Effects of hydrostatic pressure on hydraulic fracturing properties of shale using X-ray computed tomography and acoustic emission

Zhao, Hang; Li, Bing; Sun, Weiji; Hu, Zhiming; Ma, Yangqi; Liu, Qi

doi:10.1016/j.petrol.2022.110725

Cited by 13 publications

(7 citation statements)

References 43 publications

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“…It can be seen on the figures, as the confining stresses increase more, there will be more tensile As stress within the material increases, microcracks tend to coalesce, and as stress approaches the fracturing point, the b-value diminishes. This analysis method helps in understanding the crack formation process in more detail (Aggelis, 2011;Zhang et al, 2020). Niu et al (2020) discussed the fracture in sandstone under uniaxial compressive loading by using AE.…”

Section: Analysis Of the Classification Of Crack Typesmentioning

confidence: 99%

“…They found that there are lots of tensile cracks in all hydraulic fracturing experiments (Jiang et al, 2020). Zhao et al (2022) conducted the hydraulic fracturing tests on full-diameter shale cores using X-ray computed tomography and acoustic emission. The hydraulic fracturing characteristics of shale with different bedding angles under high hydrostatic pressure have been studied (Zhao et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Zhao et al (2022) conducted the hydraulic fracturing tests on full-diameter shale cores using X-ray computed tomography and acoustic emission. The hydraulic fracturing characteristics of shale with different bedding angles under high hydrostatic pressure have been studied (Zhao et al, 2022). Guo et al analyzed the influence of natural stress levels and the angle of the shale's bedding on the process of hydraulic fracturing in shale by using acoustic emission detection and CT scans and the resulting fracture geometry also investigated (Guo et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

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Experimental Study on Hydraulic Fracturing with Acoustic Emission under Tri-Axial Stress Conditions

Esmaeilzadeh,

Nikkhah

2024

Preprint

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Hydraulic fracturing method is known as one of the most important stimulation methods, especially in unconventional gas and petroleum reservoirs. Acoustic emission (AE) is a popular technique to monitor the process of geomaterial failure during hydraulic fracturing. In the present paper, AE monitoring has been employed for a better understanding of the mechanism of crack and fracture generation in experimental hydraulic fracturing. Concrete blocks were subjected to true tri-axial stress conditions while AE was synchronously recorded during fluid injection. The experiments have been performed on the specimens under different loading stresses in order to investigate the effect of the applied pre-stress combinations. Based on the results, as the minimum horizontal stress increases, the fracturing pressure increases; moreover, when the maximum horizontal stress and vertical stress increase, the fracturing pressure shows an increasing and decreasing trend. Observed fractures align with the direction of maximum horizontal stress under anisotropic conditions, while isotropic stress conditions result in randomly oriented radial fractures. Analysis of AE parameters provides valuable insights, correlating with the physical fractures and cracks behavior and demonstrating the potential of AE monitoring as a predictive tool for hydraulic fracturing behavior.

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Section: Analysis Of the Classification Of Crack Typesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental Study on Hydraulic Fracturing with Acoustic Emission under Tri-Axial Stress Conditions

Esmaeilzadeh,

Nikkhah

2024

Preprint

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“…Most laboratory hydraulic fracturing experiments in transversely isotropic rocks have focused on the initiation and early-time growth of HF, in which the fracture behavior is primarily governed by the release of the fluid volume stored in the injection system prior to initiation (Gehne et al, 2019(Gehne et al, , 2020Tan et al, 2017;Y. Zhang et al, 2023;Zhao et al, 2022). Consequently, these HFs' initiation and propagation experiment are dominated by the toughness-dominated regime with a significant early-time compressibility effect (Abbas & Lecampion, 2013;Lecampion et al, 2017;Lu et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…While these results are instrumental in exploring the relationship between fracture initiation and rock anisotropy, limited experimental work has studied the stable growth of HFs in anisotropic rocks. Furthermore, the presence of weak bedding planes in sedimentary rocks like shale often leads to complex HF networks in lab‐scale experiments (Tan et al., 2017; Y. Zhang et al., 2023; Zhao et al., 2022), making it difficult to distinguish the influence of intrinsic anisotropy of rocks from the governing effect of pre‐existing beddings/discontinuities. For a comprehensive understanding of the impact of rock intrinsic anisotropy, including both the elastic stiffnesses anisotropy and fracture toughness anisotropy, on various naturally occurring and human‐related HFs, a thorough analysis of the fracture propagation in anisotropic rocks across a wide parametric space covering different propagation regimes is imperative.…”

Section: Introductionmentioning

confidence: 99%

Rock Anisotropy Promotes Hydraulic Fracture Containment at Depth

Lu,

Momeni,

Peruzzo

et al. 2024

JGR Solid Earth

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We report laboratory experiments and numerical simulations demonstrating that the anisotropic characteristics of rocks play a major role in the elongation of hydraulic fractures (HFs) propagating in a plane perpendicular to the rocks' inherent layering (the bedding planes in sedimentary rocks and foliation planes in metamorphic rocks). Transverse anisotropy leads to larger HF extension in the parallel‐to‐layers/divider direction compared to the perpendicular‐to‐layers/arrester direction. This directly promotes vertical containment of HFs in most sedimentary basins worldwide even in the absence of any favorable in‐situ stress contrasts or other material heterogeneities. More importantly, the ratio of the energy dissipated in fluid viscous flow in the fracture to the energy dissipated in the creation of new surfaces is found to play a critical role on fracture elongation, with fracture‐energy dominated HFs being the most elongated while the viscous dominated ones remain more circular. These results open the door to a better engineering and control of HFs containment at depth in view of the competition between material anisotropy (both elastic stiffnesses and fracture toughness anisotropy) and injection parameters (fluid viscosity and rate of injection).

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Identification of Fracture Extension Modes During Hydraulic Fracturing in Coalbed Methane Vertical Wells: A Case Study From the Southern Shizhuang Area of the Qinshui Basin, China

Yan,

Ni,

Zhang

et al. 2024

Geological Journal

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The accurate identification of fracture extension patterns in hydraulic fracturing can provide important guidance for the optimisation of fracturing parameters. In this paper, factors such as effective hole friction and wellbore flow friction during fracturing are fully considered, and a calculation model of net bottom‐hole pressure of fracturing is constructed. By introducing the change rate of net bottom‐hole pressure and the changing characteristics of the fracturing curve, seven fracture extension modes during hydraulic fracturing in coalbed methane vertical wells are established. The accuracy of the identification method is verified by the fracture monitoring and production results in Shizhuang South Block. The results show that fracture elongation is mainly controlled by in situ stress difference, angle between natural fracture and maximum principal stress, coal tensile strength, fracturing time, proppant and angle between other factors. When the fracture construction parameters are fixed, the smaller the difference between maximum and minimum horizontal principal stresses and the smaller the natural fractures and maximum horizontal principal stresses. When the reservoir potential is similar, the effective extension index is positively correlated with the gas production effect, and the effective extension index can effectively judge the fracturing effect. The higher the proportion of effective extension mode, the longer the extension time and the higher the stable daily gas production. The research results provide a method and reference for clearly identifying the fracture extension and the occurrence conditions of different extension modes in the hydraulic fracturing process.

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Effects of hydrostatic pressure on hydraulic fracturing properties of shale using X-ray computed tomography and acoustic emission

Cited by 13 publications

References 43 publications

Experimental Study on Hydraulic Fracturing with Acoustic Emission under Tri-Axial Stress Conditions

Experimental Study on Hydraulic Fracturing with Acoustic Emission under Tri-Axial Stress Conditions

Rock Anisotropy Promotes Hydraulic Fracture Containment at Depth

Identification of Fracture Extension Modes During Hydraulic Fracturing in Coalbed Methane Vertical Wells: A Case Study From the Southern Shizhuang Area of the Qinshui Basin, China

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