Hydration kinetics modeling of the effect of curing temperature and pressure on the heat evolution of oil well cement

The heat evolution of Class G and Class H oil well cements cured under different temperatures (25°C to 60°C) and pressures (2MPa to 45MPa) was examined by isothermal calorimetry. Curing pressure was found to have a similar effect on cement hydration kinetics as curing temperature. Under isothermal and isobaric conditions, the dependency of cement hydration kinetics on curing temperature and pressure can be modeled by a scale factor which is related to the activation energy and the activation volume of the cement. The estimated apparent activation energy of the different cements at 2MPa varies from 38.7kJ/mol to 41.4kJ/mol for the temperature range of 25°C to 40°C, which decreases slightly with increasing curing temperature and pressure. The estimated apparent activation volume of the cements at 25°C varies from −23.1cm3/mol to −25.9cm3/mol for the pressure range studied here, which also decreases slightly in magnitude with increasing curing temperature.