Effect of Shear Displacement and Stress Changes on Fracture Hydraulic Aperture and Flow Anisotropy

Geothermal energy is renewable, clean and green energy generated and stored in the Earth’s crust. The most important consideration for geothermal energy development in non-hydrothermal scenarios is the use of hydraulic fracturing technology to establish an effective network pathway to conduct fluid from injectors to producers. Hydraulic fracturing in geothermal wells is referred to as hydro-shearing and the aim is to improve the conductivity of natural fractures. In this paper, linear elastic constitutive relationships and shear strength of discontinuities in the pre-peak region are initially considered. Based on the dynamic frictional weakening, a proved conductive aperture and the post-peak elastoplastic constitutive models are proposed to analyze the deformation and conductivity of the natural fracture. Simulation research has shown that the joint compressive strength (JCS) mainly affects the shear displacement and hardly affects the dilation. The joint roughness coefficient (JRC) is more important for decreasing the shear strength and improves the dilation aperture. To no one’s surprise, reducing the effective normal stress is the best way for increasing the shear displacement, dilation and conductivity of the natural fracture. Almost 90% of the slip displacement and dilation occurs after fracture shear failure. This displacement not only increases the hydraulic conductivity of the fracture, but also reduces the required surface pumping pressure.

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Effect of Shear Stress and Displacement on the Hydraulic Properties of a Marble Fracture with Sand

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.306-308.1503 ◽

2006 ◽

Vol 306-308 ◽

pp. 1503-1508

Author(s):

Cai Hua Liu ◽

Cong Xin Chen ◽

Xia Ting Feng

Keyword(s):

Shear Stress ◽

Experimental Tests ◽

Shear Displacement ◽

Test Results ◽

Coupling Process ◽

Flow Coupling ◽

Hydraulic Aperture ◽

Two Phases ◽

Mechanical Aperture ◽

Stress Flow

A test apparatus was developed to study shear-flow coupling properties for a marble fracture with sand. Experimental tests include shear stress-flow coupling process and shear displacement-flow coupling process. The shear stress-flow coupling test results, revealed that mechanical aperture keeps constant during shear, and that hydraulic aperture and conductivity decrease almost linearly with increasing shear stress. The shear displacement-flow coupling test results showed that hydraulic behavior under shear displacement includes two phases. During the first about 0.05mm shear displacement, hydraulic aperture and conductivity decrease with increasing shear displacement, and mechanical aperture remains constant or increases only by several microns of magnitude. After shear displacement is up to about 0.05mm, the fracture dilates remarkably, and hydraulic aperture and conductivity increase with shear displacement increasing.

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Impact of Parent Well Depletion on Stress Changes and Infill Well Completion in Multiple Layers in Permian Basin

Proceedings of the 7th Unconventional Resources Technology Conference ◽

10.15530/urtec-2019-972 ◽

2019 ◽

Cited By ~ 2

Author(s):

Anusarn Sangnimnuan ◽

Jiawei Li ◽

Kan Wu ◽

Stephen A. Holditch

Keyword(s):

Permian Basin ◽

Well Completion ◽

Stress Changes

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Perceived Changes in Sexuality during the COVID-19 Pandemic among Adults in the United States

Sexes ◽

10.3390/sexes2030026 ◽

2021 ◽

Vol 2 (3) ◽

pp. 331-344

Author(s):

Jessamyn Bowling ◽

Erika Montanaro ◽

Sarai Guerrero-Ordonez ◽

Stuti Joshi ◽

Diana Gioia

Keyword(s):

United States ◽

Sexual Behavior ◽

Qualitative Study ◽

Social Interactions ◽

Nationwide Survey ◽

The United States ◽

Self Reflection ◽

Sex Drive ◽

Stress Changes ◽

Sexual Experimentation

In the United States, the COVID-19 pandemic has decreased partnered sexual behavior and increased the use of enhancement (e.g., toys). This has been partly attributed to reduced social interactions and stress. However, individuals’ perceptions of changes are missing in research. This study aims to examine how adults perceive changes in their sexuality during the pandemic. We conducted a nationwide survey of US adults from April–June 2020 (N = 326). This qualitative study examines the open-ended responses using thematic analyses. The following themes emerged from the data: (1) changes in the purpose of sex; (2) changes in sexual identity; (3) decreases in sex drive and desire; (4) increases in sex drive and desire; (5) fluctuations in sex drive and desire; (6) increased sexual experimentation and reflection. The stress, changes in home responsibilities and living situations, and time spent with partners (more or less) has affected individuals by increasing or decreasing their sex drive and desire. Participants responded to changes with self-reflection and awareness, and incorporating new practices (e.g., technology, kink). The purpose of sex has shifted in order to gain intimacy or connect, or to pass time. These changes were perceived as both positive and negative, and more research is needed to determine the durability of these changes.

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Using Eulerian and Lagrangian Approaches to Investigate Wind-Driven Changes in the Southern Ocean Abyssal Circulation

Journal of Physical Oceanography ◽

10.1175/jpo-d-13-0108.1 ◽

2013 ◽

Vol 44 (2) ◽

pp. 662-675 ◽

Cited By ~ 8

Author(s):

Paul Spence ◽

Erik van Sebille ◽

Oleg A. Saenko ◽

Matthew H. England

Keyword(s):

Southern Ocean ◽

Wind Stress ◽

Climate Model ◽

Meridional Overturning Circulation ◽

Global Ocean ◽

Lagrangian Particle ◽

Stress Changes ◽

Abyssal Circulation ◽

Flow Pathways ◽

Ocean Wind

Abstract This study uses a global ocean eddy-permitting climate model to explore the export of abyssal water from the Southern Ocean and its sensitivity to projected twenty-first-century poleward-intensifying Southern Ocean wind stress. The abyssal flow pathways and transport are investigated using a combination of Lagrangian and Eulerian techniques. In an Eulerian format, the equator- and poleward flows within similar abyssal density classes are increased by the wind stress changes, making it difficult to explicitly diagnose changes in the abyssal export in a meridional overturning circulation framework. Lagrangian particle analyses are used to identify the major export pathways of Southern Ocean abyssal waters and reveal an increase in the number of particles exported to the subtropics from source regions around Antarctica in response to the wind forcing. Both the Lagrangian particle and Eulerian analyses identify transients as playing a key role in the abyssal export of water from the Southern Ocean. Wind-driven modifications to the potential energy component of the vorticity balance in the abyss are also found to impact the Southern Ocean barotropic circulation.

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Impact of Environmental Stressors on Gene Expression in the Embryo of the Italian Wall Lizard

Applied Sciences ◽

10.3390/app11114723 ◽

2021 ◽

Vol 11 (11) ◽

pp. 4723

Author(s):

Rosaria Scudiero ◽

Chiara Maria Motta ◽

Palma Simoniello

Keyword(s):

Gene Expression ◽

Protein Interactions ◽

Membrane Trafficking ◽

Translational Regulation ◽

Cellular Protection ◽

Terrestrial Vertebrate ◽

Expression Of Genes ◽

Stress Changes ◽

Probable Consequence ◽

The Impact

The cleidoic eggs of oviparous reptiles are protected from the external environment by membranes and a parchment shell permeable to water and dissolved molecules. As a consequence, not only physical but also chemical insults can reach the developing embryos, interfering with gene expression. This review provides information on the impact of the exposure to cadmium contamination or thermal stress on gene expression during the development of Italian wall lizards of the genus Podarcis. The results obtained by transcriptomic analysis, although not exhaustive, allowed to identify some stress-reactive genes and, consequently, the molecular pathways in which these genes are involved. Cadmium-responsive genes encode proteins involved in cellular protection, metabolism and proliferation, membrane trafficking, protein interactions, neuronal transmission and plasticity, immune response, and transcription regulatory factors. Cold stress changes the expression of genes involved in transcriptional/translational regulation and chromatin remodeling and inhibits the transcription of a histone methyltransferase with the probable consequence of modifying the epigenetic control of DNA. These findings provide transcriptome-level evidence of how terrestrial vertebrate embryos cope with stress, giving a key to use in population survival and environmental change studies. A better understanding of the genes contributing to stress tolerance in vertebrates would facilitate methodologies and applications aimed at improving resistance to unfavourable environments.

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In Situ X-Ray Diffraction Investigations during Diffusion Anneals of Ni-Cu Thin Film Diffusion Couples

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.89-91.503 ◽

2010 ◽

Vol 89-91 ◽

pp. 503-508 ◽

Cited By ~ 1

Author(s):

J. Sheng ◽

U. Welzel ◽

Eric J. Mittemeijer

Keyword(s):

Thermal Stresses ◽

Stress Generation ◽

Ex Situ ◽

Diffusion Annealing ◽

X Ray Diffraction ◽

Individual Layer ◽

X Ray ◽

Bilayer System ◽

Stress Changes

The stress evolution during diffusion annealing of Ni-Cu bilayers (individual layer thicknesses of 50 nm) was investigated employing ex-situ and in-situ X-ray diffraction measurements. Annealing at relatively low homologous temperatures (about 0.3 - 0.4 Tm) for durations up to about 100 hours results in considerable diffusional intermixing, as demonstrated by Auger-electron spectroscopy investigations (in combination with sputter-depth profiling). In addition to thermal stresses due to differences of the coefficients of thermal expansion of layers and substrate, tensile stress con-tributions in the sublayers arise during the diffusion anneals. The obtained stress data have been discussed in terms of possible mechanisms of stress generation. The influence of diffusion on stress development in the sublayers of the diffusion couple during heating and isothermal annealing was investigated by comparing stress changes in the bilayer system with corresponding results obtained under identical conditions for single layers of the components in the bilayer system. The specific residual stresses that emerge due to diffusion between the (sub)layers in the bilayer could thereby be identified.

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Characterization of Mechanical Heterogeneity in Dissimilar Metal Welded Joints

Materials ◽

10.3390/ma14154145 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4145

Author(s):

He Xue ◽

Zheng Wang ◽

Shuai Wang ◽

Jinxuan He ◽

Hongliang Yang

Keyword(s):

Mechanical Properties ◽

Finite Element ◽

Welded Joints ◽

Structural Integrity ◽

Material Interfaces ◽

Mechanical Heterogeneity ◽

Finite Element Software ◽

Dissimilar Metal ◽

Stress Changes

Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.

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Time-Dependent Response of a Recycled C&D Material-Geotextile Interface under Direct Shear Mode

Materials ◽

10.3390/ma14113070 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3070

Author(s):

Fernanda Bessa Ferreira ◽

Paulo M. Pereira ◽

Castorina Silva Vieira ◽

Maria de Lurdes Lopes

Keyword(s):

Shear Stress ◽

Stress Relaxation ◽

Shear Displacement ◽

Time Dependent ◽

Shear Behaviour ◽

Displacement Rate ◽

Shear Mode ◽

Direct Shear ◽

Constant Displacement ◽

Shear Box

Geosynthetic-reinforced soil structures have been used extensively in recent decades due to their significant advantages over more conventional earth retaining structures, including the cost-effectiveness, reduced construction time, and possibility of using locally-available lower quality soils and/or waste materials, such as recycled construction and demolition (C&D) wastes. The time-dependent shear behaviour at the interfaces between the geosynthetic and the backfill is an important factor affecting the overall long-term performance of such structures, and thereby should be properly understood. In this study, an innovative multistage direct shear test procedure is introduced to characterise the time-dependent response of the interface between a high-strength geotextile and a recycled C&D material. After a prescribed shear displacement is reached, the shear box is kept stationary for a specific period of time, after which the test proceeds again, at a constant displacement rate, until the peak and large-displacement shear strengths are mobilised. The shear stress-shear displacement curves from the proposed multistage tests exhibited a progressive decrease in shear stress with time (stress relaxation) during the period in which the shear box was restrained from any movement, which was more pronounced under lower normal stress values. Regardless of the prior interface shear displacement and duration of the stress relaxation stage, the peak and residual shear strength parameters of the C&D material-geotextile interface remained similar to those obtained from the conventional (benchmark) tests carried out under constant displacement rate.

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Analysis of Fracture Roughness Control on Permeability Using SfM and Fluid Flow Simulations: Implications for Carbonate Reservoir Characterization

Geofluids ◽

10.1155/2019/4132386 ◽

2019 ◽

Vol 2019 ◽

pp. 1-19 ◽

Cited By ~ 9

Author(s):

Miller Zambrano ◽

Alan D. Pitts ◽

Ali Salama ◽

Tiziano Volatili ◽

Maurizio Giorgioni ◽

...

Keyword(s):

Fluid Flow ◽

Reservoir Characterization ◽

Flow Simulation ◽

Carbonate Reservoir ◽

Single Fracture ◽

Parallel Plates ◽

Surface Mapping ◽

Navier Stokes Equation ◽

Hydraulic Aperture ◽

Fracture Modeling

Fluid flow through a single fracture is traditionally described by the cubic law, which is derived from the Navier-Stokes equation for the flow of an incompressible fluid between two smooth-parallel plates. Thus, the permeability of a single fracture depends only on the so-called hydraulic aperture which differs from the mechanical aperture (separation between the two fracture wall surfaces). This difference is mainly related to the roughness of the fracture walls, which has been evaluated in previous works by including a friction factor in the permeability equation or directly deriving the hydraulic aperture. However, these methodologies may lack adequate precision to provide valid results. This work presents a complete protocol for fracture surface mapping, roughness evaluation, fracture modeling, fluid flow simulation, and permeability estimation of individual fracture (open or sheared joint/pressure solution seam). The methodology includes laboratory-based high-resolution structure from motion (SfM) photogrammetry of fracture surfaces, power spectral density (PSD) surface evaluation, synthetic fracture modeling, and fluid flow simulation using the Lattice-Boltzmann method. This work evaluates the respective controls on permeability exerted by the fracture displacement (perpendicular and parallel to the fracture walls), surface roughness, and surface pair mismatch. The results may contribute to defining a more accurate equation of hydraulic aperture and permeability of single fractures, which represents a pillar for the modeling and upscaling of the hydraulic properties of a geofluid reservoir.

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