Investigation of conglomerate softening effect induced by supercritical CO₂-water-rock interaction via micro-scratch test

Authors

  • Liu Yang* State Key Laboratory for Tunnel Engineering, China University of Mining and Technology, Beijing 100083, P. R. China; School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083, P. R. China (Email: shidayangliu@126.com)
  • Zhaoyang Liu State Key Laboratory for Tunnel Engineering, China University of Mining and Technology, Beijing 100083, P. R. China; School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083, P. R. China
  • Yunhui Lu State Key Laboratory for Tunnel Engineering, China University of Mining and Technology, Beijing 100083, P. R. China; School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083, P. R. China
  • Haoru Chen State Key Laboratory for Tunnel Engineering, China University of Mining and Technology, Beijing 100083, P. R. China; School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083, P. R. China
  • Yuhang Dong State Key Laboratory for Tunnel Engineering, China University of Mining and Technology, Beijing 100083, P. R. China
  • Manchao He State Key Laboratory for Tunnel Engineering, China University of Mining and Technology, Beijing 100083, P. R. China; School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083, P. R. China

Abstract

Supercritical CO₂-water-rock interactions significantly impact the mechanical integrity of heterogeneous conglomerate reservoirs, challenging their suitability for CO₂ sequestration and enhanced oil recovery. To evaluate these microscale mechanical and structural changes, this study uses a combination of micro-scratch testing, scanning electron microscopy, and nuclear magnetic resonance. The results reveal that the micro-scratch method enables the acquisition of a continuous mechanical property profile, addressing the limitation of traditional rock mechanics that only allows discrete point measurements. Importantly, the scratch failure modes significantly depend on the lithology of conglomerate reservoirs: Felsic and quartz conglomerates exhibit sharp grooves with interfacial shear failure, whereas debris-rich variants develop wavy, fragmented paths. CO₂-water exposure reduces the deformation resistance and causes fracture toughness to initially increase and then decline, with the most severe reduction observed in quartz conglomerates. The degradation of mechanical properties is mainly through mineral dissolution and increased porosity. The findings of this study offer key insights for optimizing storage and recovery strategies in complex reservoirs.

Document Type: Original article

Cited as: Yang, L., Liu, Z., Lu, Y., Chen, H., Dong, Y., He, M. Investigation of conglomerate softening effect induced by supercritical CO₂-water-rock interaction via micro-scratch test. Advances in Geo-Energy Research, 2025, 18(1): 21-37. https://doi.org/10.46690/ager.2025.10.03

Keywords:

Conglomerate, scCO₂-water-rock interaction, micro-scratch test, micro-mechanical properties, micro-structural characteristics

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Published

2025-09-10

How to Cite

Yang*, L., Liu, Z., Lu, Y., Chen, H., Dong, Y., & Manchao He. (2025). Investigation of conglomerate softening effect induced by supercritical CO₂-water-rock interaction via micro-scratch test. Advances in Geo-Energy Research, 18(1), 21–37. Retrieved from https://ager.yandypress.com/index.php/2207-9963/article/view/582

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Vol. 18 No. 1 (2025): October (In Progress)

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