Abstract: Gravity heat pipe is used in the course of well bore heating by utilizing its characteristics of efficient heat-transfer.Several external factors are analyzed during well bore heating.The result shows that gravity heat pipe technology can increase the temperature of the upper fluid in well bore by absorbing the surplus energy of the lower fluid in well bore and no extra energy is consumed,thereby,the method can balance fluid temperature field and improve the temperature distribution profile along the wellbore.Under some favorable conditions,the temperature of crude oil can be raised up to condensation point,viscosity will be decreased,flow ability improved,the load of sucker rod at bottom hole decreased,the demand of production met.Heating course of gravity heat pipe is affected by many external factors such as downhole temperature,setting depth,production rate and physical property of oil.As the increase of downhole temperature,setting depth and production rate,the effect of gravity heat pipe improves.

Key words: gravity heat pipe, well bore heating, well bore temperature distribution, flow ability, hollow sucker rod, North China Oilfield