Experimental Study on Mechanical, Brittleness, and Fracture Behavior of Deep Shales Subjected to Fracturing Fluid-Shale Interactions at Reservoir Temperature and In-Situ Stress Conditions

Zhao, Guokai; Guo, Yintong; Wang, Lei; Chang, Xin; Yang, Hanzhi; Guo, Wuhao; Wu, Xiaolong; Yang, Chunhe

doi:10.1007/s00603-023-03555-1

Cited by 3 publications

(1 citation statement)

References 34 publications

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“…Although σ ci /σ p tends to decrease with increasing soaking time, it only decreases slightly. For carbonate-rich shale, σ ci /σ p still shows a variation pattern that fluctuates within a certain range with the increase in soaking time, which may be caused by the dissolution and regeneration of carbonate minerals [32,33]. With increasing soaking time, the effect of hydration at HTHP on the internal crack initiation in carbonate-rich shale samples is more significant, while it has little effect on quartz-rich and clay-rich shales.…”

Section: Characteristics Of the Relationships Between Peak Stress And...mentioning

confidence: 96%

Effect of Hydration under High Temperature and Pressure on the Stress Thresholds of Shale

Wu,

Guo,

Huang

et al. 2023

Energies

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The stress threshold of deep reservoir shale subjected to fracturing fluid immersion is an important factor affecting fracture initiation and propagation during fracturing. However, little information has been reported on the effect on shale of soaking at high temperature and high pressure (HTHP). In this study, immersion tests and triaxial compression tests were carried out at reservoir temperature and in-situ stress on the downhole cores with different mineral compositions. The characteristics of stress thresholds, i.e., crack initiation stress (σci), crack damage stress (σcd), and peak deviator stress (σp), of shale affected by the different times of soaking with low-viscosity fracturing fluid (a) and the different viscosity fracturing fluids (a, b, and c) were investigated. The results show that hydration at HTHP has a significant softening effect on the stress thresholds (σci, σcd, σp) of reservoir shale, but the softening rate varies for samples with different mineral compositions. The crack initiation stresses of quartz-rich and clay-rich shales treated with different soaking times and different soaking media remain almost unchanged in the range of 47 to 54% of the corresponding peak strength, while the crack initiation stresses of carbonate-rich shales are significantly affected. The ratio σcd/σp of quartz-rich shale is significantly affected by the different viscosity fracturing fluids (a, b) and the different times of soaking with low-viscosity fracturing fluid (a), while clay- and carbonate-rich shales are less affected. The results of this study can provide a reference for the fracturing design of deep shale gas development.

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Section: Characteristics Of the Relationships Between Peak Stress And...mentioning

confidence: 96%

Effect of Hydration under High Temperature and Pressure on the Stress Thresholds of Shale

Wu,

Guo,

Huang

et al. 2023

Energies

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Decoding Rock Fracture Behavior: A Classification of Frost Heave Pressure Evolution in Freeze–Thaw Process

Wang,

Zhang,

Tian

et al. 2024

Rock Mech Rock Eng

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Experimental investigation to understand the effect of fracturing fluid on the geomechanical behavior of mowry shale

Dabbaghi,

Ng,

Kou

et al. 2024

J Petrol Explor Prod Technol

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Hydraulic fracturing of shale reservoirs is one of the important technologies in the oil and gas industry. To ensure the safe operation of oil and gas recovery, it is important to study the shale-fluid interactions on the geomechanical behavior of shale. This study investigated the effect of fracturing fluid treatment on the mechanical and elastic properties of the Mowry Shale formation, Wyoming, USA. Cylindrical Mowry Shale specimens with a diameter of 12.5 mm collected from the United States Geological Survey (USGS) and School of Energy Resources (SER) of the University of Wyoming were treated with brine and brine + stimulation fluid for one month each at pressures of 9 and 11.7 MPa and temperatures of 96 and 66 °C, respectively. Triaxial compression experiments were conducted on the specimens. Results showed that all Mowry Shale specimens experienced an increase in maximum volumetric strain with the increase in effective confining pressure (Pd). Regardless of aging fluids, the maximum deviatoric stress (Δσd) of most Mowry Shale specimens increases with the increase in Pd. At a lower Pd, the USGS specimen aged with brine and stimulation fluid exhibits higher maximum Δσd than those aged with brine only. However, at a higher Pd, the USGS specimen aged with brine exhibits a higher maximum Δσd. SER specimens aged with brine and stimulation fluid exhibit higher maximum Δσd values than those aged with brine for all three Pd values. Regardless of the aging fluids, most USGS specimens experience a brittle failure mode, while SER specimens aged with brine and stimulation fluid experienced a more ductile behavior.

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Experimental Study on Mechanical, Brittleness, and Fracture Behavior of Deep Shales Subjected to Fracturing Fluid-Shale Interactions at Reservoir Temperature and In-Situ Stress Conditions

Cited by 3 publications

References 34 publications

Effect of Hydration under High Temperature and Pressure on the Stress Thresholds of Shale

Effect of Hydration under High Temperature and Pressure on the Stress Thresholds of Shale

Decoding Rock Fracture Behavior: A Classification of Frost Heave Pressure Evolution in Freeze–Thaw Process

Experimental investigation to understand the effect of fracturing fluid on the geomechanical behavior of mowry shale

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