scholarly journals A scale-consistent method for imaging porosity and micrite in dual-porosity carbonate rocks

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. MR115-MR127 ◽  
Author(s):  
Kevin Miller ◽  
Tiziana Vanorio ◽  
Sam Yang ◽  
Xianghui Xiao
Keyword(s):  
Carbonate Rocks ◽  
Total Porosity ◽  
Coarse Grained ◽  
Dual Porosity ◽  
Laboratory Equipment ◽  
X Ray ◽  
Clastic Rocks ◽  
Consistent Method ◽  
Porosity Measurements ◽  
Effective Medium Models

Unlike many other clastic rocks, relating velocity and permeability to porosity for micrite-bearing carbonate rocks has been largely unsuccessful. Recent studies have shown that additional parameters, most notably the distribution and/or proportion of micrite, can be used to parameterize the velocity and permeability behavior. However, there is currently no scale-consistent, 3D methodology for differentiating macroporosity and microporosity from the total porosity measured on bench-top laboratory equipment. Previous studies estimated microporosity and micrite content by combining total porosity measurements conducted on whole 50 mm cores with measurements of phase volumes on 1 mm digital rocks (i.e., scale-inconsistent). As a step forward from those, we imaged dual-porosity carbonate rocks using X-ray microcomputed tomography and then leveraged a recently developed, optimization-based technique, called data-constrained modeling, to map the macroporosity and microporosity distribution of our samples. We evaluate the volumetric proportions of macropores, micropores, and coarse-grained calcite as a function of micrite content — with their respective uncertainties — all measured on the same digital rock and with the same method. Finally, we determine how measurements of the volumetric phase proportions could be extended using standard effective medium models to predict reservoir physical properties. The sensitivity of these models to the proportion of micrite and microporosity within the micrite is evidence that the nonuniqueness among permeability, velocity, and porosity that is commonly observed of micrite-bearing carbonate rocks can be explained by a variation of micrite content and microporosity at a similar porosity.

scholarly journals X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1154
Author(s):  
Diego E. Lozano ◽  
George E. Totten ◽  
Yaneth Bedolla-Gil ◽  
Martha Guerrero-Mata ◽  
Marcel Carpio ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
High Speed ◽  
Spring Steel ◽  
X Ray Diffraction ◽  
Laboratory Equipment ◽  
X Ray ◽  
Water Chamber ◽  
Hardened Case ◽  
Compressive Residual Stresses

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

scholarly journals Vacuum-Free and Highly Dense Nanoparticle Based Low-Band-Gap CuInSe2 Thin-Films Manufactured by Face-to-Face Annealing with Application of Uniaxial Mechanical Pressure

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 484
Author(s):  
Matthias Schuster ◽  
Dominik Stapf ◽  
Tobias Osterrieder ◽  
Vincent Barthel ◽  
Peter J. Wellmann
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Coarse Grained ◽  
High Porosity ◽  
Low Band Gap ◽  
Seeding Layer ◽  
X Ray ◽  
Face To Face ◽  
Copper Indium ◽  
Vis Spectroscopy

Copper indium gallium sulfo-selenide (CIGS) based solar cells show the highest conversion efficiencies among all thin-film photovoltaic competition. However, the absorber material manufacturing is in most cases dependent on vacuum-technology like sputtering and evaporation, and the use of toxic and environmentally harmful substances like H2Se. In this work, the goal to fabricate dense, coarse grained CuInSe2 (CISe) thin-films with vacuum-free processing based on nanoparticle (NP) precursors was achieved. Bimetallic copper-indium, elemental selenium and binary selenide (Cu2−xSe and In2Se3) NPs were synthesized by wet-chemical methods and dispersed in nontoxic solvents. Layer-stacks from these inks were printed on molybdenum coated float-glass-substrates via doctor-blading. During the temperature treatment, a face-to-face technique and mechanically applied pressure were used to transform the precursor-stacks into dense CuInSe2 films. By combining liquid phase sintering and pressure sintering, and using a seeding layer later on, issues like high porosity, oxidation, or selenium- and indium-depletion were overcome. There was no need for external Se atmosphere or H2Se gas, as all of the Se was directly in the precursor and could not leave the face-to-face sandwich. All thin-films were characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and UV/vis spectroscopy. Dense CISe layers with a thickness of about 2–3 µm and low band gap energies of 0.93–0.97 eV were formed in this work, which show potential to be used as a solar cell absorber.

Morphological and synchrotron X-ray microdiffraction studies of large columnar CVD diamond crystallites

1999 ◽  
Vol 32 (5) ◽  
pp. 924-933 ◽  
Author(s):  
A. R. Lang ◽  
A. P. W. Makepeace ◽  
J. E. Butler
Keyword(s):  
Vapour Deposition ◽  
Chemical Vapour ◽  
Coarse Grained ◽  
X Rays ◽  
Small Cross Section ◽  
X Ray ◽  
Chemical Vapour Deposition Diamond ◽  
Core Column ◽  
Diffraction Patterns ◽  
Goniometric Measurements

Optical microscopic and goniometric measurements were combined with microradiography, diffraction-pattern analysis and topography to study a 2 mm thick [001]-texture CVD (chemical vapour deposition) diamond film that had developed a coarse-grained structure composed of separate columnar crystallites. Individual columns were capped by large (001) facets, with widths up to 0.5 mm, and which were smooth but not flat, whereas the column sides were morphologically irregular. The refractive deviation of X-rays transmitted through the crystallites was exploited for delineating facet edges, thereby facilitating the controlled positioning of small-cross-section X-ray beams used for recording diffraction patterns from selected volumes in two representative crystallites. Their structure consisted of a [001]-axial core column surrounded by columns in twin orientation with respect to the core. The diamond volume directly below the (001) facets was free from low-angle boundaries, and no dislocation outcrops on the facets were detected. Significant elastic deformation of this volume was only present close to the facet periphery, where misorientations reached a few milliradians. Lattice imperfection was high in the twins, with ∼1° misorientations.

A new proposed method for observing fluid in rock fractures using the enhanced X-ray image of digital radiography

2021 ◽  
Author(s):  
Huan Sun ◽  
Qijian Long ◽  
Xiaoli Liu ◽  
Zhenni Ye ◽  
Enzhi Wang ◽  
...  
Keyword(s):  
Digital Radiography ◽  
Carbonate Rocks ◽  
Interaction Mechanism ◽  
Mechanical Tests ◽  
Initial Permeability ◽  
Nonlinear Flow ◽  
Rock Fractures ◽  
Diffusion Flow ◽  
X Ray ◽  
Transition Mechanism

Abstract Fluid in rock fractures always continually induces geo-catastrophe in water-rock system engineering. Intuitively observing fluid in fractures is the key method to reveal interaction mechanism of the water-rock under different engineering background, and provide some insights for solving engineering issues. This study proposes the visual method of fluid in rock fractures using enhanced X-ray image digital radiography (EXIDR), and carries out the coupled hydro-mechanical tests on the basis of the material scale of carbonate rocks, red bed mudstone (RBM) and coals. The experimental results show the transition mechanism of pipe flow (PF) to fissure flow (FF) during carbonate rock failures. The flow regime has undergone an evolution process from laminar flow to turbulent flow, also of this change with the fractal characteristics of PF-FF in carbonate rocks under multilevel stress loading. Also, the damage coefficient of RBM under coupled hydrodynamics and multilevel stress loading is non-linearly increasing. Therefore, the initial permeability of RBM under hydrodynamics is significant for geo-hazards prevention in the engineering, which are induced by the seepage and diffusion effects. Besides, the mean square flow (MSF) describes the flow rate varies as the fracture growth and extension, i.e. the fractional exponential evolution law that has a transition changes from super-diffusion flow to sub-diffusion flow. This indicates that fluid in fractures show the double behaviors of anomalous diffusion and nonlinear flow during coal and rock failures.

scholarly journals Low-amplitude dynamic tests of fine gravel in a resonant column

2019 ◽  
Vol 97 ◽  
pp. 04024
Author(s):  
Zaven Ter-Martirosyan ◽  
Evgeny Sobolev ◽  
George Anzhelo
Keyword(s):  
Mechanical Properties ◽  
Dynamic Properties ◽  
Sample Volume ◽  
Coarse Grained ◽  
Software Systems ◽  
Resonant Column ◽  
Dynamic Effects ◽  
Laboratory Equipment ◽  
Aggregate Fractions ◽  
Sample Assembly

Construction of industrial and civil buildings, taking into account the dynamic effects on the foundations, requires special experiments on the mechanical properties of soils. This article presents the results of studying the dynamic properties of coarse gravelly soils using the resonant column method. These studies are relevant, since the determination of the dynamic properties of coarse-grained soils under laboratory conditions is associated with a restriction on the size of the fractions in the sample volume. This circumstance leads to the fact that at the moment most of the laboratory tests of the dynamic properties of coarse-grained soils are performed on smaller aggregate fractions, which, in general, significantly reduces the resulting mechanical properties of soils. It does not reflect the real operation of the foundation of buildings during dynamic effects. This paper presents a description of the available laboratory equipment, the sequence of preparation of samples of coarse grained crushed stone soil and sample assembly in the working chamber of the installation. The article contains the main graphs characterizing the change in shear modulus and damping coefficient depending on shear deformations. It is noted that the results obtained are particularly relevant for modeling the dynamic effects of natural and man-made character on the foundations of industrial and civil buildings, the bases of which are composed of coarse-grained soils. Dynamic parameters considered in this paper, can and must be used in numerical calculations by finite element method with the use of modern groundwater models in geotechnical software systems.

scholarly journals Automated and optimally FRET-assisted structural modeling

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Mykola Dimura ◽  
Thomas-Otavio Peulen ◽  
Hugo Sanabria ◽  
Dmitro Rodnin ◽  
Katherina Hemmen ◽  
...  
Keyword(s):  
Open Source Software ◽  
Structural Information ◽  
Structural Modeling ◽  
Automated Design ◽  
Design Tool ◽  
Coarse Grained ◽  
Complex Dynamic ◽  
X Ray ◽  
Link Type ◽  
Dynamics Simulations

Abstract FRET experiments can provide state-specific structural information of complex dynamic biomolecular assemblies. However, to overcome the sparsity of FRET experiments, they need to be combined with computer simulations. We introduce a program suite with (i) an automated design tool for FRET experiments, which determines how many and which FRET pairs should be used to minimize the uncertainty and maximize the accuracy of an integrative structure, (ii) an efficient approach for FRET-assisted coarse-grained structural modeling, and all-atom molecular dynamics simulations-based refinement, and (iii) a quantitative quality estimate for judging the accuracy of FRET-derived structures as opposed to precision. We benchmark our tools against simulated and experimental data of proteins with multiple conformational states and demonstrate an accuracy of ~3 Å RMSDCα against X-ray structures for sets of 15 to 23 FRET pairs. Free and open-source software for the introduced workflow is available at https://github.com/Fluorescence-Tools. A web server for FRET-assisted structural modeling of proteins is available at http://nmsim.de.

scholarly journals An integrated analysis of mineralogical and microstructural characteristics and petrophysical properties of carbonate rocks in the lower Indus Basin, Pakistan

2019 ◽  
Vol 11 (1) ◽  
pp. 1151-1167
Author(s):  
Waheed Ali Abro ◽  
Abdul Majeed Shar ◽  
Kun Sang Lee ◽  
Asad Ali Narejo
Keyword(s):  
Thin Section ◽  
Carbonate Rocks ◽  
Carbonate Rock ◽  
Indus Basin ◽  
Reservoir Quality ◽  
Data Sets ◽  
Petrophysical Properties ◽  
X Ray ◽  
Lower Indus Basin

Abstract Carbonate rocks are believed to be proven hydrocarbon reservoirs and are found in various basins of Pakistan including Lower Indus Basin. The carbonate rock intervals of the Jakkher Group from Paleocene to Oligocene age are distributed in south-western part of Lower Indus Basin of Pakistan. However, there are limited published petrophysical data sets on these carbonate rocks and are essential for field development and risk reduction. To fill this knowledge gap, this study is mainly established to collect the comprehensive high quality data sets on petrophysical properties of carbonate rocks along with their mineralogy and microstructure. Additionally, the study assesses the impact of diagenesis on quality of the unconventional tight carbonate resources. Experimental techniques include Scanning Electronic Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), and X-ray diffraction (XRD), photomicrography, Helium porosity and steady state gas permeability. Results revealed that the porosity was in range of 2.12 to 8.5% with an average value of 4.5% and the permeability was ranging from 0.013 to 5.8mD. Thin section study, SEM-EDS, and XRD analyses revealed that the samples mostly contain carbon (C), calcium (Ca), and magnesium (Mg) as dominant elemental components.The main carbonate components observed were calcite, dolomite, micrite, Ferron mud, bioclasts and intermixes of clay minerals and cementing materials. The analysis shows that: 1) the permeability and porosity cross plot, the permeability and slippage factor values cross plots appears to be scattered, which showed weaker correlation that was the reflection of carbonate rock heterogeneity. 2) The permeability and clay mineralogy cross plots have resulted in poor correlation in these carbonate samples. 3) Several diagenetic processes had influenced the quality of carbonates of Jakkher Group, such as pore dissolution, calcification, cementation, and compaction. 4) Reservoir quality was mainly affected by inter-mixing of clay, cementation, presence of micrite muds, grain compactions, and overburden stresses that all lead these carbonate reservoirs to ultra-tight reservoirs and are considered to be of very poor quality. 5) SEM and thin section observations shows incidence of micro-fractures and pore dissolution tended to improve reservoir quality.

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