in the poor formation consolidation and cement mantle damages during steam injection, with a result of steam channeling outside casing . The technology has completed several round heat insulation, steam injection and production together on one string trip in the casing of φ139. 7mm, by which the operation work load and downtime have been decreased, and the steam energy is used fully. At present , this new technology has been fully promoted in the shallow layer heavy oil field and become a leading technology.