1 research outputs found
Rietveld Quantitative Phase Analysis of Oil Well Cement: in Situ Hydration Study at 150 Bars and 150 °C
Oil and gas well cements are multimineral materials that hydrate under high pressure
and temperature. Their overall reactivity at early ages is studied by a number of techniques
including through the use of the consistometer. However, for a proper understanding of the
performance of these cements in the field, the reactivity of every component, in realâworld
conditions, must be analysed. To date, in situ high energy synchrotron powder diffraction studies
of hydrating oil well cement pastes have been carried out, but the quality of the data was not
appropriated for Rietveld quantitative phase analyses. Therefore, the phase reactivities were
followed by the inspection of the evolution of nonâoverlapped diffraction peaks. Very recently, we
have developed a new cell specially designed to rotate under high pressure and temperature. Here,
this spinning capillary cell is used for in situ studies of the hydration of a commercial oil well
cement paste at 150 bars and 150 °C. The powder diffraction data were analysed by the Rietveld
method to quantitatively determine the reactivities of each component phase. The reaction degree
of alite was 90% after 7 hours, and that of belite was 42% at 14 hours. These analyses are accurate,
as the in situ measured crystalline portlandite content at the end of the experiment, 12.9 wt%,
compares relatively well with the value determined ex situ by thermal analysis, i.e., 14.0 wt%. The
crystalline calcium silicates forming at 150 bars and 150 °C are also discussed.This research was funded by Spanish MINECO, grant number BIA2017â82391âR which is coâfunded
by FEDER.
We thank Marc Malfois for his help during the experiment performed at NCDâSWEET
beamline at ALBA synchrotron. We also thank Marcus Paul (Dyckerhoff GmbH) for providing the OWC
sample with its characterization and helpful discussions