Article
Geosciences, Multidisciplinary
Arqam Muqtadir, Saud Al-Dughaimi, Taqi Alzaki, Jack Dvorkin
Summary: This study compares the P-wave and S-wave velocities obtained under different hydrostatic loading conditions using ultrasonic pulse transmission experiments. The results show significant differences in velocities when a smaller hydrostatic stress is added to axial stress, but these differences become smaller as the hydrostatic stress increases. The findings suggest that laboratory hydrostatic experiments can be used for in-situ velocity estimates even under strong in-situ contrasts between the vertical and horizontal stresses.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Mechanics
Xin Zheng, Junhua Xiao, Peng Yan, Yaoling Xu
Summary: The effective elastic properties of composites with double periodic nanofibers are studied theoretically using the Gurtin-Murdoch surface elasticity theory and a functional variational method. The analytical solution of the effective anti-plane shear modulus of the periodic nanocomposites is presented, and its convergence is discussed. Comparisons with existing results demonstrate the effectiveness and accuracy of the proposed method. The size effect of the effective properties and the effects of microstructure, stiffness matching, and nanoporous volume fraction on the effective shear modulus are also discussed.
Article
Engineering, Geological
Qi Zhang, Ronaldo I. Borja
Summary: Closed-form expressions for poroelastic coefficients are derived for anisotropic materials exhibiting single and double porosity, using the principle of superposition to derive governing mass conservation equations. Numerical values of the poroelastic coefficients are calculated for granite and sandstone to guide modelers in determining these coefficients for full-scale modeling and simulations.
Article
Construction & Building Technology
Osvaldo P. M. Vitali, Tarcisio B. Celestino, Antonio Bobet
Summary: This study investigates the 3D effects of tunnels misaligned with the geostatic principal stress directions and/or with the material principal directions. Through 3D finite element modeling, it is found that misaligned tunnels undergo asymmetric deformations near the face and have an impact on the ground support.
TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY
(2022)
Article
Engineering, Geological
Huan He, Siyue Li, Kostas Senetakis, Matthew Richard Coop, Songyu Liu
Summary: Investigation of the dynamic properties of carbonate/calcareous soils is crucial in earthquake and offshore engineering. This study focused on the stiffness and stiffness anisotropy of calcareous sands from Western Australia and the Philippines. Experimental results showed that the stiffness of calcareous sands was significantly influenced by anisotropic loading, with different weighted influences in different directions. Furthermore, comparisons with silica sands highlighted the different responses of calcareous soils in terms of stiffness, stiffness anisotropy, and loading history.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2022)
Article
Mechanics
Bulat N. Galimzyanov, Anatolii Mokshin
Summary: The porous titanium nickelide is characterized by unique physical and mechanical properties, and the degree of porosity affects its mechanical behavior under tension, compression, and shear. Different types of pore structures influence the elastic characteristics and resistance to tensile and shear, providing insights for developing and improving amorphous metal foams.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2021)
Article
Mathematics, Applied
Dingwen Deng, Qiang Wu
Summary: This article proposes a two-level linearized compact alternating direction implicit (ADI) scheme for solving two-dimensional nonlinear coupled wave equations, which has lower computational cost and better stability compared to existing methods.
NUMERICAL ALGORITHMS
(2022)
Article
Mathematics, Applied
Yuan Xu, Siu-Long Lei, Hai-Wei Sun
Summary: The anisotropic space-fractional diffusion equations in two dimensions are discretized using the Crank-Nicolson difference scheme with the weighted and shifted Grunwald formula. The coefficient matrix of the discretized linear system possesses a two-level Toeplitz-like structure. By utilizing the GMRES method with a newly proposed tridiagonal preconditioner as a smoother, the convergence rate of the multigrid method can be significantly accelerated.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2022)
Article
Geochemistry & Geophysics
Weichen Zhan, Mingwei Zhuang, Qi Qiang Liu, Linlin Shi, Yuefeng Sun, Qing Huo Liu
Summary: It is known that the spectral element method (SEM) is more effective than traditional finite element methods (FEM) for complex geophysical problems. Developing a frequency domain SEM can improve efficiency for narrowband simulations and solve multiphysics coupling problems through different interface types coupling conditions.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Engineering, Geological
Xinyu Liu, Xianwei Zhang, Lingwei Kong, Ran An, Guofang Xu
Summary: This study found that natural residual soils exhibit significant anisotropy in strength, different from normally consolidated clays. To address this, two parameters were proposed to quantify the anisotropic strength of residual soils under general conditions.
Article
Automation & Control Systems
Qingkai Yang, Hao Fang, Ming Cao, Jie Chen
Summary: This article studies the problem of affine formation stabilization for multiagent systems in the plane. It proposes an estimator to address the challenge of limited information access and designs an integrated control scheme to achieve unique stabilization of the formation. Simulation and experimental results demonstrate the effectiveness of the proposed control strategy.
IEEE TRANSACTIONS ON CYBERNETICS
(2022)
Article
Engineering, Geological
Xiongying Ma, Hang Lei, Xin Kang
Summary: In this study, the effects of particle shape on the shear behavior of granular soils were investigated through experiments and simulations. It was found that increasing the shape parameter S-h can enhance the interlock between particles and limit the deformation in the direction of shearing. Additionally, changes in particle shape can significantly affect the fabric anisotropy of the soil.
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
(2022)
Article
Mathematics, Applied
Pei-Liang Bian, Hai Qing
Summary: Using a nonlocal strain gradient integral model, this study investigates the elastic buckling and free vibration of Bernoulli-Euler beams under different boundary conditions. Through the application of Hamilton's principle, differential governing equations and boundary conditions are derived, and the Laplace transform technique is used to solve integro-differential equations, obtaining explicit expressions for bending deflections and moments. Nonlinear characteristic equations are derived to determine characteristic buckling load and vibration frequency, with validation against existing literature results showing consistent softening and toughening responses.
ZAMM-ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND MECHANIK
(2022)
Article
Geochemistry & Geophysics
C. A. Bacon, J. H. Johnson, R. S. White, N. Rawlinson
Summary: The unique tectonic setting in Iceland leads to the formation of an oceanic plateau from mantle melting. Research shows that seismic anisotropy in the crust is mainly concentrated in the top 3-4 km and is controlled by the regional stress field, with areas of high seismic activity also exhibiting high shear wave anisotropy values.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Engineering, Geological
Ali Aminzadeh, Florian Amann
Summary: This article studies the stresses at the center of a disk made of transversely isotropic rocks in Brazil. It finds that the solution for these stresses depends on the radius of the disk, the applied load, the material orientation, and two dimensionless ratios related to Young's modulus and apparent shear modulus. Finite element simulations are conducted to determine the stresses at the disk center, and an approximate formula is derived from analytical results. The formula is compared to numerical solutions, and simple and practical equations are proposed for estimating the stresses at the center of the disk specimen.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Review
Energy & Fuels
Ahmed Fatah, Ziad Bennour, Hisham Ben Mahmud, Raoof Gholami, Md. Mofazzal Hossain
Article
Chemistry, Physical
Mehdi Safari, Ali Rahimi, Raoof Gholami, Andrian Permana, Wee Siaw Khur
Summary: Low salinity water flooding is a method used in the EOR process to change the surface wettability and reduce interfacial tension. This study investigates the effects of ions on the surface wettability of shale rocks and the interfacial tension of brine/oil. It is found that decreasing the concentration of monovalent ions changes the wettability of shale from neutral wet to weakly water wet, while decreasing the concentration of divalent ions induces an oil wet system. Time and salt ion concentration have significant impacts on shale wettability and interfacial tension.
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
(2022)
Article
Energy & Fuels
Daniel Asante Otchere, Tarek Omar Arbi Ganat, Raoof Gholami, Syahrir Ridha
Summary: The use of Artificial Intelligence (AI) in the petroleum industry has increased to accelerate decision making, reduce cost and time. Supervised machine learning has become popular in establishing relationships between complex non-linear datasets. Support Vector Machine (SVM) and Relevant Vector Machine (RVM) have emerged as competitive algorithms, often outperforming Artificial Neural Network (ANN).
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Green & Sustainable Science & Technology
Ahmed Fatah, Ziad Bennour, Hisham Ben Mahmud, Raoof Gholami, Mofazzal Hossain
Summary: Surface wettability plays a crucial role in controlling CO2 seal capacity and storage potential of shales. Strong correlation between mineral composition and alteration in shale/water wettability was observed, with clay-rich shales showing a possible transition to CO2-wet behavior. Increasing temperature accelerates CO2/shale interactions, while higher cohesive energy density of CO2 promotes a favorable CO2 wetting environment. Shales with high quartz contents exhibit strong water wetting behavior after SCCO2 treatment, enhancing their sealing capacity and potential for CO2 containment in geological storage sites.
INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL
(2021)
Article
Green & Sustainable Science & Technology
Raoof Gholami, Arshad Raza, Pal Andersen, Alejandro Escalona, Nestor Cardozo, Dora Marin, Mohammad Sarmadivaleh
Summary: Many studies have been conducted to evaluate the long-term integrity of seals in CO2 storage sites, focusing on the geochemical reactions, mineral transformations, and surface wettability alterations that may occur. This study specifically examined changes in mineralogy and surface wettability of shales exposed to supercritical CO2 for 6 months, finding that quartz dissolution and kaolinite precipitation can be induced in the presence of CO2. The study suggests that maintaining water wettability of clay surfaces in storage sites is important to prevent CO2 migration. Further research is needed to ensure the integrity of seals in storage sites during and after injection.
INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL
(2021)
Article
Energy & Fuels
Li Yisong, Raoof Gholami, Mehdi Safari, Ali Rahimi, Wee Siaw Khur
Summary: The study extracts and characterizes a natural surfactant with high thermal stability, demonstrating its synergistic effects with low salinity water, effectively reducing interfacial tension and altering sandstone surface wettability to enhance hydrocarbon production efficiency.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Energy & Fuels
Mehdi Safari, Mohammad Javad Ameri, Raoof Gholami, Ali Rahimi
Summary: Undesirable water production due to water coning in hydrocarbon reservoirs has been a significant issue, affecting oil production and well shutdown. A new approach combining boundary control and Ensemble Kalman Filter showed promising results in controlling water coning and estimating reservoir permeability accurately.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Energy & Fuels
Daniel Asante Otchere, Tarek Omar Arbi Ganat, Raoof Gholami, Mutari Lawal
Summary: With the advancement of technology, new well logs carrying vital information about reservoir and subsurface layers have been acquired. The application of machine learning models for predicting petrophysical parameters is increasing, with this study demonstrating the potential of ensemble modeling to improve reservoir characterization.
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2021)
Article
Energy & Fuels
Raoof Gholami, Arshad Raza, Bernt Aadnoy, Minou Rabiei, Vamegh Rasouli
Summary: This study, based on a case study from a gas field in Australia, reveals that the compaction mechanism of deep-water sandstone reservoirs can exhibit elasto-plastic or viscoplastic behavior depending on the type of clays in the rock matrix, confining pressure, and loading rate. The deformation during compaction is shown to be time-dependent and influenced by the clay type in the sandstone matrix. Different behaviors are observed based on the presence of kaolinite or illite/smectite, with a transition to viscous response above a threshold confining pressure and a shift to viscoplastic deformation with increasing loading rate.
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2021)
Review
Geosciences, Multidisciplinary
Raoof Gholami, Arshad Raza, Stefan Iglauer
Summary: Carbon Capture and Storage (CCS) is considered as an effective strategy to achieve the net zero emission target by 2050, but attention should be paid to the interactions between rocks and sealing materials with CO2 to prevent leakage during operation. Discrepancies between laboratory results and field observations may be due to limited testing time, complexity of mechanisms involved, and slow reaction rates of chemical processes.
EARTH-SCIENCE REVIEWS
(2021)
Article
Engineering, Geological
Daniel Fraser, Raoof Gholami, Mohammad Sarmadivaleh
Summary: Magnitude and direction of in-situ stresses are crucial inputs for geomechanical analysis, with Deformation Rate Analysis (DRA) being an effective method for unconventional shale gas reservoirs. However, the elapsed time between sample extraction and testing, as well as the impact of loading cycles on results, should not be ignored during laboratory measurements.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Energy & Fuels
Mehdi Safari, Raoof Gholami, Morteza Jami, Mavvinesh Arul Ananthan, Ali Rahimi, Wee Siaw Khur
Summary: This study developed a new mathematical equation to correct the porosity-permeability relationship in rocks with ellipsoidal grains, showing that deviations in the sphericity of grains increase permeability. Models with an aspect ratio of 1.0 had the lowest permeability, suggesting that irregular grain shapes can impact fluid flow paths.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Energy & Fuels
Ahmed Fatah, Hisham Ben Mahmud, Ziad Bennour, Raoof Gholami, Mofazzal Hossain
Summary: The injection of supercritical CO2 (SCCO2) has a significant impact on the petrophysical properties and pore structure of shales during geological storage. The alteration of mineralogy and pore structure is influenced by SCCO2 treatment, with clay-rich shales showing greater changes in pore volume compared to quartz-rich shales. The development of micro-cracks in the surface of Mancos shale creates new pores and increases pore volume. The results provide important insights into the effect of CO2 on the pore structure and mineralogical alteration of shale.
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2022)
Article
Energy & Fuels
Atif Ismail, Hafiz Muhammad Awais Rashid, Raoof Gholami, Arshad Raza
Summary: This study investigated the impact of grass additives on the rheological properties of drilling mud using machine learning techniques, showing that grass can improve the gel strength and viscosity of drilling mud. Random tree was found to be the most effective technique for modeling gel strength.
JOURNAL OF PETROLEUM EXPLORATION AND PRODUCTION TECHNOLOGY
(2022)
Article
Energy & Fuels
Raoof Gholami, Arshad Raza, Minou Rabiei, Nikoo Fakhari, Punissha Balasubramaniam, Vamegh Rasouli, Ramasamy Nagarajan
Summary: A new water-based mud formulated with nano-materials was proposed to stabilize active shale layers during drilling, showing significant reduction in filtration loss without impacting mud density and rheology. However, caution must be taken to ensure proper dispersion of the additives in the mud.