Fumed silica A-200K (or similar grades such as Evonik’s Aerosil® 200) plays a crucial role in optimizing oilwell cement slurries by improving rheology, enhancing high-temperature stability, preventing sedimentation, and boosting mechanical properties of set cement. Below are its key applications and case studies:

1. Enhancing High-Temperature Stability
Fumed silica (e.g., A200) has a high specific surface area (~200 m²/g) and nano-sized particles (~12 nm), enabling it to adsorb free water on cement particles and form a 3D network structure. This significantly improves cement slurry stability under high temperatures. Examples include:

Ultra-High-Temperature Anti-Degradation Slurry: In heavy oil thermal recovery wells (up to 345°C), fumed silica combined with silica flour and dead-burned magnesia acts as a high-temperature stabilizer, preventing strength degradation of cement under steam injection. The compressive strength remains above 35 MPa even after prolonged exposure.

High-Temperature Suspension Stabilizer: When blended with polyaluminum ferric chloride and attapulgite, fumed silica effectively prevents cement slurry sedimentation in 50–160°C environments.

2. Optimizing Rheology & Preventing Sedimentation
The thixotropic nature of fumed silica helps:
Control Rheology: Acts as a viscosifier to adjust slurry viscosity, preventing excessive thinning or settling at high temperatures. For example, a patented formulation combines fumed silica with silica flour (10–15% dosage) to balance thickening at ambient conditions and stability at elevated temperatures.
Prevent Particle Settling: In deep or ultra-deep wells, fumed silica nanoparticles adsorb onto cement particles, minimizing stratification and ensuring slurry homogeneity.

3. Improving Mechanical Properties of Set Cement
Nano-silica promotes cement hydration, generating more C-S-H gel, which:
Increases Compressive Strength: At high temperatures, adding fumed silica can enhance 28-day compressive strength to 37 MPa while maintaining long-term stability.
Reduces Permeability: By filling cement matrix pores, it enhances zonal isolation and reduces fluid migration risks.

4. Case Studies
Case 1: A Chinese oilfield applied a high-temperature stabilizer (containing fumed silica, silica flour, and dead-burned magnesia) in thermal recovery wells. After 98 days under 345°C steam, the cement retained a compressive strength of 35 MPa, outperforming conventional silica-based slurries.

话题标签#fumed silica#silica fumed#silicon dioxide 话题标签#white carbon black 话题标签#pyrogenic silica# Synthetic Amorphous Silica#nanoscale fumed silica 话题标签#Email:rhea@sdyingrui.cn; michael@sdyingrui.cn#Whatsapp: +8613583505605;+8615154536501#https://lnkd.in/e4Kd-suw