A comparative study of the stress-dependence of dynamic and static moduli for sandstones

Geophysics ◽  
2020 ◽  
Vol 85 (4) ◽  
pp. MR179-MR190 ◽  
Author(s):  
Yang Wang ◽  
De-Hua Han ◽  
Hui Li ◽  
Luanxiao Zhao ◽  
Jiali Ren ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Young’S Modulus ◽  
Stress Condition ◽  
Young's Modulus ◽  
Deviatoric Stress ◽  
Stress Conditions ◽  
Stress Dependence ◽  
Static Modulus ◽  
Static Young’S Modulus ◽  
Stress Changes

Understanding the differences between the static and dynamic elastic moduli of reservoir rocks is essential for the successful exploration and production of hydrocarbon reservoirs. However, the controlling factors on the dynamic-static discrepancy for sandstones remain ambiguous. Consequently, we have purposely selected three outcrop sandstone samples with large porosity contrast to investigate the effects of the stress state, magnitude, and load-unload history on the dynamic and static moduli through laboratory measurements. The results suggest that the dynamic moduli are systematically larger than the static moduli at almost any hydrostatic or deviatoric stress magnitude. In contrast, the static moduli are much more sensitive to the stress variations than the dynamic ones, leading to the decreasing dynamic-static difference upon hydrostatic loading and the increasing dynamic-static difference upon deviatoric loading. When the maximum stress in a cycle is initially reversed, the dynamic-static ratio tends to approach one, whatever the bulk modulus under hydrostatic pressure condition or the Young’s modulus under triaxial stress condition. Under the subsequent unloading process, the static bulk modulus is always higher than that derived during loading. However, the unloading static Young’s modulus is larger than the loading Young’s modulus only at a relatively high deviatoric stress magnitude greater than 30 MPa, while showing an opposite trend at a low-stress condition of less than 25 MPa. From the microstructural viewpoint, it is believed that the static tests accumulate the elastic, viscoelastic, and nonelastic properties within a certain stress or strain range. In contrast to the dynamic modulus, the static modulus exhibits greater sensitivity to the pressure or stress changes under hydrostatic and deviatoric stress conditions. The strong stress dependence makes it important to consider the in situ stress conditions when establishing dynamic-static modulus relations.

Mechanical Properties and Decay Resistance of Wood Polymer Composites (WPC)

2011 ◽  
Vol 264-265 ◽  
pp. 819-824 ◽  
Author(s):  
Md. Rezaur Rahman ◽  
Sinin Hamdan ◽  
M. Saiful Islam ◽  
Md. Shahjahan Mondol
Keyword(s):  
Polymer Composites ◽  
Young’S Modulus ◽  
Modulus Of Elasticity ◽  
Young's Modulus ◽  
Decay Resistance ◽  
Modulus Of Rupture ◽  
Wood Polymer ◽  
Static Young’S Modulus ◽  
Wood Polymer Composites ◽  
Wood Polymer Composite

In Malaysia, especially Borneo Island Sarawak has a large scale of tropical wood species. In this study, selected raw tropical wood species namely Artocarpus Elasticus, Artocarpus Rigidus, Xylopia Spp, Koompassia Malaccensis and Eugenia Spp were chemically treated with sodium meta periodate to convert them into wood polymer composites. Manufactured wood polymer composites were characterized using mechanical testing (modulus of elasticity (MOE), modulus of rupture (MOR), static Young’s modulus) and decay resistance test. Modulus of elasticity and modulus of rupture were calculated using three point bending test. Static Young’s modulus and decay resistance were calculated using compression parallel to gain test and natural laboratory decay test respectively. The manufactured wood polymer composites yielded higher modulus of elasticity, modulus of rupture and static Young’s modulus. Wood polymer composite had high resistant to decay exposure, while Eugenia Spp wood polymer composite had highly resistant compared to the other ones.

Elastic constants of inflated lobes of dog lungs

1976 ◽  
Vol 40 (4) ◽  
pp. 508-513 ◽  
Author(s):  
S. J. Lai-Fook ◽  
T. A. Wilson ◽  
R. E. Hyatt ◽  
J. R. Rodarte
Keyword(s):  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Young's Modulus ◽  
Poisson Ratio ◽  
Inflation Pressure ◽  
Initial State ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Indentation Tests

The elastic constants of dog lungs were determined at various degrees of inflation. In one set of experiments, the lobes were subjected to deformations that approximated the conditions of uniaxial loading. These data, together with the bulk modulus data obtained from the local slope of the pressure-volume curve, were used to determine the two elastic moduli that are needed to describe small nonuniform deformations about an initial state of uniform inflation. The bulk modulus was approximately 4 times the inflation pressure, and Young's modulus was approximately 1.5 times the inflation pressure. In a second set of experiments, lobes were subjected to indentation tests using cylindric punches 1–3 cm in diameter. The value for Young's modulus obtained from these data was slightly higher, approximately twice the inflation pressure. These experiments indicate that the lung is much more easily deformable in shear than in dilatation and that the Poisson ratio for the lung is high, approximately 0.43.

scholarly journals Application of Machine Learning in Evaluation of the Static Young’s Modulus for Sandstone Formations

2020 ◽  
Vol 12 (5) ◽  
pp. 1880 ◽  
Author(s):  
Ahmed Abdulhamid Mahmoud ◽  
Salaheldin Elkatatny ◽  
Dhafer Al Shehri
Keyword(s):  
Machine Learning ◽  
Young’S Modulus ◽  
Transit Time ◽  
Young's Modulus ◽  
Wellbore Stability ◽  
Learning Models ◽  
Static Young’S Modulus ◽  
Data Points ◽  
Sandstone Formation ◽  
Machine Learning Models

Prediction of the mechanical characteristics of the reservoir formations, such as static Young’s modulus (Estatic), is very important for the evaluation of the wellbore stability and development of the earth geomechanical model. Estatic considerably varies with the change in the lithology. Therefore, a robust model for Estatic prediction is needed. In this study, the predictability of Estatic for sandstone formation using four machine learning models was evaluated. The design parameters of the machine learning models were optimized to improve their predictability. The machine learning models were trained to estimate Estatic based on bulk formation density, compressional transit time, and shear transit time. The machine learning models were trained and tested using 592 well log data points and their corresponding core-derived Estatic values collected from one sandstone formation in well-A and then validated on 38 data points collected from a sandstone formation in well-B. Among the machine learning models developed in this work, Mamdani fuzzy interference system was the highly accurate model to predict Estatic for the validation data with an average absolute percentage error of only 1.56% and R of 0.999. The developed static Young’s modulus prediction models could help the new generation to characterize the formation rock with less cost and safe operation.

Measuring the quasi-static Young’s modulus of the eardrum using an indentation technique

2010 ◽  
Vol 263 (1-2) ◽  
pp. 168-176 ◽  
Author(s):  
S. Mohammad Hesabgar ◽  
Harry Marshall ◽  
Sumit K. Agrawal ◽  
Abbas Samani ◽  
Hanif M. Ladak
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Indentation Technique ◽  
Static Young’S Modulus

Differences between static and dynamic elastic moduli: Importance of experimental methods

2020 ◽  
Author(s):  
Elisabeth Bemer ◽  
Noalwenn Dubos-Sallée ◽  
Patrick N. J. Rasolofosaon
Keyword(s):  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Moduli ◽  
Young's Modulus ◽  
Local Strain ◽  
Experimental Methods ◽  
Triaxial Tests ◽  
Strain Gauges ◽  
Strain Measurements ◽  
Dynamic Elastic Moduli

<p>The differences between static and dynamic elastic moduli remain a controversial issue in rock physics. Various empirical correlations can be found in the literature. However, the experimental methods used to derive the static and dynamic elastic moduli differ and may entail substantial part of the discrepancies observed at the laboratory scale. The representativeness and bias of these methods should be fully assessed before applying big data analytics to the numerous datasets available in the literature.</p><p>We will illustrate, discuss and analyze the differences inherent to static and dynamic measurements through a series of triaxial and petroacoustic tests performed on an outcrop carbonate. The studied rock formation is Euville limestone, which is a crinoidal grainstone composed of roughly 99% calcite and coming from Meuse department located in Paris Basin. Sister plugs have been cored from the same quarry block and observed under CT-scanner to check their homogeneity levels.</p><p>The triaxial device is equipped with an internal stress sensor and provides axial strain measurements both from strain gauges glued to the samples and LVDTs placed inside the confinement chamber. Two measures of the static Young's modulus can thus be derived: the first one from the local strain measurements provided by the strain gauges and the second one from the semi-local strain measurements provided by the LVDTs. The P- and S-wave velocities are measured both through first break picking and the phase spectral ratio method, providing also two different measures of the dynamic Young's modulus.</p><p>The triaxial tests have been performed in drained conditions and the measured static elastic moduli correspond to drained elastic moduli. The petroacoustic tests have been performed using the fluid substitution method, which consists in measuring the acoustic velocities for various saturating fluids of different bulk modulus. No weakening or dispersion effects have been observed. Gassmann's equation can then be used to derive the dynamic drained elastic moduli and the solid matrix bulk modulus, which is otherwise either taken from the literature for pure calcite or dolomite samples, or computed using Voigt-Reuss-Hill or Hashin-Shtrikman averaging of the mineral constituents.</p><p>For the studied carbonate formation, we obtain similar values for static and dynamic elastic moduli when derived from careful lab experiments. Based on the obtained results, we will finally make recommendations, emphasizing the necessity of using relevant experimental techniques for a consistent characterization of the relation between static and dynamic elastic moduli.</p>

The Effect of Nitrogen Doping on the Elastic Properties of Silicene

2015 ◽  
Vol 245 ◽  
pp. 14-18
Author(s):  
Mary A. Chibisova ◽  
Andrey N. Chibisov
Keyword(s):  
Density Functional Theory ◽  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Density Functional ◽  
Nitrogen Doping ◽  
Young's Modulus ◽  
Functional Theory ◽  
Nitrogen Doped

This paper deals with the elastic properties of pure and nitrogen-doped silicene using density functional theory. During the compression (tension) from –2 to 2 GPa of pure and nitrogen-doped silicene, the corresponding values for the bulk modulus are obtained. It is found that the doping of the silicene structure with nitrogen has practically no effect on the value of its bulk modulus. However, the Young's modulus is increased of about 1.25 times.

Mechanical and thermodynamics properties of Al2Ca and Mg2Ca under various pressure: A first principle study

2021 ◽  
Vol 11 (9) ◽  
pp. 1571-1578
Author(s):  
Zai Gao Huang
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Coefficient Of Thermal Expansion ◽  
Young's Modulus ◽  
Structural Parameters ◽  
Harmonic Approximation ◽  
Polycrystalline Materials ◽  
Ductile Phase

The mechanical and thermodynamic properties of Al2Ca and Mg2Ca in the pressure range of 0~100 Gpa were investigated using first-principles calculations. The structural parameters, such as lattice constant ratio, unit cell volume ratio, density, were investigated. The calculated elastic constants satisfy the born’s stability criterion, indicating that they are mechanically stable at normal and high pressure. Mechanical parameters such as bulk modulus, shear modulus, and Young’s modulus of polycrystalline materials have been derived from single-crystal elastic constants. The Poisson’s ratio and anisotropy were investigated. The results show that the B/G value of Mg2Ca is greater than 1.75, indicating it is a ductile phase under various pressures. When the pressure was equal to 40 Gpa, Al2Ca was transferred brittle to toughness, and the bulk modulus, shear modulus, and Young’s modulus of Al2Ca were all larger than those of Mg2Ca, indicating that the comprehensive mechanical properties of Al2Ca are better than those of Mg2Ca. The constant heat capacity obtained by the quasi-harmonic approximation indicates that the ability of Mg2Ca to release or store heat is greater than that of Al2Ca. Moreover, the coefficient of thermal expansion (α) increases exponentially at lower temperatures and linearly at higher temperatures for both alloys.

Experimental Research on the Dynamic Young’s Modulus of Specified Density Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 164-167
Author(s):  
Xiao Er Zhou ◽  
Yan Kun Zhang ◽  
De Min Jiang
Keyword(s):  
Young’S Modulus ◽  
Experimental Research ◽  
Vibration Frequency ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Natural Vibration ◽  
Young's Modulus ◽  
Natural Vibration Frequency ◽  
Dynamic Modulus Of Elasticity ◽  
Static Young’S Modulus

From the experimental research, the relations between the dynamic modulus of elasticity and natural vibration frequency of specified density concrete are studied, the static Young’s modulus and dynamic modulus are compared. Based on regression analysis, the influence of different Substitution ratio of lightweight aggregate, age of concrete and cement water ratio is studied. According to the test results, the formula of natural vibration frequency and the dynamic modulus of elasticity of Specified density concrete is given, which provide theory basis for the nondestructive detector of the specified density concrete.

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