Abstract: It is important for the drilling and completion to learn about accurate distribution of circulating temperature in the wellbore. According to the first law of thermodynamics and the theorems of heat transfer, a new two dimension transient math-ematical model of circulating temperature of heat exchange be-
tween the liquid in wellbore, pipe string and underground for-mation has been proposed, which has been solved by termless steady finite difference method. The predicted results from the new model presented in this paper are satisfactorily close to those from other proven models. The sensitivities of parameters to affect the circulating temperature in wellbore have also been
analyzed. The new model can be employed to calculate tempera-ture distribution of drilling mud, pipe string, fluid in the annu-lar and the formation of real circulating circumstance.

Key words: circulating temperature, sensitivity analysis, cementing, drilling