Geomechanics of Gas Shales

Rasouli, Vamegh

doi:10.1002/9781119039228.ch8

Cited by 6 publications

(4 citation statements)

References 134 publications

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“…Figure 5 illustrates the six velocities, as follows [90]: one compressional wave (Vpv) and two shear waves (Vsv1 = Vsv2), which propagate normally to the bedding plane in a vertical plug (as shown in Figure 5a, θ = 0°); and one compressional wave (Vph) and two shear waves (Vsh > Vsv), which propagate parallel to the bedding plane in a horizontal plug (as shown in Figure 5b, θ = 90°). These six ultrasonic velocity parameters could then be employed to calculate the elastic parameters, which are used for describing the anisotropic elastic properties of a vertically transverse isotropic (VTI) material like shale rock [91,92]. In the study conducted by Yin [93], the wave's attenuation by bedding planes in the transversely isotropic rock is also described.…”

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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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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“…More than 20 years after that, shale resources, tight gas, coalbed gas, tar sands, etc. have gradually become the focus of petroleum geology. − In addition, in comparison to other types of unconventional energy, shale gas has two advantages: (1) low carbon dioxide emission and (2) zero sulfur dioxide content . Therefore, traditional fossil fuels, which are not environmentally friendly, may still dominate in the energy structure in the near future but will account for a smaller and smaller share, and gas will account for a larger share. − …”

Section: Introductionmentioning

confidence: 99%

“…3−8 In addition, in comparison to other types of unconventional energy, shale gas has two advantages: (1) low carbon dioxide emission 9 and (2) zero sulfur dioxide content. 10 Therefore, traditional fossil fuels, which are not environmentally friendly, may still dominate in the energy structure in the near future but will account for a smaller and smaller share, and gas will account for a larger share. 11−14 In comparison to the constant breakthroughs of shale gas in the marine basins globally, including Northern American Haynesville shale, 15,16 Canadian Montney shale, 17 and Southeastern China Ordovician−Silurian shale, 18 the pace of exploration in lacustrine basins is relatively slow.…”

Section: Introductionmentioning

confidence: 99%

Gas Generation Potential and Characteristics of Oil-Prone Shale in the Saline Lacustrine Rifting Basins: A Case Study of the Dongpu Depression, Bohai Bay Basin

et al. 2021

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In comparison to the continuous breakthrough in shale gas of marine basins, the pace of study of lacustrine basins is relatively slow. The latest studies have shown the saline lacustrine rifting basins (SLRBs) are one of the favorable exploration areas from the view of shale pore, mineral composition, and organic matter accumulation. However, the study on the gas generation potential and characteristics is still lacking because the traditional view is that lacustrine source rocks are oil-prone. Therefore, to identify gas generation potential and characteristics of oil-prone shale in SLRBs, the samples from the saline area (SA) and non-saline area (NA) of the Dongpu Depression are selected for the organic geochemical experiments and closed gold cube thermal simulation experiments. Geochemical results show that the SA samples are definitely oil-prone source rocks with high quality, and their main type is II kerogen. However, the results from thermal simulation experiments indicate that the gas generation potential of oil-prone shale in SLRBs is enough for the accumulation of shale gas with the peak gas yield of 469.11 mg/g of TOC at the heating rate of 20 °C/h TOC and 466.75 mg/g of TOC at the heating rate of 2 °C/h and TOC. Moreover, according to the dynamic hydrocarbon yields and carbon isotope (ln C2/C3, ln C1/C2, and δ13C1–δ13C2) during the increasing temperature, the gas generation process for SA and NA samples can be divided into three stages: kerogen cracking, oil cracking, and wet gas cracking. In comparison to other types of source rocks (marine shale, coal, and coal mudstone), the SA oil-prone shale can experience longer intervals in kerogen cracking and oil cracking, which may be the main stage of gas generation. The model based on kinetic parameters shows that the main gas generation period for SA and NA samples is the late Es1 (the first member of Shahejie Formation) to Ed (the Dongying Formation) of the Early Cenozoic, which can be consist of the depression stage with the deepest depth and the largest subsidence amplitude in the Dongpu Depression. Such information can be a reference for other SLRBs.

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“…Shale gas is one of the main forms of unconventional natural gas. It occurs within certain organic-rich shale and is generally present in an adsorbed or free state [1][2][3][4]. China was the third country to commercially develop shale gas, after the United States and Canada [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Reservoir Characteristics of the Lower Silurian Longmaxi Shale in Zhaotong Region, Southern China

et al. 2020

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The lower Silurian Longmaxi Formation hosts a highly productive shale gas play in the Zhaotong region of southern China. According to core observation, X-ray diffraction analyses, and scanning electron microscopy (SEM) observations, the shale comprises primarily quartz, carbonate minerals, and clay minerals, with minor amounts of plagioclase, K-feldspar, and pyrite. The clay mineral content ranges from 15.0% to 46.1%, with an average of 29.3% in the Zhaotong region. Organic geochemical analyses show that the Longmaxi Formation has good potential for shale gas resources by calculating total organic carbon, vitrinite reflectance, and gas content. Scanning electron microscope images demonstrate that reservoir pore types in the Longmaxi shale include organic pores, interparticle pores, intercrystalline pores, intraparticle pores, and fractures. Reservoir distribution is controlled by lithofacies, mineral composition, and geochemical factors. In addition, we investigated the relationships between reservoir parameters and production from 15 individual wells in the Zhaotong region by correlation coefficients. As a result, the brittleness index, total organic carbon (TOC), porosity, and gas content were used to define high-quality reservoirs in the Longmaxi shale. Based on these criteria, we mapped the thickness and distribution of high-quality reservoirs in the Longmaxi Formation and selected highlighted several key sites for future exploration and development.

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Geomechanics of Gas Shales

Cited by 6 publications

References 134 publications

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

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

Gas Generation Potential and Characteristics of Oil-Prone Shale in the Saline Lacustrine Rifting Basins: A Case Study of the Dongpu Depression, Bohai Bay Basin

Reservoir Characteristics of the Lower Silurian Longmaxi Shale in Zhaotong Region, Southern China

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