TEMPERATURE REGIME OF DEEP WELLS DURING CEMENTING (PREDICTION OF STATIC, CIRCULATING, AND SHUTIN TEMPERATURES: EVALUATION OF THE THERMAL EFFECT OF CEMENT HYDRATION).

摘要

One of the important factors in a successful well completion is the proper performance of the cement slurry. The circulating temperature and test procedure used in the design, and the laboratory testing of the cement are critical to its successful performance in the well. Because of the importance of bottom-hole circulating temperatures in a well completion, a new formula has been developed to predict this temperature with greater accuracy.; The current API correlation which is used to predict the bottom-hole circulating temperature permits prediction only in wells with geothermal gradients up to {dollar}2spcirc{lcub}rm F{rcub}/100{dollar} ft; however, the empirical formula allows the prediction in wells with larger temperature gradients. In addition, the results indicate that for deep wells with high temperature gradients, the API correlation predicts bottom-hole temperatures which are too high.; The principal factor controlling the chemical reaction and the resulting performance of a cementing composition is the temperature to which it is exposed. The shut-in temperature affects how long the slurry will pump and how well it develops the strength necessary to support pipe.; A new method has been developed to calculate the bottom-hole shut-in temperature. Plots of dimensionless bottom-hole shut-in temperature versus shut-in time for various bit sizes have been constructed. Values obtained from these plots can be used in a formula to calculate the shut-in temperature.; The relation between the heat of hydration and the temperature increase inside the casing was another phase of this study. A computer program was developed to calculate the temperature increase due to cement hydration. The impact of bentonite, formation temperature, volume of the cement, and thermal properties of the formation on heat of hydration and ultimately the temperature increase inside casing is shown.