Elastic Properties of Low Density Core (LDC) Ti-6Al-4V Sandwich Cores

ABSTRACTLightweight, structurally efficient low density core (LDC) sandwich structures can be produced by entrapping argon gas within a finely dispersed distribution of pores in a microstructure and using a high temperature anneal to cause pore growth by gas expansion. This results in a porous microstructure with a relative density as low as ∼0.70. Laser ultrasonic methods have been used to measure the longitudinal and shear wave velocities and hence the elastic properties of LDC Ti-6Al-4V cores prior to, and after gas expansion treatments of up to 48 hr at 920°C. The data was compared with several analytical models for predicting the volume fraction of porosity dependent elastic properties of porous materials.

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Estimation of Dry-Rock Elastic Moduli Based on the Simulation of Mud-Filtrate Invasion Effects on Borehole Acoustic Logs

SPE Reservoir Evaluation & Engineering ◽

10.2118/109879-pa ◽

2009 ◽

Vol 12 (06) ◽

pp. 898-911 ◽

Cited By ~ 2

Author(s):

Tobiloluwa B. Odumosu ◽

Carlos Torres-Verdín ◽

Jesús M. Salazar ◽

Jun Ma ◽

Benjamin Voss ◽

...

Keyword(s):

Bulk Modulus ◽

Shear Wave ◽

Elastic Properties ◽

Elastic Moduli ◽

Compressional Wave ◽

Shear Rigidity ◽

Spatial Distributions ◽

Wave Velocities ◽

Shear Wave Velocities ◽

Mud Filtrate

Summary Reliable estimates of dry-rock elastic properties are critical to the accurate interpretation of the seismic response of hydrocarbon reservoirs. We describe a new method for estimating elastic moduli of rocks in-situ based on the simulation of mud-filtrate invasion effects on resistivity and acoustic logs. Simulations of mud-filtrate invasion account for the dynamic process of fluid displacement and mixing between mud-filtrate and hydrocarbons. The calculated spatial distributions of electrical resistivity are matched against resistivity logs by adjusting the underlying petrophysical properties. We then perform Biot-Gassmann fluid substitution on the 2D spatial distributions of fluid saturation with initial estimates of dry-bulk (kdry) modulus and shear rigidity (µdry) and a constraint of Poisson's ratio (?d) typical of the formation. This process generates 2D spatial distributions of compressional and shear-wave velocities and density. Subsequently, sonic waveforms are simulated to calculate shear-wave slowness. Initial estimates of the dry-bulk modulus are progressively adjusted using a modified Gregory-Pickett (1963) solution of Biot's (1956) equation to estimate a shear rigidity that converges to the well-log value of shear-wave slowness. The constraint on dynamic Poisson's ratio is then removed and a refined estimate of the dry-bulk modulus is obtained by both simulating the acoustic log (monopole) and matching the log-derived compressional-wave slowness. This technique leads to reliable estimates of dry-bulk moduli and shear rigidity that compare well to laboratory core measurements. Resulting dry-rock elastic properties can be used to calculate seismic compressional-wave and shear-wave velocities devoid of mud-filtrate invasion effects for further seismic-driven reservoir-characterization studies.

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Relationships between Dynamic Elastic Moduli in Shale Reservoirs

Energies ◽

10.3390/en13226001 ◽

2020 ◽

Vol 13 (22) ◽

pp. 6001

Author(s):

Sheyore John Omovie ◽

John P. Castagna

Keyword(s):

Organic Carbon ◽

Shear Modulus ◽

Elastic Moduli ◽

Volume Fraction ◽

P Wave ◽

Wave Velocities ◽

Shear Wave Velocities ◽

Average Formation ◽

Dynamic Elastic Moduli ◽

Shale Reservoirs

Sonic log compressional and shear-wave velocities combined with logged bulk density can be used to calculate dynamic elastic moduli in organic shale reservoirs. We use linear multivariate regression to investigate modulus prediction when shear-wave velocities are not available in seven unconventional shale reservoirs. Using only P-wave modulus derived from logged compressional-wave velocity and density as a predictor of dynamic shear modulus in a single bivariate regression equation for all seven shale reservoirs results in prediction standard error of less than 1 GPa. By incorporating compositional variables in addition to P-wave modulus in the regression, the prediction standard error is reduced to less than 0.8 GPa with a single equation for all formations. Relationships between formation bulk and shear moduli are less well defined. Regressing against formation composition only, we find the two most important variables in predicting average formation moduli to be fractional volume of organic matter and volume of clay in that order. While average formation bulk modulus is found to be linearly related to volume fraction of total organic carbon, shear modulus is better predicted using the square of the volume fraction of total organic carbon. Both Young’s modulus and Poisson’s ratio decrease with increasing TOC while increasing clay volume decreases Young’s modulus and increases Poisson’s ratio.

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Physical and elastic properties of some khondalites from the Eastern Ghat Belt of Peninsular India

Canadian Journal of Earth Sciences ◽

10.1139/e76-136 ◽

1976 ◽

Vol 13 (9) ◽

pp. 1333-1342 ◽

Cited By ~ 3

Author(s):

B. S. Gogte ◽

Y. V. Ramana

Keyword(s):

Elastic Wave ◽

Manganese Oxide ◽

Elastic Properties ◽

Fracture Strength ◽

Elastic Wave Velocity ◽

Eastern Ghats ◽

Peninsular India ◽

Wave Velocities ◽

Shear Wave Velocities ◽

Rock Suite

Khondalites, which form an important rock suite of the Eastern Ghats, are studied for their physical and elastic properties together with their petrology and petrochemistry. Garnetiferous quartzites exhibit compressional and shear wave velocities between 4.9–5.6 km/s and 2–3 km/s; these are higher than garnet sillimanite gneisses, which are between 3.4–5.2 km/s and 1.4–2.6 km/s, respectively. The latter are more anisotropic than the former. Velocity and anisotropy are affected by alteration of garnet and sillimanite in these rocks. The velocities show a decreasing tendency with increasing manganese oxide. Garnetiferous quartzites bear a higher fracture strength than garnet sillimanite gneisses. Elastic wave velocity studies under hydrostatic pres sure to 5 kbar indicate slight changes with increasing pressure; and the absence of kyanite and the presence of cordierite in negligible amounts suggest their formation near the low to intermediate pressure granulite field.

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Elastic properties of gas hydrate‐bearing sediments

Geophysics ◽

10.1190/1.1444966 ◽

2001 ◽

Vol 66 (3) ◽

pp. 763-771 ◽

Cited By ~ 55

Author(s):

Myung W. Lee ◽

Timothy S. Collett

Keyword(s):

Shear Wave ◽

Elastic Properties ◽

Gas Hydrate ◽

Poisson’S Ratio ◽

Pore Space ◽

Poisson's Ratio ◽

The Arctic ◽

Wave Velocities ◽

Shear Wave Velocities ◽

Hydrate Bearing Sediments

Downhole‐measured compressional- and shear‐wave velocities acquired in the Mallik 2L-38 gas hydrate research well, northwestern Canada, reveal that the dominant effect of gas hydrate on the elastic properties of gas hydrate‐bearing sediments is as a pore‐filling constituent. As opposed to high elastic velocities predicted from a cementation theory, whereby a small amount of gas hydrate in the pore space significantly increases the elastic velocities, the velocity increase from gas hydrate saturation in the sediment pore space is small. Both the effective medium theory and a weighted equation predict a slight increase of velocities from gas hydrate concentration, similar to the field‐observed velocities; however, the weighted equation more accurately describes the compressional- and shear‐wave velocities of gas hydrate‐bearing sediments. A decrease of Poisson’s ratio with an increase in the gas hydrate concentration is similar to a decrease of Poisson’s ratio with a decrease in the sediment porosity. Poisson’s ratios greater than 0.33 for gas hydrate‐bearing sediments imply the unconsolidated nature of gas hydrate‐bearing sediments at this well site. The seismic characteristics of gas hydrate‐bearing sediments at this site can be used to compare and evaluate other gas hydrate‐bearing sediments in the Arctic.

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Direct numerical simulation of wave propagation in saturated random granular packings using coupled LBM-DEM

EPJ Web of Conferences ◽

10.1051/epjconf/202124914003 ◽

2021 ◽

Vol 249 ◽

pp. 14003

Author(s):

Hongyang Cheng ◽

Stefan Luding ◽

Jens Harting ◽

Vanessa Magnanimo

Keyword(s):

Granular Media ◽

Volume Fraction ◽

Saturated Porous Medium ◽

Pore Fluid ◽

Frequency Space ◽

Wave Velocities ◽

Shear Wave Velocities ◽

Confining Pressures ◽

Granular Packings ◽

Boltzmann Method

Poroelasticity theory predicts wave velocities in a saturated porous medium through a coupling between the bulk deformation of the solid skeleton and porous fluid flow. The challenge emerges below the characteristic wavelengths at which hydrodynamic interactions between grains and pore fluid become important. We investigate the pressure and volume fraction dependence of compressional- and shear-wave velocities in fluid-saturated, random, isotropic, frictional granular packings. The lattice Boltzmann method (LBM) and discrete element method (DEM) are two-way coupled to capture the particle-pore fluid interactions; an acoustic source is implemented to insert a traveling wave from the fluid reservoir to the saturated medium. We extract wave velocities from the acoustic branches in the wavenumber-frequency space, for a range of confining pressures and volume fractions. For random isotropic granular media the pressure-wave velocity data collapse on a single curve when scaled properly by the volume fraction.

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Comparative study of elastic properties and mode I fracture energy of carbon nanotube/epoxy and carbon fibre/epoxy laminated composites

Micro and Nano Systems Letters ◽

10.1186/s40486-020-00120-1 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Jyotikalpa Bora ◽

Sushen Kirtania

Keyword(s):

Carbon Nanotube ◽

Carbon Fibre ◽

Fracture Energy ◽

Elastic Properties ◽

Volume Fraction ◽

Laminated Composites ◽

Laminated Composite ◽

Fe Analysis ◽

Mode I ◽

Mode I Fracture

Abstract A comparative study of elastic properties and mode I fracture energy has been presented between conventional carbon fibre (CF)/epoxy and advanced carbon nanotube (CNT)/epoxy laminated composite materials. The volume fraction of CNT fibres has been considered as 15%, 30%, and 60% whereas; the volume fraction of CF has been kept constant at 60%. Three stacking sequences of the laminates viz.[0/0/0/0], [0/90/0/90] and [0/30/–30/90] have been considered in the present analysis. Periodic microstructure model has been used to calculate the elastic properties of the laminated composites. It has been observed analytically that the addition of only 15% CNT in epoxy will give almost the same value of longitudinal Young’s modulus as compared to the addition of 60% CF in epoxy. Finite element (FE) analysis of double cantilever beam specimens made from laminated composite has also been performed. It has been observed from FE analysis that the addition of 15% CNT in epoxy will also give almost the same value of mode I fracture energy as compared to the addition of 60% CF in epoxy. The value of mode I fracture energy for [0/0/0/0] laminated composite is two times higher than the other two types of laminated composites.

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