Reservoir Simulation of CO2 Flooding vs. CO2 Huff-and-Puff in Shale Formations: Comparative Analysis of Storage and Recovery Mechanisms


Zhumakhanova N. Sepehrnoori K. Delikesheva D. Ismailova J. Khagag F.
July 2025Multidisciplinary Digital Publishing Institute (MDPI)

Energies
2025#18Issue 13

Anthropogenic CO2 emissions are a major driver of climate change, highlighting the urgent need for effective mitigation strategies. Carbon Capture, Utilization, and Storage (CCUS) offers a promising approach, particularly through CO2-enhanced gas recovery (EGR) in shale reservoirs, which enables simultaneous hydrocarbon production and CO2 sequestration. This study employs a numerical simulation model to compare two injection strategies: CO2 flooding and huff-and-puff (H&P). The results indicate that, without accounting for key mechanisms such as adsorption and molecular diffusion, CO2 H&P provides minimal improvement in methane recovery. When adsorption is included, methane recovery increases by 9%, with 14% of the injected CO2 stored over 40 years. Incorporating diffusion enhances recovery by 19%, although with limited storage potential. In contrast, CO2 flooding improves methane production by 26% and retains up to 94% of the injected CO2. Higher storage efficiency is observed in reservoirs with high porosity and low permeability, particularly in nano-scale pore systems. Overall, CO2 H&P may be a viable EGR option when adsorption and diffusion are considered, while CO2 flooding demonstrates greater effectiveness for both enhanced gas recovery and long-term CO2 storage in shale formations.

CO2 injection , CO2 sequestration , enhanced gas recovery , reservoir simulation , shale gas

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Petroleum Engineering Department, Satbayev University, Almaty, 05000, Kazakhstan
Hildebrand Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, Austin, 78712, TX, United States

Petroleum Engineering Department
Hildebrand Department of Petroleum and Geosystems Engineering

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