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<p>Supercritical CO₂ (SC-CO₂) fracturing is a promising technology for the stimulation of hot dry rock (HDR) reservoirs. To clarify the fracture evolution behavior of SC-CO₂ fracturing under HDR reservoir environment, SC-CO₂ fracturing experiments with different injection modes were carried out under high-temperature true triaxial stress conditions in this study. The results show that SC-CO₂ fracturing exhibited lower breakdown pressure than hydraulic fracturing, which is related to the low viscosity and other distinctive physical properties of SC-CO₂. In terms of fracture morphology evolution, SC-CO₂ fracturing tended to activate natural fractures and formed a more complex fracture system composed of a main fracture and activated natural fractures; meanwhile, the roughness of the main fracture surface was also improved. Compared with hydraulic fracturing, SC-CO₂ fracturing was characterized by lower AE signal amplitude and total AE energy, but a higher proportion of high-frequency energy above 100&#xa0;kHz, indicating that rock damage was dominated by microcrack initiation. Moreover, SC-CO₂ fracturing exhibited a higher fracture propagation rate than hydraulic fracturing, thereby promoting rapid fracture development. This study provides laboratory-scale evidence for understanding the fracture propagation behavior of SC-CO₂ fracturing and may help optimize injection strategies for future engineering applications in HDR reservoirs. </p>

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Experimental Study on Supercritical CO₂ Fracturing in Granite Under Different Injection Modes

  • 期刊论文

  • 发表日期：

    2026年7月14日

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  • Wuhao Guo,
  • Yintong Guo,
  • Xinao Zhang,
  • Jiawei Kao,
  • Shilong Teng,
  • Zhenhui Bi,
  • Mingnan Xu,
  • Chunhe Yang

摘要

Supercritical CO₂ (SC-CO₂) fracturing is a promising technology for the stimulation of hot dry rock (HDR) reservoirs. To clarify the fracture evolution behavior of SC-CO₂ fracturing under HDR reservoir environment, SC-CO₂ fracturing experiments with different injection modes were carried out under high-temperature true triaxial stress conditions in this study. The results show that SC-CO₂ fracturing exhibited lower breakdown pressure than hydraulic fracturing, which is related to the low viscosity and other distinctive physical properties of SC-CO₂. In terms of fracture morphology evolution, SC-CO₂ fracturing tended to activate natural fractures and formed a more complex fracture system composed of a main fracture and activated natural fractures; meanwhile, the roughness of the main fracture surface was also improved. Compared with hydraulic fracturing, SC-CO₂ fracturing was characterized by lower AE signal amplitude and total AE energy, but a higher proportion of high-frequency energy above 100 kHz, indicating that rock damage was dominated by microcrack initiation. Moreover, SC-CO₂ fracturing exhibited a higher fracture propagation rate than hydraulic fracturing, thereby promoting rapid fracture development. This study provides laboratory-scale evidence for understanding the fracture propagation behavior of SC-CO₂ fracturing and may help optimize injection strategies for future engineering applications in HDR reservoirs.