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Influence of magnesium chloride on hydration of Portland cement for Cementing Oil Wells


Daniel Martins Aleixo; A.C.R Martho; Valdecir Angelo Quarcioni


Abstract

This study has the purpose to investigate the action of Magnesium Chloride (MgCl2), which is present in the rocks of the salterns pre-salt layers, when it is incorporated to the Portland cement of G class, during the hardening period of the designated paste to the petroleum well cementation. It was evidenced on the biography review a blank of knowledge about the magnesium’s influence on the cement hardening. The information of the study seeks to provide subsidies to technology of the oil wells cementation in salt rocks specific of the pre-salt, where there is the presence of magnesium in the composition. The experimental program has consisted on submitting the G cement paste to different ratios of MgCl2, prepared in laboratory, aiming to evaluate the magnesium’s influence on the cement hydration evolution and to correlate with properties on the fresh state. Preliminary exploratory essays indicate an expressive gain of consistence in the paste with the MgCl2 addition and an elevated solubility of the pre-salt layers rocks when in contact witch the paste. The experiments were divided into essays witch where designed to monitor the hydration on the fresh state and to characterize the paste on frozen ages. There were prepared two pastes, one with the G cement only (reference) and the other with an addition of 4 % of MgCl2 in relation to the mass of the cement. The hydrations periods of the samples were interrupted by freezing with liquid nitrogen followed by freeze-drying. There were used analytical techniques of isothermal calorimetry, TG\DTG, XRD (in situ and conventional) and SEM. The results indicates significant changes on the mechanism and on the kinetics of cement hydration in presence of MgCl2, by accelerating the chemical reactions on the fresh state, formation of hydrated magnesium aluminates and changes in the microstructure of the paste with addition of magnesium, with differenced morphologies and less crystallized phases in relation to the reference paste.

Reference

Aleixo, Daniel Martins. Martho, A.C.R; Quarcioni, Valdecir Angelo . Influence of magnesium chloride on hydration of Portland cement for Cementing Oil Wells. In: INTERNATIONAL CONGRESS ON THE CHEMISTRY OF CEMENT, 14., 2015, Beijing, China. Proceedings... 14 p.