Squirt flow in fully saturated rocks

Geophysics ◽  
1995 ◽  
Vol 60 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Jack Dvorkin ◽  
Gary Mavko ◽  
Amos Nur
Keyword(s):  
High Frequency ◽  
Pore Space ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Confining Pressure ◽  
Biot Theory ◽  
Unknown Parameters ◽  
High Confining Pressure ◽  
Confining Pressures ◽  
Dispersion And Attenuation

We estimate velocity/frequency dispersion and attenuation in fully saturated rocks by employing the squirt‐flow mechanism of solid/fluid interaction. In this model, pore fluid is squeezed from thin soft cracks into the surrounding large pores. Information about the compliance of these soft cracks at low confining pressures is extracted from high‐pressure velocity data. The frequency dependence of squirt‐induced pressure in the soft cracks is linked with the porosity and permeability of the soft pore space, and the characteristic squirt‐flow length. These unknown parameters are combined into one expression that is assumed to be a fundamental rock property that does not depend on frequency. The appropriate value of this expression for a given rock can be found by matching our theoretical predictions with the experimental measurements of attenuation or velocity. The low‐frequency velocity limits, as given by our model, are identical to those predicted by Gassmann’s formula. The high‐frequency limits may significantly exceed those given by the Biot theory: the high‐frequency frame bulk modulus is close to that measured at high confining pressure. We have applied our model to D’Euville Limestone, Navajo Sandstone, and Westerly Granite. The model realistically predicts the observed velocity/frequency dispersion, and attenuation.

Magnetic Permeability and Relaxation Frequency in High Frequency Magnetic Materials.

2001 ◽  
Vol 674 ◽  
Author(s):  
M.I. Rosales ◽  
H. Montiel ◽  
R. Valenzuela
Keyword(s):  
High Frequency ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Anisotropy Constant ◽  
Relaxation Frequency ◽  
Resonance Relaxation ◽  
Frequency Behavior

ABSTRACTAn investigation of the frequency behavior of polycrystalline ferrites is presented. It is shown that the low frequency dispersion (f < 10 MHz) of permeability is associated with the bulging of pinned domain walls, and has a mixed resonance-relaxation character, closer to the latter. It is also shown that there is a linear relationship between the magnetocrystalline anisotropy constant, K1, and the relaxation frequency. The slope of this correlation depends on the grain size. Such a relationship could allow the determination of this basic parameter from polycrystalline samples.

scholarly journals Intragranular deformation mechanisms in calcite deformed by high-pressure torsion at room temperature

2020 ◽  
Vol 114 (2) ◽  
pp. 105-118
Author(s):  
Roman Schuster ◽  
Gerlinde Habler ◽  
Erhard Schafler ◽  
Rainer Abart
Keyword(s):  
High Pressure ◽  
Twin Boundary ◽  
Brittle Failure ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Confining Pressure ◽  
Temperature Deformation ◽  
Orientation Relationships ◽  
High Confining Pressure ◽  
Confining Pressures

AbstractPolycrystalline calcite was deformed to high strain at room-temperature and confining pressures of 1–4 GPa using high-pressure torsion. The high confining pressure suppresses brittle failure and allows for shear strains >100. The post-deformation microstructures show inter- and intragranular cataclastic deformation and a high density of mechanical e$$ \left\{01\overline{1}8\right\} $$011¯8 twins and deformation lamellae in highly strained porphyroclasts. The morphologies of the twins resemble twin morphologies that are typically associated with substantially higher deformation temperatures. Porphyroclasts oriented unfavorably for twinning frequently exhibit two types of deformation lamellae with characteristic crystallographic orientation relationships associated with calcite twins. The misorientation of the first deformation lamella type with respect to the host corresponds to the combination of one r$$ \left\{10\overline{1}4\right\} $$101¯4 twin operation and one specific f$$ \left\{01\overline{1}2\right\} $$011¯2 or e$$ \left\{01\overline{1}8\right\} $$011¯8 twin operation. Boundary sections of this lamella type often split into two separated segments, where one segment corresponds to an incoherent r$$ \left\{10\overline{1}4\right\} $$101¯4 twin boundary and the other to an f$$ \left\{01\overline{1}2\right\} $$011¯2 or e$$ \left\{01\overline{1}8\right\} $$011¯8 twin boundary. The misorientation of the second type of deformation lamellae corresponds to the combination of specific r$$ \left\{10\overline{1}4\right\} $$101¯4 and f$$ \left\{01\overline{1}2\right\} $$011¯2 twin operations. The boundary segments of this lamella type may also split into the constituent twin boundaries. Our results show that brittle failure can effectively be suppressed during room-temperature deformation of calcite to high strains if confining pressures in the GPa range are applied. At these conditions, the combination of successive twin operations produces hitherto unknown deformation lamellae.

scholarly journals Macroscopic and Mesoscopic Mechanical Properties of Mine Tailings with Different Dry Densities under Different Confining Pressures

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhi-jun Zhang ◽  
Yao-hui Guo ◽  
Ya-kun Tian ◽  
Lin Hu ◽  
Xi-xian Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coordination Number ◽  
Mine Tailings ◽  
Confining Pressure ◽  
Simulation Software ◽  
Particle Flow ◽  
Dry Density ◽  
Stress Strain ◽  
High Confining Pressure ◽  
Confining Pressures

Particle flow numerical simulation software (PFC3D) was utilized to establish the consolidated-undrained triaxial compression test numerical models of mine tailings with different dry densities to deeply investigate the macroscopic and microscopic characteristics of mine tailings in a tailing pond in Hunan Province. Comparing the results of the simulation and the laboratory experiment, the mesoscopic parameters of the particle flow numerical simulation were obtained through continuously adjusting the mesoscopic parameter with the higher degree of agreement between the stress-strain curve, the peak strength, and the elastic modulus as the determining standard. The macroscopic and microscopic characteristics of mine tailings were studied from the perspectives of stress-strain, axial strain-volume strain, coordination number, particle velocity vector, and contact force between particles. After numerous numerical tests, it was found that the PFC3D simulation results are consistent with experiment results of the dry density tailing samples under different confining pressures; compared with the high confining pressure, the simulation test results at lower confining pressures were more with that of the laboratory tests; low density and high confining pressure both have inhibitory effect on the dilatancy characteristics of triaxial samples; with the same confining pressure, the dilatancy tendency of low dry density samples is suppressed comparing with the high dry density samples. The initial coordination number of the numerical model is large, which proves that the contact degree of the model is good to some extent.

“Deformation of Rocks under High Confining Pressures. I. Experiments at Room Temperature.” Journal of Geology, Vol. xliv, no. 5, pp. 541–577. By David T. Griggs. (1936).

Geophysics ◽  
1936 ◽  
Vol 1 (3) ◽  
pp. 378-379
Author(s):  
M. Mott‐Smith
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
Room Temperature ◽  
Confining Pressure ◽  
Earth’S Crust ◽  
Differential Stress ◽  
High Confining Pressure ◽  
Confining Pressures ◽  
Earth's Crust

This article describes experiments on the flow and rupture of rocks under compression, tension, and torsion, while at the same time subjected to a high confining pressure supplied through a liquid surrounding the specimen. The hydrostatic pressure of this liquid could be measured very accurately and could be maintained constant. In addition, a “differential” stress was applied to the specimen, and the deformation was measured directly. By using the high pressure technique of P. W. Bridgman the confining pressure was carried up to 13,000 atmospheres, equivalent to a depth in the earth’s crust of 28 miles, and four times that available to F. W. Adams in his pioneering experiments (1901–1917).

scholarly journals Shaft Resistance of Long (Flexible) Piles Considering Strength Degradation

2021 ◽  
Vol 27 (3) ◽  
pp. 54-66
Author(s):  
Aysar Hassan Subair ◽  
Ala Nasir Aljorany
Keyword(s):  
Soil Structure ◽  
Frictional Resistance ◽  
Confining Pressure ◽  
Strength Degradation ◽  
Analysis Tool ◽  
Shaft Resistance ◽  
Model Pile ◽  
High Confining Pressure ◽  
Confining Pressures ◽  
Shear Strength Degradation

Soil-structure frictional resistance is an important parameter in the design of many foundation systems. The soil-structure interface area is responsible for load transferring from the structure to the surrounding soil. The mobilized shaft resistance of axially loaded, long slender pile embedded in dense, dry sand is experimentally and numerically analyzed when subjected to pullout force. Experimental setup including an instrumented model pile while the finite element method is used as a numerical analysis tool. The hypoplasticity model is used to model the soil adjacent to and surrounding the pile by using ABAQUS FEA (6.17.1). The soil-structure interface behavior depends on many factors, but mainly on the interface soil's tendency to contract or dilate under shearing conditions. To investigate this tendency, three piles with different surface roughness and under different confining pressures are used. A dilation behavior is observed in the relation of the average shaft resistance with the axial displacement for piles with rough and medium roughness surfaces, while contraction behavior is noticed when shearing piles with smooth surfaces. A large shear strength degradation of about (10%) reduction in the shaft resistance is observed under low confining pressure compared to a lesser reduction value of about (2%) under high confining pressure. Good agreement is obtained between the experimental and the numerical results.

Low-frequency dispersion and attenuation in anisotropic partially saturated rocks

2017 ◽  
Vol 209 (3) ◽  
pp. 1572-1584 ◽  
Author(s):  
Fabio Cavallini ◽  
José M. Carcione ◽  
Daniel Vidal de Ventós ◽  
Lisbeth Engell-Sørensen
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion ◽  
Partially Saturated ◽  
Dispersion And Attenuation

Effects of Confining Pressure on Gas and Water Permeabilities of Rocks

2000 ◽  
Vol 663 ◽  
Author(s):  
M. Zhang ◽  
M. Takeda ◽  
T. Esaki ◽  
M. Takahashi ◽  
H. Endo
Keyword(s):  
Rock Specimen ◽  
Pulse Method ◽  
Confining Pressure ◽  
Great Depth ◽  
Test System ◽  
Saturated Rock ◽  
Underground Disposal ◽  
High Confining Pressure ◽  
Confining Pressures ◽  
The Difference

ABSTRACTKnowledge of the permeability of hydraulically-tight rock at great depth is crucially important for the design and/or assessment of facilities associated with underground disposal of radioactive nuclear wastes. This paper presents a recently developed laboratory permeability test system capable of testing low permeability rocks either by using air as a permeant or by the transient-pulse method under high confining pressure conditions that simulate ground pressures at depths. The new system was used to test Shirahama sandstone and Inada granite, which are two types of rock widely available in Japan. To investigate the effects of heterogeneity on rock permeability, specimens cored parallel to and perpendicular to bedding for sandstone, and specimens cored in the direction perpendicular to Rift Plane, Grain Plane and Hardway Plane for granite, were used. The results of this study showed that: 1) gas permeabilities of a dried rock specimen tested by air permeation are almost the same values as water permeabilities of the same saturated rock specimen tested by the transient-pulse method; 2) the intrinsic permeabilities of Shirahama sandstone and Inada granite range from about 8.33E-16 to 7.38E-17 m2 and from 1.86E-17 to 6.94E-20 m2, respectively. They decrease monotonously with increase in effective confining pressure (defined as the difference between the confining and pore pressures), while the rate of decrease diminishes at higher confining pressures. The reduction in permeabilities is due to the closure of microcracks that control fluid flow at low confining pressures; and 3) Inada granite is a heterogeneous and isotropic material. Its hydraulic heterogeneity is more significant in Rift Plane than in Hardway and Grain Planes.

Permeability and borehole Stoneley waves: Comparison between experiment and theory

Geophysics ◽  
1989 ◽  
Vol 54 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Kenneth W. Winkler ◽  
Hsui‐Lin Liu ◽  
David Linton Johnson
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Theoretical Models ◽  
Oil Field ◽  
Stoneley Wave ◽  
Biot Theory ◽  
Frequency Dependent ◽  
Low Frequencies ◽  
High Frequencies ◽  
Theoretical Predictions

We performed laboratory experiments to evaluate theoretical models of borehole. Stoneley wave propagation in permeable materials. A Berea sandstone and synthetic samples made of cemented glass beads were saturated with silicone oils. We measured both velocity and attenuation over a frequency band from 10 kHz to 90 kHz. Our theoretical modeling incorporated Biot theory and Deresiewicz‐Skalak boundary conditions into a cylindrical geometry and included frequency‐dependent permeability. By varying the viscosity of the saturating pore fluid, we were able to study both low‐frequency and high‐frequency regions of Biot theory, as well as the intermediate transition zone. In both low‐frequency and high‐frequency regions of the theory, we obtained excellent agreement between experimental observations and theoretical predictions. Velocity and attenuation (1/Q) are frequency‐dependent, especially at low frequencies. Also at low frequencies, velocity decreases and attenuation increases with increasing fluid mobility (permeability/viscosity). More complicated behavior is observed at high frequencies. These results support recent observations from the oil field suggesting that Stoneley wave velocity and attenuation may be indicative of formation permeability.

Prefabricated Structures Surface Marble Rheological Tests and Constitutive Model Analysis

2014 ◽  
Vol 501-504 ◽  
pp. 419-425
Author(s):  
Qing Xu ◽  
Jiang Da He ◽  
Hong Qiang Xie ◽  
Ming Li Xiao ◽  
Jian Feng Liu
Keyword(s):  
Mechanical Properties ◽  
Rheological Properties ◽  
Flow Rate ◽  
Axial Stress ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Rheological Parameters ◽  
Structural Plane ◽  
High Confining Pressure ◽  
Confining Pressures

The mechanical properties of intact rock and rock containing structural plane are very different. From the diversion tunnel of Jinping deep rock site to retrieve the complete block of marble, after a high confining pressure triaxial compression simulation tectonic movements, the formation of structural plane, it represents the mechanical properties of the original rock. On the surface of the marble structure containing triaxial compression creep tests, the results showed: at low confining pressure, the weak marble surface as micro-damage accumulation, the emergence of non-uniform partial destruction, while at high confining pressure, creep curve better continuity and integrity; different confining pressures, marble initial rheology and stability both appear rheological phase, accelerated phase rheological obvious; different confining pressures, the same stage of the axial stress steady flow rate compared with the confining pressure increases, the axial steady state flow rate becomes smaller; marble under test showed the rheological properties, the use of Nishihara model can better demonstrate the rheological properties and determine the rheological parameters for other practical engineering reference.

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