Subjects -> ENERGY (Total: 414 journals)
    - ELECTRICAL ENERGY (12 journals)
    - ENERGY (252 journals)
    - ENERGY: GENERAL (7 journals)
    - NUCLEAR ENERGY (40 journals)
    - PETROLEUM AND GAS (58 journals)
    - RENEWABLE ENERGY (45 journals)

ENERGY (252 journals)                  1 2 | Last

Showing 1 - 200 of 406 Journals sorted alphabetically
ACS Applied Energy Materials     Hybrid Journal   (Followers: 4)
ACS Energy Letters     Hybrid Journal   (Followers: 4)
Advanced Energy and Sustainability Research     Open Access   (Followers: 5)
Advanced Materials Technologies     Hybrid Journal   (Followers: 2)
Advances in Applied Energy     Open Access   (Followers: 2)
Advances in Building Energy Research     Hybrid Journal   (Followers: 11)
Advances in Energy and Power     Open Access   (Followers: 16)
Advances in High Energy Physics     Open Access   (Followers: 23)
Advances in Natural Sciences : Nanoscience and Nanotechnology     Open Access   (Followers: 28)
American Journal of Energy and Environment     Open Access   (Followers: 4)
American Journal of Energy Research     Open Access   (Followers: 7)
Annals of Nuclear Energy     Hybrid Journal   (Followers: 7)
Annual Reports on NMR Spectroscopy     Full-text available via subscription   (Followers: 4)
Annual Review of Resource Economics     Full-text available via subscription   (Followers: 11)
Applications in Energy and Combustion Science     Open Access   (Followers: 3)
Applied Energy     Partially Free   (Followers: 26)
Applied Nanoscience     Open Access   (Followers: 7)
Applied Solar Energy     Hybrid Journal   (Followers: 20)
Archives of Thermodynamics     Open Access   (Followers: 10)
Asian Bulletin of Energy Economics and Technology     Open Access   (Followers: 1)
Atomic Energy     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 8)
Batteries & Supercaps     Hybrid Journal   (Followers: 5)
Biofuel Research Journal     Open Access   (Followers: 1)
Biofuels     Hybrid Journal   (Followers: 11)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
BioPhysical Economics and Resource Quality     Hybrid Journal  
BMC Energy     Open Access  
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 50)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 18)
Carbon Energy     Open Access   (Followers: 1)
Carbon Management     Hybrid Journal   (Followers: 5)
Carbon Resources Conversion     Open Access   (Followers: 2)
CERN courier. International journal of high energy physics     Free   (Followers: 8)
Chain Reaction     Full-text available via subscription  
Clean Energy     Open Access   (Followers: 2)
Clean Technologies     Open Access   (Followers: 1)
Clefs CEA     Full-text available via subscription   (Followers: 1)
Climate and Energy     Full-text available via subscription   (Followers: 6)
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 5)
CPSS Transactions on Power Electronics and Applications     Open Access   (Followers: 2)
CSEE Journal of Power and Energy Systems     Open Access   (Followers: 1)
CT&F - Ciencia, Tecnología y Futuro     Open Access  
Current Opinion in Green and Sustainable Chemistry     Hybrid Journal  
Dams and Reservoirs     Hybrid Journal   (Followers: 3)
Development of Energy Science     Open Access   (Followers: 4)
Discover Energy     Open Access  
Discover Sustainability     Open Access   (Followers: 3)
Distributed Generation & Alternative Energy Journal     Hybrid Journal   (Followers: 3)
e-Prime : Advances in Electrical Engineering, Electronics and Energy     Open Access   (Followers: 2)
E3S Web of Conferences     Open Access  
Economics and Policy of Energy and the Environment     Full-text available via subscription   (Followers: 13)
Electricity Journal     Hybrid Journal   (Followers: 1)
Energetic Materials Frontiers     Open Access  
ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations     Open Access  
Energy     Partially Free   (Followers: 40)
Energy & Environment     Hybrid Journal   (Followers: 25)
Energy & Fuels     Hybrid Journal   (Followers: 27)
Energy and AI     Open Access   (Followers: 1)
Energy and Buildings     Hybrid Journal   (Followers: 12)
Energy and Climate Change     Hybrid Journal   (Followers: 4)
Energy and Emission Control Technologies     Open Access   (Followers: 3)
Energy and Environment Focus     Free   (Followers: 7)
Energy and Environment Research     Open Access   (Followers: 13)
Energy and Environmental Engineering     Open Access   (Followers: 5)
Energy and Power     Open Access   (Followers: 18)
Energy and Power Engineering     Open Access   (Followers: 23)
Energy Conversion and Economics     Open Access  
Energy Conversion and Management     Hybrid Journal   (Followers: 15)
Energy Conversion and Management : X     Open Access   (Followers: 1)
Energy Efficiency     Hybrid Journal   (Followers: 9)
Energy Geoscience     Open Access  
Energy Informatics     Open Access  
Energy Journal The     Hybrid Journal   (Followers: 14)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 19)
Energy Nexus     Open Access  
Energy Policy     Partially Free   (Followers: 73)
Energy Prices and Taxes     Full-text available via subscription   (Followers: 6)
Energy Reports     Open Access   (Followers: 5)
Energy Research & Social Science     Full-text available via subscription   (Followers: 11)
Energy Science & Engineering     Open Access   (Followers: 6)
Energy Science and Technology     Open Access   (Followers: 10)
Energy Storage     Hybrid Journal   (Followers: 2)
Energy Storage Materials     Full-text available via subscription   (Followers: 5)
Energy Strategy Reviews     Open Access   (Followers: 8)
Energy Studies Review     Open Access   (Followers: 5)
Energy Systems     Hybrid Journal   (Followers: 11)
Energy Technology     Partially Free   (Followers: 5)
Energy Technology & Policy     Open Access   (Followers: 2)
Energy Transitions     Open Access  
Energy, Ecology and Environment     Hybrid Journal  
Energy, Sustainability and Society     Open Access   (Followers: 15)
EnergyChem     Hybrid Journal   (Followers: 1)
Environmental Progress & Sustainable Energy     Hybrid Journal   (Followers: 7)
EPJ Photovoltaics     Open Access   (Followers: 2)
eScience     Open Access   (Followers: 1)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Forces in Mechanics     Open Access   (Followers: 2)
Foundations and Trends® in Renewable Energy     Full-text available via subscription   (Followers: 4)
Frontiers in Energy     Hybrid Journal   (Followers: 4)
Frontiers in Energy Research     Open Access   (Followers: 5)
Fuel and Energy Abstracts     Full-text available via subscription   (Followers: 7)
Fuel Communications     Open Access   (Followers: 2)
Functional Materials Letters     Hybrid Journal   (Followers: 3)
Gcb Bioenergy     Open Access   (Followers: 2)
Geomechanics and Geophysics for Geo-Energy and Geo-Resources     Hybrid Journal  
Geomechanics for Energy and the Environment     Full-text available via subscription  
Geothermal Energy     Open Access   (Followers: 5)
Global Challenges     Open Access  
Global Energy Interconnection     Open Access  
Global Energy Law and Sustainability     Hybrid Journal  
Global Transitions     Open Access   (Followers: 1)
Global Transitions Proceedings     Open Access  
Green Energy & Environment     Open Access   (Followers: 2)
High Voltage     Open Access  
IEEE Open Access Journal of Power and Energy     Open Access   (Followers: 1)
IEEE Open Journal of Power Electronics     Open Access   (Followers: 12)
IEEE Power and Energy     Full-text available via subscription   (Followers: 36)
IEEE Transactions on Energy Conversion     Hybrid Journal   (Followers: 16)
IEEE Transactions on Nuclear Science     Hybrid Journal   (Followers: 10)
IEEE Transactions on Power Systems     Hybrid Journal   (Followers: 45)
IET Energy Systems Integration     Open Access   (Followers: 1)
IET Power Electronics     Open Access   (Followers: 76)
IET Smart Grid     Open Access   (Followers: 2)
Ingeniería Energética     Open Access  
Innovations : Technology, Governance, Globalization     Hybrid Journal   (Followers: 10)
International Journal of Alternative Propulsion     Hybrid Journal   (Followers: 23)
International Journal of Ambient Energy     Hybrid Journal  
International Journal of Applied Power Engineering     Open Access   (Followers: 4)
International Journal of Clean Coal and Energy     Open Access   (Followers: 2)
International Journal of Coal Science & Technology     Open Access   (Followers: 1)
International Journal of Electric and Hybrid Vehicles     Hybrid Journal   (Followers: 8)
International Journal of Energy & Engineering Sciences     Open Access  
International Journal of Energy and Environmental Engineering     Open Access   (Followers: 3)
International Journal of Energy and Power     Open Access   (Followers: 8)
International Journal of Energy and Smart Grid     Open Access   (Followers: 1)
International Journal of Energy and Statistics     Hybrid Journal   (Followers: 3)
International Journal of Energy and Water Resources     Hybrid Journal  
International Journal of Energy Research     Hybrid Journal   (Followers: 8)
International Journal of Global Energy Issues     Hybrid Journal   (Followers: 8)
International Journal of Green Energy     Hybrid Journal   (Followers: 8)
International Journal of Hydrogen Energy     Partially Free   (Followers: 19)
International Journal of Nuclear Desalination     Hybrid Journal   (Followers: 1)
International Journal of Nuclear Energy Science and Technology     Hybrid Journal   (Followers: 4)
International Journal of Nuclear Governance, Economy and Ecology     Hybrid Journal  
International Journal of Nuclear Hydrogen Production and Applications     Hybrid Journal   (Followers: 1)
International Journal of Nuclear Knowledge Management     Hybrid Journal   (Followers: 2)
International Journal of Power and Energy Conversion     Hybrid Journal   (Followers: 1)
International Journal of Smart Grid and Green Communications     Hybrid Journal   (Followers: 2)
International Journal of Sustainable Energy     Hybrid Journal   (Followers: 12)
International Journal of Sustainable Energy Planning and Management     Open Access   (Followers: 5)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 4)
International Journal of Thermodynamics     Open Access   (Followers: 15)
International Journal of Turbomachinery, Propulsion and Power     Open Access   (Followers: 23)
Joule     Hybrid Journal   (Followers: 5)
Journal of Alternate Energy Sources & Technologies     Full-text available via subscription   (Followers: 2)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 5)
Journal of China Coal Society     Open Access  
Journal of Computational Multiphase Flows     Open Access   (Followers: 1)
Journal of Energy     Open Access   (Followers: 2)
Journal of Energy & Natural Resources Law     Hybrid Journal   (Followers: 5)
Journal of Energy and Environment Technology of Graduate School Siam Technology College     Open Access  
Journal of Energy Chemistry     Full-text available via subscription   (Followers: 3)
Journal of Energy in Southern Africa     Open Access   (Followers: 2)
Journal of Energy Research and Reviews     Open Access  
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
Journal of Energy Systems     Open Access  
Journal of Energy Technologies and Policy     Open Access   (Followers: 5)
Journal of Energy, Environment & Carbon Credits     Full-text available via subscription   (Followers: 4)
Journal of Energy, Mechanical, Material and Manufacturing Engineering     Open Access   (Followers: 3)
Journal of Fusion Energy     Hybrid Journal   (Followers: 2)
Journal of International Energy Policy     Open Access   (Followers: 4)
Journal of Modern Power Systems and Clean Energy     Open Access   (Followers: 9)
Journal of Nano Energy and Power Research     Full-text available via subscription   (Followers: 4)
Journal of Nuclear Energy Science & Power Generation Technology     Hybrid Journal   (Followers: 2)
Journal of Ocean and Climate     Open Access   (Followers: 9)
Journal of Ocean Engineering and Marine Energy     Hybrid Journal   (Followers: 2)
Journal of Photochemistry and Photobiology A: Chemistry     Hybrid Journal   (Followers: 3)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 4)
Journal of Photochemistry and Photobiology C: Photochemistry Reviews     Full-text available via subscription   (Followers: 3)
Journal of Photonics for Energy     Hybrid Journal   (Followers: 2)
Journal of Physical Chemistry C     Hybrid Journal   (Followers: 36)
Journal of Power and Energy Engineering     Open Access   (Followers: 2)
Journal of Power Electronics     Hybrid Journal   (Followers: 8)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 19)
Journal of Power Sources Advances     Open Access  
Journal of Renewable Energy     Open Access   (Followers: 8)
Journal of Solar Energy     Open Access   (Followers: 11)
Journal of Solar Energy Engineering     Full-text available via subscription   (Followers: 18)
Journal of Sustainable Bioenergy Systems     Full-text available via subscription  
Journal of Technology Innovations in Renewable Energy     Hybrid Journal   (Followers: 2)
Journal of Technology Management for Growing Economies     Open Access   (Followers: 4)
KnE Energy     Open Access  
Materials for Renewable and Sustainable Energy     Open Access   (Followers: 6)
Materials Reports : Energy     Open Access   (Followers: 1)
Materials Today Energy     Hybrid Journal   (Followers: 2)
Mekanika : Jurnal Teknik Mesin i     Open Access  
Michigan Journal of Sustainability     Open Access   (Followers: 1)
Multequina     Open Access  
Natural Resources     Open Access  

        1 2 | Last

Similar Journals
Journal Cover
Geomechanics and Geophysics for Geo-Energy and Geo-Resources
Number of Followers: 0  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2363-8419 - ISSN (Online) 2363-8427
Published by Springer-Verlag Homepage  [2469 journals]
  • Non-isothermal two-phase flow in deformable porous media: systematic
           open-source implementation and verification procedure

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      Abstract: We propose a formulation for non-isothermal two-component two-phase flow through deformable porous media. The approach covers phase transitions among both phases, i.e. liquid phase components evaporate into the gas phase while gas phase components dissolve or condensate into the liquid phase. These phase transitions always take place in thermodynamic equilibrium. The set of model equations is thereby largely independent of the specific constitutive relations. Starting from general equilibrium equations, we show the evolution of the system of weak formulations of all governing equations, which are then discretised with Taylor-Hood elements in a standard finite element approach. The model equations and the construction of the constitutive equilibria are implemented in the open-source simulator OpenGeoSys, which can be freely used and modified. To verify the implementation, we have selected a number of complementary test cases covering a wide range of process couplings. The numerical model is compared with analytical and semi-analytical solutions of these problems as well as with experimental results. It is shown in the paper that by including thermodynamic effects, solid mechanics, and phase transition processes, the proposed numerical model covers many characteristic features of unsaturated geomaterials and can be employed for the description of a broad range of problems encountered in geotechnical engineering. Article highlights An open-source FEM tool for non-isothermal two-phase flow in deformable porous or fractured media is presented in detail. The model features phase transitions across both fluid phases based on simple equilibrium conditions. A variety of benchmark tests is presented and compared to other software results and to exact solutions.
      PubDate: 2022-05-21
       
  • Development and application of a hydraulic impact test machine for
           simulating rockburst conditions

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      Abstract: Existing testing techniques do not meet the requirements for static-dynamic composite loading tests of anti-impact supports for rockburst protection in mines. In this study, a hydraulic impact test machine was designed to simulate the rockburst conditions. The test machine was designed with the maximum impact load of 6500 kN, starting time (for static-dynamic loading conversion) of less than 50 ms, effective impact displacement of 0.8 m, maximum impact speed of 8 m/s, and a maximum energy accumulation of 8 × 106 J. Based on the proposed technical specifications, a symmetrical layout of four accumulator groups was opted to meet the impact energy requirements. Secondly, a novel extra-high-flow high-pressure quick-opening valve structure (with rated pressure of 31.5 MPa, an instantaneous flow rate of 120,000 L/min, and starting time < 50 ms) was innovatively designed and shown to sufficiently meet the maximum impact speed requirement. Furthermore, an impact cylinder with a blowing device was developed to minimize the liquid return resistance of the hydraulic impact cylinder for achieving the required impact load and speed. An anti-rigid impact protector is also proposed to protect the test machine during high-energy impact tests. The design validation was performed through various tests. The results confirm that the test machine successfully provides a reliable method for laboratory dynamic testing of anti-impact supports. In addition, the data collected during the tests can be used for future development of novel anti-impact hydraulic supports. Article Highlights Designed a novel static-dynamic composite loading test machine for rockburst in mines. Designed an innovative extra high flow and pressure traffic quick opening valve to re-create rockburst scenario. Developed a new cylinder structure to meet impact load and speed requirement by minimizing liquid return resistance.
      PubDate: 2022-05-19
       
  • Coal permeability alteration prediction during CO2 geological
           sequestration in coal seams: a novel hybrid artificial intelligence
           approach

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      Abstract: The technology of CO2 geological storage while enhancing coalbed methane recovery has attracted significant attention. In this technology, the permeability alteration of coal after the injection of CO2 is directly related to the injectability of CO2, which is known as the CO2 geological storage effect. Currently, laboratory tests are often carried out to obtain coal permeability, however, this method has several drawbacks due to the complicated testing procedure, high cost and complex sample preparation. To efficiently forecast the permeability alteration of coal in the process of CO2 geological storage, this paper proposes an integrated new hybrid intelligent model of firefly algorithm (FA), sparrow search algorithm (SSA), and support vector machines (SVM). This FA-SSA-SVM hybrid intelligent model is trained and tested by a total of 154 data samples retrieved from the literature. The input variables include CO2 injection pressure, effective stress, coal rank, coal temperature and coal seam buried depth. The output variable is coal permeability. The evaluation indicators are R, MAE, RMSE, and MAPE. The results show that the FA-SSA-SVM prediction model have good potential for predicting the permeability alteration of coal during CO2 geological storage. In addition, by comparing and analysing the evaluation indicators among the FA-SSA-SVM, SSA-SVM and L-MRA models, the model FA-SSA-SVM shows the highest accuracy, while the L-MRA model has the lowest accuracy. These research results can provide important guidance for promoting and applying CO2 storage technology in coal seams. Article Highlights The novel hybrid artificial intelligence model that integrates SVM, SSA, and FA is proposed to forecast coal permeability alteration. Firefly improved sparrow search algorithm can effectively optimize the hyper-parameters of SVM. The range of experimental/predictive permeability probability distribution of different prediction models are analyzed.
      PubDate: 2022-05-19
       
  • Influences of hydrate morphology and hydrate distribution heterogeneity on
           the mechanical properties of hydrate-bearing sediments using the discrete
           element method

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      Abstract: The presence of gas hydrates in sediments affects the interaction between hydrate and sediment particles, which is associated with the most fundamental aspect of the mechanical behavior of hydrate-bearing sediments (HBS). The discrete element models of HBS with pore-filling, cementing, and load-bearing hydrates are proposed. In addition, homogeneous and heterogeneous distribution modes of hydrates are considered for the three hydrate morphologies. A series of triaxial compression test simulations are carried out to investigate the influences of hydrate morphology and hydrate distribution heterogeneity on the mechanical properties of hydrate-bearing sediments. The simulation results reveal that hydrate morphology can significantly while hydrate distribution heterogeneity can slightly affect the macro and micromechanical properties. Heterogeneous HBS shows a larger shear strength than homogeneous HBS. The cementing type of HBS exhibits the largest mid-strain modulus among the three hydrate morphologies. Sediment-sediment contacts contribute the most, while hydrate-hydrate contacts contribute the least to the shear strength regardless of hydrate morphology and hydrate distribution heterogeneity. It is also found that the cracks that occurred in HBS specimens depend on hydrate morphology and distribution heterogeneity. These findings are helpful to establish an accurate constitutive model for the HBS with a complex distribution of hydrates. Article Highlights Hydrate morphology significantly affects the mechanical properties of hydrate-bearing sediments. Heterogeneous hydrate-bearing sediments exhibit a larger shear strength than homogeneous ones. Sediment-sediment contacts primarily contribute to the shear strength of hydratebearing sediments.
      PubDate: 2022-05-19
       
  • The Importance of deformation modulus on design of rocks with numerical
           modeling

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      Abstract: The elasticity modulus of the rock material (Ei) is a parameter of these developed empirical formulas and is a constant value obtained from laboratory test. The rock material takes different Ei values under different stresses. The deformation modulus of rock mass (Em) is the parameter used in the design of rock structures and reveals the deformation properties of the rock mass. This behavior is affected by rock mass characteristics such as discontinuities, discontinuities properties and groundwater conditions, as well as the properties of rock material, which is the smallest unit of rock masses. The strength and deformation behavior of the rock material directly affect the deformation characteristic of the rock masses. Determination of the Em is done either by in-situ tests or estimates from empirical formulas developed by different researchers. The locations, where rock structures are built, can be different depths and different geological units. In this case, the amount of stress that the same rock structure is exposed at different depths will be different. Therefore, Ei will take different values under different stresses (depending on parameters such as depth, excavation-support geometry). When the Ei value, which varies depending on the depth, is used in the formulas developed by the researchers, different Em values will be calculated against different Ei values. Currently, designs are made with the classical method. In the classical method, the Ei value obtained from the deformability test performed in the laboratory is used in empirical formulas and Em is calculated. These Ei and Em values are fixed values. However, the Em value also changes depending on the stretch. In the new method proposed in this study, it is recommended to use the value of Em, which varies according to the stress conditions. This new method includes a function based on time-stress-deformation-strength was developed to calculate the Ei value, which takes different values at different stresses. The Ei values that can be changed by this function are used in the empirical formulas used in calculating Em. In the projects within the scope of the research, numerical modeling analyzes including the Em values obtained by this time-stress-deformation-strength dependent function and the Em values obtained by the classical method were performed and very important results were obtained. Article highlights Geotechnical studies have been carried out on different mining and tunnel projects and the rock mass properties have been revealed. Time and stress dependent laboratory tests have been carried out on the rock materials taken from these projects. With these experiments, deformation modules that change depending on time and stress were produced. An empirical formula has been developed to calculate the varying deformation modulus depending on time and stress. This formula was defined as a user defined material for a software (as sub-routine) used in rock structure designs. With this formula, numerical modeling analyzes including varying deformation modules were made and compared with models made with constant deformation module.
      PubDate: 2022-05-18
       
  • Competitive propagation simulation of multi-clustered fracturing in a
           cracked shale oil reservoir

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      Abstract: The occurrence of stratum layers and natural fractures in the cracked shale oil reservoir in Junggar Basin significantly affects the hydraulic fracturing process. A three-dimensional numerical model of the fracture propagation during multi-clustered fracturing was established based on the 3-Dimensional Distinct Element Code (3DEC). The bedding seams and randomly distributed high-angle natural cracks in the model were set based on image logging data. The interlayer interfaces and rock mechanical parameters were set according to the vertical stratification data. The complex fracture propagation process was simulated under different cluster numbers and cluster spacings. The multi-fracture competitive propagation during multi-clustered fracturing and the three-dimensional occurrence of the fracture system after fracturing were analyzed. The opening area increment curve and the fracture width of the fracture system during fracturing were recorded, which made it convenient to quantitatively analyze the fracture propagation. The numerical simulations revealed the following. (1) During multi-clustered fracturing of the shale oil reservoir, the competitive propagation occurred in two stages: a competitive stage and a continuous stage. (2) The degree of competitive multi-cluster fracture propagation increased as the cluster number increased and the cluster spacing decreased. (3) The unbalanced propagation of fractures caused the fracture width to exhibit a bimodal distribution. (4) The expansion range of the fracture system under the same pump displacement and fracturing time was negatively correlated with the Fracture Surface Area (FSA). (5) The expansion of the bedding seams and interlayer interfaces was negatively correlated with the FSA. Article Highlights A three-dimensional numerical model of fracture propagation of multi-clustered fracturing in cracked shale oil reservoirs was established based on the 3Dimensional Distinct Element Code (3DEC). The bedding seams and high angle natural cracks of random distribution were set according to the imaging logging data. The interlayer interfaces and rock mechanical parameters were set according to the vertical stratification data. The influence of mudstone interbedded, natural fractures and interlayer interfaces was fully considered in the modeling process. 3D occurrence of fracture system was recorded and colored by aperture, which could clearly and intuitively observe the characteristics of fracture morphology under competitive propagation in a cracked shale oil reservoir. The FSA (Fracture surface area) increment curve and fracture width of transverse fracture, natural fracture and interlayer interface during fracturing were recorded, which was convenient for quantitative analysis of fracture propagation law.
      PubDate: 2022-05-09
       
  • Role of heterogeneity on joint size effect, and influence of anisotropy
           and sampling interval on rock joint roughness quantification

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      Abstract: Abstract Rock joint roughness influences the mechanical and hydraulic properties of joints. To find reasons for the contradictory findings on roughness scale effects appearing in the literature, the surface roughness of a large rock joint was digitized and then quantified using six statistical parameters. The results obtained for the statistical parameters were then compared with a set of fractal parameter results obtained through the variogram method. Computed roughness parameter values showed significant roughness heterogeneity of the rock joint surface. Roughness heterogeneity has been neglected in the literature in making decisions on scale effects due to joint size. Therefore, the influence of roughness heterogeneity on the joint size effect was investigated carefully in the paper. Highly consistent results were obtained for both the statistical and fractal parameters for different joint sizes. No joint size effect was found on all the important roughness parameters when those were applied to relatively homogeneous sections of the rock joint. Negligible or slight joint size effect was found on all the important roughness parameters when those were applied to heterogeneous rock joint profiles. The possibility of having a joint size effect with increasing heterogeneity was found. Theoretically, no joint size effect exists on 100% smooth homogeneous joints. Based on this theory and the results obtained from this study, the authors strongly believe that the contradictory findings that appear in the literature on joint size effects for more than 40 years have resulted from roughness heterogeneity. This means that the rock joint heterogeneity controls the scale effect, and it can be either negative, positive, or no scale effect depending on the type and level of the heterogeneity of the rock joint surface. The studied rock joint showed significant roughness anisotropy and sampling interval effect. RMS parameter was found to be an unsuitable parameter to quantify rock joint roughness. Useful comparisons are made between several 2-D and 3-D roughness parameters. All the aforementioned are important contributions to the literature and have advanced our understanding of rock joint roughness quantification.
      PubDate: 2022-05-03
       
  • Mechanical, micro-structure and contour mapping analyses of highly-porous
           intermediate-texture analog rock from instrumented micro-indentation in
           conjunction with statistical/machine learning tools

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      Abstract: Abstract Exploring the spatial variability of the mechanical properties of rocks and cementitious/porous materials, provides an understanding on the distribution of the mechanical phases and the surface characteristics of the material. This type of analysis often necessitates instrumented indentation experiments to be performed, which comprises a highly promising technique in the characterization of rocks in the fields of unconventional reservoir and energy geomechanics, as the indentation test results can offer an alternative and cost-effective assessment of the bulk behavior of rocks and help to interpret geophysical and stratigraphic analyses. In the present study, we investigated through micro-indentation experiments the elastic properties of a crystalline-to-vesicular intermediate-texture analog rock and the relationship of modulus and hardness with the different phases of the material. For this purpose, alumina-based ceramic was used as a paradigm analog rock, which conforms with the columnar class displaying a structure similar to that of some types of extrusive igneous rocks, resembling a porous structure which can be of interest in many areas of geo-energy and resources engineering. An instrumented experimental program adopting the grid method was implemented and the samples were tested in their original (non-abraded) and in abraded states. The results revealed high spatial variability of hardness and modulus and significant influence of the position the indenter penetrates the sample. This provides a qualitative inference that a single value of hardness (or modulus) may not adequately represent the inherent properties of rocks. Clustering analysis, Weibull statistics and contour mapping were some of the major tools used to characterize the analog rock. The Weibull analysis could provide better qualitative inferences on the influence of abrasion on the elastic properties of the material compared with the direct use of mean values, and the mapping showed, on a qualitative standpoint, a good correlation between elastic properties, chemical composition and textural characteristics of the samples. These results provide some new directions in the application of instrumented indentation, in conjunction with Weibull and machine learning analyses, in the characterization of rocks and solids of complex structures, dictating that interpretation of mean values may not be the most effective way to analyze indentation test data, but an approach such as Weibull statistics can provide a more effective means to deal with the large discrepancy of the test results, which is expected to be the case for many rocks. As porous rocks are often encountered in sedimentary basins and have been identified as a potential path for expanding geo-energy production, the present study provides promising directions in the application of instrumented indentation for the characterization of such materials with direct interest in oil/gas exploitation and design of the production process.
      PubDate: 2022-04-30
       
  • Numerical investigation of spontaneous imbibition in an anisotropic
           reservoir

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      Abstract: In this study, co-current spontaneous imbibition in two-dimensional reservoir formations saturated with two immiscible and incompressible fluids is investigated. A computational workbench is proposed assuming that the porosity of the medium is constant however permeability is anisotropic i.e., direction-dependent. Numerical experiments are performed for two geometrically distinct reservoir domains, namely, narrow channel and square duct. The numerical experiments reveal that the dynamics of the recovery significantly depend on the ratio of the vertical to the horizontal intrinsic permeability i.e., anisotropic ratio. Specifically, the front propagation shows a striking dependency on the anisotropy of the medium. This analysis indicates that the cross-flow behavior triggers early water breakthrough and consequently substantial amount of oil/non-wetting phase bypassing. In addition, it is noted that the onset of forced imbibition is regulated by the mean pressure distribution of the underground formation. This article develops a correlation between the oil recovery percentage (%) and the reservoir quality index (RQI). This can predict the oil recovery trend at a particular instance for a given reservoir configuration depending on the corresponding RQI values. Article highlights Analyzed the influence of permeability anisotropy on the spontaneous imbibition. The consequence of the cross-flow behavior is captured. A correlation between the reservoir quality index and the oil recovery percentage is developed.
      PubDate: 2022-04-30
       
  • Investigation of rock mass structural similarity in two islands in Vietnam

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      Abstract: In a rock mass, the joint geometry pattern may change from one area to another. Rock masses having similar joint geometry patterns are known as structural domains in the engineering geology literature (also termed as structural similar regions in this paper). Geometrical properties of joints control the geomechanical behavior of jointed rock masses. Therefore, the demarcation of structural domains should be the first step in working with field jointed rock mass geomechanical behavior. To investigate the structural similarity of the rock masses of two islands in Vietnam, three procedures are implemented in this paper. The results indicated the possibility of obtaining somewhat different structural similarities for the investigated rock masses for each of the applied procedures. It indicates that the conclusions made on structural similarity of rock masses based on only one procedure can lead to poor or low reliability. The paper illustrates how to arrive at better judgements on rock mass structural similarity by combining the results coming from all the applied procedures. Article Highlights Analysis methods yielded various degrees of ranking on structural similarity. Better judgement on rock mass structural similarity is made when results from several methods are combined. Investigated sites showed a complicated structural similarity.
      PubDate: 2022-04-30
       
  • Modeling of Navier–Stokes flow through sheared rough-walled granite
           fractures split after thermal treatment

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      Abstract: The Navier–Stokes flow through rough-walled granite fractures during shearing, where the fractures are prepared by splitting the granite blocks after heating and the onset of nonlinear fluid flow is closely related to the temperature and shear displacement, is modeled in this paper. The results show that as the temperature increases from 25 °C to 900 °C, the joint roughness coefficient of split granite surfaces increases from 16.07 to 21.62, following an exponential function.The predicted normal displacements during shearing under different initial normal stresses are consistent with the normal displacements in shearing reported in the literature, verifying the validity of the utilized expressions for calculating the shear-induced dilation. The rock strength weakens and the normal displacement decreases with the increment of surrounding temperature. As a result, the contact area increases, and the void spaces providing flow paths for fluids are decreased. The permeability holds constant at a small hydraulic gradient and then gradually decreases with increasing hydraulic gradient, indicating that the fluid flow transits from a linear regime to a nonlinear regime. The onset of nonlinear fluid flow can be quantify using the indicator of the critical hydraulic gradient which is positively proportional to the temperature and shear displacement and it ranges from 0.27 × 10–3 to 6.71 × 10–3. Article Highlights Navier-Stokes flow through sheared rough-walled joints is modelled. Tortuous streamlines and eddies are simulated and analyzed. Critical hydraulic gradient quantifying onset of nonlinear flow is determined.
      PubDate: 2022-04-29
       
  • Acoustic emission characteristics of high-temperature granite through
           different cooling paths

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      Abstract: Cooling shock is a key technical means to improve rock breakage rate and drilling rate. Studying the acoustic emission characteristics of high-temperature granite under cooling shock is of great significance for analyzing the damage of hot dry rock (HDR) reservoirs and improving the heat extraction efficiency. This paper analyses the temperature change and acoustic emission (AE) characteristics of the granite heating process (25–600 ℃), air cooling, pore water injection, surface water spraying, and liquid nitrogen cooling, exploring the heat treatment method and the microstructural changes of granite. The results show that (1) During the cooling process, the violent cooling impact on the high temperature granite is the main reason for the AE signal. (2) In the cooling process, the effect of rapid cooling on high temperature granite damage is much greater than slow cooling. (3) When the high-temperature granite is cooled, the cumulative acoustic emission count is significantly smaller than that during the heating process. Therefore, there is a general law of greater heating damage and less cooling damage. This article has certain research significance for the engineering applications of geothermal energy mining. Article Highlights In this paper, the acoustic emission characteristics of high-temperature granite under different cooling impacts are investigated. During the heating process of granite, its crack density gradually increases. Granite in the first heating and then cooling process, thermal damage is obvious, while the cooling damage changes less.
      PubDate: 2022-04-29
       
  • Numerical simulation on the deformation characteristics of borehole
           failure in gas-bearing coal seams considering the effective stress
           principle under complicated stress path conditions

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      Abstract: To numerically investigate the stress distribution and deformation failure level of gas drainage boreholes in deep soft coal seams, ABAQUS is applied to numerical simulations based on the effective stress principle, under various conditions of compressive strengths, in-situ stresses, borehole diameters, gas pressures, and other factors. Simulation results indicate that the occurrence of vertical stress peak and position vary with the geo-stress, compressive strength of the coal mass, and gas pressure of the coal, accordingly the displacement and deformation of the borehole wall emerge. The maximum vertical stress of the coal mass is increased to 35.11 MPa while the imposed geo-stress is 25 MPa. Correspondingly, the displacement and deformation of the borehole wall reach 17.16 mm. Although the compressive strength of the coal mass increases from 2.6 to 5.2 MPa, the displacement and deformation of the borehole wall decreases from 17.3 to 5.19 mm. Nevertheless, the change in the borehole diameter will not trigger dramatic variations on the stress and deformation failure of the borehole. Research results provide theoretical support required to effectively address the stuck and collapse of long inseam boreholes while drilling in deep and soft coal seams. In addition, research results demonstrate a positive influence on the gas drainage with long and large inseam boreholes in highly gassy coal mines. Article highlights The stress distribution and deformation failure of boreholes in deep gassy coal seams have been numerically investigated on the basis of effective stress principle. The occurrence position of vertical peak stress of boreholes in gassy coal seam will gradually shift away from the borehole center as the geo-stress and the gas pressure of the coal seam increase. The variation of the borehole diameter negligibly influence the stability of the borehole in gassy and soft coal seams.
      PubDate: 2022-04-28
       
  • A new approach to estimate drilling time, rate of penetration, and
           drillability of formations in oil and gas exploration and production
           basins of Turkey

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      Abstract: Abstract It is of great importance that the drilling program required for the newly drilled wells is estimated by using the drilling data of the previously drilled wells in a field or basin to complete the drilling under economic and optimum conditions within the estimated time. In this study, in the Southeastern Anatolia and Thrace basins of Turkey, where both oil and gas exploration and production are performed, a new approach has been presented for the estimation of drilling time before drilling, using the rate of penetrations (ROPs), weights on bit (WOB), rotation speeds, and actual (net) drilling times of the previously drilled wells as well as based on the formation thicknesses predicted by the geological and geophysical data provided from any field. For the formations in both basins, equations for the actual drilling time estimation and drillability factors have been determined depending on them. The results of the new approach show that the actual drilling times can be estimated with high accuracy according to the formation thickness to be drilled before drilling. Moreover, ROPs can be forecasted based on the estimated actual drilling times.
      PubDate: 2022-04-28
       
  • Effects of supercritical carbon dioxide under different conditions on
           mechanical properties and energy evolution of coal

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      Abstract: Abstract The experiments of soaking coal in supercritical carbon dioxide for different times and under different temperatures were performed. Combined with computed tomography scanning, acoustic emission detection and uniaxial compression tests, the micro damage and macro mechanical response characteristics of coal after supercritical carbon dioxide action were studied. The results showed that the effect of supercritical carbon dioxide on coal strength was significant. With increasing soaking time, the compressive strength of the coal decreased and then became constant. The coal strength increased linearly with increasing soaking temperature. In addition, when the soaking time was less than 3 days, a large number of pores and fractures were left by supercritical carbon dioxide extraction and dissolution, and the acoustic emissions energy rate of the coal decreased rapidly in the process of uniaxial compression. Finally, the fracture and instability forms of coal after the action of supercritical carbon dioxide of different conditions were also different. With increasing soaking time, the fracture form of the coal changed from tensile shear fracture to shear fracture. When the temperature of supercritical carbon dioxide increased, the fracture form of coal sample changed from shear fracture to tension shear fracture. On the whole, the influence of supercritical carbon dioxide soaking time on the mechanical properties of the coal was significantly greater than that of the soaking temperature. The evolution results of coal strength and structure under the action of supercritical carbon dioxide of different conditions obtained in this paper can provide a reference for the application of the safe and efficient exploitation of coalbed methane through the use of supercritical carbon dioxide.
      PubDate: 2022-04-28
       
  • Modeling of in-situ horizontal stresses and orientation of maximum
           horizhontal stress in the gas hydrate-bearing sediments of the Mahanadi
           offshore basin, India

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      Abstract: Horizontal stresses are key parameters of reservoir geomechanics and wellbore stability modeling. For scientific well drilling, where direct measurements are not always available, modeling of horizontal stresses is challenging, especially for highly porous un-compacted gas hydrate-bearing sediments below the seafloor. We have estimated the minimum (Sh) and maximum (SH) horizontal stresses by using rock poro-elastic models based on three wells data which are situated at the national gas hydrate program (NGHP)-01 sites of the offshore Mahanadi basin. The stress magnitudes are validated by wellbore breakout. We have computed the stress magnitudes using 2D seismic for mapping the gas hydrate-bearing sediments. The average gradients of SH and Sh (10.58 MPa/km and 10.48 MPa/km) are less than the gradient of vertical stress, SV (10.67 MPa/km). The present-day stress distribution at the NGHP-01 site is principally a normal faulting (SV > SH > Sh) regime as obtained from stress polygons. The breakouts identified from both formation image and caliper data, suggest a NNW-SSE orientation for SH in the Pleistocene age, which is slightly anti-clock wise relative to the northward oriented of the Indian sub-continent. This change in the orientation of SH could be due to a local structure/fault system cross-cutting the bottom simulating reflector, and mass sliding/slumping on the seafloor. The orientation of SH varies from N11.25°W to N25.7°W of D-quality. We have analysed wellbore stability using the Mohr–Coulomb circle and hoop stress techniques. These results will enable numerical modeling of production from gas hydrate reservoirs planned for the future. Article Highlights Identification of breakout from formation image and caliper log data and hence, orientation of horizontal stress in the gas hydrates-bearing sediments of the offshore Mahanadi basin. Magnitude of the maximum horizontal stress at breakout intervals and the continuous profile of the horizontal stresses using both well data at NGHP-01 sites and multi-channel seismic data. Analysis of stress polygons, Mohr circles and hoop stress distributions at the selected depth intervals near the gas hydrate-bearing sediments.
      PubDate: 2022-04-23
       
  • Mesoscopic damage evolution characteristics of jointed sandstone under
           different loading conditions

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      Abstract: Abstract To reveal the influence of different loading conditions on the damage evolution of jointed sandstone, the numerical model with realistic mesostructure was established using CT scans and RFPA3D. Moreover, uniaxial compression tests of similar simulated specimens were performed. Three-dimensional fractures were extracted and reconstructed. A digital image-based rock microscopic scale fractured box dimension algorithm was written in MATLAB to analyze the three-dimensional fractal features of the AE fields. Studies have revealed that plane-to-plane and point-to-plane loading are both the mixed failure of tension and compression. Whereas point-to-point loading is a compression failure, and multi-point loading is a tensile failure. There are significant variations in damage characteristics and evolution of multi-point loading; the specimen’s fractal dimension is 2.5622, which is the largest, and it has the most significant crack propagation, the most complicated rupture mode, and a relatively good damage effect. The fractal dimension determined by the AE field can quantitatively assess the mesoscale damage evolution. The research findings are significant in understanding the rules of jointed sandstone breakage and energy consumption, in addition to searching for an effective and energy-saving rock-breaking technology.
      PubDate: 2022-04-23
       
  • Numerical research on response characteristics of surrounding rock for
           deep layered clastic rock roadway under static and dynamic loading
           conditions

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      Abstract: Abstract The stability of the layered clastic rock roadway is a major difficulty encountered in deep mining process of the gold deposit in Southwestern Guizhou. According to field geological situation, the response characteristics of deep layered clastic rock roadway under static-dynamic loading condition are studied by using the FLAC3D numerical software. The study found that the roof-floor deformation is largest under the static load, and the excavation process causes plastic failure of the weak mudstone. While under static-dynamic loading condition, the surrounding rock has more complex responses. The rib sides deformation is most significantly affected by the buried depth, and the deformation at the buried depth of 1000 m is about 2.8 times larger than that at 600 m. The plastic zone around the roadway tends to intersect with the weak mudstone. The dynamic load amplitude is the key to the response time of surrounding rock, and the response time increases from 0.1 to 0.25 s when the peak particle velocity (PPV) increase from 2 to 10 cm/s. The plastic zone around the roadway and the weak mudstone finally intersect. As the weak mudstone thickness increases, the disturbance degree of the dynamic load to the roadway first increases and then decreases. Based on these analyses, empirical equation for response of surrounding rock under different conditions is proposed through regression analysis. The results can provide references for stability analysis and support optimization of deep layered clastic rock roadway under similar geological parameters.
      PubDate: 2022-04-23
       
  • Study of mechanical properties and failure characteristics of combined
           rock mass with weak interlayer

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      Abstract: Abstract To research the failure characteristics of rock masses with weak interlayers, a combined rock mass model composed of sandstone-mudstone-siltstone is established (CRM). Theoretical analysis, mechanical tests, and numerical simulations are used to study the failure mechanism of CRM with weak interlayers. The RMT-301 mechanical test system is used to execute the compression testing of the combined rock mass, and the FLAC3D strain softening constitutive model is used for comparative analysis. The results show the following: the strength difference causes additional stress near the contact surface; the strength of the both ends of the CRM decreases while the strength of the weak interlayer increases; the thickness ratio of the mudstone interlayer has a powerful impact on the force state and deformation characteristics of CRM; the peak strength of CRM rises with increasing confining pressure (σ3); when the combined rock mass is under uniaxial compression, its peak strength shows obvious strain-softening behavior; when the σ3 raises, the failure mode of the combined rock mass alters from tensile failure to shear failure; high σ3 enhances the mechanical properties of the weak interlayers and weakens the weakening effect of weak interlayers on the CRM to a certain degree; the level of damage deterioration of the combined rock mass declines with the rise of σ3 because while the σ3 improves the stress state of the CRM, the initial damage of the weak interlayer is reduced.
      PubDate: 2022-04-22
       
  • Physical simulation of the nonlinear transient flow behavior in closed
           high-pressure gas reservoirs. Part II: pressure-depleted flow experiments
           on fractured cores

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      Abstract: In this study, a pressure-depleted flow (PDF) experiment on 5 artificially fractured cores was conducted for the first time to simulate physically the transient flow behavior (TFB) in closed high-pressure (HP) gas reservoirs. The experimental method was the same as the matrix core experiment described in Part I. A series of flow rate and pressure curves were drawn, and then matched using regression equations. The nonlinear TFB characteristics were thoroughly analyzed and compared with those of the matrix cores (Part I). The pressure curves between the fractured and matrix cores were similar, but the flow rate curves were different. Particularly, the curves of decline in the flow rate are plotted. It was observed that the decline in flow rate curves reflected the typical inter-porosity flow behavior of dual porosity media, which completely differed from the matrix cores. Additionally, the final recovery factor was calculated using the pressure arithmetic mean method. Finally, the nonlinear TFB characteristics were summarized. The results of this study revealed that the nonlinearity of gas flow through fractured cores was stronger than that through matrix cores. This work can be an excellent reference for investigators to research the nonlinear TFB of fluids in complex porous media. Article Highlights The experiment of the flow behavior on fractured cores was first performed and the nonlinear flow characteristics were analyzed. The inter-porosity flow phenomenon between matrix and fracture media was first discerned from decline rate curves. The pressure-depleted of experimental results were compared between the fractured and matrix cores.
      PubDate: 2022-04-17
       
 
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