Controlling the early-age hydration heat release of cement paste for deep-water oil well cementing: A new composite designing approach

摘要

During the deep-water oil well cementing process, the concentrated heat release of cement paste reduces the zonal isolation quality of the cement sheath. A new approach is proposed in this work to lower the hydration heat release of cement paste and meanwhile give the assurance to the early-age strength development at low curing temperature. This is achieved by the synergistic effects of the admixtures addition, which includes 20% ultrafine fly ash (UFA), 1% C-S-H seeds, 1% nano-SiO2 and 0.3% polycarboxylate super plasticizer. Combined methods of ICC, XRD, SEM and MIP are used to characterize the phase and microstructure evolutions in cement paste. The results show that when compared with the original low-density cement paste without UFA addition, the cumulative heat release after 24 h of hydration decreases by 28% from 75.7 J/g to 54.6 J/g. The concentrated hydration heat release peak is separated into two moderate peaks, because the silicate reaction is accelerated, and the sulfate depletion is delayed. The compressive strength of the paste cured at 10 degrees C for 24 h is 3.8 MPa, which increases by 41%. (C) 2021 Elsevier Ltd. All rights reserved.