silica fume for oil well cementing
Oil well cementation technology refers to the reinforcement of oil well walls, ensuring continued safe drilling, sealing of oil, gas and water layers, ensuring stratified oil testing during exploration and reasonable oil and gas production throughout the mining process. The high-strength steel casing is cut into the well and the cement is filled in the annular space of the wellbore and casing. In this technology, the injection of cement is an important technical requirement. In order to fix the casing and seal the oil, gas and water layers, cement must be injected between the casing and the well wall after the casing is laid. The method of cementing oil and gas wells is different from that of ground construction. Pumps are used to pump cement slurry to the bottom of a few hundred meters or even several kilometers underground, and then return to the annulus outside the pipe and push the drilling fluid away. The cement should fill the entire annulus and solidify and harden to form a hard and dense cement ring. These characteristics determine the performance difference between oil well cement and ordinary building cement. Oil well cement slurry is required to have good fluidity and proper solidification time, and has high early strength. The cement ring outside the casing will be in contact with groundwater for a long time and should have good water impermeability and resistance to groundwater corrosion.
The average particle size of the silica fume for oil well cementing is 0.1μm, which is 1% of cement. The color ranges from light gray to carbon black. It has pozzolanic reaction characteristics and can be hydrated to form a silicon-rich gel with higher strength than hydrogen peroxide. Calcium crystal, which works together with cement hydration gel CSH, is a highly active hydraulic cementitious material, silica fume for oil well cementing is added to make the physical properties of concrete greatly improved. In recent years, micro-silica powder has also begun to be widely used in various oil fields. Especially in oil field cementing, due to the use of micro-silica powder, the high-temperature strength degradation performance of the slurry solidified body is improved. It is widely used in high-temperature deep wells, oil wells and thermal recovery wells. The general dosage is 8%-15%.