Imaging hydraulic fractures of shale cores using combined positron emission tomography and computed tomography (PET-CT) imaging technique

Li, Shouding; Liu, Linan; Chai, Peiqi; Xiao, Li; He, Jianming; Zhang, Zhi Ming; Wei, Long

doi:10.1016/j.petrol.2019.106283

Cited by 20 publications

(9 citation statements)

References 33 publications

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“…By laboratory experiments, the computed tomography (CT) imaging and nuclear magnetic resonance techniques are used to analyse the behaviour of hydraulic fractures and the dynamic evolution of fractures. In addition, laboratory scale acoustic emission techniques are used to identify microseismic events generated by fracturing to track fracture propagation paths and explain the internal mechanisms of stress shadow effects (Chitrala et al, 2013;Li et al, 2019a;Lu et al, 2020). However, neither field monitoring nor laboratory experiments can accurately obtain the evolution law of the stress field in the process of multiple well hydrofracturing in deep reservoirs, nor can they accurately reveal the internal mechanism of the influence of stress shadow effects on nucleation, propagation and stress evolution (Vogler et al, 2018).…”

Section: Continuum-discontinuum Numerical Methods and Modelsmentioning

confidence: 99%

“…Using simultaneous fracturing in close spacing, the side fractures experience obvious coalescence and outward deflection, while the middle fracture forms a transverse fracture. Simultaneous fracturing leads to overclosure of the middle fracture, which in turn leads to a high proppant injection (Haddad and Sepehrnoori, 2016; Li et al. , 2019a; Tang et al.…”

Section: Unstable Dynamic Propagation Behaviours Of the Multistage Hy...mentioning

confidence: 99%

“…In addition, laboratory scale acoustic emission techniques are used to identify microseismic events generated by fracturing to track fracture propagation paths and explain the internal mechanisms of stress shadow effects (Chitrala et al. , 2013; Li et al. , 2019a; Lu et al.…”

Section: Numerical Analysis Of Continuous Stress Field and Discontinu...mentioning

confidence: 99%

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Stress-dependent unstable dynamic propagation of multiple hydraulic fractures: a review of stress shadow effects and continuum-discontinuum methods

Wang

Liu

2023

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PurposeThe unstable dynamic propagation of multistage hydrofracturing fractures leads to uneven development of the fracture network and research on the mechanism controlling this phenomenon indicates that the stress shadow effects around the fractures are the main mechanism causing this behaviour. Further studies and simulations of the stress shadow effects are necessary to understand the controlling mechanism and evaluate the fracturing effect.Design/methodology/approachIn the process of stress-dependent unstable dynamic propagation of fractures, there are both continuous stress fields and discontinuous fractures; therefore, in order to study the stress-dependent unstable dynamic propagation of multistage fracture networks, a series of continuum-discontinuum numerical methods and models are reviewed, including the well-developed extended finite element method, displacement discontinuity method, boundary element method and finite element-discrete element method.FindingsThe superposition of the surrounding stress field during fracture propagation causes different degrees of stress shadow effects between fractures and the main controlling factors of stress shadow effects are fracture initiation sequence, perforation cluster spacing and well spacing. The perforation cluster spacing varies with the initiation sequence, resulting in different stress shadow effects between fractures; for example, the smaller the perforation cluster spacing and well spacing are, the stronger the stress shadow effects are and the more seriously the fracture propagation inhibition arises. Moreover, as the spacing of perforation clusters and well spacing increases, the stress shadow effects decrease and the fracture propagation follows an almost straight pattern. In addition, the computed results of the dynamic distribution of stress-dependent unstable dynamic propagation of fractures under different stress fields are summarised.Originality/valueA state-of-art review of stress shadow effects and continuum-discontinuum methods for stress-dependent unstable dynamic propagation of multiple hydraulic fractures are well summarized and analysed. This paper can provide a reference for those engaged in the research of unstable dynamic propagation of multiple hydraulic structures and have a comprehensive grasp of the research in this field.

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Section: Continuum-discontinuum Numerical Methods and Modelsmentioning

confidence: 99%

Section: Unstable Dynamic Propagation Behaviours Of the Multistage Hy...mentioning

confidence: 99%

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Stress-dependent unstable dynamic propagation of multiple hydraulic fractures: a review of stress shadow effects and continuum-discontinuum methods

Wang

Liu

2023

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“…It can provide a very accurate pore surface area, size distribution, and fractal dimensions based on the experimentally derived isotherm. N 2 is used as an adsorbate for accessing mesopores, whereas micropores are accessed using CO 2 as an adsorbate. ,− Aside from this widely popular analytical method, neutron scattering techniques, − mercury-intrusive porosimetry, and high-resolution 2D and 3D imaging techniques − have been extensively used to characterize pores in coal. Although imaging studies are not as reliable as analytical methods for characterizing micropores, especially in organic-rich materials, , recent advancement in imaging techniques and the corresponding image analysis have transformed the dynamics of image-based study, providing excellent resolution. , It also includes high magnification, a better signal to noise ratio during imaging with the filtering techniques, proper edge detection, and faster processing while extracting information from the images. ,, SEM imaging has an upper hand over LPGA studies to provide critical information about the disposition, shapes, and interconnectivity of the pores on the plane of observation. ,, …”

Section: Introductionmentioning

confidence: 99%

A Comparative Analysis of Pore Attributes of Sub-Bituminous Gondwana Coal from the Damodar and Wardha Valleys: Implication for Enhanced Coalbed Methane Recovery

Chandra

Vishal

2022

Energy Fuels

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With the increasing drive for geological CO2 sequestration, unconventional resources like shale gas and coalbed methane have gained massive popularity. With a vast resource of bituminous Gondwana coal, India has a good potential for enhanced coalbed methane recovery through CO2 sequestration. Pore attributes and their interconnectivity play a significant role in determining the gas storage capacity and ease of injection/production. In this study, samples from both opencast and underground measures were collected for a thorough comparison between coal samples of the Damodar and Wardha valleys belonging to the same Gondwana coal measure. Quantitative pore attributes determined using CO2 and N2 low-pressure gas adsorption suggests that the coal samples from Wardha are more adsorptive and thus have more gas storage capacity. The total mesopore volume in Wardha coals determined using the density functional theory model (low-pressure N2 adsorption branch) is higher with coals from opencast mines showing the highest pore volume. Two distinct Frenkel–Halsey–Hill fractal dimensions were observed in the mesopore range. Here, larger mesopores demonstrated higher fractal dimensions, indicating that surface roughness is higher for larger mesopores. The total micropore volume determined using CO2-density functional theory (DFT) (on low-pressure CO2 adsorption isotherm) is higher in the Wardha coals, showcasing a positive correlation with increasing depth and organic matter composition. The adsorption-derived pore attributes were validated using high-resolution microscopic imaging and subsequent image analysis. Elemental analysis of the isolated kerogen indicates an escalation of organic carbon with depth, whereas clay content (primarily kaolinite) shows an opposite trend. This study has elucidated the entire spectrum of micro- to mesopore attributes for these two significant coal basins, illustrating their distinguishing characteristics caused by different depositional settings and diagenesis, despite belonging to the same Gondwana measure.

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“…In the aspect of fracture morphology analysis, an optical scanner was used to reconstruct the rough fracture surface at the macroscale (Song et al, 2019;Yang et al, 2022), while scanning electron microscopy (SEM) was applied to observe hydraulic fractures at the local microscale (He et al, 2020). Computed tomography (CT) scanning is another powerful tool for 3-D hydraulic fracture characterization (Guo et al, 2014;Zhang et al, 2017;Li et al, 2019). Referring to the concept of "Stimulated Reservoir Volume" (SRV) (Fisher et al, 2004;Mayerhofer et al, 2010), "Stimulated Rock Area" (SRA) is proposed to quantitatively evaluate the laboratory hydraulic fracture networks (Hou et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Laboratory investigation and evaluation of the hydraulic fracturing of marine shale considering multiple geological and engineering factors

Wang

Zhou²,

Guo³

et al. 2022

Front. Earth Sci.

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Hydraulic fracturing is widely implemented in the exploration of marine shale gas. Affected by various geological and engineering factors, gas production after stimulation is not always satisfactory. To reveal the influential effect of multiple factors, laboratory hydraulic fracturing experiments are performed on Longmaxi marine shales by considering key parameters (deviatoric stress, confining pressure, pumping rate, fracturing fluid type, and bedding angle). The variation of breakdown pressures and the characteristics of hydraulic fractures are recorded and analyzed. The results show that the breakdown pressure increases with increasing deviatoric stress, confining pressure, pumping rate, and viscosity of the fracturing fluid. As the bedding angle varies from 0° to 90°, the breakdown pressure declines first and increases again. Furthermore, parameter sensitivity analysis indicates that geological factors (confining pressure, bedding angle, and deviatoric stress) would largely determine the breakdown pressure, while engineering factors (pumping rate, fracturing fluid type) could only affect it to a lesser extent. Computed tomography measurements show that natural fractures, originating from tectonic shear failure, could possess greater width than tension-dominated hydraulic and bedding fractures. Statistical analysis shows that the length of the hydraulic fractures alone is only approximately 150 mm. However, the fully activated natural and/or bedding fractures could help substantially increase the total fracture length to 600 mm. Low deviatoric stress, low confining pressure, low viscous slick-water, and high bedding angle are conducive to activating natural and bedding fractures and forming a complex fracture network. The aforementioned findings are valuable for the optimal design of field hydraulic fracturing.

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Imaging hydraulic fractures of shale cores using combined positron emission tomography and computed tomography (PET-CT) imaging technique

Cited by 20 publications

References 33 publications

Stress-dependent unstable dynamic propagation of multiple hydraulic fractures: a review of stress shadow effects and continuum-discontinuum methods

Stress-dependent unstable dynamic propagation of multiple hydraulic fractures: a review of stress shadow effects and continuum-discontinuum methods

A Comparative Analysis of Pore Attributes of Sub-Bituminous Gondwana Coal from the Damodar and Wardha Valleys: Implication for Enhanced Coalbed Methane Recovery

Laboratory investigation and evaluation of the hydraulic fracturing of marine shale considering multiple geological and engineering factors

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