Study on Anti-Carbonation Performance of TA@Gr-OTES Hydrophobic Cement System

Carbon capture, utilization and storage (CCUS) is a key technology for carbon neutrality and efficient oilfield development. Oil well cement suffers serious carbonation degradation under high-temperature, high-pressure and high CO2 partial pressure environments, leading to well cementing failure. In this study, TA@Gr-OTES (TGO) composite was prepared by surface grafting modification, and a hydrophobic oil well cement system suitable for CCUS was constructed. The anti-carbonation performance was tested under simulated formation conditions (130 °C, 25 MPa, CO2 partial pressure 7 MPa). Results show that TGO-modified cement maintains stable hydrophobicity, with a 60-day compressive strength attenuation rate of only 6.7%, and its permeability and porosity are much lower than those of plain cement. TGO inhibits deep carbonation and corrosion product leaching, preserves hydration products, and reduces defect volume. The potential triple mechanisms of a hydrophobic barrier, graphene physical shielding and matrix densification effectively blocks CO2 intrusion. This study provides theoretical and technical support for long-life cementing materials in CCUS wells.