Ultrasonic Shear Wave Velocities Research Articles

Stress-Dependent Petrophysical Properties of the Bakken Unconventional Petroleum System: Insights from Elastic Wave Velocities and Permeability Measurements

The net-effective stress is a fundamental physical property that undergoes dynamic changes in response to variations in pore pressure during production and injection activities. Petrophysical properties, including porosity, permeability, and wave velocities, play a critical role and exhibit strong dependence on the mechanical stress state of the formation. The Williston basin’s Bakken Formation represents a significant reservoir of hydrocarbons within the United States. To investigate this formation, we extracted core plugs from three distinct Bakken members, namely Upper Bakken, Middle Bakken, and Lower Bakken. Subsequently, we conducted a series of measurements of ultrasonic compressional and shear wave velocities, as well as pulse decay permeabilities using nitrogen, under various confining pressures employing the Autolab-1500 apparatus. Our experimental observations revealed that the ultrasonic wave velocities and permeability display a significant sensitivity to stress changes. We investigated existing empirical relationships on velocity-effective stress, compressional-shear wave velocities, and permeability-effective stress, and proposed the best models and associated fitting parameters applicable to the current datasets. In conjunction with the acquired datasets, these models have considerable potential for use in time-lapse seismic monitoring and the study of production decline behavior. The best fitting models can be used to forecast the petrophysical and geomechanical property changes as the reservoir pore pressure is depleted due to the production, which is critical to the production forecast for unconventional reservoirs.

Study of the anisotropic elastic response of a foliated phyllite

Anisotropy is a crucial characteristic of metamorphic rocks whereby minerals oriented in a preferential direction can originate mineral foliation. Inherent anisotropy can affect the rock behaviour significantly. Transverse isotropy is a particular case of anisotropy where foliation planes are distributed in the rock mass. Therefore, in this study the anisotropy effect on the elastic properties of a foliated phyllite is considered. To this end, a series of laboratory tests was programmed. Triaxial tests were carried out under confining pressures up to 20 MPa. Elastic parameters such as elasticity modulus, E, and Poisson's ratio, ν, are assessed from triaxial test results as well as from ultrasonic tests, where compression and shear wave velocities are determined. Empirical relationships for elastic parameters are suggested as a function of foliation angle, β, and confinement. In addition, anisotropy indexes are adopted to evaluate results, comparing when possible with those of previous works. It was found that E increases with confinement; however, the effect of anisotropy on E reduces with confinement. It was also found that ν is affected by β but not by confinement.

Quantifying the impact of effective stress on changes in elastic wave velocities due to CO2 injection into a depleted carbonate reef

AbstractThe interpretation of time‐lapse seismic monitoring of CO2 sequestration has typically focused on mapping the saturation and pressure changes. However, elastic wave velocity and associated seismic attribute variation also depend on the poroelastic response to CO2 injection. In this study, we investigated the impact of effective stress changes on elastic wave velocity responses during CO2 storage within a carbonate reef of the Michigan basin. The geomechanical multiphase flow modeling combined with the experimental measurements were used to investigate the impact of effective stress on changes in velocities. We measured the ultrasonic compressional (Vp) and shear (Vs) wave velocities in cores acquired from the carbonate formations under different stress‐pressure scenarios. Experimental scenarios were applied by changing the effective stress and pore pressure conditions simulating injection into the depleted reservoir. Experimental results show that incorporating stress changes of injection avoids overestimation of changes in velocities due to considering only pore pressure effects. Coupled multiphase flow – geomechanical simulations were performed to assess stress and saturation change during CO2 injection. We discussed expected changes in elastic wave velocities using combined simulation results with experimental ones. The simulation results show that both effective stress and saturation changes contribute to changes in velocities in the main reservoir. Effective stress is the dominant parameter that contributes to changes in velocities in the upper formations. Results of this work show that quantifying the poroelastic effect of stress on elastic wave velocities changes can lead to a better interpretation of changes in seismic attributes during CO2 injection. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.

A comparative study of different concentrations of (Co/Ni/Cu) effects on elastic properties of Li–Mn ferrite employing IR spectroscopy and ultrasonic measurement

Three series of divalent ions (Co2+/Ni2+/Cu2+) substituted into lithium-manganese ferrites were synthesized using a typical ceramic technique. Two different methods were used to investigate their elastic properties. Infrared (IR) spectroscopy showed two essential bands referring to the tetrahedral ‘υA’ and the octahedral ‘υB’ sites. The force constant, elastic wave velocity and elastic moduli of all specimens have been calculated from the results of IR spectroscopy. Using the ultrasonic pulse transmission (UPT) technique, the longitudinal and shear wave velocities were measured. Using these values; bulk modulus (B), rigidity modulus (G), Young's modulus (E), and Poisson ratio (σ) were determined. In comparison, the elastic moduli resulting from IR spectroscopy results were larger than those obtained from UPT measurements. Because the present ferrite systems are porous, the elastic moduli of the compositions from UPT have been adjusted to zero porosity by two models. The values of the adjusted elastic moduli have been shown to have the same trend as those of the uncorrected elastic moduli. Elastic parameters have generally improved dramatically for Li–Mn–Co ferrite and Li–Mn–Ni ferrite compared to Li–Mn–Cu ferrite. Higher elastic moduli values have been obtained in Li–Mn–Co spinel ferrites, suggesting that such materials are ideal for use in core shapes. Two methods were used to evaluate the Debye temperature of all compositions.

Experimental and theoretical elastic moduli of sodium–zinc–tellurite glasses

70TeO2-(30-x)ZnO-xNa2O, x = 0, 3, 7, 10 and 15 mol% glasses were prepared. Samples amorphousity has been checked by XRD. Density and molar volume have been estimated. Longitudinal and shear ultrasonic wave velocities were measured by using pulse echo technique. Elastic moduli (bulk, shear, longitudinal, Young's), Poisson’s ratio, Debye temperature, microhardness and softening temperature of the glasses were measured. Theoretical analysis of the elastic moduli has been achieved. Bond compression (B.C) and Makishima - Mackenzie (M.M) models have been used to interpret the experimental data of elastic moduli.

Elastic and attenuation behavior of the Bi1-x Re x FeO3 (x = 0 & 0.1; Re = La, Pr, Nd & Sm) multiferroic system

ABSTRACT A series of single-phase rare earth-doped bismuth ferrites were prepared by the solid state reaction method. After characterizing the samples with XRD, the bulk density measurements were carried out by the immersion method. The ultrasonic longitudinal (Vl ) and shear (Vs ) wave velocities were measured using 1 MHz quartz transducers with the help of the pulse transmission technique. Using the ultrasonic velocity values, Young’s and rigidity moduli along with Poisson’s ratio and Debye temperatures were calculated. As the materials are porous, the zero porous moduli have also been calculated using the Hasselman and Fulrath model. The observed variation of elastic moduli with different dopants has been explained qualitatively. The low-temperature behavior of ultrasonic longitudinal (Vl ) wave velocities was also measured. A small change of slope was observed at 208 K in BFO, BLFO and BSFO samples. Finally, the ultrasonic attenuation coefficient values of all the samples were also measured.

Effects of plastic fines content on the engineering properties of cement-stabilized sands

Cement-stabilization of soil is a common and useful ground improvement method to increase the strength and stiffness of weak soils. The engineering properties of cement-stabilized soil can be affected by the amount of fines in the soil, but there exist controversial views on the effects of fines in the literature, indicating that the underlying mechanism in such cemented soils is not fully understood yet. This paper presents a laboratory study to investigate the effects of fines content on the strength and the wave velocities of cement-stabilized soil using specimens with well-controlled packing densities. The effects of void ratio and cement content are also examined. Experimental results show an interesting finding that the strength and the wave velocities of the cement-stabilized sand first increase and then decrease as the fines content increases from 0 to 15%. The contact and bonding characteristics at the particle level indicate that the strength of the sample is affected by the bonding area and the bonding strength. For a given cement content, the addition of fines increases the bonding area but decreases the bonding strength. Such controversial effects of fines enable to better understand the observed trend of strength variation. A similar mechanism can also be applied to the effects of fines on the wave velocity. Based on the particle-level mechanism, an empirical equation is proposed to characterize the effects of fines. The unconfined compressive strength of the samples can be correlated with the ultra-sonic pulse velocity and shear wave velocity for field monitoring and quality control. The correlations are affected by the fines content.

Elastic and Attenuation Studies of Some Rare Earth Substituted Multiferroic Bismuth Ferrites

A series of rare earth substituted bismuth ferrites are prepared without any detectable impurity phase, by the solid‐state reaction method. The structural characterization of the samples is conducted using X‐ray diffraction (XRD) and bulk density studies. Later, the ultrasonic longitudinal (Vl) and shear wave (Vs) velocities are measured by the pulse transmission technique and using these values, the elastic moduli are calculated. As the materials are porous, zero porous elastic moduli have been computed using Hasselmann and Fulrath model. It is observed that the elastic moduli of samples are found to increase continuously with decreasing of ionic radii of the substituted element and the observed behavior is explained qualitatively. Finally, the attenuation coefficient values of all the samples are also calculated and are found to increase with decreasing of ionic radii of the rare earth substituted ion.

Physical and mechanical properties of ternary Ge-Se-Sb glasses for near-infrared applications

Many physical properties such as the average coordination number (CN), the compactness (δ), the overall bond energy (〈E〉), the cohesive energy (CE), the mean bond energy (E s), and the overall electronegativity difference (Δχ) as well as the degrees of ionicity (Ion) and covalency (Cov) were estimated theoretically. The chemical bond approach (CBA) was used to predict the type and proportion of the formed bonds in the studied glasses. Consequently, several structural and physical properties have been estimated. The results show that the studied glasses are rigidly connected, having an average coordination number increase from 2.41 to 2.61. Two approaches have been successfully used to estimate the band gap (E g) theoretically compared with the previously published experimental values for the Ge18Se82−xSbx (5 ≤ x ≤ 25 at. %) glasses. Values of E g decrease from 1.59 to 1.15 eV by an increase of the Sb content from 5 to 25 at. %. i.e. the wavelengths corresponding to E g values lie in the near-infrared range of spectra, which make these glasses candidates for the near-infrared applications. Furthermore, the ultrasonic longitudinal (v L ) and shear wave (v T ) velocities propagating through the glasses have been used to estimate the mechanical parameters such as the elastic bulk modulus, Poisson’s ratio, Young’s modulus, micro-hardness, and temperature of Debye. It was found that a change in slope occurs for various physical, mechanical, and structural properties near the stoichiometric composition (x ≈ 18 at. %) at which the glass structure consists of heteropolar bonds only.

Studying petrophysical properties of micritic limestones using machine learning methods

It is important in geophysical applications to relate the compressional and shear ultrasonic wave velocities of micritic limestone to its porosity, volume fraction and density of micrite grains as well as the effective confining pressure. In this paper, this difficulty task is successfully realized by using the most relevant machine learning methods: The artificial neural network method, the support vector machine method and the extreme gradient boosting method (XGB). A relevant dataset available in literature is considered to train and test the models. It is observed that the XGB method significantly outperform the other methods in term of accuracy and training time. It allow obtaining a very high R-squared value of 0.96 and a very small relative root mean squared error of 3% while predicting the sonic velocities from other petrophysical properties. The robustness of the models is also confirmed by studying the sensitivity of the random splittings between the training and the testing sets

Influence of samarium on some acoustical, physical and radiation shielding characteristics of Bi2O3–ZnO–PbO glasses

Bi2O3–ZnO–PbO glass formulations with various concentrations of samarium oxide Sm2O3 were synthesized using the rapid-quenching route. The deconvoluted FTIR spectra were recorded through the domain of 400–2000 cm−1. System characteristics including density as well as molar volume have been studied. Ultrasonic longitudinal and shear wave velocities and elastic moduli were found to reduce with Sm2O3 concentration. Both bulk compression and Makishima–Mackenzie models were found to diminish with the increase of Sm2O3 and in good harmony with the experimental results. Theoretical radiation shielding properties have been analyzed for the obtained glass system and showed high tendency to be used as radiation protection fabrics for γ rays.

Microscale analysis to characterize effects of water content on the strength of cement-stabilized sand–clay mixtures

Cement stabilization is a useful and widely adopted method to improve the engineering properties of soils. However, characterization of the unconfined compressive strength, a simple and useful design property, is not straightforward due to complex interactions of various influence factors. This study investigated the effects of water content on the unconfined compressive strength of cement-stabilized clayey sands. The results show that the strength of the cemented binary mixtures increases with water content and water-to-cement ratio until a threshold value is reached and then decreases with further increase in water content and water-to-cement ratio. The unconfined compressive strength is correlated with ultrasonic wave velocity and shear wave velocity, respectively, showing two nearly unique correlations. Microscale analysis based on the coated sphere model revealed that the strength of the sample is affected by the bonding area and the strength of the binder material (cement–clay mixture). An empirical equation is also proposed based on the microscale analysis so as to capture the effects of water content on the strength.

Elastic and spectroscopic properties of 0.7TeO2–0.1ZnO–0.1NaF–(0.1–x) WO3−xNd2O3 tellurite glasses

New tellurite glasses in the composition of 0.7TeO2–0.1ZnO–0.1NaF–(0.1–x) WO3−xNd2O3 and x = 0.005, 0.01, 0.015, 0.025, 0.035, 0.04 and 0.05 mol% were prepared. Density (ρ) and molar volume (Vm) have measured and calculated. Longitudinal and shear ultrasonic wave velocities (Ul, Us) were measured by the pulse-echo technique using Krautkramer USIP 20 at 4 MHz. Moduli of elasticity, longitudinal modulus (L), shear modulus (G), bulk modulus (K), Young’s modulus (E) and Poisson’s ratio (σ) were calculated for every glass sample. The UV spectra in the range 200–2500 nm were measured. The Judd–Ofelt intensity parameters Ωλ (λ = 2, 4, 6) were measured for the whole glass series. The Judd–Ofelt intensity parameters were in the order Ω2 < Ω4 < Ω6 for all Nd3+-doped tellurite glasses. Both oscillator strengths, experimental and calculated (fexp and fcal) from the ground state 4I9/2, were measured. Also, lifetime (τ) and ranching ratio (β) were calculated for each parentage of Nd2O3. Discussion was built on Judd–Ofelt parameters and the dissociation energy of bonds.

Material Damage Evolution for Plain and Steel-Fiber-Reinforced Concrete Under Unconfined Compression Loading by Dynamic Ultrasonic Tests

This paper summarizes the results of a research aimed at assessing the damage of plain and steel-fiber-reinforced concrete when using ultrasonic compression and shear wave velocities. The ultrasonic waves and the axial compression loading were oriented to the same direction in order to track the damage progress during several loading steps. The concrete damage was monitored based on the evolution of the dynamic mechanical properties. The experimental program included 18 cylindrical specimens from six different mixtures that were cast by using 0, 0.3 and 0.5% fiber volume contents. Quantitative models were established linking the axial loads, the wave velocities, the dynamic Young’s and shear moduli, the Poisson’s ratio and a damage index.

Kızılçam (Pinus brutia Ten.) odunu kesme modüllerinin Ultrasonik dalga yayılımı ile tahmini

Shear moduli of Calabria pine (Pinus Brutia Ten.) predicted using non-destructive test method in this study. Calabria pine logs harvested from Beşkonak, Burdur and sawn in to Radial and Tangential planks. 26 surface polyhedral NDT samples prepared in 65x65x65mm dimensions. All samples acclimatized at 20±1°C temperature and %65RH conditions. Ultrasonic shear wave velocities of Calabria pine wood calculated using time of flight (ToF) values. ToF values obtained using Olympus EPOCH 650 flaw detector and Panametrics NDT V153 shear wave transducers. Shear moduli predicted using calculated velocities. Average density and moisture content of the non-destructive test samples determined as 0.558g/cm3 and %12.66, respectively. Shear wave velocities and shear moduli of LR, LT, and RT planes were determined as 1408, 1306 and 666m/s and 1108, 952 and 248N/mm2, respectively.

Low temperature acoustic characterization of PMN single crystal

This acoustic study of the relaxor single crystal PbMg1/3Nb2/3O3 is focused on the temperature evolution of longitudinal and shear ultrasonic wave velocities as well as on their attenuation within the temperature range of 4.2–300 K. Temperature dependences of all three independent elastic constants for the cubic structure (C11, C44, and C12) along with the bulk modulus B, the Cauchy ratio, and the degree of lattice anisotropy were derived from the velocity data set. Important parameters such as the Debye temperature, the Grüneisen parameter H, and the Poisson ratio were determined at cryogenic temperatures as well. Deep minima were found for C11 and C44 around the temperature Tm where the dielectric constant reaches a maximum, followed by a drastic increase of C11 and C44 at decreasing temperature and ultimately by a saturation at temperatures below 25 K. The behavior of these constants at T &amp;lt; Tm corresponds well to relations resulting from the Einstein-oscillator model. A changeover of C12(T) dependence from increasing at T &amp;lt; Tm to unexpected monotonic decreasing behavior upon cooling from inflection temperature Ti ≈ 220 K followed by a saturation at T &amp;lt; 25 K was found. Furthermore, the behavior of C12 (T) and interrelated parameters such as B and H was analyzed on the basis of the concept of phonon pressure due to the thermal expansion. It is essential that the electrostriction contribution was taken into account, as well.

Acoustic characterization of crack damage evolution in sandstone deformed under conventional and true triaxial loading

AbstractWe present a comparative study of crack damage evolution in dry sandstone under both conventional (σ1 &gt; σ2 = σ3), and true triaxial (σ1 &gt; σ2 &gt; σ3) stress conditions using results from measurements made on cubic samples deformed in three orthogonal directions with independently controlled stress paths. To characterize crack damage, we measured the changes in ultrasonic compressional and shear wave velocities in the three principal directions, together with the bulk acoustic emission (AE) output contemporaneously with stress and strain. We use acoustic wave velocities to model comparative crack densities and orientations. In essence, we create two end‐member crack distributions; one displaying cylindrical transverse isotropy (conventional triaxial) and the other planar transverse isotropy (true triaxial). Under the stress conditions in our experiments we observed an approximately fivefold decrease in the number of AE events between the conventional and true triaxial cases. When taken together, the AE data, the velocities, and the crack density data indicate that the intermediate principal stress suppresses the total number of cracks and restricts their growth to orientations subnormal to the minimum principal stress. However, the size of individual cracks remains essentially constant, controlled by the material grain size. Crack damage is only generated when the differential stress exceeds some threshold value. Cyclic loading experiments show that further damage commences only when that previous maximum differential stress is exceeded, regardless of the mean stress, whether this is achieved by increasing the maximum principal stress or by decreasing the minimum principal stress.

Ultrasonic Characterisation of Epoxy Resin/Polyethylene Terephthalate (PET) Char Powder Composites

This study is carried out in order to determine the elastic properties of the Epoxy Resin (ER) / Polyethylene terephthalate (PET) Char Powder Composites by ultrasonic wave velocity measurement method. Plastic waste was recycled as raw material for the preparation of epoxy composite materials. The supplied chars were mixed with epoxy resin matrix at weight percentages of 10 %, 20 % and 30 % for preparing ER/PET Char Powder (PCP) composites. The effect of PET char powder on the elastic properties of ER/PCP composites were investigated by ultrasonic pulse-echo method. According to the obtained results, the composition ratio of 80:20 is the most appropriate composition ratio, which gave the highest elastic constants values for ER/PCP composites. On the other hand, the best electrical conductivity value was obtained for 70:30 composition ratio. It was observed that ultrasonic shear wave velocity correlated more perfectly than any other parameters with hardness. DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12190

Pore network microarchitecture influences human cortical bone elasticity during growth and aging

Cortical porosity is a major determinant of bone strength. Haversian and Volkmann׳s canals are׳seen’ as pores in 2D cross-section but fashion a dynamic network of interconnected channels in 3D, a quantifiable footprint of intracortical remodeling. Given the changes in bone remodeling across life, we hypothesized that the 3D microarchitecture of the cortical pore network influences its stiffness during growth and ageing.Cubes of cortical bone of 2 mm side-length were harvested in the distal 1/3 of the fibula in 13 growing children (mean age±SD: 13±4 yrs) and 16 adults (age: 75±13 yrs). The cubes were imaged using desktop micro-CT (8.14µm isotropic voxel size). Pores were segmented as a solid to assess pore volume fraction, number, diameter, separation, connectivity and structure model index. Elastic coefficients were derived from measurements of ultrasonic bulk compression and shear wave velocities and apparent mass density.The pore volume fraction did not significantly differ between children and adults but originates from different microarchitectural patterns. Compared to children, adults had 42% (p=0.033) higher pore number that were more connected (Connective Density: +205%, p=0.001) with a 18% (p=0.007) lower pore separation. After accounting for the contribution of pore volume fraction, axial elasticity in traction-compression mode was significantly correlated with better connectivity in growing children and with pore separation among adults.The changes in intracortical remodeling across life alter the distribution, size and connectedness of the channels from which cortical void fraction originates. These alterations in pore network microarchitecture participate in changes in compressive and shear mechanical behavior, partly in a porosity-independent manner. The assessment of pore volume fraction (i.e., porosity) provides only a limited understanding of the role of cortical void volume fraction in its mechanical properties.

Simulateneous high P-T measurements of ultrasonic compressional and shear wave velocities in Oki-Dogo mantle xenoliths

Simulateneous high P-T measurements of ultrasonic compressional and shear wave velocities in Oki-Dogo mantle xenoliths