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)

PETROLEUM AND GAS (58 journals)

Showing 1 - 55 of 55 Journals sorted alphabetically
Advances in Petroleum Exploration and Development     Open Access  
Applied Energy     Partially Free   (Followers: 30)
Applied Petrochemical Research     Open Access   (Followers: 2)
Biofuels, Bioproducts and Biorefining     Hybrid Journal   (Followers: 3)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 8)
Chemistry and Technology of Fuels and Oils     Hybrid Journal   (Followers: 1)
Egyptian Journal of Petroleum     Open Access  
Energy & Fuels     Hybrid Journal   (Followers: 29)
Energy Geoscience     Open Access  
Energy Policy     Partially Free   (Followers: 77)
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects     Hybrid Journal   (Followers: 1)
Energy Sources, Part B: Economics, Planning, and Policy     Hybrid Journal   (Followers: 8)
Extractive Industries and Society     Hybrid Journal   (Followers: 2)
Fuel     Hybrid Journal   (Followers: 9)
Fuel Communications     Open Access   (Followers: 6)
Fuel Processing Technology     Hybrid Journal   (Followers: 4)
Gases     Open Access   (Followers: 3)
International Journal of Mining, Reclamation and Environment     Hybrid Journal   (Followers: 4)
International Journal of Oil, Gas and Coal Technology     Hybrid Journal   (Followers: 6)
International Journal of Petroleum Engineering     Hybrid Journal   (Followers: 1)
Journal of Petroleum & Environmental Biotechnology     Open Access   (Followers: 1)
Journal of Natural Gas Geoscience     Open Access  
Journal of Natural Resources Policy Research     Hybrid Journal   (Followers: 10)
Journal of Petroleum Engineering & Technology     Full-text available via subscription  
Journal of Petroleum Exploration and Production Technology     Open Access   (Followers: 2)
Journal of Petroleum Geology     Hybrid Journal   (Followers: 12)
Journal of Petroleum Science and Engineering     Hybrid Journal   (Followers: 3)
Journal of Petroleum Science and Technology     Open Access  
Journal of Synthetic Lubrication     Hybrid Journal  
Journal of the Energy Institute     Hybrid Journal  
Journal of Tribology     Full-text available via subscription   (Followers: 41)
Lubrication Science     Hybrid Journal   (Followers: 2)
Marine and Petroleum Geology     Hybrid Journal   (Followers: 20)
Natural Gas & Electricity     Full-text available via subscription  
Natural Gas Industry B     Open Access  
Natural Resources Research     Hybrid Journal   (Followers: 7)
OGEL Oil, Gas and Energy Law     Full-text available via subscription   (Followers: 6)
Oil and Energy Trends     Hybrid Journal   (Followers: 3)
Oil and Energy Trends : Annual Statistical Review     Full-text available via subscription  
Oil and Gas Journal     Full-text available via subscription   (Followers: 12)
OPEC Energy Review     Hybrid Journal   (Followers: 2)
Open Petroleum Engineering Journal     Open Access  
Petroleum     Open Access  
Petroleum Chemistry     Full-text available via subscription   (Followers: 1)
Petroleum Exploration and Development     Open Access   (Followers: 1)
Petroleum Research     Open Access  
Petroleum Science     Open Access  
Petroleum Science and Technology     Hybrid Journal   (Followers: 1)
Petrology     Full-text available via subscription   (Followers: 6)
Pipeline & Gas Journal     Partially Free  
Regional Maritime University Journal     Full-text available via subscription  
Rudarsko-geološko-naftni Zbornik     Open Access  
Scientific Drilling     Open Access  
Upstream Oil and Gas Technology     Open Access   (Followers: 1)
World Oil Trade     Hybrid Journal   (Followers: 2)
Similar Journals
Journal Cover
Natural Resources Research
Journal Prestige (SJR): 0.8
Citation Impact (citeScore): 3
Number of Followers: 7  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1573-8981 - ISSN (Online) 1520-7439
Published by Springer-Verlag Homepage  [2467 journals]
  • Geophysical Data Inversion in a Gold-Rich Porphyry System: A Case Study of
           the Dalli Deposit, Iran

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      Abstract: Abstract Obtaining spatial correlation between estimated physical parameters and corresponding lithological features is always challenging in geophysical exploration. This research provides various estimated geophysical models at two porphyry centers in the Dalli Cu–Au deposit in central Iran to characterize hydrothermal alteration zones, host lithologies, and mineralization. The dataset used in this research consists of ground magnetic and direct current electrical resistivity and induced polarization data and core drilling geochemical analyses. Constraints such as appropriate depth weighting via calculation of the power spectrum and Euler deconvolution of the magnetic data were used to relieve the non-uniqueness nature of magnetic data inversion. The resulting estimated models from 3D inversion of magnetic data to 2D inversion of direct current electrical resistivity and induced polarization data inversion indicated that higher chargeability zones and strong copper and Au mineralization zones are spatially associated with a significant modulus of magnetic susceptibility gradient. The models also confirm the presence of a U-shape pyrite shell at the Dalli porphyry deposit. Overlaying the geochemical drilling data on this shell showed that the inner boundaries correspond well with the zones of significant Cu–Au mineralization. Comparing the geophysical models with the host lithologies indicated that the inner part of the primary quartz diorite porphyry as the host rock dominantly has potassic alteration, with lower Cu–Au grades, higher magnetic susceptibility, and lower resistivity. In contrast, the main Cu–Au mineralization concentration occurs between the quartz diorite intrusion and the pyrite shell that is located mainly in the wall rock andesite porphyries, where magnetic susceptibility is decreased.
      PubDate: 2023-02-02
       
  • Quantitative Mineralogy in Characterization of Historical Tailings: A Case
           from the Abandoned Balya Pb–Zn Mine, Western Turkey

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      Abstract: Abstract This study investigated the abandoned Balya Pb–Zn mine tailing in Turkey. We performed sieve analyses, X-ray diffraction (XRD), scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS), major and trace element analyses, and SEM-based quantitative mineralogical analyses on collected samples. A schematic oxidation model comprising at least three stages is proposed based on the mineral paragenesis, textural properties of minerals, and elemental deportments. Oxidation caused the development of vertical zones such as vadose (oxidation) and capillary zones with physical, mineralogical, and chemical differences. For example, the near-surface vadose zone of sulfide oxidation contained intensely oxidized pyrite (18 wt.%) and 16 wt.% secondary minerals (As-bearing plumbojarosite, jarosite and gypsum). In contrast, the capillary zone representing a depth of 20–60 cm contained unaltered 13 wt.% pyrites, primary sulfides (e.g., sphalerite, galena, and arsenopyrite), and 23 wt.% secondary Mn–Fe–Zn-bearing oxy-hydroxides. The distribution of secondary minerals also reflected the elemental mobility depending on pH. Precipitation of plumbojarosite under acidic conditions limited the mobility of Pb and As, thereby keeping them in the vadose zone. Mn, Fe, and Zn seeped deep, and their mobility was limited by forming oxy-hydroxides at moderately acidic to circumneutral pH conditions in the capillary zone. The precipitation of the secondary minerals changed the textural properties of primary sulfides such as pyrite and galena restricted their reactivity, and caused a change in the rate and degree of oxidation over time. This case study showed that mineralogical constituents, key factors in the characterization of mine tailings, may change due to the secondary minerals, as in historical tailings with a long exposure time. Therefore, it should be noted that assessments based on the existing mineralogical properties of unoxidized tailing samples may cause uncertainties in determining the long-term behavior of the tailings.
      PubDate: 2023-02-01
       
  • Change Characteristics of Radicals in Different Stages of Coal Spontaneous
           Combustion

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      Abstract: Abstract Residual coal in mine goafs will be oxidized in the presence of air leakage, which can be well tracked through the radical reaction. This study aimed to explore the changes in radical parameters and the reactivity and persistence of newly produced radicals of coal at different temperature stages. To this end, an in situ electron spin resonance (ESR) spectrometer was adopted to measure changes in radical parameters at the heating, maintaining and cooling stages in real time. The following conclusions were drawn. At the heating stage, the radical concentration first rises slowly and then surges; the g factor remains small initially and increases rapidly later; the linewidth falls continuously. At the maintaining stage (230 °C), the radical concentration keeps increasing, while the g factor and the linewidth remain stable. At the cooling stage, the radical concentration first decreases and then stabilizes at a relatively high level, and both the g factor and the linewidth nearly return to the initial values. Based on the changes in radical parameters at different oxidation stages, the radicals in coal are divided into transient radicals and persistent radicals according to their survival times. Transient radicals, which are strongly reactive, are quickly consumed, while persistent radicals, which is of weak reactivity, can exist in the system for a long time. That is, the active radicals in coal are transient, while the stable ones are persistent. In addition, this paper gives insight into the changes in contents of active radicals and stable radicals at these stages. Finally, the changes in indicator gas and oxygen concentrations at these stages were analyzed. The research finding further explains the mechanism of radical reactions during coal spontaneous combustion.
      PubDate: 2023-02-01
       
  • A Novel Magnetic Interpretational Perspective on Charmaleh Iron Deposit
           Through Improved Edge Detection Techniques and 3D Inversion Approaches

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      Abstract: Abstract Edge detection is an important part of interpreting potential field geophysics data. It helps better recognition of magnetic anomaly features such as superficial position and shape. Many edge detection methods have been presented; however, due to the natural complexity of subsurface features, only a few of the processing techniques might be accurate. Because, in practical cases, multi-dimensional precision is essential, using other methodologies along with edge detection can be useful. As a new research, this study utilized the 3D inverse modeling procedure as a confirmation and completion tool for combining both subsurface magnetic susceptibility distribution and surface anomaly projection. This research focused on investigating simultaneous application of 3D inversion and edge-detecting methods that provide an accurate perspective view of sought sources with high magnetic susceptible properties. To perform the mentioned task, along with the definition of two new edge detection filters, some beneficial edge detection filters were implemented on synthetic data. Then, these filters were applied to the Charmaleh Iron deposit magnetic data to obtain a valid anomaly edge perimeter. Subsequently, a 3D inverse modeling scheme was run on the data to investigate the magnetic susceptibility properties of surface and underground structures. In order to validate our edge detection results and to achieve a proper interpretation, the utilized edge detectors and the inverted model results were overlaid, compared, and depicted concurrently. Drilling operations were also conducted within the jointly achieved favorable zones, which were in line with the research findings. Conclusively, it can be stated that joint consideration of the mentioned approaches can be advantageous attitude toward accurate interpretation of environments with highly magnetic anomalies.
      PubDate: 2023-02-01
       
  • Mineral Prospectivity Mapping Using Deep Self-Attention Model

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      Abstract: Abstract Multi-source data integration for mineral prospectivity mapping (MPM) is an effective approach for reducing uncertainty and improving MPM accuracy. Multi-source data (e.g., geological, geophysical, geochemical, remote sensing, and drilling) should first be identified as evidence layers that represent ore-prospecting-related features. Traditional methods for MPM often neglect the correlations between different evidence layers that vary with their spatial locations, which results in the loss of useful information when integrating them into a mineral potential map. In this study, a deep self-attention model was adopted to integrate multiple evidence layers supported by a self-attention mechanism that can capture the internal relationships between various evidence layers and consider the spatial heterogeneity simultaneously. The attention matrix of the self-attention mechanism was further visualized to improve the interpretability of the proposed deep neural network model. A case study was conducted to demonstrate the advantages of the deep self-attention model for producing a potential map linked to gold mineralization in the Suizao district, Hubei Province, China. The results show that the delineated high potential area for gold mineralization has a close spatial association with known mineral deposits and ore-controlling geological factors, suggesting a robust predictive model with an accuracy of 0.88. The comparative experiments demonstrated the effectiveness of the self-attention mechanism and the optimum depth of the deep self-attention model. The targeted areas delineated in this study can guide gold mineral exploration in the future.
      PubDate: 2023-02-01
       
  • Creep Behaviors of Extremely Soft and Fractured Coal Rock with Different
           Moisture Contents and Rare Secondary Creep Performance

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      Abstract: Abstract Water injection technology has been widely used to prevent and reduce coal caving during roadway excavations in extremely soft and loose coal seams. To evaluate the influence of this technology on the long-term stability of such roadways, a self-developed triaxial creep test system was adopted to obtain the creep behaviors of extremely soft coals with various moisture contents (0.95, 2.30, and 3.26%) at a 0.2 MPa confinement, the creep characteristics and failure modes were compared, the formation condition of a rare secondary creep phenomenon was discussed, and a nonlinear creep model was newly established. The findings showed the following. (1) Extremely soft and fractured coal was characterized by significant rheological features, i.e., a large creep strain, a fast creep rate, and susceptibility to accelerated creep failure. The cumulative strain in natural water state and after 328 h was 2.99%. The steady-state creep rate was as high as 4.89 × 10–5/h, which remained unchanged during the entire steady-state creep stage. These features are markedly different from those of other rocks. (2) When the moisture content increased to 2.3%, the creep strain reached 9.19% within 61 h, and the steady-state creep rate was 4.23 × 10–4/h. After the primary creep, there was an obvious secondary creep process, during which the secondary transient creep stage and secondary steady-state creep stage occurred successively. (3) As the moisture content increased from 0.95% to 3.26%, the ability of the coal sample to resist long-term deformation decreased, i.e., the creep duration before specimen failure decreased dramatically and the creep rate increased markedly; in particular, the steady-state creep rate increased in a power function. (4) A certain water content (~ 2.30%) and confining pressure were required for the occurrence of secondary creep process. (5) The proposed nonlinear creep model could describe the full creep stage perfectly, especially the tertiary creep stage in primary creep process and the entire secondary creep process.
      PubDate: 2023-02-01
       
  • Predictive Modeling of Prospectivity for VHMS Mineral Deposits,
           Northeastern Bathurst Mining Camp, NB, Canada, Using an Ensemble
           Regularization Technique

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      Abstract: Abstract The volcanic-hosted massive sulfide (VHMS) deposits of the Bathurst Mining Camp have been significant contributors to Canada's historic Zn, Pb, Cu, and Ag production. Most of these deposits are hosted by the Tetagouche Group, many of which occur at the top of the Nepisiguit Falls Formation (footwall) along the contact with the conformably overlying Flat Landing Brook Formation (hanging wall), i.e., the Brunswick belt. Exploration along this prolific belt can benefit greatly from predictive modeling of prospectivity for VHMS deposits using machine learning (ML)-based mineral prospectivity mapping (MPM), which is the chief objective of this study. However, ML-aided MPM of this belt is faced with three challenges: (i) weak geochemical and geophysical signatures of VHMS deposits (i.e., poor predictor variables) owing to the complex tectono-stratigraphy of the host sequence and extensive glacial cover, (ii) over-fitting stemming from its limited number of VHMS deposits, and (iii) stochastic uncertainties of predictive models linked to the diversity in local geological settings of various VHMS deposits. This study adopted an ensemble regularized regression methodology combining ensemble modeling with LASSO, Ridge, and Elastic Net regularized regression techniques for addressing the above challenges. Herein, we demonstrate that the adopted framework can reduce the severity of over-fitting, handle poor predictor variables, and mitigate the effects of stochastic uncertainties in ML-based MPM. These results are followed by discussions of the pros and cons of the framework adopted in this study.
      PubDate: 2023-02-01
       
  • Quantification of Water Resource Sustainability in Response to Drought
           Risk Assessment for Afghanistan River Basins

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      Abstract: Abstract Drought in Afghanistan has many impacts from the interaction between environmental and socio-economic factors in the agriculture and water supply sectors. The complex topography and climate change impacts cause high spatial and temporal variation in the precipitation pattern and pose several challenges in managing water resources. Therefore, this paper aimed to quantify the sustainability of water resources against the progression of drought. Observed monthly precipitation data monitored by 23 stations located across five river basins covering the entire country for the period 1970–2016 were used to demonstrate the potential impacts of drought on water resources sustainability. Based on severe drought estimation, the year 2000 and 2001 were identified as change points. Accordingly, datasets pertaining to before and after the change points were partitioned to analyze the long-term temporal shift of drought. The spatiotemporal variability of sustainability indicators was estimated using reliability resiliency and vulnerability concept. The results indicated a positive trend of precipitation in most of the river basins after the change points leading to an increase in sustainability. However, the major portion in the upstream of the Kabul River basin showed a decrease in sustainability of around 15% due to a reduction in precipitation. As the Kabul city has high population density, it needs immediate attention in effectively planning and managing available water resources. Furthermore, the comprehensive analyses reported in this paper discuss the possible implications of drought risk assessment and its impact on largely varying sustainability both spatially and temporally in Afghanistan.
      PubDate: 2023-02-01
       
  • Gas Extraction Mechanism and Effect of Ultra-High-Pressure Hydraulic
           Slotting Technology: a Case Study in Renlou Coal Mine

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      Abstract: Abstract Ultra-high-pressure hydraulic slotting technology is an effective method to realize pressure relief and permeability enhancement of a single coal seam. In this paper, through a hydraulic slotting borehole-based total gas extraction amount calculation model, it was concluded that ultra-high-pressure hydraulic slotting technology could increase the gas extraction surface area, improve the gas flow mechanism, and transform single-layer radial flow into interlayer, radial composite flow, thus greatly enhancing the gas extraction efficiency. Based on theoretical results, a field test was conducted in the Renlou coal mine, Anhui Province, China. According to the actual characteristics of the 72 coal seam in the Renlou coal mine, the key slotting parameters of this coal seam were determined. The gas extraction sources of each coal seam could be determined accurately through multi-gas source identification and tracer technology, and the effect of hydraulic slotting pressure relief and permeability enhancement was investigated. The test results indicated that the 100-day gas extraction concentration in boreholes using ultra-high-pressure hydraulic slotting technology was 2.68–7.59 times that in conventional boreholes. The average daily pure extraction volume of slotting boreholes was 3.94 times that of conventional boreholes. Based on the calculation of the gas extraction radius of boreholes in the slotted area, it was found that, under the condition of meeting the same control range of outburst elimination, drilling work could be reduced by more than two-thirds. These achievements could provide critical references for the application of ultra-high-pressure hydraulic slotting technology.
      PubDate: 2023-02-01
       
  • Driving Mechanisms and Their Relative Importance in Focusing Hydrothermal
           Fluid Flow in the Chanziping Ore District, South China

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      Abstract: Abstract Numerical simulations were performed to examine the driving mechanisms and their relative dominance in concentrating hydrothermal ore-forming fluid flow in the Chanziping ore district, South China. A numerical scheme was employed to provide realistic strain-dependent porosity and permeability during tectonic deformation. The results indicate that the buoyancy resultant from typical geothermal gradients alone during tectonically quiescent periods could not focus ore-forming fluids to the trap area for U precipitation. The extensional tectonic deformation in the late Yanshanian-early Himalayan period caused a broad downwelling flow in the red sandstone, channeling downwards along the regional fault to mix with the basement-derived upwelling reducing fluid driven by the buoyancy force. This leads to the ore genesis in the black shale below the fracture zone. The compressive deformation in the Indo-Chinese epoch would have essentially squeezed the basinal fluid and basal brine out of the basin, and hence would have been unfavorable for the formation of the Chanziping deposit. It was also observed that tectonic deformation always overwhelms the effect of buoyancy in driving hydrothermal flow, even if an extension or shortening of as little as 1% is applied.
      PubDate: 2023-02-01
       
  • Mineralized-Anomaly Identification Based on Convolutional Sparse
           Autoencoder Network and Isolated Forest

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      Abstract: Abstract According to the characteristic that mineralized-anomaly samples have larger reconstruction errors, traditional autoencoder networks have been applied widely in mineralized-anomaly identification. However, they easily ignore spatial coupling information of multi-source ore-indicating factors have lower generalization abilities caused by excessive feature redundancies, and rely on known non-mineralization samples when they are utilized in mineralized-anomaly identification. This paper utilizes a convolutional sparse autoencoder network for realizing mineralized-anomaly identification. The proposed method retains the extraction of spatial coupling correlations of geological and geochemical variables through the addition of convolutional operations, learning the relationship between mineralized-features and the locations of mineralization, and being conducive to analyzing results with geological structures. The establishment of sparse terms of using ReLU activation functions and adding sparsity constraints into the objective loss function improves the generalization ability of the whole network through suppression of several feature units to reduce redundant features. Moreover, the isolated forest is employed as an autonomous extractor of background multichannel image samples, overcoming the limitation of traditional autoencoder networks that rely on labeled non-mineralization samples. The integration of convolutional sparse autoencoder network and isolated forest can accurately predict more known mineral deposits (68.96%) in smaller prospective areas (16.77%) in the Fengxian District, Shaanxi Province, China. The obtained mineralized-anomaly map reveals that most of the known mineralization is distributed in the delineated areas of larger reconstruction errors, demonstrating that this approach can effectively identify mineralized-anomalies without relying on prior knowledge.
      PubDate: 2023-02-01
       
  • Utilization and Effectiveness of Numerical Simulation Based on a
           Cold-Water Trapping Mechanism for Epithermal Gold Exploration

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      Abstract: Abstract Exploration of low-sulfidation epithermal Au deposits is expected to increase because these deposits are economically competitive and globally occurring as well as produce low environmental load via underground mining. Drilling is the main exploration tool for identifying mineralized zones in three dimensions; however, selecting drill targets is a major technical challenge in exploration work. This challenge can be addressed by effectively employing our conceptual model of a “cold-water trap,” an ore-deposition mechanism induced by cold groundwater in shallow aquifer. In two previous case studies on low-sulfidation epithermal deposits, this mechanism was verified via geological modeling and numerical simulations, and potential mineralized zones were three-dimensionally confirmed in undrilled areas. Here, we methodize the utilization of numerical simulations for epithermal Au exploration and prepare the operational guidelines for a new exploration method. In this method, the trapping scenario can be modified to explore deposits generated by incomplete cold-water trapping. Because this method functions effectively from the time at which the necessary data for geological modeling are obtained, it is adapted to operate over the time of drill exploration. Furthermore, the proposed method can be adapted to brownfield explorations, such as around the existing deposits. Sensitivity analysis revealed permeability to be the most important parameter for the numerical simulation. Analyzing drill cores with respect to fracture properties such as width and density as well as the extent of the hydrothermal alteration halo is crucial for the accurate estimation of permeability.
      PubDate: 2023-02-01
       
  • Natural Gas Genesis, Source and Accumulation Processes in Northwestern
           Qaidam Basin, China, Revealed by Integrated 3D Basin Modeling and
           Geochemical Research

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      Abstract: Abstract The northwestern Qaidam Basin has great potential for natural gas exploration. Research and exploration activities of natural gas conducted over the last two decades have provided abundant information about natural gas geochemistry. However, its genesis, source, and accumulation process are still controversial. This research utilized a published comprehensive natural gas dataset and a 3D basin modeling approach to ascertain the genesis of natural gas in the northwestern Qaidam Basin and to discuss its accumulation process. Moreover, diagrams for classifying the source material type were revised to better understand the origin of natural gas. In the northwestern Qaidam Basin, the source material type of natural gas is chiefly coal-type gas with a few oil-type gases. Natural gases from the Jianshan anticline originated predominantly from the Jurassic source rock, while those in most other regions were derived mainly from the Upper Xiaganchaigou source rocks. However, some oil-associated gas related to oil accumulation came chiefly from the Shangganchaigou source rock. In addition, a small amount of early mature thermogenic gas in the Xiaoliangshan, Yondunzi, and Xianshuiquan regions may have come from the Lower Youshashan source rock. Moreover, this research discovered the secondary cracking gas of oil in the northwestern Qaidam Basin, which has a great significance in broadening the natural gas exploration in an area. Similarly, the gas accumulation models were established for three types of gases, i.e., oil-associated gas, late primary cracking gas, and oil-cracking gas. This study emphasizes geological research based on a comprehensive field dataset analysis and comparing adjacent mature blocks. This methodology can be used in other emerging natural gas exploration areas.
      PubDate: 2023-02-01
       
  • Poromechanics of Fractured/Faulted Reservoirs During Fluid Injection Based
           on Continuum Damage Modeling and Machine Learning

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      Abstract: Abstract The reactivation of faults is governed by the variation of effective stresses in the fault’s plane. These effective stresses are dependent on the total stresses (solely related to the regional geological stresses and lithology) and pore pressure (strongly affected by rock properties, fluid content, and saturation conditions). Injecting fluids into a reservoir formation may change the distribution of pore pressures, which influences the effective stresses and may cause the reactivation of existing faults, which has a wide range of consequences. This study investigated the reactivation of preexisting faults due to fluid injection into hydrocarbon reservoirs at different pressures and temperatures. A 3D model containing a continuous normal fault that divides the domain into two compartments was used. A user-defined constitutive model based on continuum damage mechanics implemented as a Fortran subroutine to predict the behavior of fractured and faulted reservoirs was used. A parametric analysis was performed to examine the influence of geometric parameters, such as the fault dip angle, reservoir characteristics, and fluid injection parameters. A machine learning approach based on artificial neural networks (ANNs) is incorporated to predict the enhanced oil recovery using fluid injection. The results predicted by the ANN were further confirmed by numerical modeling.
      PubDate: 2023-02-01
       
  • Effects of Acidification on the Wettability Modification of Coal and
           Adsorption Characteristics of Coalbed Methane

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      Abstract: Abstract To study the effect of acidification on wettability and adsorption characteristics of coalbed methane (CBM), the anthracite in Guizhou mining area was taken as the research object. X-ray diffraction, Fourier transform infrared spectroscopy, contact angle measurement, and isothermal adsorption experiments were carried out successively. Based on the chemical reaction principle, the main acid was determined. The optimum wettability modification conditions were selected using the CRITIC–gray relational analysis method. Moreover, the evolution law of coal wetting modification and CBM adsorption characteristics under acidification was analyzed. The results showed that the main acid of the testing coal sample was hydrofluoric acid, and the optimum wettability modification condition was an acid concentration of 6% and a reaction time of 12 h. After modification, the coal-water contact angle of the testing coal sample decreased by 20.7%, and its wettability was largely enhanced. In addition, the oxygen-containing functional groups of the modified coal samples increased, alkyl side chains decreased, degree of aromatic condensation and aliphatic chain length decreased to varying degrees, and the adsorption of coal sample on CBM weakened. The results of isothermal adsorption experiments showed that the adsorption constants a and b of the modified coal samples decreased by 14.0 and 23.6%, respectively, which further confirms the correctness of the above analysis. The wettability of the testing coal sample was found to be negatively correlated with its adsorption capacity: better wettability correlated to a weaker adsorption capacity.
      PubDate: 2023-02-01
       
  • Formation Mechanism of Thick Coal Seam in the Lower Indus Basin, SE
           Pakistan

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      Abstract: Abstract The energy sector and coal scientists have been enthusiastic about characterizing and understanding the vertical and lateral depositional systems of thick coal seam. However, there are no detailed studies that provide well-connected insight into the regional depositional characteristics of the thick coal seam in the Lower Indus Basin, SE Pakistan. Therefore, field emission scanning electron microscopy, scanning electron microscopy backscattered electron, electron probe microanalysis, X-ray powder diffraction spectrometry, Fourier transform infrared spectroscopy, Raman spectroscopy and coal facies were adopted to study major and subclassified maceral petrography and coal sequence stratigraphic characteristics; coal depositional models were then established. Preferential depositional systems were identified by low-stand system tracts, high-stand system tracts and transgressive system tracts and are likely to include shallow marine sequences that were propagated by slow to rapid regression. The high contents of telohuminite and detrohuminite indicate highly gelified and non-gelified tissue derived from angiosperms and herbaceous plants, which were the most prevalent. The qualitative analysis of the function group suggests peaks, hence stretching the region band adsorption intensity of the particle. Major identified features of Raman spectra with hidden peak intensities tend to include the oscillation of energy particles due to the carbon crystallinity and high reflectance of mineral surfaces. The extensive lateral depositional analytical models revealed that the thick coal seam was deposited in the upper delta during waterlogged/wet and dry cyclic conditions, which were the most prevalent in the mires. This continuation of wet–dry cyclic conditions moves quickly to humification and gelification. Environmental changes led to the accumulation and transformation of organic matter, which resulted in the formation of thick peat deposits.
      PubDate: 2022-12-22
       
  • Positional Prediction of Undiscovered Seafloor Massive Sulfide Resources
           on Carlsberg Ridge, Northwest Indian Ocean

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      Abstract: Abstract Increasingly more attention is being paid to the exploration of seafloor massive sulfide (SMS) resources because of the rich metal resources in them. Research has shown that the slow-spreading mid-ocean ridge is a hotspot for large-scale massive sulfide deposits, and should be prioritized in the future. Because of the complex technology and high cost of investigating the location of the mid-ocean ridge, it is necessary to narrow the prospecting space. In this study, a novel method is proposed that combines weights-of-evidence method and prospecting-information content method to quantitatively predict locations of undiscovered SMS resources on the typical slow-spreading Carlsberg Ridge. First, controlling factors were selected, which included topography, geophysics, and geology aspects. Then, the favorable value range of each controlling factor was determined to develop the prospecting prediction model. Finally, this study developed a mineral prospectivity map with four levels of likelihood for the occurrence of SMS deposits. Eight prospective targets were delineated, four of which were level A and four were level B (level A is better than level B). This research has great significance in guiding future research of SMS resources on the Carlsberg Ridge and similar ridges.
      PubDate: 2022-12-21
       
  • Machine Learning Prediction of Ore Deposit Genetic Type Using Magnetite
           Geochemistry

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      Abstract: Abstract Magnetite geochemistry is crucial for the discrimination of ore deposit genetic type. Traditional two-dimensional discrimination diagrams based on particular data for limited deposits cannot meet the requirements of high-precision classification. The continuous compilation of magnetite geochemical big data and high-precision machine learning algorithms provide a new research route. In this study, a laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) magnetite geochemical dataset compiled from published literature for different geological environments worldwide was used to train different machine learning (ML) classifiers, including random forest, support vector machine, and multilayer perceptron neural network, to predict the genetic type of ore deposits. To verify the efficacy of the classifier, LA–ICP–MS analysis was performed on magnetite samples collected from the Makeng and Luoyang iron deposits in Fujian Province, southeastern China. The obtained data were used to predict the ore deposit genetic type with the aid of the ML classifiers. The classifiers established by all three algorithms yielded good predictive outcomes. The results were consistent with those obtained from detailed petrogeochemical and isotopic studies, showing that the deposits are skarn-type, validating the suitability of the classifier. This article also provides an executable program of the classifiers for anyone to use. The executable program meets the requirements for ore deposit-type classification and can be considered a powerful tool for magnetite exploration and prospecting.
      PubDate: 2022-12-12
       
  • Techno-Economic Assessment of Geothermal Resources in the Variscan
           Basement of the Northern Upper Rhine Graben

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      Abstract: Abstract Deep geothermal energy represents an essential component of the future energy supply because the resources greatly exceed the demand, and the base load capability can compensate for temporal fluctuations in wind and solar power. By far, the largest amount of heat is contained in the crystalline basement, accessible almost everywhere through deep drilling. An interdisciplinary approach for a techno-economic resource assessment was applied to provide stakeholders with a more reliable basis for decision-making in the Northern Upper Rhine Graben. This approach incorporated data from various sources such as boreholes, outcrops, geophysical surveys, geomechanical models, and operating geothermal power plants. Emphasis was placed on resources tied to large-scale fault zones, exhibiting preferential hydraulic properties. Uncertainties in the calculations were quantified using Monte Carlo simulations. The resource base in the basement of the Northern Upper Rhine Graben is about 830 PWhth, of which about 8.2–16.1 PWhth could potentially be extracted with current technologies in enhanced geothermal systems. A comprehensive sensitivity analysis was carried out, examining the economic influence of nine parameters. Considering the reference power plant and the energy prices before the Ukraine war began in February 2022, the geothermal reserves are about 65% of the resources. However, given the massive recent increase in heat and electricity prices, a higher percentage is also possible. Finally, a socio-economic-environmental assessment shows that in the Northern Upper Rhine Graben, geothermal resources largely coincide with favorable conditions at the surface, making the region a preferred target for geothermal utilization.
      PubDate: 2022-12-09
       
  • Continuous–Discontinuous Element Numerical Modeling of Damage and
           Fracture Characteristics of a Loaded Coal

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      Abstract: Abstract In preventing and controlling coal–rock dynamic disasters, the damage and fracture characteristics of the loaded coal play an important role. Using the continuous–discontinuous element coupling numerical software and the experimental test results of the acoustic emission (AE) of the loaded coal, the damage and fracture modes as well as the evolution laws of crack propagation of coal under uniaxial compression were thoroughly analyzed in this study. The results showed that the physical and mechanical properties, such as uniaxial compressive strength, have no bearing on the generation of AE signals, which are only related to the number and expansion evolution laws of cracks in the loaded coal. The mode of internal crack propagation in loaded coal is influenced by its uneven stress distribution, and the interior of loaded coal frequently develops a mixture of multiple crack types, as opposed to a single type. Besides, the system’s unbalanced rate in power and heating transmission systems was incorporated into the damage and fracture analysis of loaded coal, and it varied with the degree of fracture development in coal, which can be used as alternative expression method of damage variable under specific conditions. The main fracture surface’s propagation direction was also affected by the initial crack’s location, as demonstrated by the numerical simulation results. To compensate for the limitations of conventional testing methods, we developed a numerical model that recreates the internal cracks’ spatio-temporal evolution process and elucidates the damage fracture modes and the evolution laws of crack propagation in the loaded coal.
      PubDate: 2022-12-08
       
 
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