A cement hydration kinetics model and its application in designing cement formulation for natural gas hydrate well

To guide the research and development of cement slurries with low hydration heat release for natural gas hydrates (NGHs), the effects of fly ash (FA) and phase-change material (PCM) on the early performance of cement at low temperatures were investigated using isothermal calorimetry (IC), semi-adiabatic temperature (ST), and mechanical strength tests. A specialized in-house device was designed to simulate NGHs well conditions and examine the impact of cement slurries on the formation temperature field. A novel model for cementing temperature prediction based on hydration kinetics was developed, and a new methodology for NGHs well cement slurry design was proposed. The experimental and modeling results indicated that the prediction error of the temperature model was within 6.5 %. By adding approximately 14 wt% of PCM the temperature rise could be controlled below the hydrate decomposition temperature, while achieving a 72 h compressive strength of greater than 2.5 MPa.