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 degrees C to 60 degrees C) and pressures (2 MPa to 45 MPa) 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 2 MPa varies from 38.7 kJ/mol to 41.4 kJ/mol for the temperature range of 25 degrees C to 40 degrees C, which decreases slightly with increasing curing temperature and pressure. The estimated apparent activation volume of the cements at 25 degrees C varies from -23.1 cm(3)/mol to -25.9 cm(3)/mol for the pressure range studied here, which also decreases slightly in magnitude with increasing curing temperature. (C) 2013 Elsevier Ltd. All rights reserved.