The strength degradation of silica-enriched oil well cement under high-temperature curing conditions poses a challenge to wellbore integrity. Using the single-peak Scherrer equation, this study evaluated xonotlite crystallite size evolution in cements cured at different setting temperatures. Low-temperature setting (80 °C) maintained stable crystallite size (≈35–36 nm), accompanied by strength gain and pore refinement. High-temperature setting (240 °C) induced crystallite coarsening (up to 40 nm), concurrent with strength degradation and pore coarsening. Similar crystallite sizes led to divergent mechanical performance depending on crystal morphology, highlighting the need for combined size-morphology assessment. These findings identify xonotlite crystallite coarsening as a key indicator of high-temperature cement retrogression.
Cheng et al. (Mon,) studied this question.