Preparation of Novel Ultra‐High Temperature Polymer/Montmorillonite Nanocomposite Suspension Stabilizer and Its Effects on Properties of Well Cementing Slurry

Abstract

To address the sedimentation and instability of cement slurries under the high‐temperature and high‐pressure conditions of deep and ultra‐deep well cementing, a novel organic–inorganic hybrid suspension stabilizer, LXCH, was designed and synthesized. Four functional monomers were copolymerized in situ with modified nano‐montmorillonite to construct a hybrid framework combining rigid inorganic components with flexible polymer chains. The target structure was confirmed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and X‐ray photoelectron spectroscopy, while thermogravimetric analysis demonstrated excellent thermal stability, with no obvious degradation below 282°C. At 210°C and 90 MPa, the incorporation of LXCH significantly improved slurry suspension stability, resulting in a hardened cement column density difference below 0.04 g/cm 3 , without adversely affecting rheological properties, thickening behavior, or compressive strength. Rheological frequency sweeps, hydrodynamic radius and zeta potential measurements, environmental scanning electron microscopy observations, and molecular dynamics simulations revealed a dual‐network stabilization mechanism. Partial polymer crosslinking forms an initial chemical network at relatively low temperatures, while hydrophobic association at elevated temperatures generates a dynamic physical network. Together with electrostatic adsorption and steric hindrance, these networks effectively maintain slurry stability, providing a promising strategy for high‐performance stabilizers for deep and ultra‐deep well cementing.