New Study Proposes Smarter Framework for CCUS-EOR

By Muhammad OsamaReviewed by Laura ThomsonJul 15 2025

A recent study published in Engineering introduces a fresh framework for optimizing carbon capture, utilization, and storage (CCUS) integrated with enhanced oil recovery (EOR), with a focus on carbon dioxide (CO₂)-EOR. The research outlines how this approach can simultaneously boost energy production and enable long-term carbon sequestration, cutting emissions and improving resource efficiency.

The findings position CCUS-EOR as a vital strategy for climate mitigation and sustainable energy development, especially in the global push toward carbon neutrality.

The Role of CCUS-EOR in Climate Action

Tackling global climate change, one of the defining challenges of the 21^st century, requires scalable, effective solutions for reducing carbon emissions. Among these, CCUS is a key technology that captures CO₂ from industrial sources and stores it deep underground.

Within the suite of CCUS approaches, CO₂-EOR remains the most widely adopted, making up about 77% of global carbon capture efforts. This method involves injecting captured CO₂ into depleted oil reservoirs to extract more oil while securely storing the gas below the surface.

According to the International Energy Agency (IEA), CO₂-EOR projects have sequestered over 400 million tons of CO₂, the equivalent of emissions from roughly 100 million gasoline-powered cars annually. As the method scales to new fields and larger projects, its relevance in clean energy strategies continues to rise.

A Two-Stage Framework for CCUS-EOR

The study examines key factors that influence the performance of CCUS-EOR, focusing on reservoir characteristics, fluid properties, and operational settings. Researchers proposed a two-stage framework to better understand and enhance the process.

In the first stage, during active CO₂ injection, the gas mixes with crude oil, reducing viscosity and improving flow. Depending on reservoir conditions, this mixing may occur either miscibly or immiscibly. At the same time, CO₂ occupies pore spaces within the reservoir, contributing to physical storage.

In the second stage, after the injection ends, CO₂ gradually dissolves into the formation water and reacts with the surrounding minerals. These reactions form stable carbonate compounds that securely trap the gas over time.

The study breaks down several critical variables across both stages, including:

• Reservoir factors: Porosity, permeability, temperature, pressure, and mineral makeup
• Fluid properties: Oil composition, water salinity, gas impurities
• Operational parameters: Injection pressure, rate, and methods

By mapping out the interactions among these elements, researchers identified key ways to improve oil recovery and CO₂ storage. They also reviewed advanced techniques such as water-alternating-gas (WAG) injection and the use of smart, eco-friendly materials to further enhance efficiency.

Factors That Shape CO₂ Storage and Recovery Performance

Results showed that permeability and porosity are central to CO₂ movement and storage capacity. While higher permeability generally improves oil recovery, too much variation can lead to uneven gas flow and reduced efficiency. Optimal oil recovery was observed in reservoirs with permeability between 10 and 31.6 millidarcies (mD), though CO₂ storage behavior within this range proved more complex and non-linear.

When CO₂ reaches supercritical conditions (above 304.2 K and 7.39 MPa), its low viscosity and high density enhance mixing with crude oil. Increased pressure raises density and solubility of CO₂, which benefits oil recovery and storage. However, very high temperatures (over 150 °C) and pressures (above 60 MPa) raise leakage risks and lower storage reliability.

Mineral composition ALSO plays a significant role. Minerals rich in calcium, magnesium, aluminum, and iron react with CO₂ to form solid carbonates, improving storage by altering pore structures and permeability over time.

Oil composition also affects recovery and storage. CO₂ tends to extract lighter hydrocarbons (C1–C9), which improves oil recovery but lowers CO₂ retention. Heavier hydrocarbons (C20+) adsorb more CO₂ but are less miscible.

Injection pressure must exceed the oil’s minimum miscibility pressure to ensure adequate recovery and storage. Meanwhile, formation water chemistry—especially salinity and pH—also influences outcomes. Lower salinity improves CO₂ solubility and storage potential, while high salinity reduces it due to the salting-out effect. Acidic conditions support CO₂ dissolution; alkaline conditions tend to result in free gas, decreasing overall storage efficiency.

Implications for the Energy Sector

These findings have practical implications for the energy industry. By improving CCUS-EOR technologies, companies can increase oil yields while locking away carbon, helping to meet sustainability and net-zero targets.

The study also recommends adopting advanced tools such as AI-based optimization methods, smart hydrogel agents, and integrated monitoring systems to enhance CCUS-EOR performance. Economic evaluations that factor in carbon credits, project costs, and regulatory risks are also essential for gauging viability.

Researchers emphasize the importance of cross-industry collaboration and data sharing to speed up CCUS-EOR deployment. They also call for ongoing technological and practice innovation to keep pace with evolving climate and energy demands.

Conclusion

CCUS-EOR offers a practical and scalable approach to balancing energy production with effective carbon management. This research provides a comprehensive reference for scientists, engineers, and policymakers working to refine these technologies. It underscores the need for continued innovation and collaboration to develop reliable, long-term carbon strategies that support a more sustainable, climate-resilient future.

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