Abstract: The circulating temperature is one of key factors that determine whether cementing is successful. In order to calculate the circulating temperature accurately, thermal physical property data of the cement slurry and drilling fluids have to be given exactly besides setting up mathematical model corresponding with reality in the wellbore. Firstly, a measuring device of heat
capacity was developed according to electric current calorimeter method that is used to measure heat capacity of a liquid. Secondly, heat capacity at seventemperature scope was measured for fifteen kinds of cement slurry and two kinds of drilling fluids with five densities. Finally the influences of composition, density and temperature of the cement slurry and drilling fluids on the heat capacity were analyzed. Results indicate that the heat capacity is different at the same density and temperature when the composition of the slurry and mud is not identical; the heat capacity increases at any temperature when the density of the slurry and mud in the same composition reduces. For any cement slurry and drilling fluids, the heat capacity increases with temperature. In general, the heat capacity of drilling fluids is higher than that of cement slurry.

Key words: specific heat, circulating temperature, cementing, laboratory test