Oil-Well Cement and C3S Hydration Under High Pressure as Seen by In Situ X-Ray Diffraction, Temperatures ≤80°C with No Additives

Abstract

The hydration kinetics of a white cement and batches of both Class G and H oil‐well cements were examined between 0 and 60 MPa, at ≤80°C, using in situ synchrotron X‐ray diffraction. This gives a continuous measure of the C3S (Ca3SiO5), CH (Ca(OH)2), C4AF (Ca2FeAlO5), ettringite, and other phases in the hydrating slurries. Slurries prepared from single‐phase C3S; synthetic C4AF, and gypsum; and white cement, synthetic C4AF and gypsum were also examined. An increasing pressure enhanced the rate of hydration for all slurries. Analysis of the data, using a kinetic model, provided rate constants that were used to obtain activation volumes for C3S hydration. For all the cement and C3S slurries studied, similar activation volumes were obtained (average ΔV‡∼−35 cm3/mol), indicating that the presence of cement phases other than C3S has a modest influence on the pressure dependence of C3S hydration. An alternative analysis, using the time at which 90% of the initial C3S remained, gave similar activation volumes. Pressure accelerated the formation of ettringite from synthetic C4AF in the presence of gypsum. However, in slurries containing cement, the pressure dependence of C3S hydration plays a major role in determining the pressure dependence of ettringite formation.

Modeling cement hydration by connecting a nucleation and growth mechanism with a diffusion mechanism. Part II: Portland cement paste hydration

“…Assuming that n and c are independent of curing pressure, the activation volumes obtained for g 1 and g 2 are -28.1 and -33.8 cm 3 /mol, respectively. Similar values have also been obtained by other studies [21,27,28] . Figure 7 shows representative results of fitting the proposed model to hydration kinetics data of Class H cement prepared with varied w/c ratios.…”

Recent studies of cements and concretes by synchrotron radiation crystallographic and cognate methods

“…The studied temperature range was 25-170°C, which was obtained by heating the capillary with a hot air flow system. In a second work, [85] (ii) Class H oil well cements mixed with silica flour, silica fume and a natural zeolite which are used to improve the mechanical properties of the binder [93]; (iii) White cement, class G and class H oil well cements, without additives, for analysing the reaction kinetics of the main phases [94]; and (iv) C 3 S in the presence of several retarders to counterbalance the accelerating behaviour of pressure. [95] These authors have also developed a cell to allow simultaneous measurement of SXRPD data and ultrasound shear-wave reflection data from cement slurries at variable temperatures and pressures.…”

Rietveld Quantitative Phase Analysis of Oil Well Cement: In Situ Hydration Study at 150 Bars and 150 °C

“…The pastes derived from OWC are subjected to high pressures (up to 1000 bar) and high temperatures (up to 300 °C) during curing. Consequently, the hydration processes changes substantially, and the hydration phases formed under these conditions are different (or they can be) than those obtained at room temperature and atmospheric pressure [6,7]. Based on previous studies [7,8,9], it is evident that the effect of temperature is larger than that of pressure in cement hydration.…”

“…Furthermore, these studies were qualitative or semi-quantitative as they mainly followed selected diffraction peaks [see for instance [10] and references therein]. These studies were mainly dedicated to the hydration of C 3 S [6,7,11,12].…”

“…High pressures increase the hydration rate [11] of a cement, mainly the hydration kinetics of C 3 S [6]. Moreover, it was found that the length of the induction period, very much related to the time required for initial setting, is reduced as the pressure and temperature increases [6,7,11]. However, high temperature and high pressure also lead to the formation of different hydrated products.…”