Preparation Methodology, Properties, and Applications of Nano-Silica in the Cement Slurry

Nano-silica can be produced by tuning the morphological features by controlling the synthetic conditions, such as time, temperature, and concentration of materials. This paper will describe the development methodology and laboratory testing performed to qualify an advanced nano-silica slurry recipe to develop an effective cement lost circulation plug. The lab test was conducted following API 10B2 standards. Nano-silica was prepared by selecting conventional routes, including Stober's, sol-gel, flame synthesis, and microemulsion. The reaction mechanism of Nano silica combined with class G-cement was observed during cement hydration. Both nano silica and calcium hydroxide were dissolved, and Calcium Silicate & Hydrite (CSH) gel was formed. Later, a comparative study was conducted on the performance efficiency of the cement slurry at a typical density of 118 pcf (15.8lbm/gal). This study also focused on slurry stability, free fluid reduction, lower fluid loss value, and fine rheology. The study proved that the cement slurry with nano-silica has shown 40% improvement in compressive strength due to the increased rate of hydration, thus thickening time was only within 5 hours compared to 7-8 hours as an average thickening time in legacy Cement Lost Circulations designs. The new CSH binder enhances the cement paste density, reinforcing the structure between cement grains. Cement slurry was designed with 118 pcf densities; a compressive strength of 50 psi was achieved at 9:35 hours: minutes, 500 psi compressive strength was achieved at 11:14 hours: minutes, and a compressive strength of 2809 psi was recorded in the 24-hour chart. Furthermore, experiments proved that the new slurry can be used for thixotropic properties to achieve more effective cementing squeeze, treating lost circulation, and fluid-loss control. In summary, this slurry design was found to be more cost-effective as well as more efficient in lost circulation prevention and placement of kick-off plugs. This paper introduces to the industry a newly developed advanced slurry that significantly enhances the lost circulation treatment efficiency while reducing its cost at the same time. The paper will provide a detailed description of the application of Nano Silica Slurries in well cementing and lost circulation plugs. The paper will offer a discussion of the methodology, material properties, and applications.