Article
Geosciences, Multidisciplinary
Ammar Abdlmutalib, Osman Abdullatif, Mohamed Yassin
Summary: This study aimed to characterize pore types, sizes, and abundance in three carbonate mudrocks units in Central Saudi Arabia. Different lithofacies were identified within the formations, with distinctive pore characteristics linked to corresponding diagenetic processes. These results could be used for fluid flow simulation in evaluating the reservoir potential of these carbonate-rich mudrocks.
JOURNAL OF AFRICAN EARTH SCIENCES
(2021)
Article
Water Resources
Jafar Qajar, Christoph H. Arns
Summary: This paper investigates the evolution of pore structure and permeability of a microporous carbonate rock during chemical dissolution using X-ray micro-computed tomography (μ-CT) and mercury intrusion porosimetry (MIP) techniques. The study compares the capabilities and limitations of the μ-CT and MIP methods in quantifying the evolution of pore size and surface area. Predictive results on permeability changes are presented using different models, and the effect of changes in microporosity on permeability evolution is assessed. The results show that the predicted changes in permeability based on the calculated parameters from the μ-CT and MIP methods are reasonably accurate.
ADVANCES IN WATER RESOURCES
(2022)
Article
Geosciences, Multidisciplinary
Wenwen Wei, Fiona Whitaker, Hussein Hoteit, Volker Vahrenkamp
Summary: Calcite microcrystals and associated microporosity in Middle Eastern Jurassic and Cretaceous carbonate sequences are believed to have formed due to the expulsion of compaction fluids during rapid burial. Hydro-mechanical simulations and numerical models suggest that the recrystallization of calcite occurred at greater depths than previously estimated based on temperature analysis.
MARINE AND PETROLEUM GEOLOGY
(2022)
Article
Geochemistry & Geophysics
Wei Huang, Ming Ju, Qiqiang Chen, Baohua Jin, Wenjun Song
Summary: This letter proposes a novel pansharpening method that combines deep learning with multiresolution analysis methods to tackle spatial distortion in high-resolution multispectral images. By injecting details and using an asymmetric residual network, the method outperforms state-of-the-art pansharpening methods according to experimental results.
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2022)
Article
Materials Science, Multidisciplinary
X. H. Gong, Z. D. Feng, D. Fan, L. Lu, S. N. Luo
Summary: Strain localization in commercially pure titanium under uniaxial tension was investigated using in situ digital image correlation at different length scales. The study found that strain localization mainly occurs at grain boundaries and inside deformation twins, particularly at large-angle grain boundaries. The amplitude and rate of strain accumulation at grain boundaries are higher than inside deformation twins. The microscale strain-localized regions dispersed at grain boundaries and within deformation twins correspond to the strain concentration bands observed with the macroscale speckles, and both are oriented at ±45° with the tensile direction.
MATERIALS CHARACTERIZATION
(2022)
Article
Engineering, Chemical
Naif J. Alqahtani, Yufu Niu, Ying Da Wang, Traiwit Chung, Zakhar Lanetc, Aleksandr Zhuravljov, Ryan T. Armstrong, Peyman Mostaghimi
Summary: Reliable quantitative analysis of digital rock images, especially in heterogeneous rocks like carbonates with complex pore size distributions, requires precise segmentation and identification. In recent years, deep learning algorithms have provided efficient and automated solutions for digital rock super-resolution and segmentation. This study presents a framework that uses convolutional neural networks (CNNs) to achieve super-resolved segmentations of carbonate rock images in order to identify sub-resolution porosity. Comparison of voxel-wise segmentation accuracy metrics, topological features, and effective properties confirms the accuracy of the trained model and highlights the value of integrating deep learning frameworks in digital rock analysis.
TRANSPORT IN POROUS MEDIA
(2022)
Article
Energy & Fuels
Weichao Tian, Shuangfang Lu, Zhigang Wen, Xiu Chen, Yang Gao, Yang Li
Summary: This study proposed an improved method that combines nuclear magnetic resonance (NMR) tests and multicycle mercury intrusion porosimetry to quantitatively evaluate the microdistributions of different fluid types, classify the pore throat structure, and analyze the relationship between pore throat structure and different fluid types in low-permeability conglomerates. The study found that the movable fluids were mainly distributed in macropore throats and mesopore throats, capillary-bound fluid (CAF) mainly existed in micropore throats, and clay-bound fluid (CLF) was mainly distributed in clay-related pores.
Article
Energy & Fuels
Muhammad Bisri Mustofa, Umar Fauzi, Fourier Dzar Eljabbar Latief, Warsa Warsa
Summary: This study analyzed the influence of micro-spatial distribution of fluids on electrical resistivity through laboratory measurements and computer modeling. The results indicated that the proposed model accurately represented spatial fluid distribution in pore spaces and explained the electrical resistivity jump phenomenon in the imbibition process. It was concluded that considering the spatial distribution of fluids is crucial in estimating electrical resistivity and understanding the electrical properties of rocks.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Engineering, Mechanical
Behzad Farahani, Frederico Direito, Pedro J. Sousa, Paulo J. Tavares, Virginia Infante, Pedro P. M. G. Moreira
Summary: This study focuses on developing a complementary fatigue crack-tip evaluation approach using multiscale optical techniques. By comparing calculated parameters for different systems to shift to higher resolution techniques, the proposed methodologies are validated.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Materials Science, Multidisciplinary
F. Hild, A. Misra, F. dell'Isola
Summary: This study aims to characterize detailed deformations of pantographic metamaterials unit cells through digital image correlation at different scales, with microscale results found to be in better agreement with experiments. Detailed analyses reveal relative displacements between two beam layers around hinges.
EXPERIMENTAL MECHANICS
(2021)
Article
Materials Science, Composites
Shuwei Huang, Junjie Zhang, Bohong Gu, Baozhong Sun
Summary: Thermal stress concentration, caused by the mismatch of coefficients of thermal expansion, plays a significant role in the fatigue and failure of composites. We demonstrated the practicality of fiber Bragg grating sensors and high-resolution digital image correlation technique for in-situ characterization of thermal strain field evolution in 3D angle-interlocked woven composites. Our study found that the CTE mismatch leads to stress localization at the interface and exhibits a periodic distribution within the 3DAWC. The thermal stress in the resin reaches a maximum of 22 MPa around Tg, close to half of its yield stress.
COMPOSITES SCIENCE AND TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Behrad Koohbor, Nicholas Pagliocca, George Youssef
Summary: This study quantitatively characterized the micro-to-macro transition length scale in polymeric foams using an experimental-statistical approach, showing that this transition is a function of material density.
MECHANICS OF MATERIALS
(2021)
Article
Geochemistry & Geophysics
Zhao JianGuo, Pan JianGuo, Hu YangMing, Li JinSong, Yan BoHong, Li Chuang, Sun LangQiu, Liu XinZe
Summary: This study explores how the complex pore structure of carbonate rock affects its elastic properties using digital cores, aiming to make quantitative predictions of carbonate reservoirs and effectively obtain seismic attribute volumes. It involves acquiring representative samples, CT scanning digital core data, image processing, static elastic simulation, pore structure factor extraction, quantification of elastic properties and porosity, and obtaining seismic property bodies. The study is divided into two parts, focusing on processes validation, theoretical aspects, and practical applications for carbonate reservoir prediction.
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
(2021)
Article
Geochemistry & Geophysics
Zhao JianGuo, Pan JianGuo, Hu YangMing, Li JinSong, Liu XinZe, Li Chuang, Yan BoHong
Summary: This study explores the impact of complex pore structures in carbonate rock on elastic properties, aiming to establish a relationship analysis template for elastic properties vs porosity. The study combines digital cores, well logging, and seismic data to provide a new approach for predicting and characterizing carbonate reservoirs.
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
(2021)
Article
Materials Science, Multidisciplinary
S. Bhagavath, Z. Gong, T. Wigger, S. Shah, B. Ghaffari, M. Li, S. Marathe, P. D. Lee, S. Karagadde
Summary: High pressure metal die casting is a complex process with a wide range of cooling rates and pressures, leading to various solid fractions and deformation rates. This study investigated the effect of solid fraction, loading conditions, and semisolid flow on microstructural inhomogeneity, revealing different characteristics under different solid fractions and a mechanism of porosity formation based on stress state and microstructure. These findings will be used for the numerical modeling of defect formation during die casting.
Article
Geosciences, Multidisciplinary
Liene Spruzeniece, Michael Spaeth, Janos L. Urai, Estibalitz Ukar, Michael Selzer, Britta Nestler, Alexander Schwedt
Summary: The study on Liassic limestones in Somerset, UK, revealed a special microstructure of calcite microveins with wide-blocky crystals, formed in open, fluid-filled fractures. The results suggest that growth competition and different types of seed grain play a crucial role in the formation of wide-blocky crystals in the veins.
JOURNAL OF THE GEOLOGICAL SOCIETY
(2021)
Article
Geosciences, Multidisciplinary
Leticia Rodriguez Blanco, Gregor P. Eberli, Ralf J. Weger, Donald F. McNeill, Peter K. Swart
Summary: This study quantifies the occurrence of calcite concretions along stratigraphic horizons in the Vaca Muerta Formation of the Neuque = n Basin in Argentina. The size, spacing, and density of the concretions vary laterally and vertically, with larger and more elongated concretions observed in more proximal settings. The availability of calcium carbonate is an important controlling factor for the size and shape of the concretions.
Article
Geochemistry & Geophysics
Peter B. Kelemen, Juan Carlos de Obeso, James A. Leong, Marguerite Godard, Keishi Okazaki, Alissa J. Kotowski, Craig E. Manning, Eric T. Ellison, Manuel D. Menzel, Janos L. Urai, Greg Hirth, Matthew Rioux, Daniel F. Stockli, Romain Lafay, Andreas M. Beinlich, Jude A. Coggon, Nehal H. Warsi, Jurg M. Matter, Damon A. H. Teagle, Michelle Harris, Katsuyoshi Michibayashi, Eiichi Takazawa, Zaher Al Sulaimani
Summary: This paper provides an overview of research on the core from Oman Drilling Project Hole BT1B and the surrounding area, and presents new data and calculations to constrain processes in the Tethyan subduction zone beneath the Samail ophiolite. The study reveals the formation of important reservoirs for subducted CO2 in the area and suggests that the processes could lead to aseismic subduction and significant changes in rock mass and volume.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Energy & Fuels
Yulun Wang, G. Michael Grammer, Gregor Eberli, Ralf Weger, Runar Nygaard
Summary: The study shows that RHN data is correlated with mineralogy and porosity, with variations in significance levels among different facies groups. RHN can assist in rock typing and enhance the prediction of porosity and sonic velocity, providing a faster, cheaper, and non-destructive way to estimate rock properties compared to conventional laboratory analyses.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
Michael Spath, Janos L. Urai, Britta Nestler
Summary: This work presents a comprehensive phase-field study on the formation of multi-crack-seal veins in quartz microstructures. It explores the effects of fracture aperture, crystal orientation, and sealing state on the morphology of the forming grain boundaries. The study successfully reproduces a wide range of crystal structures frequently observed in natural quartz veins using a combined crack-seal phase-field model.
JOURNAL OF STRUCTURAL GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Michael Spaeth, Janos L. Urai, Britta Nestler
Summary: This study investigates the mechanisms of cyclic microfracturing and epitaxial crystal growth in crack-seal veins using a phase-field model. The sealing degree is found to be a key parameter in hydrothermal systems, and multi-crack-seal veins exhibit mechanical weakness in rocks.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geology
Mara R. Diaz, Gregor P. Eberli, Ralf J. Weger
Summary: This study investigates the microbial mediation of early cementation processes and finds that microbes and associated organic material play a significant role in the formation of early cements in carbonate grains. The study suggests that microbially mediated cementation can occur at fast rates and has implications for the stabilisation of slopes and the formation of firmground to hardgrounds.
DEPOSITIONAL RECORD
(2023)
Article
Geography, Physical
Leticia Rodriguez Blanco, Peter K. Swart, Gregor P. Eberli, Ralf J. Weger
Summary: The study investigates the carbon isotopic compositions of carbonate sediments in the Neuquen Basin, Argentina, and compares them with pelagic strata in the Tethys. The results show that the overall trend of the carbon isotopes in the basin is increasing and is closely related to TOC content and sea-level changes. The study also finds that clastic-dominated transgressive hemicycles have higher TOC content and more negative carbon isotopes, while carbonate-rich regressive hemicycles have the opposite characteristics.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Ralf J. Weger, Gregor P. Eberli, Jose Luis Massaferro, Yuefeng Sun, Gregor T. Baechle
Summary: Carbonates exhibit scatter in velocity-porosity cross plots due to variability in pore geometry stiffness. Digital image analysis (DIA) allows objective measurement of pore geometry parameters to explain this scatter. The Extended Biot Theory captures these parameters using poroelastic data, and their correlation with DIA-derived parameters was confirmed in limestone samples. This study highlights the importance of incorporating quantitative pore geometry information to improve porosity estimation and indirectly estimate permeability from acoustic data.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Environmental Sciences
Michael Spaeth, Michael Selzer, Benjamin Busch, Daniel Schneider, Christoph Hilgers, Janos L. L. Urai, Britta Nestler
Summary: Fluid flow in fracture porosity in the Earth's crust can lead to crystallization or dissolution depending on the saturation state. The evolution of the microstructure affects the transport and mechanical properties of rocks, but the understanding of this coupled system is incomplete. In this study, we simulate laboratory experiments at the grain scale to investigate crystal growth in fractures during reactive flow. By using a multiphase-field modeling approach, we accurately capture the varying growth rate along the fracture due to saturation differences. These simulations provide valuable insights for upscaling to larger scale computations and have potential applications in groundwater protection, geothermal energy, hydrocarbon reservoir prediction, water recovery, and subsurface storage of H-2 or CO2.
WATER RESOURCES RESEARCH
(2023)
Article
Geochemistry & Geophysics
Jessica Barabasch, Joyce Schmatz, Jop Klaver, Alexander Schwedt, Janos L. Urai
Summary: Based on the microstructural analysis of Zechstein rock salt from the northern Netherlands, the study reveals that rheology of salt rock is strongly influenced by grain size, indicating the significance of pressure solution and dislocation creep in different grain sizes. This finding is important for predicting the long-term deformation of solution-mined caverns and radioactive-waste repositories in rock salt, contributing to the energy transition. It is recommended to include grain-size-dependent rheology more consistently in constitutive laws describing the deformation of rock salt.
Article
Geochemistry & Geophysics
Sivaji Lahiri, Kitty L. Milliken, Peter Vrolijk, Guillaume Desbois, Janos L. Urai
Summary: The input sediments of the North Sumatra subduction zone margin exhibit remarkable uniformity in composition and grain size. The study shows that compaction proceeds by micromechanical processes and there is no evidence of deformation or fracturing during the compaction process.
Article
Geochemistry & Geophysics
Manuel D. Menzel, Janos L. Urai, Estibalitz Ukar, Thierry Decrausaz, Marguerite Godard
Summary: The formation of listvenite (quartz-carbonate rock) from serpentinized peridotite through the reaction with CO2 bearing fluids requires a large amount of fluid flux and significant permeability despite the increase in solid volume. This study on listvenite and serpentinite samples from Hole BT1B of the Oman Drilling Project reveals the mechanisms and feedbacks during vein formation in this process. It is found that the earliest structures to form during carbonation of serpentinite are antitaxial, zoned magnesite veins with elongated grains growing from a median zone towards the wall rock. The presence of voids and dolomite precipitation along the vein-wall rock interface indicates that these veins acted as preferred fluid pathways for the infiltration of CO2-rich fluids necessary for carbonation to progress.
Article
Geochemistry & Geophysics
Lisa Winhausen, Kavan Khaledi, Mohammadreza Jalali, Janos L. Urai, Florian Amann
Summary: This study investigates the failure mode of Opalinus Clay under different stress conditions. The results show a transition from brittle to ductile deformation with increasing stress, and the deformation localizes in distinct shear bands. The study also reveals less dilation in the shear zones at higher stresses.
Article
Geochemistry & Geophysics
Lisa Winhausen, Jop Klaver, Joyce Schmatz, Guillaume Desbois, Janos L. Urai, Florian Amann, Christophe Nussbaum
Summary: The microphysics-based study on Opalinus Clay reveals that deformation mechanisms are controlled by both brittle and ductile processes, leading to the formation of networks of deformation bands with widths up to tens of micrometres. The compaction and local dilation effects have a significant impact on permeability, while additional solution-precipitation processes may operate during long-term deformation.