Evaluation of Influence of Salt in the Cement Hydration to Oil Wells

The influence of NaCl salt in the hydration of the Portland cement paste class G was studied using a Non Conventional Differential Thermal Analysis (NCDTA) on the first 24 hours of cement hydration. The mass of salt used corresponds to 0, 5, 10, 15 and 20% of mass of water used in the preparation of the pastes. The water/cement ratio (w/c) remained constant, being 0.46, and the pastes final volume was 99.9mL. Applying a deconvolution method to separate overlapped NCDTA peaks it was possible to estimate the energy released during the different stages of hydration and the effect of salt in cement hydration process. The presence of up to 10% of salt accelerated the hydration process and increased the hydration of C3S and C3A, while the 20% of the salt causes a delayed hydration and decreased the hydration of C3S and C3A. Futhermore, cement pastes with the same percentages of NaCl and with different hydration times were evaluated by Thermogravimetry (TG), Derivative Thermogravimetry (DTG) and Differential Thermal Analysis (DTA). After 28 days the presence of salt caused a greater increase in the formation of hydrated products.