Chemical structure of cement aged at normal and elevated temperatures and pressures, Part II: Low permeability class G oilwell cement

Recently, Low Permeability Cement formulation has been developed for oilwell cementing. Therefore, it is important to understand the physical and chemical processes causing cement degradation in the downhole environment. In this study, we have characterised a Low Permeability Class G oilwell Cement...

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Bibliographic Details
Published in:Cement and concrete research 2006-03, Vol.36 (3)
Main Authors: Le Saout, Gwenn, Lecolier, Eric, Rivereau, Alain, Zanni, Helene
Format: Article
Language:English
Subjects:
BRINES
CALCITE
CEMENTING
CEMENTS
LEACHING
MATERIALS SCIENCE
NUCLEAR MAGNETIC RESONANCE
PERMEABILITY
POLYMERIZATION
TEMPERATURE RANGE 0273-0400 K
X-RAY DIFFRACTION
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Summary:Recently, Low Permeability Cement formulation has been developed for oilwell cementing. Therefore, it is important to understand the physical and chemical processes causing cement degradation in the downhole environment. In this study, we have characterised a Low Permeability Class G oilwell Cement immersed for one year in brine at T = 293 K, p = 10{sup 5} Pa and T = 353 K, p = 7 x 10{sup 6} Pa using {sup 29}Si, {sup 27}Al NMR and XRD techniques. Elevated temperature and pressure conditions increase the rate of the pozzolanic reaction and have significant effects on the polymerisation of C-S-H and on the incorporation of Al in the C-S-H structure. Leaching resulted in the formation of calcite and a more polymerised C-S-H with the appearance of tobermorite in the sample cured at elevated temperature and pressure.
ISSN:0008-8846
1873-3948
DOI:10.1016/J.CEMCONRES.2005.1