Phase Evolution of Oil Well Cements with Nano-Additive at Elevated Temperature/Pressure

Ma, Siwei; Yu, Tony; Wang, Yanbin; Chaouche, Mohend; Kawashima, Shiho

Phase characterization of Class A oil well cement slurries was performed through synchrotron X-ray diffraction technique. This allowed for real-time, in-place measurements of X-ray diffraction patterns to be obtained and, subsequently, the continuous formation and decomposition of select phases over time (up to 8 hours). Phases of interest included alite, ferrite, portlandite, ettringite, monosulfate, and jaffeite (crystalline form of calcium silicate hydrate). The effects of elevated temperatures (140, 185, and 300°F [60, 85, and 149°C]) at elevated pressure (up to approximately 15 ksi [100 MPa]), as well as the effect of nanomaterial addition were investigated. Rate of conversion of ettringite to monosulfate increased with increasing temperature, and monosulfate became unstable when temperatures reached 185°F (85°C). The results of synchrotron X-ray diffraction provided evidence of a seeding effect introduced by nano-sized attapulgite clays at 0.5% addition by mass of cement, where acceleration in the rate of formation of portlandite and jaffeite was observed. This was supported by isothermal calorimetry results.


Also Published In

ACI Materials Journal

More About This Work

Academic Units
Civil Engineering and Engineering Mechanics
American Concrete Institute
Published Here
January 24, 2017