Power-law relationship between joint spacing and bed thickness in sedimentary rocks and implications for layered rock mechanics

Ji, Shaocheng; Li, Le; Marcotte, Denis

doi:10.1016/j.jsg.2021.104413

Cited by 18 publications

(4 citation statements)

References 91 publications

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“…All these observations are quite consistent with pattern of Mode I fractures mechanically restricted to layers of variable thickness, so called joint sets Hu and Evans, 1989;Odling et al, 1999;Rives et al, 1992;Soliva et al, 2006;Soliva and Schultz, 2008). The mean spacing obtained for these sets and the relationship between joint spacing and thickness of mechanical layers described in the literature (Gillespie et al, 2001;Ji et al, 2021;Strijker et al, 2012) suggest that mechanical units of several meters thickness are affected by these 540 sets. This is also consistent with the description of the Tchirezrine II deposit as fluvial sequences ranging in thickness from a few decimetres to several meters (Orano, Emmanuelle Chanvry personal communication, 2023).…”

Section: Interpretations Of Lineaments Sets 530supporting

confidence: 77%

Naturally fractured reservoir characterization in heterogeneous sandstones: insight for Uranium In Situ Recovery (Imouraren, Niger)

Jamet,

Ballas,

Soliva

et al. 2024

Preprint

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Abstract. This study delves into the characterization of a complex reservoir, the Tchirezrine II sandstone unit in North Niger, crucial for potential Uranium In Situ Recovery (ISR) in a naturally fractured and faulted context. Employing a multifaceted approach, including well log data, optical borehole imagery, and hydrogeological tests, alongside satellite-based lineament analysis, this study provides a comprehensive understanding of the structures and its impact on fluid flow. Lineament analysis reveals scale-dependent patterns, consistent with spatially homogeneous joint networks restricted to mechanical units, as well as nearly scale-invariant patterns, better corresponding to spatially heterogeneous fault networks. Various deformation structures are detected from borehole imagery, including Mode I fractures, cataclastic deformation bands, and brecciated-cataclastic fault cores. The Tchirezrine II reservoir displays heterogeneous porosity and permeability related to its fluviatile sedimentary context. These data differ from traditional porosity-permeability relationship obtained in sandstone reservoir matrix but are instead consistent with Nelson’s classification, emphasizing the impact of deformation structures on such petrophysical properties. Hydrological tests have been implemented into a zone of E-W trending deformation structures, revealing a strong permeability anisotropy of this heterogeneity. This strong E-W anisotropy is consistent with the presence of the observed E-W structures, i.e. with a drain behaviour of Mode I open fractures and a sealing behaviour of both cataclastic bands and fault rocks. Considering implications for ISR mining, this study allows discussing the interplay between fractures, faults, and fluid flow properties. It suggests that a well pattern perpendicular to the main permeability orientation can attenuate channelled flow, thus improving contact of the leach solution with the mineralized matrix. These results provide an integrated approach and multi-scale characterization of Naturally Fractured Reservoir (NFR) properties in sandstone, offering a basis for optimization of NFR production such as ISR development.

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Section: Interpretations Of Lineaments Sets 530supporting

confidence: 77%

Naturally fractured reservoir characterization in heterogeneous sandstones: insight for Uranium In Situ Recovery (Imouraren, Niger)

Jamet,

Ballas,

Soliva

et al. 2024

Preprint

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“…They therefore play an essential role in the stability of geological and man‐made structures, the management of water and hydrocarbons, CO 2 sequestration, and waste storage, among other applications. For this reason, joints have been the subject of extensive research for a long time using diverse approaches, including mechanical analysis and modeling (Bai & Pollard, 2000; Chemenda, 2019, 2022; Cherepanov, 1997; Engelder et al., 1997; English, 2012; Gross, 1993; Gross et al., 1995; Guo et al., 2017; Hobbs, 1967; Hooker & Katz, 2015; Huang & Angelier, 1989; Jain et al., 2007; Ji et al., 1998, 2021; Li et al., 2012; Mandal et al., 1994; Narr & Suppe, 1991; Olson et al., 2009; Pollard & Aydin, 1988; Price, 1966; Price & Cosgrove, 1990; Schopfer et al., 2011; Tang et al., 2008).…”

Section: Introductionmentioning

confidence: 99%

Gravity‐Driven Jointing in Layered Rocks: Mechanical Analysis and Numerical Modeling

Chemenda

2024

JGR Solid Earth

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The origin of open‐mode fractures or joints, common in sedimentary basins (reservoirs), remains incompletely understood. These fractures require effective tensile stress for their formation, yet they usually develop at depths where effective compressive stresses dominate. Through 2‐D finite‐difference elastoplastic modeling, we demonstrate that effective tensile stresses and fracturing can be internally generated in stiff competent layers separated by compliant incompetent layers. Two primary factors drive this phenomenon: the layered structure of sedimentary units with varying mechanical properties of the layers and the lithostatic compression of the unit, leading to its gravity‐driven horizontal widening or stretching. This stretching occurs when the average horizontal stress over the unit’s thickness is compressive. Various mechanisms can accommodate the stretching, including preexisting faults or weak zones, free borders like canyons, and horizontal extension of tectonic or gravitational origin. Tensile horizontal effective stresses σxx occur within the competent layers, while the incompetent layers generally remain under effective compression. The magnitude of σxx increases with the lithostatic stress or burial depth, as does the tensile strength σt of incompletely lithified sediments. Jointing occurs within depth intervals where |σxx| > σt. In our modeling approach, effective tensile stresses σxx are generated due to lithostatic compression σv. In the previous numerical modeling studies, these stresses resulted from extension directly applied to the lateral boundaries of the layers and did not depend on σv. We provide an analysis of the distinctions between these two approaches.

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“…Liu [29] proposed a dynamic constitutive model employing the principles of the Taylor-Chen-Kuszmaul (TCK) model to simulate damage in pre-jointed rock. In foliated rock, damage progression is affected by many randomly distributed flaws and the directional plane of foliation [18]. Using statistical methods and damage mechanics creates a practical approach to analyze dynamic failure within foliated rock masses.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Loading Effects on the Mechanical Behavior and Constitutive Damage Model of Foliated Slate

Ou,

Xu,

et al. 2024

Preprint

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Understanding the anisotropic mechanical properties of rocks is crucial in rock engineering planning and execution. Layered structures, including foliation and bedding, introduce planes of weakness that profoundly affect the rock's mechanical response. This research aimed to examine the impact of foliation orientation, indicated by the dip angle (θ), and the strain rate (\(\dot {\varepsilon }\)) on the dynamic mechanical behaviour of the slate. To this end, dynamic compression tests were conducted on slate samples utilizing a split-Hopkinson pressure bar (SHPB). When the foliation is parallel to horizontal plane (θ = 0°), tensile mechanism dominates the failure mode. When the foliation planes take a dip angle to horizontal plane (θ = 30°, 45° and 60°), shear-sliding along foliation planes gradually dominated as the angle increased, resulting in shear-tensile failure. When the foliation planes are perpendicular to horizontal plane (θ = 90°), the sample primarily exhibits tensile splitting failure along foliation planes. Motivated by experimental results, we developed a constitutive model to characterize the damage process of foliated slate. The model assumes that the strength of microstructural units within foliated slate follows a Weibull distribution. To account for the effects of different dip angles and strain rates on the slate foliation planes' response, a dynamic loading viscous coefficient, η, is incorporated. The proposed model has precise physical meanings and proficiently illustrates the complete stress-strain process of the slate.

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Power-law relationship between joint spacing and bed thickness in sedimentary rocks and implications for layered rock mechanics

Cited by 18 publications

References 91 publications

Naturally fractured reservoir characterization in heterogeneous sandstones: insight for Uranium In Situ Recovery (Imouraren, Niger)

Naturally fractured reservoir characterization in heterogeneous sandstones: insight for Uranium In Situ Recovery (Imouraren, Niger)

Gravity‐Driven Jointing in Layered Rocks: Mechanical Analysis and Numerical Modeling

Dynamic Loading Effects on the Mechanical Behavior and Constitutive Damage Model of Foliated Slate

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