scholarly journals Stress dependency of elastic properties of shales: The effect of uniaxial stress

2011 ◽  
Author(s):  
Marina Pervukhina ◽  
Boris Gurevich ◽  
Pavel Golodoniuc ◽  
David N. Dewhurst
Keyword(s):  
Elastic Properties ◽  
Uniaxial Stress ◽  
Stress Dependency

Elastic properties of two VTI shale samples as a function of uniaxial stress: Experimental results and application of the porosity-deformation approach

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. C201-C210 ◽  
Author(s):  
Viacheslav A. Sviridov ◽  
Sibylle I. Mayr ◽  
Serge A. Shapiro
Keyword(s):  
Elastic Properties ◽  
Pore Space ◽  
Uniaxial Stress ◽  
Data Sets ◽  
Seismic Velocities ◽  
Transverse Isotropic ◽  
Compliant Parts ◽  
Stress Dependent ◽  
Deformation Approach ◽  
Stress Dependency

Shale is a complex medium composed of clay, other mineral phases, and a pore space. The combined elastic properties of these components control the effective (anisotropic) properties of the composite solid. The factor that is the most dependent on the stress field is the structure of the pore space, which greatly influences the elastic properties of the medium. We have further developed and experimentally validated the porosity deformation approach (PDA) for understanding and modeling stress-dependent changes of the elastic properties of sedimentary rocks. PDA separates the pore space into stiff and compliant parts. The load dependencies of the elastic properties have linear contributions due to the former and exponential contributions due to the latter. We evaluate data sets of elastic properties of two vertical transverse isotropic shale samples measured under uniaxial stress. Then we apply the PDA and our optimization algorithm to the measured data sets to model the stress dependency of the seismic velocities and validate the modeling with experimentally obtained results. We have developed for the first time the constant anellipticity approach (CAN), which estimates the off-axis velocity (in an inclined direction relative to the symmetry axis direction) as a function of stress. Measurements of off-axis velocities are often missing information, and CAN permits us to fill this gap. This provides further background for the reconstruction of the stress dependency of the compliance tensor from acoustic log data.

scholarly journals Parameterization of elastic stress sensitivity in shales

Geophysics ◽  
2011 ◽  
Vol 76 (3) ◽  
pp. WA147-WA155 ◽  
Author(s):  
Marina Pervukhina ◽  
Boris Gurevich ◽  
Pavel Golodoniuc ◽  
David N. Dewhurst
Keyword(s):  
Elastic Properties ◽  
Anisotropy Parameter ◽  
Transversely Isotropic ◽  
Bedding Plane ◽  
Stress Sensitivity ◽  
Crack Orientation ◽  
Fluid Identification ◽  
Orientation Anisotropy ◽  
Characteristic Pressure ◽  
Stress Dependency

Stress dependency and anisotropy of dynamic elastic properties of shales is important for a number of geophysical applications, including seismic interpretation, fluid identification, and 4D seismic monitoring. Using Sayers-Kachanov formalism, we developed a new model for transversely isotropic (TI) media that describes stress sensitivity behavior of all five elastic coefficients using four physically meaningful parameters. The model is used to parameterize elastic properties of about 20 shales obtained from laboratory measurements and the literature. The four fitting parameters, namely, specific tangential compliance of a single crack, ratio of normal to tangential compliances, characteristic pressure, and crack orientation anisotropy parameter, show moderate to good correlations with the depth from which the shale was extracted. With increasing depth, the tangential compliance exponentially decreases. The crack orientation anisotropy parameter broadly increases with depth for most of the shales, indicating that cracks are getting more aligned in the bedding plane. The ratio of normal to shear compliance and characteristic pressure decreases with depth to 2500 m and then increases below this to 3600 m. The suggested model allows us to evaluate the stress dependency of all five elastic compliances of a TI medium, even if only some of them are known. This may allow the reconstruction of the stress dependency of all five elastic compliances of a shale from log data, for example.

scholarly journals Stress Dependency of Shale Elastic Properties: Measurements, Modelling and Prediction

2010 ◽  
Vol 2010 (1) ◽  
pp. 1-4
Author(s):  
Marina Pervukhina ◽  
Boris Gurevich ◽  
David N. Dewhurst ◽  
Pavel Golodoniuc
Keyword(s):  
Elastic Properties ◽  
Stress Dependency

scholarly journals Elastic properties of microcomponents under uniaxial stress

PAMM ◽  
2007 ◽  
Vol 7 (1) ◽  
pp. 4080011-4080012
Author(s):  
K. Jöchen ◽  
T. Böhlke
Keyword(s):  
Elastic Properties ◽  
Uniaxial Stress

Effect of asperities on stress dependency of elastic properties of cracked rocks

2016 ◽  
Vol 98 ◽  
pp. 116-125 ◽  
Author(s):  
Stanislav Glubokovskikh ◽  
Boris Gurevich ◽  
Maxim Lebedev ◽  
Vassily Mikhaltsevitch ◽  
Samantha Tan
Keyword(s):  
Elastic Properties ◽  
Stress Dependency

Electron Microscopy and image reconstruction reveal the structural basis for spectrin's elastic properties

1992 ◽  
Vol 50 (1) ◽  
pp. 510-511
Author(s):  
Amy M. McGough ◽  
Robert Josephs
Keyword(s):  
Electron Microscopy ◽  
Elastic Properties ◽  
Conformational Changes ◽  
Quaternary Structure ◽  
Three Dimensional ◽  
Membrane Skeleton ◽  
Projection Algorithm ◽  
Structural Basis ◽  
Iterative Approximation ◽  
Membrane Skeletons

The remarkable deformability of the erythrocyte derives in large part from the elastic properties of spectrin, the major component of the membrane skeleton. It is generally accepted that spectrin's elasticity arises from marked conformational changes which include variations in its overall length (1). In this work the structure of spectrin in partially expanded membrane skeletons was studied by electron microscopy to determine the molecular basis for spectrin's elastic properties. Spectrin molecules were analysed with respect to three features: length, conformation, and quaternary structure. The results of these studies lead to a model of how spectrin mediates the elastic deformation of the erythrocyte.Membrane skeletons were isolated from erythrocyte membrane ghosts, negatively stained, and examined by transmission electron microscopy (2). Particle lengths and end-to-end distances were measured from enlarged prints using the computer program MACMEASURE. Spectrin conformation (straightness) was assessed by calculating the particles’ correlation length by iterative approximation (3). Digitised spectrin images were correlation averaged or Fourier filtered to improve their signal-to-noise ratios. Three-dimensional reconstructions were performed using a suite of programs which were based on the filtered back-projection algorithm and executed on a cluster of Microvax 3200 workstations (4).

The buckling of thin EM specimens

1990 ◽  
Vol 48 (4) ◽  
pp. 850-851
Author(s):  
A.R. Thölén
Keyword(s):  
Electron Microscope ◽  
Elastic Properties ◽  
Crystal Surface ◽  
Specimen Surface ◽  
Radius Of Curvature ◽  
Thin Foils ◽  
Thin Electron ◽  
Regular Patterns

Thin electron microscope specimens often contain irregular bend contours (Figs. 1-3). Very regular bend patterns have, however, been observed around holes in some ion-milled specimens. The purpose of this investigation is twofold. Firstly, to find the geometry of bent specimens and the elastic properties of extremely thin foils and secondly, to obtain more information about the background to the observed regular patterns.The specimen surface is described by z = f(x,y,p), where p is a parameter, eg. the radius of curvature of a sphere. The beam is entering along the z—direction, which coincides with the foil normal, FN, of the undisturbed crystal surface (z = 0). We have here used FN = [001]. Furthermore some low indexed reflections are chosen around the pole FN and in our fcc crystal the following g-vectors are selected:

Two- and three-photon spectroscopy of ZnO under uniaxial stress

1998 ◽  
Vol 184-185 (1-2) ◽  
pp. 686-690 ◽  
Author(s):  
J Wrzesinski
Keyword(s):  
Uniaxial Stress
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