Silicone fume improves the thermal stability of oil well cement
The silicon metal powder can improve the thermal stability of oil well cement, because the silicon metal powder is rich in more than 95% SiO2, and its participation changes the C/S ratio of cement, and changes the structure and layout of the hydration product C/ S-H of cement. The experimental results show that there are three layers of C-S-H type hypocolids with different C/S around the C3S particles in the metallic silicon powder. The C/S of the inner layer is about 115 and the C/S of the outer layer is about 1. The difference is C/S, different product layouts, different functions. Aylers et al. believed that a series of hydration products with good thermal stability, high strength and low permeability coefficient could be obtained with the addition of gold and stone micrometallic silicon powder in the cement and the difference between the addition amount and the ambient temperature.
When the cement system C/S is close to 1, when the temperature is higher than 120℃, snow calcite is mainly formed, and when the temperature is higher than 150℃, hard calcite is formed. A few white calcium zeolites stably exist below 400℃. In addition, the products of a small number of white calcium magnesium zeolite, naphthite, lamella calcite on the thermal stability of cement also have a certain effect, thus improving the cement high temperature resistance.
The inorganic powder with active silica as the main component is a fine metallic silicon powder material, which can be used as high temperature stabilizer of low density cement slurry. The cement slurry was cured at 350℃ for 3 days at 20 MPa with 45% micrometallic silicon powder, and the strength reached 1211 MPa. It fills the pores between the cement mortar particles, forms a gel with hydration products, and forms a gel with the alkaline material magnesia.
