Effects of temperature and water-to-cement ratio on autogenous shrinkage of oil well cement

Abstract

The chemical shrinkage and corrugated tube test methods were used to study the shrinkage behaviour of Class G oil well cement with water-to-cement (w/c) ratios of 0.3 and 0.5, cured at temperatures from 15 to 60°C. The experimental results show that the typical linear shrinkage evolution curve of a cement slurry obtained by corrugated tube method have an obvious inflection point, beyond which the linear shrinkage increase is close to zero. The time at which the inflection point is observed decreases significantly with increasing curing temperature, but varies very little with w/c ratio. The inflection time also shows approximately linear correlation with the setting time of the cement (The two are almost equal for w/c=0.3). The degree of hydration corresponding with the initial and final setting time were estimated based on chemical shrinkage test results and the relationships between estimated volumetric bulk shrinkage and chemical shrinkage were analyzed.