scholarly journals Elastic Properties of Pannonian Basin Limestone under Different Saturation Conditions

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7291
Author(s):  
Domagoj Vukadin ◽  
Jasna Orešković ◽  
Csaba Kutasi
Keyword(s):  
Shear Modulus ◽  
Elastic Properties ◽  
Wave Velocity ◽  
Pannonian Basin ◽  
Empirical Relationship ◽  
Type System ◽  
Confining Pressure ◽  
Strengthening Effect ◽  
Hydrocarbon Reservoir ◽  
Payne Model

Understanding elastic properties of reservoir rocks is essential for seismic modeling under different saturation conditions as well as lithology discrimination. Experiments on elastic properties of limestones are significantly less published compared to siliciclastic sedimentary rocks. The current study presents the results of laboratory measurements on Pannonian Basin limestone cores. The research was carried out for the first time for a hydrocarbon reservoir in the Bjelovar Depression, located in the southern part of the Pannonian Basin. Ultrasonic velocity measurements and determination of dynamic elastic properties were performed on limestone plugs, in dry and saturated condition under different confining pressure steps. Based on the results obtained in laboratory conditions, an empirical relationship between shear wave velocity (Vs) and compressional wave velocity (Vp) has been defined. The saturated samples show an effect of shear modulus weakening, while three samples have a shear modulus strengthening effect. Two models were used in the interpretation of the measured data, the Kuster and Toksöz and the Xu-Payne model. The results show that the Xu-Payne model describes the data well and the dominant pore type system in the limestone samples can been identified. The interpretation revealed an interparticle pore system with a fraction of microcracks from 20% to 35%. The results have helped to understand the elastic properties of limestones from the southern part of the Pannonian Basin, which are necessary for any process of reservoir characterization, such as porosity distribution and permeability variation.

scholarly journals Shear modulus of hydrate bearing calcareous sand-fines mixture

2019 ◽  
Vol 92 ◽  
pp. 04002
Author(s):  
Litong Ji ◽  
Abraham C.F. Chiu ◽  
Lu Ma ◽  
Chao Jian
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Hydrate Formation ◽  
Confining Pressure ◽  
Specimen Preparation ◽  
Bender Element ◽  
Calcareous Sand ◽  
Bender Element Test

This article presents a laboratory study on the maximum shear modulus of a THF hydrate bearing calcareous sand (CS)–fines mixture. The maximum shear modulus was inferred from the shear wave velocity measured from the bender elements installed in a temperature-controlled triaxial apparatus. The specimen preparation procedures were specially designed to mimic the hydrate formation inside the internal pores of CS. A trial test was conducted to validate whether the shear wave velocity is a feasible parameter to monitor the formation and dissociation of hydrate in the CS-fines mixture. Based on the bender element test results, hydrate has a more profound effect than confining pressure on enhancing the maximum shear modulus of CS-fines mixture.

Origin of the temporal evolution of elastic properties during laboratory seismic cycle.

2020 ◽  
Author(s):  
Federica Paglialunga ◽  
François X. Passelègue ◽  
Mateo Acosta ◽  
Marie Violay
Keyword(s):  
Elastic Properties ◽  
Wave Velocity ◽  
Confining Pressure ◽  
Seismic Damage ◽  
P Wave ◽  
Seismic Cycle ◽  
Stick Slip ◽  
P Wave Velocity ◽  
Confining Pressures ◽  
Thermally Treated

<p>Recent seismological observations highlighted that earthquakes are associated to drops in elastic properties around the fault zone (Brenguier et al., 2008). This drop is often attributed to co-seismic damage produced at the rupture tip, and can mostly be observed at shallow depths. However, it is known that in the upper crust, faults are surrounded by a zone of damage (Caine, Evans, & Forster, 1996). Because of this, the origin of the velocity change associated to earthquakes, as well as its recovery in the months following the rupture remains highly debated.</p><p>We conducted stick-slip experiments to explore the evolution of elastic waves velocities during the entire seismic cycle. The tests were run on saw-cut La Peyratte granite samples presenting different initial degrees of damage, obtained through thermal treatment. Three types of samples were studied: not thermally treated, thermally treated at 650 °C and thermally treated at 950 °C. Seismic events were induced in a triaxial configuration apparatus at different confining pressures ranging from 15 MPa to 120 MPa. Active acoustic measurements were carried through the whole duration of the tests and P-wave velocities were measured.</p><p> </p><p>The evolution of P-wave velocity follows the evolution of the shear stress acting on the fault, showing velocity drops during dynamic slip events. The evolution of the P-wave velocity drops with increasing confining pressure shows two different trends; the largest drops can be observed for low confining pressure (15 MPa) and decrease for intermediate confining pressures (up to 45 MPa), while for confining pressures of 60 MPa to 120 MPa, drops in velocity slightly increase with confining pressure.</p><p>Our results highlight that at low confining pressures (15-45 MPa), the change in elastic velocity is controlled by the sample bulk properites (damage of the medium surrounding the fault), while for higher confining pressures (60-120 MPa), it might be the result of co-seismic damage.</p><p>These preliminary results bring a different interpretation to the seismic velocity drops observed in nature, attributed to co-seismic damage. In our experiments co-seismic damage is not observed, except for high confining pressures (laboratory equivalent for large depths), while the change in P-wave velocity seems to be highly related to combined stress conditions and initial damage around the fault for low confining pressures (laboratory equivalent for shallow depths).</p>

Effect of fabric on the behaviour of reservoir sandstones

2012 ◽  
Vol 49 (9) ◽  
pp. 1036-1051 ◽  
Author(s):  
Giovanny Alvarado ◽  
Neville Lui ◽  
Matthew R. Coop
Keyword(s):  
Shear Modulus ◽  
Experimental Evidence ◽  
Mechanical Behaviour ◽  
Confining Pressure ◽  
Large Strains ◽  
Hydrocarbon Reservoir ◽  
Small Strains ◽  
Reservoir Sandstones ◽  
Observed Behaviour ◽  
Stress Dependency

A laboratory investigation was undertaken on the mechanical behaviour of two sandstones that are commonly used as analogous hydrocarbon reservoir sandstones, using triaxial apparatuses with a capacity of up to 70 MPa confining pressure. Both materials are lightly cemented, but show a mechanical behaviour at large strains that is similar to that seen in rocks with much stronger cementation. At small strains, however, these materials behave more like uncemented sands in that they show a strong stress dependency of the shear modulus and yield takes places at relatively small strains. It is believed that fabric plays a fundamental role in the observed behaviour and this is supported by the experimental evidence, so that the concept of strong fabric in sandstones is introduced.

Elastic Properties and Electronic Structure of L12 (Al,Si)3Sc

2011 ◽  
Vol 284-286 ◽  
pp. 1987-1990 ◽  
Author(s):  
Qiang Yao
Keyword(s):  
Electronic Structure ◽  
Shear Modulus ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Strengthening Effect ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Al Matrix

The method of ultrasoft pseudopotential within the generalized gradient approximation has been employed to study the elastic constants and electronic structure of (Al,Si)3Sc precipitate with L12structure in Al-base alloys. Based on the calculated results, the elastic properties of (Al,Si)3Sc precipitate were investigated. The Young’s and shear modulus of the polycrystals for (Al,Si)3Sc precipitate were calculated using Voigt-Reuss-Hill averaging scheme. The calculated results of elastic properties showed that the (Al,Si)3Sc precipitate has a strengthening effect in the Al matrix, owing to the larger shear modulus differences between (Al,Si)3Sc and Al matrix. The calculated results also showed that (Al,Si)3Sc precipitate is brittle in nature.

Velocity‐porosity relationships, 1: Accurate velocity model for clean consolidated sandstones

Geophysics ◽  
2003 ◽  
Vol 68 (6) ◽  
pp. 1822-1834 ◽  
Author(s):  
Mark A. Knackstedt ◽  
Christoph H. Arns ◽  
W. Val Pinczewski
Keyword(s):  
Experimental Data ◽  
Shear Modulus ◽  
Elastic Properties ◽  
Poisson’S Ratio ◽  
Empirical Relationship ◽  
Numerical Data ◽  
Empirical Method ◽  
Poisson's Ratio ◽  
Mineral Phase ◽  
Water Saturated

We use numerical simulations to derive the elastic properties of model monomineralic consolidated sandstones. The model morphology is based on overlapping spheres of a mineral phase. We consider model quartzose and feldspathic sands. We generate moduli‐porosity relationships for both the dry and water‐saturated states. The ability to control pore space structure and mineralogy results in numerical data sets which exhibit much less noise than corresponding experimental data. The numerical data allows us to quantitatively analyze the effects of porosity and the properties of the mineral phase on the elastic properties of porous rocks. The agreement between the numerical results and available experimental data for clean consolidated sandstones is encouraging. We compare our numerical data to commonly used theoretical and empirical moduli‐porosity relationships. The self‐consistent method gives the best theoretical fit to the numerical data. We find that the empirical relationship of Krief et al. is successful at describing the numerical data for dry shear modulus and that the recent empirical method of Arns et al. gives a good match to the numerical data for Poisson's ratio or Vp/Vs ratio of dry rock. The Raymer equation is the best of the velocity‐porosity models for the water‐saturated systems. Gassmann's relations are shown to accurately map between the dry and fluid‐saturated states. Based on these results, we propose a new empirical method, based solely on a knowledge of the mineral modulus, to estimate the full velocity‐porosity relationship for monomineralic consolidated sands under dry and fluid‐saturated states. The method uses the equation of Krief et al. for the dry shear modulus and the empirical equation of Arns et al. for the dry Poisson's ratio. Gassmann's relations are applied to obtain the fluid‐saturated states. The agreement between the new empirical method, the numerical data and available experimental data for dry and water‐saturated states is encouraging.

scholarly journals NMR-Based Study of the Pore Types’ Contribution to the Elastic Response of the Reservoir Rock

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1513 ◽  
Author(s):  
Naser Golsanami ◽  
Xuepeng Zhang ◽  
Weichao Yan ◽  
Linjun Yu ◽  
Huaimin Dong ◽  
...  
Keyword(s):  
Elastic Wave ◽  
Wave Velocity ◽  
Transverse Relaxation Time ◽  
Seismic Attributes ◽  
Elastic Wave Velocity ◽  
Reservoir Rock ◽  
Elastic Response ◽  
Hydrocarbon Reservoir ◽  
Statistical Ensembles ◽  
Pore Types

Seismic data and nuclear magnetic resonance (NMR) data are two of the highly trustable kinds of information in hydrocarbon reservoir engineering. Reservoir fluids influence the elastic wave velocity and also determine the NMR response of the reservoir. The current study investigates different pore types, i.e., micro, meso, and macropores’ contribution to the elastic wave velocity using the laboratory NMR and elastic experiments on coal core samples under different fluid saturations. Once a meaningful relationship was observed in the lab, the idea was applied in the field scale and the NMR transverse relaxation time (T2) curves were synthesized artificially. This task was done by dividing the area under the T2 curve into eight porosity bins and estimating each bin’s value from the seismic attributes using neural networks (NN). Moreover, the functionality of two statistical ensembles, i.e., Bag and LSBoost, was investigated as an alternative tool to conventional estimation techniques of the petrophysical characteristics; and the results were compared with those from a deep learning network. Herein, NMR permeability was used as the estimation target and porosity was used as a benchmark to assess the reliability of the models. The final results indicated that by using the incremental porosity under the T2 curve, this curve could be synthesized using the seismic attributes. The results also proved the functionality of the selected statistical ensembles as reliable tools in the petrophysical characterization of the hydrocarbon reservoirs.

Mechanical behaviour of powders using a medium pressure flexible boundary cubical triaxial tester

2003 ◽  
Vol 217 (3) ◽  
pp. 233-241 ◽  
Author(s):  
F Li ◽  
V M Puri
Keyword(s):  
Shear Modulus ◽  
Mechanical Behaviour ◽  
Triaxial Compression ◽  
Three Dimensional ◽  
Volumetric Strain ◽  
Confining Pressure ◽  
Alumina Powder ◽  
Medium Pressure ◽  
Mean Pressure ◽  
Confining Pressures

A medium pressure (<21 MPa) flexible boundary cubical triaxial tester was designed to measure the true three-dimensional response of powders. In this study, compression behaviour and strength of a microcrystalline cellulose powder (Avicel® PH102), a spray-dried alumina powder (A16SG), and a fluid-bed-granulated silicon nitride based powder (KY3500) were measured. To characterize the mechanical behaviour, three types of triaxial stress paths, that is, the hydrostatic triaxial compression (HTC), the conventional triaxial compression (CTC), and the constant mean pressure triaxial compression (CMPTC) tests were performed. The HTC test measured the volumetric response of the test powders under isostatic pressure from 0 to 13.79MPa, during which the three powders underwent a maximum volumetric strain of 40.8 per cent for Avicel® PH102, 30.5 per cent for A16SG, and 33.0 per cent for KY3500. The bulk modulus values increased 6.4-fold from 57 to 367MPa for Avicel® PH102, 3.7-fold from 174 to 637 MPa for A16SG, and 8.1-fold from 74 to 597MPa for KY3500, when the isotropic stress increased from 0.69 to 13.79 MPa. The CTC and CMPTC tests measured the shear response of the three powders. From 0.035 to 3.45MPa confining pressure, the shear modulus increased 28.7-fold from 1.6 to 45.9MPa for Avicel® PH102, 35-fold from 1.7 to 60.5MPa for A16SG, and 28.5-fold from 1.5 to 42.8MPa for KY3500. In addition, the failure stresses of the three powders increased from 0.129 to 4.41 MPa for Avicel® PH102, 0.082 to 3.62 MPa for A16SG, and 0.090 to 4.66MPa for KY3500, respectively, when consolidation pressure increased from 0.035 to 3.45MPa. In addition, the shear modulus and failure stress values determined from the CTC test at 2.07, 2.76, and 3.45MPa confining pressures are consistently greater than those from the CMPTC test at the same constant mean pressures. This observation demonstrates the influence of stress paths on material properties. The CTT is a useful tool for characterizing the three-dimensional response of powders and powder mixtures.

scholarly journals Integrated petrographic – rock mechanic borecore study from the metamorphic basement of the Pannonian Basin, Hungary

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
László Molnár ◽  
Balázs Vásárhelyi ◽  
Tivadar M. Tóth ◽  
Félix Schubert
Keyword(s):  
Compressive Strength ◽  
Fault Zone ◽  
Uniaxial Compressive Strength ◽  
Pannonian Basin ◽  
Damage Zone ◽  
Rock Mechanic ◽  
Fault Rock ◽  
Hydrocarbon Reservoir ◽  
Migration Pathway ◽  
Metamorphic Basement

AbstractThe integrated evaluation of borecores from the Mezősas-Furta fractured metamorphic hydrocarbon reservoir suggests significantly distinct microstructural and rock mechanical features within the analysed fault rock samples. The statistical evaluation of the clast geometries revealed the dominantly cataclastic nature of the samples. Damage zone of the fault can be characterised by an extremely brittle nature and low uniaxial compressive strength, coupled with a predominately coarse fault breccia composition. In contrast, the microstructural manner of the increasing deformation coupled with higher uniaxial compressive strength, strain-hardening nature and low brittleness indicate a transitional interval between the weakly fragmented damage zone and strongly grinded fault core. Moreover, these attributes suggest this unit is mechanically the strongest part of the fault zone. Gougerich cataclasites mark the core zone of the fault, with their widespread plastic nature and locally pseudo-ductile microstructure. Strain localization tends to be strongly linked with the existence of fault gouge ribbons. The fault zone with ∼15 m total thickness can be defined as a significant migration pathway inside the fractured crystalline reservoir. Moreover, as a consequence of the distributed nature of the fault core, it may possibly have a key role in compartmentalisation of the local hydraulic system.

Shear Modulus and Damping Ratio of Gravel Material

2011 ◽  
Vol 105-107 ◽  
pp. 1426-1432 ◽  
Author(s):  
De Gao Zou ◽  
Tao Gong ◽  
Jing Mao Liu ◽  
Xian Jing Kong
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Strain Amplitude ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Dynamic Shear Modulus ◽  
Test Results ◽  
Dynamic Shear ◽  
Data Points ◽  
Shear Strain Amplitude

Two of the most important parameters in dynamic analysis involving soils are the dynamic shear modulus and the damping ratio. In this study, a series of tests were performed on gravels. For comparison, some other tests carried out by other researchers were also collected. The test results show that normalized shear modulus and damping ratio vary with the shear strain amplitude, (1) normalized shear modulus decreases with the increase of dynamic shear strain amplitude, and as the confining pressure increases, the test data points move from the low end toward the high end; (2) damping ratio increases with the increase of shear strain amplitude, damping ratio is dependent on confining pressure where an increase in confining pressure decreased damping ratio. According to the test results, a reference formula is proposed to evaluate the maximum dynamic shear modulus, the best-fit curve and standard deviation bounds for the range of data points are also proposed.

Experimental Study on Dynamic Characteristics of Ionic Soil Stabilizer Reinforcing Red Clay

2011 ◽  
Vol 374-377 ◽  
pp. 1391-1395
Author(s):  
Xue Song Lu ◽  
Wei Xiang
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Dynamic Condition ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Natural Soil ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Red Clay ◽  
Soil Stabilizer

Based on the red clay of Wuhan reinforced by Ionic Soil Stabilizer, the red clay soil is treated by different matches of ISS at first, then is tested in the Atterberg limits test and dynamic triaxia test. The results show that the plastic index decreases, and the red clay were greatly improved under the dynamic condition, the maximum dynamic shear modulus ratio acquired an incensement of 27.72% on average after mixing the ISS into the red clay. In addition, It was concluded that the confining pressure influenced the dynamic shear modulus and damping ratio to a certain extent. Given the same strain conditions, with the incensement of confining pressure increases, the dynamic shear modulus increased and the damping ratio decreased. Moreover, when plotting the dynamic shear modulus versus the dynamic shear strain, the similar curve can be formed for both the natural soil and the modified one, the dynamic shear modulus monotonously decreased with the incensement of the dynamic shear strain. However, the value of dynamic shear modulus differed in the same shear strain between the natural soil and the soil modified by ISS.

Sign in / Sign up

Export Citation Format

Share Document