A coupled model of temperature and pressure based on hydration kinetics during well cementing in deep water

Abstract

Considering the complicated interactions between temperature, pressure and hydration reaction of cement, a coupled model of temperature and pressure based on hydration kinetics during deep-water well cementing was established. The differential method was used to do the coupled numerical calculation, and the calculation results were compared with experimental and field data to verify the accuracy of the model. When the interactions between temperature, pressure and hydration reaction are considered, the calculation accuracy of the model proposed is within 5.6%, which can meet the engineering requirements. A series of numerical simulation was conducted to find out the variation pattern of temperature, pressure and hydration degree during the cement curing. The research results show that cement temperature increases dramatically as a result of the heat of cement hydration. With the development of cement gel strength, the pore pressure of cement slurry decreases gradually to even lower than the formation pressure, causing gas channeling; the transient temperature and pressure have an impact on the rate of cement hydration reaction, so cement slurry in the deeper part of wellbore has a higher rate of hydration rate as a result of the high temperature and pressure. For well cementing in deep water regions, the low temperature around seabed would slow the rate of cement hydration and thus prolong the cementing cycle.