Christoph Arns

Pore-scale morphology effects on colloid deposition by trajectory tracking simulations

Publisher: Elsevier BV

Date: 08-2023

DOI: 10.1016/J.GEOEN.2023.211772

Experimental Verification of Effect of Size on Drainage Capillary Pressure Computed from Digitized Tomographic Images

Publisher: Trans Tech Publications, Ltd.

Date: 02-2010

DOI: 10.4028/WWW.SCIENTIFIC.NET/JERA.1.1

Abstract: This paper presents comparisons between drainage capillary pressure curves computed directly from 3D micro-tomographic images (micro-CT) and laboratory measurements conducted on the same core s les. It is now possible to calculate a wide range of petrophysical and transport properties directly from micro-CT images or from equivalent network models extracted from these images. Capillary pressure is sensitive to rock microstructure and the comparisons presented are the first direct validation of image based computations. The measured data include centrifuge and mercury injection drainage capillary pressure for fired Berea, Bentheimer and Obernkirchner sandstones and unfired Mount Gambier carbonate. The measurements cover a wide range of porosities and permeabilities. The measurements were made on core s les with different diameters (2.5 cm, 1.5 cm, 1 cm and 0.5 cm) to assess the effect of up-scaling on capillary pressure measurements. The smallest diameter s les were also used to obtain the 3D micro-CT images. Good agreement was obtained between the experimental measurements and direct computations on 3D micro-CT images.

Humidity Effects on Effective Elastic Properties of Rock: An Integrated Experimental and Numerical Study

Publisher: American Geophysical Union (AGU)

Date: 08-2019

DOI: 10.1029/2019JB017672

Virtual core laboratory: Properties of reservoir rock derived from X-ray CT images

Publisher: Society of Exploration Geophysicists

Date: 2003

DOI: 10.1190/1.1817572

NMR Relaxation Modelling in Porous Media with Dual-Scale-Resolved Internal Magnetic Fields

Publisher: Springer Science and Business Media LLC

Date: 02-03-2022

DOI: 10.1007/S11242-022-01752-0

Abstract: A pore-scale forward modelling approach for NMR relaxation responses of sandstones incorporating their dual-scale nature is presented. The approach utilises X-ray micro-CT images to capture inter-granular porosity and scanning electron microscopy images to reconstruct clay regions via a resolved clay micro-structure model. A key to calculating the NMR response with resolved clay micro-structure is the development of a dual-scale internal magnetic field calculation. This is achieved by a separation of near- and far-field effects in a dipole approximation of the internal field with periodic clay micro-structures, the latter of which take local clay pocket porosity into account. Tri-linear interpolation of the micro-CT image before calculation of the internal magnetic field further reduces errors in the transition regions between coarse- and fine-scale structure, with final discretisation level matching the fine-scale clay micro-structure model across the whole domain. The method is validated against direct calculations of model media at full resolution and applied to Bentheimer sandstone. Measured and simulated NMR $$T_2$$ T 2 relaxation responses, including relaxation time distribution shape, are in excellent agreement and distributions of internal magnetic field gradients at the highest spatial resolution as well as diffusion-averaged effective gradients are reported.

An Experimental and Numerical Study of Relative Permeability Estimates Using Spatially Resolved $$T_1$$-z NMR

Publisher: Springer Science and Business Media LLC

Date: 04-04-2017

DOI: 10.1007/S11242-017-0855-7

Three-dimensional analysis of cortical bone structure using X-ray micro-computed tomography

Publisher: Elsevier BV

Date: 08-2004

DOI: 10.1016/J.PHYSA.2004.03.046

Investigation of microstructural features in regenerating bone using micro computed tomography

Publisher: Springer Science and Business Media LLC

Date: 04-2004

DOI: 10.1023/B:JMSM.0000021133.48661.62

Abstract: We illustrate some of the uses of micro-computed tomography (micro-CT) to study tissue-engineered bone using a micro-CT facility for imaging and visualizing biomaterials in three dimensions (3-D). The micro-CT is capable of acquiring 3D X-ray CT images made up of 2000(3) voxels on specimens up to 5 cm in extent with resolutions down to 2 microm. This allows the 3-D structure of tissue-engineered materials to be imaged across orders of magnitude in resolution. This capability is used to examine an explanted, tissue-engineered bone material based on a polycaprolactone scaffold and autologous bone marrow cells. Imaging of the tissue-engineered bone at a scale of 1 cm and resolutions of 10 microm allows one to visualize the complex ingrowth of bone into the polymer scaffold. From a theoretical viewpoint the voxel data may also be used to calculate expected mechanical properties of the tissue-engineered implant. These observations illustrate the benefits of tomography over traditional techniques for the characterization of bone morphology and interconnectivity. As the method is nondestructive it can perform a complimentary role to current histomorphometric techniques.

Minimal surface scaffold designs for tissue engineering

Publisher: Elsevier BV

Date: 10-2011

DOI: 10.1016/J.BIOMATERIALS.2011.06.012

Abstract: Triply-periodic minimal surfaces are shown to be a more versatile source of biomorphic scaffold designs than currently reported in the tissue engineering literature. A scaffold architecture with sheetlike morphology based on minimal surfaces is discussed, with significant structural and mechanical advantages over conventional designs. These sheet solids are porous solids obtained by inflation of cubic minimal surfaces to sheets of finite thickness, as opposed to the conventional network solids where the minimal surface forms the solid/void interface. Using a finite-element approach, the mechanical stiffness of sheet solids is shown to exceed that of conventional network solids for a wide range of volume fractions and material parameters. We further discuss structure-property relationships for mechanical properties useful for custom-designed fabrication by rapid prototyping. Transport properties of the scaffolds are analyzed using Lattice-Boltzmann computations of the fluid permeability. The large number of different minimal surfaces, each of which can be realized as sheet or network solids and at different volume fractions, provides design flexibility essential for the optimization of competing design targets.

Quantitative properties of complex porous materials calculated from X-ray mu CT images - art. no. 631811

Publisher: SPIE

Date: 31-08-2006

DOI: 10.1117/12.679205

Modeling Molecular Interactions with Wetting and Non-Wetting Rock Surfaces by Combining Electron Paramagnetic Resonance and NMR Relaxometry

Publisher: American Chemical Society (ACS)

Date: 09-2022

DOI: 10.1021/ACS.LANGMUIR.2C01681

Abstract: Three types of natural rocks─Bentheimer and Berea sandstones, as well as Liège Chalk─have been aged by immersion in a bitumen solution for extended periods of time in two steps, changing the surface conditions from water-wet to oil-wet. NMR relaxation dispersion measurements were carried out on water and oil constituents, with saturated and aromatic molecules considered in idually. In order to separate the different relaxation mechanisms discussed in the literature,

The correlation of pore morphology, interconnectivity and physical properties of 3D ceramic scaffolds with bone ingrowth

Publisher: Elsevier BV

Date: 03-2009

DOI: 10.1016/J.BIOMATERIALS.2008.10.056

Abstract: In the design of tissue engineering scaffolds, design parameters including pore size, shape and interconnectivity, mechanical properties and transport properties should be optimized to maximize successful inducement of bone ingrowth. In this paper we describe a 3D micro-CT and pore partitioning study to derive pore scale parameters including pore radius distribution, accessible radius, throat radius, and connectivity over the pore space of the tissue engineered constructs. These pore scale descriptors are correlated to bone ingrowth into the scaffolds. Quantitative and visual comparisons show a strong correlation between the local accessible pore radius and bone ingrowth for well connected s les a cutoff accessible pore radius of approximately 100 microM is observed for ingrowth. The elastic properties of different types of scaffolds are simulated and can be described by standard cellular solids theory: (E/E(0))=(rho/rho(s))(n). Hydraulic conductance and diffusive properties are calculated results are consistent with the concept of a threshold conductance for bone ingrowth. Simple simulations of local flow velocity and local shear stress show no correlation to in vivo bone ingrowth patterns. These results demonstrate a potential for 3D imaging and analysis to define relevant pore scale morphological and physical properties within scaffolds and to provide evidence for correlations between pore scale descriptors, physical properties and bone ingrowth.

Super resolution reconstruction of μ-CT image of rock sample using neighbour embedding algorithm

Publisher: Elsevier BV

Date: 03-2018

DOI: 10.1016/J.PHYSA.2017.10.022

Gradient-based fibre detection method on 3D micro-CT tomographic image for defining fibre orientation bias in ultra-high-performance concrete

Publisher: Elsevier BV

Date: 03-2020

DOI: 10.1016/J.CEMCONRES.2019.105962

Evaluation of Capillary Pressure Methods via Digital Rock Simulations

Publisher: Springer Science and Business Media LLC

Date: 28-01-2015

DOI: 10.1007/S11242-015-0459-Z

Three-dimensional porous structure reconstruction based on structural local similarity via sparse representation on micro-computed-tomography images

Publisher: American Physical Society (APS)

Date: 29-10-2018

DOI: 10.1103/PHYSREVE.98.043310

A comparison between the characteristics of a biochar-NPK granule and a commercial NPK granule for application in the soil

Publisher: Elsevier BV

Date: 08-2022

DOI: 10.1016/J.SCITOTENV.2022.155021

Abstract: Continual application of nitrogen (N), phosphorous (P) and potassium (K) fertilizer may not return a profit to farmers due to the costs of application and the loss of NPK from soil in various ways. Thus, a combination of NPK granule with a porous biochar (termed here as BNPK) appears to offer multiple benefits resulting from the excellent properties of biochar. Given the lack of information on the properties of NPK and BNPK fertilizers, it is necessary to investigate the characteristics of both to achieve a good understanding of why BNPK granule is superior to NPK granule. Therefore, this study aims to investigate the characteristics of a maize straw biochar mixed with NPK granule, before and after application to soil, and compare them to those for a commercial NPK granule. The BNPK granule, with a greater surface area and porosity, showed a higher capacity to store and donate electrons than the NPK granule. Relatively lower concentrations of Ca, P, K, Si and Mg were dissolved from the BNPK, indicating the ability of the BNPK granule to maintain these mineral elements and reduce dissolution rate. To study the nutrient storage mechanism of the BNPK granule in the soil, short- and long-term leaching experiments were conducted. During the experiments, organo-mineral clusters, comprising C, P, K, Si, Al and Fe, were formed on the surface and inside the biochar pores. However, BNPK was not effective in reducing N leaching, in the absence of plants, in a red chromosol soil.

Solving Multiphysics, Multiparameter, Multimodal Inverse Problems: An Application to NMR Relaxation in Porous Media

Publisher: American Physical Society (APS)

Date: 03-05-2021

DOI: 10.1103/PHYSREVAPPLIED.15.054003

Relative permeability from tomographic images; effect of correlated heterogeneity

Publisher: Elsevier BV

Date: 09-2003

DOI: 10.1016/S0920-4105(03)00066-4

A numerical study of field strength and clay morphology impact on NMR transverse relaxation in sandstones

Publisher: Elsevier BV

Date: 07-2021

DOI: 10.1016/J.PETROL.2021.108521

About the connectivity of dual-scale media based on micro-structure based regional analysis of NMR flow propagators

Publisher: Elsevier BV

Date: 05-2018

DOI: 10.1016/J.JCONHYD.2017.11.001

Abstract: The characterisation of heterogeneous porous media at multiple length scales typically requires the classification of structure at some scale to allow the calculation of effective transport properties at a scale relevant for macroscopic description. While such a classification may be derived from various imaging methods, a shortcoming is often the simultaneous characterisation of the connectivity between regions representing different micro-structure. In this work we combine NMR based flow propagators with the simulations performed on corresponding reconstructed structure, and relate the NMR measurements to their simulated global and local representations to study fluid transport locally and the exchange between micro- and macro-porous regions. This is achieved by carrying out detailed lattice Boltzmann simulations and random walk method to track the displacements of tracers in each kind of region. Using Euclidean distance maps (EDT) we analyse the fluid invasion to regions of different scale and relate it to the connectivity of the system. We demonstrate that numerical simulation has great flexibility in providing additional sensitivity to the inference of region-region connectivity.

Tomographic image analysis and processing to simulate micro-petrophysical experiments

Publisher: SPIE

Date: 19-08-2010

DOI: 10.1117/12.860293

High‐Precision Tracking of Sandstone Deformation From Micro‐CT Images

Publisher: American Geophysical Union (AGU)

Date: 09-2021

DOI: 10.1029/2021JB022283

Abstract: Elastic properties of sandstones can be highly pressure dependent. However, the pressure‐induced deformation of intact sandstones in X‐ray micro‐Computed Tomography (micro‐CT) images are below the resolving power of conventional image analysis methods. Also, most digital rock physics studies of the elastic properties operate with micro‐CT images acquired at ambient pressure. Here, we perform a comprehensive analysis of an intact sandstone s le with pronounced stress‐sensitivity. A purpose‐built X‐ray‐transparent pressure cell enables scanning micro‐CT images at confining pressures of up to 36 MPa. To detect the small pressure‐induced changes from these images, we design an overall deformation detection workflow with slice‐searching technique. We apply this workflow to a set of micro‐CT images of a 2 × 2 × 2 mm s le scanned at several pressures with a voxel size length of ∼1 μm. The results give the static modulus of 2.78 GPa, which is ∼0.5 times of the dynamic modulus derived from ultrasonic measurements. This ratio is consistent with literature data, showing the accuracy of the deformation detection workflow. Images scanned at different pressures are then segmented into two‐phase labels. The porosity change detected from segmented labels is consistent with the value derived from static modulus using poroelastic theory. The two‐phase segmented images are utilized to simulate the elastic properties with a finite element method. Most of the pressure dependency of elastic moduli shown in ultrasonic measurements is caused by closure of compliant pores at grain contacts, which cannot be resolved by the micro‐CT. The accuracy improvement of the estimated elastic properties from images scanned at higher pressures is negligible.

Assessment of bone ingrowth into porous biomaterials using MICRO-CT

Publisher: Elsevier BV

Date: 05-2007

DOI: 10.1016/J.BIOMATERIALS.2007.01.046

Abstract: The three-dimensional (3D) structure and architecture of biomaterial scaffolds play a critical role in bone formation as they affect the functionality of the tissue-engineered constructs. Assessment techniques for scaffold design and their efficacy in bone ingrowth studies require an ability to accurately quantify the 3D structure of the scaffold and an ability to visualize the bone regenerative processes within the scaffold structure. In this paper, a 3D micro-CT imaging and analysis study of bone ingrowth into tissue-engineered scaffold materials is described. Seven specimens are studied in this paper a set of three specimens with a cellular structure, varying pore size and implant material, and a set of four scaffolds with two different scaffold designs investigated at early (4 weeks) and late (12 weeks) explantation times. The difficulty in accurately phase separating the multiple phases within a scaffold undergoing bone regeneration is first highlighted. A sophisticated three-phase segmentation approach is implemented to develop high-quality phase separation with minimal artifacts. A number of structural characteristics and bone ingrowth characteristics of the scaffolds are quantitatively measured on the phase separated images. Porosity, pore size distributions, pore constriction sizes, and pore topology are measured on the original pore phase of the scaffold volumes. The distribution of bone ingrowth into the scaffold pore volume is also measured. For early explanted specimens we observe that bone ingrowth occurs primarily at the periphery of the scaffold with a constant decrease in bone mineralization into the scaffold volume. Pore size distributions defined by both the local pore geometry and by the largest accessible pore show distinctly different behavior. The accessible pore size is strongly correlated to bone ingrowth. In the specimens studied a strong enhancement of bone ingrowth is observed for pore diameters>100 microm. Little difference in bone ingrowth is measured with different scaffold design. This result illustrates the benefits of microtomography for analyzing the 3D structure of scaffolds and the resultant bone ingrowth.

Application of low-field, ¹H/¹³C high-field solution and solid state NMR for characterisation of oil fractions responsible for wettability change in sandstones

Publisher: Elsevier BV

Date: 02-2019

DOI: 10.1016/J.MRI.2018.10.004

A solid/fluid substitution scheme constrained by pore-scale numerical simulations

Publisher: Oxford University Press (OUP)

Date: 06-12-2019

DOI: 10.1093/GJI/GGZ556

Abstract: Estimating the effects of pore filling material on the elastic moduli or velocities of porous and fractured rocks attracts widespread attention. This effect can be modelled by a recently proposed triple-porosity scheme, which quantifies this effect from parameters of the pressure dependency of the elastic properties of the dry rock. This scheme ides total porosity into three parts: compliant, intermediate and stiff. Each type of pores is assumed to be spheroidal and characterized by a single aspect ratio. However, the implementation of this model requires the asymptotic values of the elastic moduli at much higher pressures where only non-closable pores remain open. Those pressures are beyond the capacity of most rock physics laboratories and can even crush typical sandstone s les. Experimental data at such pressures are usually unavailable. To address this issue, we introduce pore-scale numerical simulations in conjunction with effective medium theories (EMT) to compute the asymptotic values directly from the microtomographic images. This workflow reduces the uncertainty of model predictions on the geometric information of stiff pores and strengthens the predictive power and usefulness of the model without any adjustable parameters. Applying this to a Bentheim sandstone fully filled with liquid and solid octadecane gives a reasonable match between model predictions and laboratory measurements. This success verifies the accuracy and applicability of the model and indicates its potential in further exploitation and characterization of heavy oil reservoirs and other similar reservoirs.

Mechanical and transport properties of polymeric foams derived from 3D images

Publisher: Elsevier BV

Date: 08-2005

DOI: 10.1016/J.COLSURFA.2004.12.040

Relaxation and relaxation exchange NMR to characterise asphaltene adsorption and wettability dynamics in siliceous systems

Publisher: Elsevier BV

Date: 05-2018

DOI: 10.1016/J.FUEL.2018.02.059

Structure and properties of clinical coralline implants measured via 3D imaging and analysis

Publisher: Elsevier BV

Date: 05-2006

DOI: 10.1016/J.BIOMATERIALS.2005.12.016

Abstract: The development and design of advanced porous materials for biomedical applications requires a thorough understanding of how material structure impacts on mechanical and transport properties. This paper illustrates a 3D imaging and analysis study of two clinically proven coral bone graft s les (Porites and Goniopora). Images are obtained from X-ray micro-computed tomography (micro-CT) at a resolution of 16.8 microm. A visual comparison of the two images shows very different structure Porites has a homogeneous structure and consistent pore size while Goniopora has a bimodal pore size and a strongly disordered structure. A number of 3D structural characteristics are measured directly on the images including pore volume-to-surface-area, pore and solid size distributions, chord length measurements and tortuosity. Computational results made directly on the digitized tomographic images are presented for the permeability, diffusivity and elastic modulus of the coral s les. The results allow one to quantify differences between the two s les. 3D digital analysis can provide a more thorough assessment of biomaterial structure including the pore wall thickness, local flow, mechanical properties and diffusion pathways. We discuss the implications of these results to the development of optimal scaffold design for tissue ingrowth.

Tuning Elasticity of Open-Cell Solid Foams and Bone Scaffolds via Randomized Vertex Connectivity

Publisher: Wiley

Date: 21-09-2012

DOI: 10.1002/ADEM.201100145

Abstract: Tuning mechanical properties of and fluid flow through open‐cell solid structures is a challenge for material science, in particular for the design of porous structures used as artificial bone scaffolds in tissue engineering. We present a method to tune the effective elastic properties of custom‐designed open‐cell solid foams and bone scaffold geometries by almost an order of magnitude while approximately preserving the pore space geometry and hence fluid transport properties. This strong response is achieved by a change of topology and node coordination of a network‐like geometry underlying the scaffold design. Each node of a four‐coordinated network is disconnected with probability p into two two‐coordinated nodes, yielding network geometries that change continuously from foam‐ or network‐like cellular structures to entangled fiber bundles. We demonstrate that increasing p leads to a strong, approximately exponential decay of mechanical stiffness while leaving the pore space geometry largely unchanged. This result is obtained by both voxel‐based finite element methods and compression experiments on laser sintered models. The physical effects of randomizing network topology suggest a new design paradigm for solid foams, with adjustable mechanical properties.

Digital and experimental rock analysis of proppant injection into naturally fractured coal

Publisher: Elsevier BV

Date: 02-2021

DOI: 10.1016/J.FUEL.2020.119368

The Influence of Syndepositional Macropores on the Hydraulic Integrity of Thick Alluvial Clay Aquitards

Publisher: American Geophysical Union (AGU)

Date: 04-0007

DOI: 10.1029/2017WR021681

Mechanisms of Confining Pressure Dependence of Resistivity Index for Tight Sandstones by Digital Core Analysis

Publisher: Society of Petroleum Engineers (SPE)

Date: 10-02-2021

DOI: 10.2118/205026-PA

Abstract: Resistivity measurements are a major input into hydrocarbon reserve estimation and are usually described by Archie’s laws. In this study, we use digital rock physics to analyze the mechanisms of non-Archie and Archie behavior of formation factor (FF) and resistivity index (RI) of low-porosity Fontainebleau (FB) sandstone for ambient conditions and under high confining pressure, respectively. FB sandstone was imaged by micro-X-ray computed tomography (micro-CT) at a resolution of 1 µm. Subresolution details of the grain contact width distribution along with their length were extracted from a set of scanning electron microscope (SEM) images. The nanoscale aperture of grain contacts, which is below tomogram resolution, is accounted for in micro-CT-based numerical calculations by assigning effective porosity and conductivity to in idual voxels of the extracted grain contact network. A porosity reduction of grain contacts and open pore space as a function of applied confining pressure is introduced, capturing the pressure dependence. The concept was implemented by grain contact labeling, introducing an additional phase derived from a Euclidean distance transform (EDT). Subvoxel stress-strain effects were incorporated by attributing all compressibility effects to the pore space (open pore space and grain contacts), treating the solid phase as perfectly rigid. Voxel-scale input conductivities are assigned using Archie’s law followed by solving the Laplace equation for s le-scale rock resistivity and RI directly on the segmented image using the finite element method. For the numerical modeling of the FF and RI of low-porosity FB sandstone as a function of confining pressure, which depends on subresolution features, a set of hypotheses were tested. These are based on two segmentation scenarios incorporating the measured contact aperture distribution from SEM analysis—a homogeneous aperture-based segmentation by assuming all grain contacts as an average constant value and a heterogeneous aperture-based segmentation assigning two groups of grain contact apertures. The segmentation scenarios enable homogeneous and heterogeneous morphological change of grain contacts due to confining pressure effects. Furthermore, partial saturation of grain contacts is considered. In all cases, strong water-wetness was assumed, and discretization effects were analyzed carefully. The numerical results highlight the relative contribution of each of two conductive components of FB sandstone (open pores vs. grain contacts) over the full range of partial saturations. Of importance is the connectivity of the system, with discretization effects having a significant effect on FF, but a small effect on the RI. Grain contacts and confining pressure are found to have a significant impact on RI behavior of low-porosity FB sandstone. Both the grain contact network with homogeneous aperture and the heterogeneous grain contact network are able to describe experimental observations. However, it is not sufficient to assume a homogeneous change in contact area, and an inhomogeneous deformation of grain contact zones is required to match the experiment.

Temperature-Dependent Oxygen Effect on NMR D-$$T_2$$ Relaxation-Diffusion Correlation of n-Alkanes

Publisher: Springer Science and Business Media LLC

Date: 19-09-2016

DOI: 10.1007/S00723-016-0830-4

Computation of Relative Permeability From In-Situ Imaged Fluid Distributions at the Pore Scale

Publisher: Society of Petroleum Engineers (SPE)

Date: 07-02-2018

DOI: 10.2118/189453-PA

Abstract: Image-based computations of relative permeability require a description of fluid distributions in the pore space. Recent advances in imaging technologies have made it possible to directly resolve actual fluid distributions at the pore scale, thus capturing a large field of view for arbitrary wetting conditions, which are numerically difficult to reproduce. In previous studies, fluid distributions were not imaged under in-situ conditions, which may cause the oil (nonwetting) phase to snap off. Consequently, computed oil relative permeability is underestimated, particularly at low oil saturations. This study extends our previous work by imaging fluid distributions under in-situ conditions as a basis for numerical computations. In this study, we perform a steady-state flow test on a homogeneous outcrop sandstone (Bentheimer) core. First, the dry core is imaged in our microcomputed-chromatography (micro-CT) facility. Afterward, the core is fully saturated with 0.4 molar sodium iodide (NaI) solutions. The saturated core is then mounted in a specially designed flow cell that allows the flow experiment to be performed with the core mounted on the CT scanner. Afterward, a steady-state injection of oil and brine is performed at four different oil/water-injection ratios. For each injection ratio, steady-state pressure drop is noted, and in-situ fluid distributions are imaged under flow conditions. These imaged fluid distributions are used to compute image-based relative permeability, whereas the measured pressure drops are used to calculate experimental relative permeability. Results demonstrate that imaging in-situ fluid distributions allows us to overcome significant limitations of our previous work: Namely, measured and computed oil relative permeability are in close agreement across the whole saturation range, and laboratory capillary end effects at the core outlet can be imaged, which allows us to apply a correction to the laboratory-measured data.

A Bayesian Optimization Approach to the Simultaneous Extraction of Intrinsic Physical Parameters from T1 and T2 Relaxation Responses

Publisher: Society of Petroleum Engineers (SPE)

Date: 08-07-2022

DOI: 10.2118/210563-PA

Abstract: Nuclear magnetic resonance (NMR) relaxation responses in porous media provide a sensitive probe of the microstructure and yet are influenced by a number of factors which are not easily detangled. Low-field T2 transverse relaxation measurements can be carried out quickly and are frequently used as pore size distributions, while adding T1 longitudinal relaxation measurements provides additional insights into surface properties and fluid content. Here we present an inverse solution workflow extracting related intrinsic physical parameters of the system by fitting experiment and numerical simulation(s). An efficient NMR forward solver for the simultaneous calculation of T1 and T2 responses is introduced, which honors existing inequality relationships between T1 and T2 parameters. We propose a Bayesian optimization approach that jointly identifies T1- and T2-related properties satisfying physical constraints by simultaneously fitting T1 and T2 experiments to simulations. This dual-task inverse solution workflow (DT-ISW) identifies the solution by minimizing the sum of the L2 norm of the fitting residuals of both T1 and T2 distributions into a single objective and jointly models the two highly correlated objectives with high efficiency using the vector-valued Gaussian process (GP) kernel for transfer learning. A multimodal search strategy is used to identify nonunique solution sets of the problem. The workflow is demonstrated on Bentheimer sandstone, identifying five intrinsic physical parameters. The performance of the joint DT-ISW (DT-ISW-J) is compared to a sequential DT-ISW (DT-ISW-S) approach as well as an independent single-task ISW (ST-ISW) of the T1 and T2 responses. Both dual-task versions converge more than two times faster than the single-task version. DT-ISW-J equally minimizes the L2 norm of T1 and T2 fitting residuals whereas DT-ISW-S only preferentially minimizes the objective assigned higher importance. A Pareto optimal solution (POS) is provided to allow operators to subjectively balance the preference of T1 and T2 data fits for the slightly conflicting objectives. The ability to extract five intrinsic physical parameters simultaneously provides new techniques for tracking wettability alteration and assessing the influence of clay amount and distribution on petrophysical property estimates.

Visualization and numerical analysis of adhesive distribution in particleboard using X-ray micro-computed tomography

Publisher: Elsevier BV

Date: 12-2010

DOI: 10.1016/J.IJADHADH.2010.08.001

An x-ray tomography facility for quantitative prediction of mechanical and transport properties in geological, biological and synthetic systems.

Publisher: SPIE

Date: 26-10-2004

DOI: 10.1117/12.559200

Image-based rock typing using local homogeneity filter and Chan-Vese model

Publisher: Elsevier BV

Date: 05-2021

DOI: 10.1016/J.CAGEO.2021.104712

Pore-Scale Characterization of Two-Phase Flow Using Integral Geometry

Publisher: Springer Science and Business Media LLC

Date: 23-03-2017

DOI: 10.1007/S11242-017-0849-5

High-fidelity replication of thermoplastic microneedles with open microfluidic channels

Publisher: Springer Science and Business Media LLC

Date: 09-10-2017

DOI: 10.1038/MICRONANO.2017.34

Abstract: Development of microneedles for unskilled and painless collection of blood or drug delivery addresses the quality of healthcare through early intervention at point-of-care. Microneedles with submicron to millimeter features have been fabricated from materials such as metals, silicon, and polymers by subtractive machining or etching. However, to date, large-scale manufacture of hollow microneedles has been limited by the cost and complexity of microfabrication techniques. This paper reports a novel manufacturing method that may overcome the complexity of hollow microneedle fabrication. Prototype microneedles with open microfluidic channels are fabricated by laser stereolithography. Thermoplastic replicas are manufactured from these templates by soft-embossing with high fidelity at submicron resolution. The manufacturing advantages are (a) direct printing from computer-aided design (CAD) drawing without the constraints imposed by subtractive machining or etching processes, (b) high-fidelity replication of prototype geometries with multiple reuses of elastomeric molds, (c) shorter manufacturing time compared to three-dimensional stereolithography, and (d) integration of microneedles with open-channel microfluidics. Future work will address development of open-channel microfluidics for drug delivery, fluid s ling and analysis.

Developing a virtual materials laboratory

Publisher: Elsevier BV

Date: 12-2007

DOI: 10.1016/S1369-7021(07)70307-3

Micro-CT facility for imaging reservoir rocks at pore scales

Publisher: Society of Exploration Geophysicists

Date: 2003

DOI: 10.1190/1.1817625

Elastic and flow properties of carbonate core derived from 3D X ray-CT images

Publisher: Society of Exploration Geophysicists

Date: 2008

DOI: 10.1190/1.3059394

Porous Media Characterization Using Minkowski Functionals: Theories, Applications and Future Directions

Publisher: Springer Science and Business Media LLC

Date: 27-11-2018

DOI: 10.1007/S11242-018-1201-4

On the Optimum Aging Time: Magnetic Resonance Study of Asphaltene Adsorption Dynamics in Sandstone Rock

Publisher: American Chemical Society (ACS)

Date: 26-07-2019

DOI: 10.1021/ACS.ENERGYFUELS.9B01609

X-ray micro-tomography applications of relevance to the petroleum industry

Publisher: AIP

Date: 2007

DOI: 10.1063/1.2723640

On the influence of wetting behaviour on relaxation of adsorbed liquids – A combined NMR, EPR and DNP study of aged rocks

Publisher: Elsevier BV

Date: 02-2019

DOI: 10.1016/J.MRI.2018.09.019

Abstract: The influence of wettability modification in natural rocks has been studied by means of NMR relaxation dispersion of water and several organic liquids, employing

Three-dimensional imaging of multiphase flow in porous media

Publisher: Elsevier BV

Date: 08-2004

DOI: 10.1016/J.PHYSA.2004.03.059

Virtual materials design: Properties of cellular solids derived from 3D tomographic images

Publisher: Wiley

Date: 04-2005

DOI: 10.1002/ADEM.200400212

Regional analysis techniques for integrating experimental and numerical measurements of transport properties of reservoir rocks

Publisher: Elsevier BV

Date: 02-2017

DOI: 10.1016/J.ADVWATRES.2016.12.011

Digital rock physics: 3D imaging of core material and correlations to acoustic and flow properties

Publisher: Society of Exploration Geophysicists

Date: 2009

DOI: 10.1190/1.3064143

Lattice Boltzmann framework for accurate NMR simulation in porous media

Publisher: American Physical Society (APS)

Date: 10-05-2022

DOI: 10.1103/PHYSREVE.105.055304

A microstructural investigation of a Na2SO4 activated cement-slag blend

Publisher: Elsevier BV

Date: 12-2021

DOI: 10.1016/J.CEMCONRES.2021.106609

Linear elastic properties of granular rocks derived from Xray-CT images

Publisher: Society of Exploration Geophysicists

Date: 2007

DOI: 10.1190/1.2792823

Polymeric foam properties derived from 3D images

Publisher: Elsevier BV

Date: 08-0002

DOI: 10.1016/J.PHYSA.2004.03.054

Techniques in helical scanning, dynamic imaging and image segmentation for improved quantitative analysis with X-ray micro-CT

Publisher: Elsevier BV

Date: 04-2014

DOI: 10.1016/J.NIMB.2013.08.072

Bayesian Optimization With Transfer Learning: A Study on Spatial Variability of Rock Properties Using NMR Relaxometry

Publisher: American Geophysical Union (AGU)

Date: 09-2022

DOI: 10.1029/2021WR031590

Abstract: Nuclear magnetic resonance measurements of sedimentary rocks are used to extract various transport properties including hydraulic conductivity and water retention curves. These estimates are controlled by intrinsic physical quantities like surface relaxivities, and effective relaxation time and restricted self‐diffusion coefficient of water in clay. S ling these properties on a set of core plugs presents a series of inverse problems where some of the extracted parameters are expected to be similar. To leverage such valuable information, we extend a previously developed single‐task inverse solution workflow (ISW) to the multi‐task case, transferring the knowledge gained from previous optimization tasks. Two multi‐task kernels: intrinsic model of coregionalization (ICM) and linear model of coregionalization are compared to capture the underlying correlations. We consider three micro‐CT images of Bentheimer sandstone from two different blocks imaged at different resolutions, following different segmentation pathways, and demonstrate our approach for the case of low and high task similarity. In both scenarios the multi‐task ISW finds lower fitting residuals and uses only one‐third to one‐half of the function evaluations required by the single‐task ISW. The scalability of the multi‐task ISW is demonstrated by transferring knowledge of two completed optimization tasks to a third task, which outperforms the single‐task ISW, with ICM showing faster convergence. The observed 4% difference for the values identified for s les from the same block and around 28% difference across blocks indicates significant spatial variability in surface relaxivity of the main mineral component, while effective clay parameters show a significantly higher variability.

Semi-quantitative multiscale modelling and flow simulation in a nanoscale porous system of shale

Publisher: Elsevier BV

Date: 12-2018

DOI: 10.1016/J.FUEL.2018.08.007

Finite element modelling of the effective elastic properties of partially saturated rocks

Publisher: Elsevier BV

Date: 06-2008

DOI: 10.1016/J.CAGEO.2007.06.009

Porous Structure Reconstruction Using Convolutional Neural Networks

Publisher: Springer Science and Business Media LLC

Date: 18-05-2018

DOI: 10.1007/S11004-018-9743-0

The heterogeneity in femoral neck structure and strength

Publisher: Wiley

Date: 17-04-2013

DOI: 10.1002/JBMR.1827

Abstract: Most measures of femoral neck strength derived using dual-energy X-ray absorptiometry or computed tomography (CT) assume the femoral neck is a cylinder with a single cortical thickness. We hypothesized that these simplifications introduce errors in estimating strength and that detailed analyses will identify new parameters that more accurately predict femoral neck strength. High-resolution CT data were used to evaluate 457 cross-sectional slices along the femoral neck of 12 postmortem specimens. Cortical morphology was measured in each cross-section. The distribution of cortical thicknesses was evaluated to determine whether the mean or median better estimated central tendency. Finite-element models were used to calculate the stresses in each cross-section resulting from the peak hip joint forces created during a sideways fall. The relationship between cortical morphology and peak bone stress along the femoral neck was analyzed using multivariate regression analysis. In all cross-sections, cortical thicknesses were non-normally distributed and skewed toward smaller thicknesses (p < 0.0001). The central tendency of cortical thickness was best estimated by the median, not the mean. Stress increased as the median cortical thickness decreased along the femoral neck. The median, not mean, cortical thickness combined with anterior-posterior diameter best predicted peak bone stress generated during a sideways fall (R(2) = 0.66, p < 0.001). Heterogeneity in the structure of the femoral neck determines the ersity of its strength. The median cortical thickness best predicted peak femoral neck stress and is likely to be a relevant predictor of femoral neck fragility.

Experimental and Theoretical Evidence for Increased Ganglion Dynamics During Fractional Flow in Mixed‐Wet Porous Media

Publisher: American Geophysical Union (AGU)

Date: 05-2018

DOI: 10.1029/2017WR022433

Micro-CT analysis of process-induced defects in composite laminates using AFP

Publisher: Informa UK Limited

Date: 15-01-2021

DOI: 10.1080/10426914.2020.1866192

3D Imaging and simulation of elastic properties of porous materials

Publisher: Institute of Electrical and Electronics Engineers (IEEE)

Date: 07-2009

DOI: 10.1109/MCSE.2009.110

Morphology and Linear-Elastic Moduli of Random Network Solids

Publisher: Wiley

Date: 16-06-2011

DOI: 10.1002/ADMA.201004094

Abstract: The effective linear‐elastic moduli of disordered network solids are analyzed by voxel‐based finite element calculations. We analyze network solids given by Poisson‐Voronoi processes and by the structure of collagen fiber networks imaged by confocal microscopy. The solid volume fraction ϕ is varied by adjusting the fiber radius, while keeping the structural mesh or pore size of the underlying network fixed. For intermediate ϕ , the bulk and shear modulus are approximated by empirical power‐laws $ K(\\phi) \\propto \\phi^n$ and $ G(\\phi) \\propto \\phi^m$ with n ≈ 1.4 and m ≈ 1.7. The exponents for the collagen and the Poisson‐Voronoi network solids are similar, and are close to the values n = 1.22 and m = 2.11 found in a previous voxel‐based finite element study of Poisson‐Voronoi systems with different boundary conditions. However, the exponents of these empirical power‐laws are at odds with the analytic values of n = 1 and m = 2, valid for low‐density cellular structures in the limit of thin beams. We propose a functional form for K ( ϕ ) that models the cross‐over from a power‐law at low densities to a porous solid at high densities a fit of the data to this functional form yields the asymptotic exponent n ≈ 1.00, as expected. Further, both the intensity of the Poisson‐Voronoi process and the collagen concentration in the s les, both of which alter the typical pore or mesh size, affect the effective moduli only by the resulting change of the solid volume fraction. These findings suggest that a network solid with the structure of the collagen networks can be modeled in quantitative agreement by a Poisson‐Voronoi process.

Elastic and transport properties of cellular solids derived from three-dimensional tomographic images

Publisher: The Royal Society

Date: 18-04-2006

DOI: 10.1098/RSPA.2006.1657

Abstract: We describe a three-dimensional imaging and analysis study of eight industrial cellular foam morphologies. The foam morphologies were generated by differing industrial processing methods. Tomograms are acquired on an X-ray micro-computed tomography facility at scales of approximately equal to at resolutions down to 7 μm. The image quality is sufficient in all cases to measure local structure and connectivity of the foamed material, and the field of view large enough to calculate a range of material properties. Phase separation into solid and porous components is straightforward. Three-dimensional structural characteristics are measured directly on the porous and solid phases of the images. A number of morphological parameters are obtained, including pore volume-to-surface-area ratio, connectivity, the pore and solid phase size distributions defined by maximal sphere openings and chord length measurements. We further calculate the pore size distribution associated with capillary pressure via simulating of mercury drainage on the digital images. The binarized microstructures are used as a basis for calculations of transport properties (fluid permeability, diffusivity and thermal conductivity) and elastic moduli. From the data, we generate property–porosity relationships for the range of foam morphologies imaged and quantitatively analyse the effects of porosity and microstructure on the resultant properties of the foams. We compare our numerical data to commonly used theoretical and empirical property–porosity relationships. For thermal conductivity, we find that the numerical results agree extremely well with an empirical expression based on experimental data of various foams. The upper Hashin–Shtrikman bound also provides an excellent prediction of the data across all densities. From simulation of the diffusivity, we can define the tortuosity of the pore space within the cellular solid. We find that different processing methods lead to strong variations in the tortuosity of the pore space of the foams. For elastic properties, our results show that for the Young modulus, E , both the differential effective medium theory and the classical correlation give a good correlation. Assuming a constant Poisson's ratio leads to reasonable agreement. The best correlation for is given by assuming a slight variation in as a linear function of porosity. The permeability of the foams varies over three orders of magnitude. Correlations for permeability based on the classical Kozeny–Carman equation lead to reasonable agreement, except at the lowest porosities. Permeability estimations based on mercury porosimetry give excellent agreement for all foams.

Discovery Projects - Grant ID: DP200103548

Start Date: 06-2020

End Date: 05-2024

Amount: $448,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE110100189

Start Date: 03-2011

End Date: 03-2012

Amount: $190,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0558185

Start Date: 2005

End Date: 12-2008

Amount: $297,022.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP190103744

Start Date: 05-2019

End Date: 12-2022

Amount: $455,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP160104995

Start Date: 2016

End Date: 12-2018

Amount: $380,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0881112

Start Date: 2008

End Date: 06-2013

Amount: $613,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100128

Start Date: 2010

End Date: 12-2011

Amount: $300,000.00

Funder: Australian Research Council

ARC Future Fellowships - Grant ID: FT120100216

Start Date: 2013

End Date: 06-2018

Amount: $757,606.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100162

Start Date: 01-2012

End Date: 12-2016

Amount: $150,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0452646

Start Date: 06-2004

End Date: 06-2007

Amount: $425,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0881458

Start Date: 2008

End Date: 12-2010

Amount: $265,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE150100132

Start Date: 02-2016

End Date: 12-2017

Amount: $860,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP180100890

Start Date: 02-2020

End Date: 02-2023

Amount: $523,756.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE230100129

Start Date: 2023

End Date: 12-2023

Amount: $1,929,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0668019

Start Date: 2006

End Date: 12-2007

Amount: $240,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE140100009

Start Date: 05-2014

End Date: 05-2015

Amount: $1,064,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP160101153

Start Date: 08-2016

End Date: 08-2020

Amount: $450,000.00

Funder: Australian Research Council