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 by number of followers
IET Power Electronics     Open Access   (Followers: 76)
Energy Policy     Partially Free   (Followers: 73)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 50)
IEEE Transactions on Power Systems     Hybrid Journal   (Followers: 45)
Energy     Partially Free   (Followers: 40)
IEEE Power and Energy     Full-text available via subscription   (Followers: 36)
Journal of Physical Chemistry C     Hybrid Journal   (Followers: 36)
Solar Energy Materials and Solar Cells     Hybrid Journal   (Followers: 29)
Advances in Natural Sciences : Nanoscience and Nanotechnology     Open Access   (Followers: 28)
Energy & Fuels     Hybrid Journal   (Followers: 27)
Nature Energy     Hybrid Journal   (Followers: 27)
Applied Energy     Partially Free   (Followers: 26)
Energy & Environment     Hybrid Journal   (Followers: 24)
International Journal of Alternative Propulsion     Hybrid Journal   (Followers: 23)
Energy and Power Engineering     Open Access   (Followers: 23)
International Journal of Turbomachinery, Propulsion and Power     Open Access   (Followers: 23)
Advances in High Energy Physics     Open Access   (Followers: 23)
Applied Solar Energy     Hybrid Journal   (Followers: 20)
Water International     Hybrid Journal   (Followers: 19)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 19)
Solar Energy     Hybrid Journal   (Followers: 19)
International Journal of Hydrogen Energy     Partially Free   (Followers: 19)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 19)
Energy and Power     Open Access   (Followers: 18)
Journal of Solar Energy Engineering     Full-text available via subscription   (Followers: 18)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 18)
Advances in Energy and Power     Open Access   (Followers: 16)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 16)
IEEE Transactions on Energy Conversion     Hybrid Journal   (Followers: 16)
Progress in Energy and Combustion Science     Hybrid Journal   (Followers: 15)
Energy Conversion and Management     Hybrid Journal   (Followers: 15)
International Journal of Thermodynamics     Open Access   (Followers: 15)
Energy, Sustainability and Society     Open Access   (Followers: 15)
Energy Journal The     Hybrid Journal   (Followers: 14)
Energy and Environment Research     Open Access   (Followers: 13)
Surface Science Reports     Full-text available via subscription   (Followers: 13)
Economics and Policy of Energy and the Environment     Full-text available via subscription   (Followers: 13)
Waste Management     Hybrid Journal   (Followers: 13)
International Journal of Sustainable Energy     Hybrid Journal   (Followers: 12)
Energy and Buildings     Hybrid Journal   (Followers: 12)
Energy Systems     Hybrid Journal   (Followers: 11)
Energy Research & Social Science     Full-text available via subscription   (Followers: 11)
Oil and Gas Journal     Full-text available via subscription   (Followers: 11)
Advances in Building Energy Research     Hybrid Journal   (Followers: 11)
Journal of Solar Energy     Open Access   (Followers: 11)
Biofuels     Hybrid Journal   (Followers: 11)
Energy Science and Technology     Open Access   (Followers: 10)
Annual Review of Resource Economics     Full-text available via subscription   (Followers: 10)
Innovations : Technology, Governance, Globalization     Hybrid Journal   (Followers: 10)
Archives of Thermodynamics     Open Access   (Followers: 10)
IEEE Transactions on Nuclear Science     Hybrid Journal   (Followers: 10)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Journal of Ocean and Climate     Open Access   (Followers: 9)
Energy Efficiency     Hybrid Journal   (Followers: 9)
Journal of Modern Power Systems and Clean Energy     Open Access   (Followers: 9)
International Journal of Green Energy     Hybrid Journal   (Followers: 8)
Energy Strategy Reviews     Open Access   (Followers: 8)
International Journal of Electric and Hybrid Vehicles     Hybrid Journal   (Followers: 8)
International Journal of Energy Research     Hybrid Journal   (Followers: 8)
International Journal of Global Energy Issues     Hybrid Journal   (Followers: 8)
Batteries     Open Access   (Followers: 8)
Wiley Interdisciplinary Reviews : Energy and Environment     Hybrid Journal   (Followers: 8)
Journal of Renewable Energy     Open Access   (Followers: 8)
International Journal of Energy and Power     Open Access   (Followers: 8)
CERN courier. International journal of high energy physics     Free   (Followers: 8)
Environmental Progress & Sustainable Energy     Hybrid Journal   (Followers: 7)
Applied Nanoscience     Open Access   (Followers: 7)
Energy and Environment Focus     Free   (Followers: 7)
American Journal of Energy Research     Open Access   (Followers: 7)
Annals of Nuclear Energy     Hybrid Journal   (Followers: 7)
Fuel and Energy Abstracts     Full-text available via subscription   (Followers: 7)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 6)
Energy Science & Engineering     Open Access   (Followers: 6)
Energy Prices and Taxes     Full-text available via subscription   (Followers: 6)
Materials for Renewable and Sustainable Energy     Open Access   (Followers: 6)
Energy Reports     Open Access   (Followers: 5)
Joule     Hybrid Journal   (Followers: 5)
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 5)
Energy Technology     Partially Free   (Followers: 5)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 5)
Journal of Energy & Natural Resources Law     Hybrid Journal   (Followers: 5)
Frontiers in Energy Research     Open Access   (Followers: 5)
Batteries & Supercaps     Hybrid Journal   (Followers: 5)
International Journal of Sustainable Energy Planning and Management     Open Access   (Followers: 5)
Atomic Energy     Hybrid Journal   (Followers: 5)
Energy and Environmental Engineering     Open Access   (Followers: 5)
Geothermal Energy     Open Access   (Followers: 5)
Energy Studies Review     Open Access   (Followers: 5)
Journal of Energy Technologies and Policy     Open Access   (Followers: 5)
Energy Storage Materials     Full-text available via subscription   (Followers: 5)
Carbon Management     Hybrid Journal   (Followers: 5)
Journal of Nano Energy and Power Research     Full-text available via subscription   (Followers: 4)
Journal of Energy, Environment & Carbon Credits     Full-text available via subscription   (Followers: 4)
American Journal of Energy and Environment     Open Access   (Followers: 4)
International Journal of Applied Power Engineering     Open Access   (Followers: 4)
Journal of International Energy Policy     Open Access   (Followers: 4)
International Journal of Nuclear Energy Science and Technology     Hybrid Journal   (Followers: 4)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 4)
ACS Energy Letters     Hybrid Journal   (Followers: 4)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 4)
Annual Reports on NMR Spectroscopy     Full-text available via subscription   (Followers: 4)
Development of Energy Science     Open Access   (Followers: 4)
ACS Applied Energy Materials     Hybrid Journal   (Followers: 4)
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
Foundations and Trends® in Renewable Energy     Full-text available via subscription   (Followers: 4)
Strategic Planning for Energy and the Environment     Hybrid Journal   (Followers: 4)
Sustainable Energy, Grids and Networks     Hybrid Journal   (Followers: 4)
Frontiers in Energy     Hybrid Journal   (Followers: 4)
Protection and Control of Modern Power Systems     Open Access   (Followers: 3)
Functional Materials Letters     Hybrid Journal   (Followers: 3)
Power Technology and Engineering     Hybrid Journal   (Followers: 3)
Dams and Reservoirs     Hybrid Journal   (Followers: 3)
Journal of Energy, Mechanical, Material and Manufacturing Engineering     Open Access   (Followers: 3)
Journal of Energy Chemistry     Full-text available via subscription   (Followers: 3)
Journal of Photochemistry and Photobiology C: Photochemistry Reviews     Full-text available via subscription   (Followers: 3)
Energy and Emission Control Technologies     Open Access   (Followers: 3)
International Journal of Energy and Environmental Engineering     Open Access   (Followers: 3)
Wind Energy     Hybrid Journal   (Followers: 3)
International Journal of Energy and Statistics     Hybrid Journal   (Followers: 3)
Distributed Generation & Alternative Energy Journal     Hybrid Journal   (Followers: 3)
Science and Technology of Nuclear Installations     Open Access   (Followers: 3)
Journal of Photochemistry and Photobiology A: Chemistry     Hybrid Journal   (Followers: 3)
Journal of Power and Energy Engineering     Open Access   (Followers: 2)
Sustainable Energy     Open Access   (Followers: 2)
Clean Energy     Open Access   (Followers: 2)
Energy Technology & Policy     Open Access   (Followers: 2)
Green Energy & Environment     Open Access   (Followers: 2)
Materials Today Energy     Hybrid Journal   (Followers: 2)
Energy Storage     Hybrid Journal   (Followers: 2)
Journal of Technology Innovations in Renewable Energy     Hybrid Journal   (Followers: 2)
Journal of Ocean Engineering and Marine Energy     Hybrid Journal   (Followers: 2)
International Journal of Smart Grid and Green Communications     Hybrid Journal   (Followers: 2)
IET Smart Grid     Open Access   (Followers: 2)
Carbon Resources Conversion     Open Access   (Followers: 2)
Advanced Materials Technologies     Hybrid Journal   (Followers: 2)
Journal of Energy     Open Access   (Followers: 2)
International Journal of Nuclear Knowledge Management     Hybrid Journal   (Followers: 2)
Proceedings of the Institution of Civil Engineers - Energy     Hybrid Journal   (Followers: 2)
EPJ Photovoltaics     Open Access   (Followers: 2)
International Journal of Clean Coal and Energy     Open Access   (Followers: 2)
Progress in Nuclear Energy     Hybrid Journal   (Followers: 2)
Journal of Fusion Energy     Hybrid Journal   (Followers: 2)
Gcb Bioenergy     Open Access   (Followers: 2)
Science and Technology for Energy Transition     Open Access   (Followers: 2)
Journal of Energy in Southern Africa     Open Access   (Followers: 2)
Journal of Alternate Energy Sources & Technologies     Full-text available via subscription   (Followers: 2)
Journal of Nuclear Energy Science & Power Generation Technology     Hybrid Journal   (Followers: 2)
Sustainable Energy & Fuels     Hybrid Journal   (Followers: 1)
International Journal of Energy and Smart Grid     Open Access   (Followers: 1)
International Journal of Nuclear Hydrogen Production and Applications     Hybrid Journal   (Followers: 1)
Clean Technologies     Open Access   (Followers: 1)
Energy Conversion and Management : X     Open Access   (Followers: 1)
IET Energy Systems Integration     Open Access   (Followers: 1)
Radioprotection     Hybrid Journal   (Followers: 1)
Electricity Journal     Hybrid Journal   (Followers: 1)
International Journal of Nuclear Desalination     Hybrid Journal   (Followers: 1)
Michigan Journal of Sustainability     Open Access   (Followers: 1)
Clefs CEA     Full-text available via subscription   (Followers: 1)
Journal of Computational Multiphase Flows     Open Access   (Followers: 1)
International Journal of Power and Energy Conversion     Hybrid Journal   (Followers: 1)
Technology Audit and Production Reserves     Open Access   (Followers: 1)
International Journal of Coal Science & Technology     Open Access   (Followers: 1)
Nigerian Journal of Technological Research     Full-text available via subscription   (Followers: 1)
Open Journal of Energy Efficiency     Open Access   (Followers: 1)
Asian Bulletin of Energy Economics and Technology     Open Access   (Followers: 1)
Biofuel Research Journal     Open Access   (Followers: 1)
International Journal of Energy and Water Resources     Hybrid Journal  
BioPhysical Economics and Resource Quality     Hybrid Journal  
Geomechanics and Geophysics for Geo-Energy and Geo-Resources     Hybrid Journal  
Energy, Ecology and Environment     Hybrid Journal  
Technology and Economics of Smart Grids and Sustainable Energy     Hybrid Journal  
BMC Energy     Open Access  
Journal of Energy and Environment Technology of Graduate School Siam Technology College     Open Access  
Global Energy Interconnection     Open Access  
Journal of Energy Systems     Open Access  
International Journal of Energy & Engineering Sciences     Open Access  
Turkish Journal of Energy Policy     Open Access  
Energy Informatics     Open Access  
Global Challenges     Open Access  
High Voltage     Open Access  
Geomechanics for Energy and the Environment     Full-text available via subscription  
ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations     Open Access  
Sustainable Energy Technologies and Assessments     Full-text available via subscription  
Journal of China Coal Society     Open Access  
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Universal Journal of Applied Science     Open Access  
Ingeniería Energética     Open Access  
E3S Web of Conferences     Open Access  
Washington and Lee Journal of Energy, Climate, and the Environment     Open Access  
Journal of Sustainable Bioenergy Systems     Full-text available via subscription  
International Journal of Ambient Energy     Hybrid Journal  
CT&F - Ciencia, Tecnología y Futuro     Open Access  
Multequina     Open Access  
Natural Resources     Open Access  
South Pacific Journal of Natural and Applied Sciences     Hybrid Journal  
Chain Reaction     Full-text available via subscription  
Wind Engineering     Hybrid Journal  
Nuclear Data Sheets     Full-text available via subscription  
Global Energy Law and Sustainability     Hybrid Journal  
International Journal of Nuclear Governance, Economy and Ecology     Hybrid Journal  

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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]
  • 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
       
  • Effects of water content on mechanical failure behaviors of coal samples

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      Abstract: Abstract The mechanical properties and degradation caused by damage within coal pillar dams determine the safety and stability of underground water reservoirs. This study investigated the influence of moisture content on the mechanical properties and failure behaviors of coal samples by conducting a series of non-destructive water immersion, uniaxial compression, acoustic emission (AE), and computed tomography tests, with the objective of providing a reference for the design and maintenance of coal pillar dams in underground water reservoirs and other engineering problems (such as roadway support) in coal mines. The coal samples had low saturated water content because of poor porosity and few clay minerals (illite and kaolinite). The uniaxial compressive strength, elastic modulus, and strain softening modulus of the coal samples decreased almost linearly with water content. Four types of post-peak variation forms of the coal samples were summarized and quantitatively studied using the post-peak gradient. The crack propagation process of coal samples with different water contents was further divided according to the AE count and cumulative AE count. Finally, a new method was proposed to calculate the inclination angle of the failure surface of the coal samples fitted using the AE location. Low water content generally resulted in larger inclination angles (37°, 39°), and high water content generally resulted in smaller inclination angles (26°, 33°); these results were consistent with the 3D reconstructions of cracks in the coal samples. Overall, this study supports the use of the inclination angle of fitted failure surfaces to approximately determine the water content and damage of coal samples.
      PubDate: 2022-04-16
       
  • Mechanical behaviour and failure modes of high-temperature jointed granite
           based on DIC and AE Technology

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      Abstract: Abstract The stability of rock masses in deep underground engineering is always a key issue in geotechnical engineering. However, it is difficult to describe the strength and deformation characteristics of fractured rock masses using the mechanical behavior of intact rocks. The study on the mechanical properties and failure modes of high-temperature jointed rock mass is significant. In this paper, Shandong granite (in China) was taken as the research object. Fracture at different angles were prefabricated at the centre of the rock sample to simulate the echelon joints in rock. the evolution of the strain field and the process of crack initiation, development, and coalescencein the process of uniaxial compression tests were recorded and analysed by digital image correlation (DIC) and acoustic emission (AE) techniques. The results show that the crack starts from the tip of the joint and develops along a certain angle from the top or bottom of the specimen when the echelon jointed granite is subjected to external loads, and the specimen is destroyed when a through-crack is formed. The crack morphology is primarily tensile and shear cracking. When the prefabricated joints are at 30° and 45°, the specimen failure is the result of the joint action of tensile and shear failure. When the prefabricated joint angle is 60°, the tensile failure of the specimen mainly occurs, and the minor shear failure is supplemented.
      PubDate: 2022-04-16
       
  • Experimental characterization of time-dependent mechanical behaviours of
           frac sand at high compressive stresses and implication on long-term
           proppant conductivity

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      Abstract: This paper experimentally examines the time-dependent mechanical behaviours of frac sand at high compressive stresses. A series of instant and sustained one-dimensional compression tests was performed on Jordan sand, White sand, and Genoa sand, and three grain size distributions for each frac sand were tested. The acoustic emission events related to sand crushing were monitored by piezoelectric sensors for understanding sand breakage during compression. The results show that Genoa sand with 25% weaker anorthite mineral grains show much more grain breakage and higher plastic and creep strains at high compressive stresses than the pure quartz Jordan and White sand. Wider grain size distributions tend to result in larger plastic strains than narrower size distributions but provide better crushing resistance and smaller creep deformation. Cyclic and creep load stages only slightly increase grain breakage compared with instant loads, but result in higher plastic and creep strains. Two creep stages were found in the time-dependent deformation of sand and can be satisfactorily depicted with the Riemann–Liouville fractional calculus model at different stress levels, with sand’s fractional derivative of increases from 0.28 to 0.35 as sand grains are gradually crushed. Lower viscosity coefficients are found in Genoa (~ 15e4 MPa*s) than White and Jordan sand (> 20e4 MPa*s). The time-dependent deformation of sand proppant has a significant implication on the long-term conductivity of sand packs, which can reduce the hydraulic conductivity by about 40%–90% after a one-year duration. The results warrant considering frac sand’s long-term deformation when choosing frac sand as proppants in hydraulic fracturing. Article Highlights Weaker Genoa sand shows 50–150% higher plastic and creep strains than Jordan and White sand at high compression. Wider grain size distributions result in larger plastic but smaller strains creep in sand at sustained loads. Creep strain is depicted by fractional calculus with an increased derivative from 0.28 to 0.35 as sand is crushed.
      PubDate: 2022-04-07
       
  • ANN-based multicomponent seismic data-driven prediction of gas-bearing
           distribution

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      Abstract: It is conducive to obtain reservoir information by effectively using the sensitivity difference of multicomponent data in them. However, it is very troublesome to find the relationship between multicomponent seismic data and reservoir properties. Although artificial neural network (ANN) can potentially solve this problem, the major challenge of ANN application in prediction of gas-bearing distribution is the generation of an accurate model under a limited dataset. Therefore, this paper expands the sample dataset, and then uses ANN to predict the gas-bearing distribution of tight sandstone reservoir based on multicomponent seismic data. First, the sample dataset of borehole-side seismic gathers was constructed through local seismic waveform data and known drilling gas-bearing information. This method extracted more labels to delineate the gas reservoir characteristics. Then, multi-layer perceptron and radial basis function neural networks were used to predict the gas-bearing distribution from multi-component seismic data. In this process, the hyperparameters of ANN were carefully selected through different evaluation indices to obtain an effective prediction model. Finally, the gas-bearing distribution throughout the entire Fenggu structural area was obtained by the developed ANN models, and the performance of the two network models were comprehensively evaluated. The results showed that compared with the support vector machine model, single component seismic attributes, and conventional geostatistics methods, the proposed method was more accurate in predicting the gas-bearing distribution, which verifies the effectiveness of the proposed method. The results of this study would be helpful in making better decisions when applying the ANNs to other datasets in the future. Article highlights Multicomponent composite attributes could highlight gas characteristics and improve prediction accuracy of ANN model. Different ANN models are constructed for reservoir prediction and compared the prediction performance with SVM model. Compared with the conventional geostatistical approach, ANN has high accuracy and reliability for reservoir prediction.
      PubDate: 2022-04-05
       
  • Factors affecting the lower limit of the safe mud weight window for
           drilling operation in hydrate-bearing sediments in the Northern South
           China Sea

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      Abstract: Abstract Maintaining wellbore stability is the basis and prerequisite for efficient methane production from offshore gas hydrates. Nevertheless, owing to the invasion and disturbance by drilling mud, gas hydrates around wellbore gradually dissociate, resulting in the rapid reduction of sediment strength, thereby the borehole collapse. Accurate design of mud density based on appropriate strength criterion is a feasible measure to avoid this case, but the traditional Mohr–Coulomb (MC) criterion was commonly used now. Herein, the self-designed low temperature triaxial experimental equipment was set up to explore the strength of sediment with different saturation of hydrate, and a new strength criterion was developed. Moreover, impact law and mechanism of several critical factors on the lower limit of the safe mud weight window (abbreviated as MDlow value) was then investigated. The investigation results showed that the MDlow value calculated by the new criterion is higher (or more conservative), which is more conducive for prevention of borehole collapse. Further analysis reveals that the increase of cohesion or hydrate saturation enhances the reservoir strength, resulting in the smaller MDlow value. In this way, the wider window is more conducive to reasonable mud density design. Furthermore, the safe mud weight window for hydrate reservoir is temperature sensitive, and it varies obviously when the drilling fluid temperature is between 288.14 K and 288.45 K. Finally, the investigation in this study also shows that the MDlow value was still affected by stress difference. The preferred design strategy is to orient the azimuth of wellbore axis at 90° if horizontal wellbore is drilled for hydrate development.
      PubDate: 2022-04-02
       
 
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