In the quest to optimize oil recovery while mitigating carbon emissions, a groundbreaking study has emerged from the Key Laboratory for EOR Technology at Northeast Petroleum University. Led by Miaoxin Zhang, the research delves into the intricate dance of CO₂ dissolution and diffusion within clay-rich, water-sensitive reservoirs, offering promising insights for the energy sector.
The study, published in the journal *Nature Scientific Reports*, targets reservoirs with high clay content, where traditional waterflooding methods can induce clay mineral swelling, narrowing pore throats, and impeding oil recovery. “We found that integrating an anti-swelling system with CO₂ flooding can significantly enhance oil recovery while simultaneously sequestering carbon,” Zhang explains. This dual benefit is a game-changer for the industry, as it addresses both economic and environmental concerns.
The research team employed a multifaceted approach, utilizing pressure decay methods, core flooding experiments, and microscopic visualization to understand the complex interactions between CO₂, clay minerals, and crude oil. They discovered that the diffusion coefficient of supercritical CO₂ increases rapidly with pressure before leveling off, indicating that clay minerals can hinder CO₂ diffusion. However, the anti-swelling system mitigates this issue by suppressing clay swelling, thereby increasing the diffusion coefficient by 20–28%.
One of the study’s most notable achievements is the development of an enhanced mathematical model that accurately describes multiphase interactions. This model combines oil-water phase partition coefficients with the PR-EOS equation of state, fitting experimental data with 92% accuracy—far superior to traditional single-phase models. “This model provides a robust tool for predicting the behavior of CO₂ in these complex systems,” Zhang notes.
The practical implications of this research are substantial. Through microscopic oil displacement experiments and core flooding tests, the team demonstrated that anti-swelling system-CO₂ flooding achieves a sweep efficiency of 73.95%, with an oil recovery rate of 58.12% and a CO₂ sequestration efficiency of 46.16%. These results underscore the technology’s potential to revolutionize oil recovery in water-sensitive reservoirs while contributing to carbon sequestration efforts.
The study’s findings offer a roadmap for future developments in the field. By stabilizing pore structure, reducing oil viscosity, and enabling efficient carbon sequestration, this technology presents a holistic solution for low-carbon development in the oil industry. As the energy sector grapples with the dual challenges of meeting global demand and reducing emissions, this research provides a beacon of hope and a practical pathway forward.
In the words of Miaoxin Zhang, “This work not only advances our scientific understanding but also offers tangible benefits for the energy sector, paving the way for more sustainable and efficient oil recovery practices.”