Carbon capture, utilization, and storage: A comprehensive review of CCUS-EOR

A recent study published in Engineering offers a comprehensive review of the synergistic impact of Carbon Capture, Utilization, and Storage (CCUS) coupled with Enhanced Oil Recovery (EOR) technologies. The research, led by Zhenhua Rui from the China University of Petroleum (Beijing), delves into the key factors influencing the efficiency of CO₂-EOR and geological storage, proposing a novel coupled two-stage CCUS-EOR process to optimize the dual objectives of enhanced oil production and carbon reduction.

The study highlights that CCUS-EOR represents a critical technological pathway for global carbon emission reduction, contributing to 77% of the world’s total carbon capture. CCUS-EOR projects worldwide have cumulatively sequestered over 400 million tons of CO₂, equivalent to offsetting the annual emissions of 100 million gasoline-powered vehicles. The technology not only enhances the economic value of low-productivity oilfields but also extends the lifespan of oil reservoirs, offering significant socio-economic benefits.

The research systematically describes the key influencing factors governing CO₂-EOR and geological storage, including reservoir properties, fluid characteristics, and operational parameters. The study proposes a two-stage CCUS-EOR process: the CO₂-EOR storage stage and the long-term CO₂ storage stage after the CO₂ injection phase is completed. In each stage, the main control factors impacting the CO₂-EOR and storage stages are screened and coupled with rigorous technical analysis.

Reservoir properties such as permeability and porosity significantly affect the flow dynamics and storage capacity. The study finds that while higher permeability and porosity can improve oil recovery and CO₂ storage capacity, excessive heterogeneity can lead to CO₂ channeling, reducing oil recovery and increasing leakage risks. The research also highlights the importance of reservoir temperature and pressure, which significantly impact the performance of CCUS-EOR processes due to their effects on miscibility and trapping mechanisms.

Fluid characteristics, including crude oil and formation water, also play a crucial role in the efficiency of CO₂-EOR and storage. The study notes that the viscosity and density of crude oil are key factors influencing the efficiency of CO₂ flooding and storage. Additionally, the solubility of CO₂ in formation water directly affects the storage capacity related to CO₂ dissolution, with low salinity being conducive to higher CO₂ solubility.

Operational factors such as injection and production rates, injection pressure, and injection modes are also critical. The study suggests that optimizing these parameters can significantly enhance the efficiency of CO₂-EOR and storage. For instance, higher injection rates can improve oil recovery but may lead to gas channeling in heterogeneous reservoirs. Injection pressure, which affects the reservoir pressure distribution and CO₂ phase, is another key factor. The study recommends maintaining injection pressure below the caprock fracture pressure to prevent leakage.

The research concludes by proposing a comprehensive synergistic method for the entire lifecycle of CCUS-EOR, including a multi-scale techno-economic evaluation method to fully assess the project performance. The study also highlights the need for further research on the impact of reservoir mineral properties on CCUS-EOR, focusing on quantifying the contributions of different mineral components to CO₂ mineral trapping.

This comprehensive review provides valuable insights into the mechanisms and parameters affecting the performance of CCUS-EOR projects, offering guidance for the optimization of these technologies to achieve dual socio-economic and environmental benefits.

The paper “Investigating the Synergistic Impact of CCUS-EOR,” is authored by Zhenhua Rui, Tingting Liu, Xin Wen, Siwei Meng, Yang Li, Birol Dindoruk. Full text of the open access paper: https://doi.org/10.1016/j.eng.2025.04.005. For more information about Engineering, visit the website at https://www.sciencedirect.com/journal/engineering.