Cement integrity under CO2 exposure remains ongoing industry challenge

New cement blends, additives, and diagnostic technologies are being tested to address the durability risks of wellbore cement in CO2-rich environments, especially in enhanced oil recovery applications

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N an era when carbon capture, utilisation and storage (CCUS) and enhanced oil recovery (EOR) are critical to climate mitigation strategies, maintaining well integrity under aggressive CO₂ rich downhole conditions has become paramount.

Recent advances in cement degradation research, combined with innovations in cement design, real time monitoring and operational frameworks, are reshaping how the energy industry ensures safe, durable zonal isolation in CCS, CCUS and CO₂ EOR wells.

In their research, 'A Comprehensive Review of Cement Degradation Analysis under Downhole Conditions: CCS/CCUS/CO2-EOR Applications', Orkhan Mammadov and his team offer an understanding of cement failure mechanisms in CO₂ injection wells.

It details how carbonation and bi-carbonation lead to micro cracking, permeability rise and ultimately compromised well integrity.

The paper reviews conventional and advanced cement systems including Portland, pozzolanic blends, calcium aluminate, geopolymers and polymer enhanced cements, with emerging nanomaterials and additive strategies proposed to strengthen long term performance.

Recent studies continue to prioritise cement systems tailored for CO₂ exposure. A study by Krunoslav Sedic and his team, called 'Carbonation study of new calcium aluminate cement-based CO 2 injection well sealants' into calcium aluminate cement (CAC) composites—with hollow glass microspheres (CAC µ) and SBR latex additives—demonstrated significantly improved resistance to carbonation under high pressure, high temperature CO₂ saturated conditions.

The CAC µ mixture maintained higher compressive strength and lower porosity after 80 days of exposure compared to standard Portland cement, making it a promising candidate for CO₂ EOR and CCS wells.

Innovative polymer, fly ash and nano silica additive blends similarly show benefit, supporting mechanical durability and chemical resistance.