| Title | Cementing of Casing - Temperature Increase at Cement Hydration |
|---|---|
| Authors | Izzy KUTASOV, Lev EPPELBAUM |
| Year | 2013 |
| Conference | Stanford Geothermal Workshop |
| Keywords | heat flow, cement hydration, optimal time lapse |
| Abstract | Assessment of the temperature development during cement hydration is necessary to determine how fast the cement will reach an acceptable compressive strength before the casing can be released. Therefore, for deep wells heat generation during cement hydration has to be taken into account at cement slurry design. The experimental data show that the maximum value of heat generation occurs during the first 5 to 24 hours. During this period the maximum temperature increase can be observed in the annulus. In order to evaluate the temperature increase during cement hydration it is necessary to approximate the heat production rate versus time curve by some analytical function. It was found that a quadratic equation can be used for a short interval of time to approximate the rate of heat generation per unit of length as a function of time. Temperature surveys following the cementing operation are used for locating the top of the cement column behind casing. Field experience shows that in some cases the temperature anomalies caused by the heat of cement hydration can be very substantial. However, even in such cases it is very important to predict the temperature increase during the cement setting. This will enable to determine the optimal time lapse between cementing and temperature survey. A new technique has been developed to estimate the temperature increase during cement hydration. The method presented in this paper will enable to select the optimal time lapse between cement placement and temperature survey. A semi-analytical equation was earlier suggested which describes the transient temperature at the borehole’s wall, while a radial heat flow rate (into formations) is a quadratic function of time. Only field or laboratory heat production rate – time data are needed to calculate the transient values of the temperature increase. Two field examples of cement hydration (when retarders were used) are presented in the paper. |