Estimation of the Effect of Anisotropy on Young’s Moduli and Poisson’s Ratios of Sedimentary Rocks Using Core Samples in Western and Central Part of Tripura, India

Brahma, Jwngsar; Sircar, Anirbid

doi:10.4236/ijg.2014.52020

Cited by 8 publications

(5 citation statements)

References 21 publications

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“…Not for all materials the dynamic modulus is higher than the static one. For example, in [22] the static Young modulus is larger than the dynamic one by the factor 2.…”

Section: Discussionmentioning

confidence: 99%

Researches Regarding the Mechanical Properties of a NewHybrid Vegetal Resin

Miriţoiu¹,

Stănescu²,

Bolcu³

2020

Mater. Plast.

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The paper presents the mechanical behaviour and properties of a new hybrid vegetal based resin. For this, through static loading tests, the main mechanical characteristics were determined: static Young modulus, breaking strength, breaking elongation and transversal Poisson ratio. Samples of the proposed materials were subjected also to free vibration tests, by clamping them at one end and leaving them free at the other. The observation and results from these were used for deduction of the first vibration mode eigenfrequency, the dynamic Young modulus, the loss and damping factors. Some representative SEM images with an electronic microscope were collected and the samples surface roughness was determined. By using the Thermogravimetric analysis (TGA), the mass loss up to 800� C was investigated. Compared to the other resins that have dammar in composition, the proposed dammar based resin from this research has a 15.32 times higher static Young modulus than the oil palm trunk and 8.885 times higher than the oil palm trunk (OPT) with 20% dammar resin.

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“…Not for all materials the dynamic modulus is higher than the static one. For example, in [22] the static Young modulus is larger than the dynamic one by the factor 2.…”

Section: Discussionmentioning

confidence: 99%

Researches Regarding the Mechanical Properties of a NewHybrid Vegetal Resin

Miriţoiu¹,

Stănescu²,

Bolcu³

2020

Mater. Plast.

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“…The anisotropy affecting wave velocity in the shale subsurface is considered to be a central difficulty, one resulting in significant issues for understanding dynamic elasticity in geophysical interpretation. Elastic constants of geologic materials, such as shale reservoirs, can be determined by measuring wave velocities [82]. Lo et al [83] conducted a series of tests on the wave velocities associated with Chicopee shale by using ultrasonic techniques.…”

Section: Ultrasonic Anisotropy Of Shale Specimensmentioning

confidence: 99%

Anisotropic Mechanical Behaviors of Shale Rock and Their Relation to Hydraulic Fracturing in a Shale Reservoir: A Review

Yin,

Yang,

Ranjith

2024

Energies

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Shale gas is an important supplement to the supply of natural gas resources and plays an important role on the world’s energy stage. The efficient implementation of hydraulic fracturing is the key issue in the exploration and exploitation of shale gas. The existence of bedding structure results in a distinct anisotropy of shale rock formation. The anisotropic behaviors of shale rock have important impacts on wellbore stability, hydraulic fracture propagation, and the formation of complex fracture networks. This paper briefly reviews previous work on the anisotropic mechanical properties of shale rock and their relation to hydraulic fracturing in shale reservoirs. In this paper, the research status of work addressing the lithological characteristics of shale rock is summarized first, particularly work considering the mineral constituent, which determines its physical and mechanical behavior in essence. Then the anisotropic physical and mechanical properties of shale specimens, including ultrasonic anisotropy, mechanical behavior under uniaxial and triaxial compression tests, and tensile property under the Brazilian test, are summarized, and the state of the literature on fracture toughness anisotropy is discussed. The concerns of anisotropic mechanical behavior under laboratory tests are emphasized in this paper, particularly the evaluation of shale brittleness based on mechanical characteristics, which is discussed in detail. Finally, further concerns such as the effects of bedding plane on hydraulic fracturing failure strength, crack propagation, and failure pattern are also drawn out. This review study will provide a better understanding of current research findings on the anisotropic mechanical properties of shale rock, which can provide insight into the shale anisotropy related to the fracture propagation of hydraulic fracturing in shale reservoirs.

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“…The elastic stiffness coefficients of geological materials are usually determined by the wave velocity of ultrasonic testing [41]. Among them, the elastic stiffness coefficients are the fundamental physical quantity used to describe the elastic deformation form of the material under the action of an external force.…”

Section: Related Concepts and Formula Calculationmentioning

confidence: 99%

Experimental Investigation of Stress Sensitivity of Elastic Wave Velocities for Anisotropic Shale in Wufeng–Longmaxi Formation

Feng,

Tang,

Tang

et al. 2023

Processes

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The shale of the Wufeng–Longmaxi formation in the Sichuan Basin is the preferred layer for shale gas exploration in China, and its petrophysical characteristics are the key to geological and engineering sweet spot prediction. However, the characteristics and impact mechanisms of its acoustic wave velocity and elastic anisotropy are currently unclear. In this paper, the Wufeng–Longmaxi shale is taken as the research object, and the P-wave and S-wave velocities of the samples are tested under the loading and unloading processes of confining pressure. The stress sensitivity variations in parameters such as wave velocity, wave velocity ratio, and anisotropy are discussed. P-wave and S-wave anisotropy parameters are correlated under different pressure conditions. X-ray diffraction, casting thin sections, scanning electron microscopy, micron CT scanning, and other analytical techniques are used to explore the mechanisms of stress sensitivity of elastic parameters. The research results indicate that: (1) the acoustic velocities of samples from different angles are V90° > V45° > V0°, and there is a positive correlation between the wave velocity and the confining pressure. After unloading the confining pressure, irreversible plastic deformation occurs due to the closure of some microfractures in the rock core, causing the wave velocity to be higher than the initial value. (2) The stress sensitivity coefficient of the P-wave (The mean is 3.00 m·s−1·MPa−1) is higher than that of the S-wave (the mean is 1.23 m·s−1·MPa−1), and the stress sensitivity coefficient of the compacted stage (the mean is 3.02 m·s−1·MPa−1) is higher than that of the elastic stage (the mean is 1.21 m·s−1·MPa−1). (3) The anisotropy of the P-wave and S-wave is negatively correlated with the confining pressure. When the confining pressure is loaded to 65 MPa, the change rate of the P-wave anisotropy coefficient is 23%, and its stress sensitivity is higher than that of S-wave anisotropy coefficient (the change rate is 13.7%). After unloading the confining pressure, the degree of anisotropy is reduced due to the closure of some microfractures. The empirical formula of P-wave and S-wave anisotropy parameters under different pressures is established through linear regression, which can provide a reference for mutual predictions. (4) The variation in wave velocity anisotropy with stress can be divided into stress and material anisotropy, which are related to the directional arrangement of microfractures and clay minerals, respectively. The quantitative characterization of shale anisotropy can be realized by evaluating the development degree of reservoir fractures and mineral components, providing a reference for logging interpretations, sweet spot prediction, and fracturing construction of shale gas reservoirs.

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Estimation of the Effect of Anisotropy on Young’s Moduli and Poisson’s Ratios of Sedimentary Rocks Using Core Samples in Western and Central Part of Tripura, India

Cited by 8 publications

References 21 publications

Researches Regarding the Mechanical Properties of a NewHybrid Vegetal Resin

Researches Regarding the Mechanical Properties of a NewHybrid Vegetal Resin

Anisotropic Mechanical Behaviors of Shale Rock and Their Relation to Hydraulic Fracturing in a Shale Reservoir: A Review

Experimental Investigation of Stress Sensitivity of Elastic Wave Velocities for Anisotropic Shale in Wufeng–Longmaxi Formation

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