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Experimental and Modelling Analysis of Shale Fracturing by True Triaxial Dynamic Impact.

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Bibliographic Details
Title:	Experimental and Modelling Analysis of Shale Fracturing by True Triaxial Dynamic Impact.
Authors:	Wang, Xiaofei^1,2 (AUTHOR), Wang, Enyuan³ (AUTHOR) weytop@cumt.edu.cn, He, Xueqiu³ (AUTHOR), Gu, Zhoujie³ (AUTHOR) guzhoujie1996@126.com, Hu, Shaobin^1,2 (AUTHOR)
Source:	Rock Mechanics & Rock Engineering. Jun2026, Vol. 59 Issue 6, p6459-6472. 14p.
Subject Terms:	Hopkinson bars (Testing), Fracturing fluids, Solubilization, Corrosion & anti-corrosives, Hydraulic fracturing, Deterioration of materials, *Impulse (Physics)
Abstract:	The production process of shale gas wells was characterised by a large number of dynamic disturbances, which posed a threat to the structural safety of the mine. For different jointed shales and different solution-treated shales, a true triaxial Hopkinson bar dynamic impact test was designed, and the damage specimens were photographed for observation and wave velocity measurement. With the assistance of scanning electron microscope photographs and XRD mineral analyses, the principles of fracturing solution-treated and dynamically impacted shale were revealed, and a failure model was constructed. The main results of the study were: 1 As the angle between the joint and the impact direction increased, the dynamic breaking strength of the shale tended to decrease and then increase, reaching a minimum value at 60°. 2 Hydrochloric acid and fracturing fluid solubilised the minerals and organic matter in the shale, led to enlargement of the original pore cleavage in the shale and reduction of the dynamic strength. 3 Dynamic impact damage models of shale with different joints were established, and the deterioration mechanism of acid-treated shale was analysed using Helgeson's formula for mineral dissolution. 4 The corrosion mechanisms of fracturing fluid and dilute hydrochloric acid were compared, and a comparative analysis model was constructed, concluding that fracturing fluid can increase the magnitude of shale dynamic strength weakening. True triaxial was able to better simulate the real stress state in kilometre-deep wells, so this study could obtain the crack extension law of dynamically loaded stress-damaged rocks downhole. Highlights: A true triaxial Hopkinson bar dynamic impact test of shale with different joints and different solution-treated shale was designed in the research, which realistically simulated the well stress state. The dynamic failure strength of shale presented a tendency of decreasing and then increasing with the increase of the angle between the joints and the impact direction, and reached the lowest value at 60°. The dilute hydrochloric acid and fracturing fluid dissolved the minerals and organic matter in the shale, which caused the expansion of the original pore fissures of the shale and the decrease of the dynamic strength. Dynamic impact damage model of shale with different joints was established, and the deterioration mechanism of acid-treated shale was analysed by Helgessen's mineral dissolution equation. [ABSTRACT FROM AUTHOR]
Database:	Energy & Power Source

Description
Abstract:	The production process of shale gas wells was characterised by a large number of dynamic disturbances, which posed a threat to the structural safety of the mine. For different jointed shales and different solution-treated shales, a true triaxial Hopkinson bar dynamic impact test was designed, and the damage specimens were photographed for observation and wave velocity measurement. With the assistance of scanning electron microscope photographs and XRD mineral analyses, the principles of fracturing solution-treated and dynamically impacted shale were revealed, and a failure model was constructed. The main results of the study were: 1 As the angle between the joint and the impact direction increased, the dynamic breaking strength of the shale tended to decrease and then increase, reaching a minimum value at 60°. 2 Hydrochloric acid and fracturing fluid solubilised the minerals and organic matter in the shale, led to enlargement of the original pore cleavage in the shale and reduction of the dynamic strength. 3 Dynamic impact damage models of shale with different joints were established, and the deterioration mechanism of acid-treated shale was analysed using Helgeson's formula for mineral dissolution. 4 The corrosion mechanisms of fracturing fluid and dilute hydrochloric acid were compared, and a comparative analysis model was constructed, concluding that fracturing fluid can increase the magnitude of shale dynamic strength weakening. True triaxial was able to better simulate the real stress state in kilometre-deep wells, so this study could obtain the crack extension law of dynamically loaded stress-damaged rocks downhole. Highlights: A true triaxial Hopkinson bar dynamic impact test of shale with different joints and different solution-treated shale was designed in the research, which realistically simulated the well stress state. The dynamic failure strength of shale presented a tendency of decreasing and then increasing with the increase of the angle between the joints and the impact direction, and reached the lowest value at 60°. The dilute hydrochloric acid and fracturing fluid dissolved the minerals and organic matter in the shale, which caused the expansion of the original pore fissures of the shale and the decrease of the dynamic strength. Dynamic impact damage model of shale with different joints was established, and the deterioration mechanism of acid-treated shale was analysed by Helgessen's mineral dissolution equation. [ABSTRACT FROM AUTHOR]
ISSN:	07232632
DOI:	10.1007/s00603-025-05061-y