Novel Polymer Development Creates New High-Temperature, High-Pressure Cement Slurry Suspending Agent

Summary A high-temperature suspending agent with temperature resistance up to 200°C has been developed to address the challenges of high-temperature, high-density cement slurry (2.0–2.6g/cm3) settling and destabilization during cementing in deep wells (4500–6000 m) and ultradeep wells (>6000 m). This suspending agent is designed to introduce modified nano-silica (nano-SiO2) and long hydrophobic side-chain temperature-sensitive monomers. The inclusion of modified nano-SiO2 enhances the temperature resistance of the suspending agent and improves the suspension stability of solid-phase particles in high-density cement slurries. Concurrently, the long hydrophobic side chains increase the viscosity of the cement slurry at high temperatures through hydrophobic bonding. The synergistic effect of these components can delay settling of high-density cement slurries at high temperatures. In performance evaluations adhering to American Petroleum Institute (API) standards, the addition of 0.6 wt% of the suspending agent to a high-density cement slurry (density of 2.35 g/cm³) reduced the density difference between the top and bottom of the slurry from 0.897 g/cm³ to 0.028 g/cm³ after curing at 200°C, surpassing the local (Chinese) standard requirement of 0.05 g/cm³. This contributes to maintaining the overall uniformity of solid-phase particles in high-density cement slurry at high temperatures. It ensures the proper development of slurry consistency and cement strength properties. This advancement can help to reduce the risks associated with deep well cementing, supporting the quality of cementing operations in deep and ultradeep wells, and holds promise for starting some field tests.