Paper contribution

Hydro-mechanical coupled behaviors of weakly cemented sandstones during two-phase fluids displacement: insights from a micro-continuum VOF-BPM method

Shihang Chen; Fengshou Zhang

Proceedings
EUROCK 2026
Pages
1141-1148
Submitted
28 January 2026
Accepted
15 June 2026
Published
12 August 2026

Summary

Abstract

Geological CO2 storage (GCS) aims to permanently reduce carbon emissions by injecting supercritical CO2 (scCO2) or water-CO2 into subsurface formations. Weakly cemented sandstones, which are widely distributed within saline aquifers, represent one of the primary storage media. However, the coupled hydro-mechanical behaviors of these formations during two-phase fluid displacement remain largely unexplored, despite significantly impacting the efficiency and safety of GCS. In this study, a micro-continuum VOF-BPM method is proposed to accurately capture the complex hydro-mechanical interactions between weakly cemented sandstones and two-phase fluids. An intra-particle porosity is first defined to transform single particles into permeable discrete elements, and the rock's mechanical behavior is simulated using the Bonded Particle Model (BPM). Simultaneously, the Volume of Fluid (VOF) algorithm, the micro-continuum method, and the two-phase Darcy model are fully coupled to resolve multiscale flow through fractures and the matrix. The great agreement between simulation and experimental results for fluid injection into a dense granular system confirms the method's validity and superior performance. A quasi-2D model is built to simulate scCO2 injection into weakly cemented sandstones under varied conditions. Results show that in high-permeability sandstones, increased injection rates trigger a rapid transition from matrix seepage to fracture propagation, revealing a clear flow-path competition. Unstable displacement fronts within the matrix, governed by the small viscosity ratio between invading and defending fluids, are also well captured. Such instability and flow-path competition strongly shape the final CO2 distribution, affecting overall storage efficiency. These findings underscore that accurate fracture prediction in high-permeability reservoirs necessitates a precise characterization of two-phase displacement dynamics, demonstrating the advanced capability of the proposed micro-continuum VOF-BPM method and providing critical insights for optimizing GCS operations.

Contributors

Authors

  1. Shihang Chen Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai 200092, China
  2. Fengshou Zhang Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai 200092, China ORCID 0000-0002-4998-6259

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References

  1. Carrillo, F.J., Bourg, I.C., Soulaine, C., (2020). Multiphase flow modeling in multiscale porous media: An open-source micro-continuum approach. Journal of Computational Physics: X 8, 100073. https://doi.org/10.1016/j.jcpx.2020.100073
  2. Goniva, C., Kloss, C., Deen, N.G., Kuipers, J.A.M., Pirker, S., (2012). Influence of rolling friction on single spout fluidized bed simulation. Particuology 10, 582–591. https://doi.org/10.1016/j.partic.2012.05.002
  3. Huang, H., Zhang, F., Callahan, P., Ayoub, J., (2012). Granular Fingering in Fluid Injection into Dense Granular Media in a Hele-Shaw Cell. Phys. Rev. Lett. 108, 258001. https://doi.org/10.1103/PhysRevLett.108.258001
  4. Kazidenov, D., Amanbek, Y., (2025). CFD-DEM modeling of fracture initiation with polymer injection in granular media. Particuology 97, 58–68. https://doi.org/10.1016/j.partic.2024.12.001
  5. Li, M., Zhang, F., Wang, S., Dontsov, E., Li, P., (2024). DEM Modeling of Simultaneous Propagation of Multiple Hydraulic Fractures Across Different Regimes, from Toughness- to Viscosity-Dominated. Rock Mech Rock Eng 57, 481–503. https://doi.org/10.1007/s00603-023-03554-2
  6. Parisio, F., Vilarrasa, V., Wang, W., Kolditz, O., Nagel, T., (2019). The risks of long-term re-injection in supercritical geothermal systems. Nat Commun 10, 4391. https://doi.org/10.1038/s41467-019-12146-0
  7. Potyondy, D.O., Cundall, P.A., (2004). A bonded-particle model for rock. International Journal of Rock Mechanics and Mining Sciences, Rock Mechanics Results from the Underground Research Laboratory, Canada 41, 1329–1364. https://doi.org/10.1016/j.ijrmms.2004.09.011
  8. Schramm, M., Tekeste, M.Z., Plouffe, C., Harby, D., (2019). Estimating bond damping and bond Young’s modulus for a flexible wheat straw discrete element method model. Biosystems Engineering 186, 349–355. https://doi.org/10.1016/j.biosystemseng.2019.08.003
  9. Snæbjörnsdóttir, S.Ó., Sigfússon, B., Marieni, C., Goldberg, D., Gislason, S.R., Oelkers, E.H., (2020). Carbon dioxide storage through mineral carbonation. Nat Rev Earth Environ 1, 90–102. https://doi.org/10.1038/s43017-019-0011-8
  10. Soulaine, C., Tchelepi, H.A., (2016). Micro-continuum Approach for Pore-Scale Simulation of Subsurface Processes. Transp Porous Med 113, 431–456. https://doi.org/10.1007/s11242-016-0701-3
  11. Span, R., Wagner, W., (1996). A New Equation of State for Carbon Dioxide Covering the Fluid Region from the Triple-Point Temperature to 1100 K at Pressures up to 800 MPa. Journal of Physical and Chemical Reference Data 25, 1509–1596. https://doi.org/10.1063/1.555991
  12. Van Genuchten, M.Th., (1980). A Closed‐form Equation for Predicting the Hydraulic Conductivity of Unsaturated Soils. Soil Science Soc of Amer J 44, 892–898. https://doi.org/10.2136/sssaj1980.03615995004400050002x