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This study aims to explore the mechanism behind the influence of stress on gas adsorption by coal during deep mining and improve the accuracy of gas disaster prevention and control. To achieve this aim, thermodynamic analysis was conducted on the process of gas adsorption by loaded coal, and modified thermodynamic model proposed by previous scholars. It is found that stress plays an important role in gas adsorption by coal. In addition, isothermal adsorption experiments were performed on coal samples under different stress states with the aid of a coal rock triaxial adsorption and desorption experimental device. Based on the experimental results, the variations in adsorption capacities of coal samples under different stress loads were obtained. Finally, molecular dynamics simulation of gas adsorption was conducted by taking lignite as the research object. The microscopic mechanism of gas adsorption by loaded coal is elucidated from the perspectives of isothermal adsorption parameters of the loaded coal, isothermal heat of adsorption, and the changing law of the probability density distribution of adsorbed gas molecules. The research findings are anticipated to offer theoretical and practical guidance for the prevention and control of gas disasters in deep coal mines and the extraction of coalbed methane., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

The wetting process of coal seam water injection is a typical unsaturated flow, but the steady-state method for measuring liquid permeability cannot reflect the unsaturated flow process of water in coal. The principle of wetting and expanding process of liquid in coal medium is very complex, and the multiscale pore characteristics of coal make the liquid permeability show multiscale characteristics. Therefore, liquid-phase triaxial seepage experiments under different working conditions are carried out, and a one-way multiscale dynamic apparent permeability coefficient model D ( t ) = D 0 exp(-β t ) is established to analyze the influence of pressure, liquid wettability, and pore structure on the unsaturated wetting process of coal seam water injection. The results show that the apparent permeability coefficient of liquid phase decreases gradually with time due to the multiscale pore characteristics of coal. The dynamic apparent permeability coefficient model can well describe the unsaturated seepage process of liquid in coal, which is helpful to characterize the liquid permeability of low permeability coal seam. The water injection pressure has a great influence on the attenuation coefficient of apparent permeability coefficient, and the higher the water pressure is, the smaller the attenuation coefficient is. The surfactant increases the permeability coefficient by enhancing the capillary wetting, while the capillary force, as an internal factor, has less influence on the model attenuation coefficient than the water pressure., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Stainless steel, as a popular corrosion resistant material, is still vulnerable to pitting corrosion in the marine environment. Therefore, in order to ensure the safety of stainless steel in the marine environment, it is necessary to implement corresponding protective measures. Titanium dioxide (TiO 2 ), as an N-type semiconductor with excellent photoelectric properties, is widely used in the field of cathodic protection. However, as a photogenerated cathodic corrosion protection material, TiO 2 has the disadvantages of low conductivity and high carrier recombination rate. Therefore, WS 2 and NIS were introduced in this paper to modify it. TiO 2 /WS 2 /NiS (TWN) composites with Type-Ⅱ heterojunction structure were prepared by hydrothermal method and titration method. The results reveal TWN5 showed the best photoelectrochemical (PEC) performance, and the photocurrent density was 69% higher than that of a pure TiO 2 photoanode, and the photochemical and photocathodic protection performance was significantly better than that of pure TiO 2 . Under simulated ocean conditions, the self-corrosion potential of 304ss combined with TW5 and TWN5 photoanodes is reduced to -0.64 V and -0.7 V, respectively. The main reason is that the contact surfaces of WS 2 and TiO 2 formed a Type II heterostructure, which accelerates the separation and diffusion processes of photoinduced carriers. In addition, the plasmon resonance effect of NiS improves the ability to absorb visible light, and the metallic-like feature of NiS also promotes charge separation., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Given the background of significant Coal Mine gas disasters worldwide, the research and development of efficient gas control technologies have become critical to ensuring mining safety. CO 2 gas fracturing (CO 2 -Frac), an innovative technology for Coal Mine gas control, has demonstrated efficiency in various mining areas across China. However, its application in outburst-prone coal seams is not yet fully understood. This study presents a field-scale CO 2 -Frac project conducted in an outburst Coal Mine in China, specifically the Pingshu Coal Mine, where the previously employed dense-borehole gas extraction technology failed to efficiently achieve gas extraction and outburst prevention. The CO 2 -Frac plan was evaluated through fracture propagation experiments utilizing both single-hole and dual-hole configurations, highlighting the advantages of the dual-hole CO 2 -Frac method. Subsequently, on-site gas extraction tests were conducted to further assess the efficacy of the CO 2 -Frac plan. The results indicate that (1) In the dual-hole CO 2 -Frac scheme, the fractured and pressure relief area expanded to approximately 26.82 m 2 , which is 220% larger than that of the single-hole scheme. (2) The dual-hole CO 2 -Frac significantly enhanced gas extraction effectiveness, increasing the flow rate from 0.026 to 0.216 m 3 /min in a 100m borehole, a 7.3-fold improvement. Additionally, the gas extraction period to reach the standard was reduced from 20 to 6 days. These findings conclusively demonstrate that the dual-hole CO 2 -Frac technique is an effective method for safe excavation in outburst-prone coal seams, providing both theoretical and practical validation for its application in similar geological settings., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

In order to meet the needs of geologists for the analysis of data characterizing field outcrops (rock sections or formations exposed on the ground surface), this study developed a field digital outcrop visualization platform based on Cesium (a 3D geospatial visualization technology) digital outcrop characterization technology. The platform was developed based on WebGL (a protocol for rendering interactions on web pages), which overcame the shortcomings of traditional software in terms of visualization, cross-device, cross-platform, and ease of use. Firstly, UAV inclined photography is used for data collection, which transforms a large amount of geological data into an intuitive 3D geological model, while the visualization platform provides rich measurement and mapping tools for the identified features, which more intuitively displays the outcrop information, helps geological explorers to understand the geological conditions in the field more quickly and comprehensively, and improves the analysis efficiency and ease-of-use of outcrop characterization data. Combined with the improved VGG19 (a deep convolutional neural network architecture) algorithm model, it has excellent performance in dealing with the fine texture and complex structure of rocks, which significantly improves the accuracy of lithology identification. The synergistic application of this technology provides geologists with a faster and more comprehensive means to understand the geological conditions in the field. The reliability of combining the Cesium digital outcrop characterization technology with the VGG19 lithology identification algorithm in geological exploration is verified through case studies. The synergistic application of this technology will greatly enhance the efficiency and ease of analysis of outcrop characterization in the field, and provide new perspectives for future research in geosciences., (© 2024. The Author(s).)

The study of isothermal adsorption models for coal and methane under supercritical conditions helps us to understand the gas content distribution in coal seams and improve gas management in coal mines. Coal samples from the Hebi mine and Longshan coal mine were selected for this research. Using the weight method, isothermal adsorption curves of supercritical methane at temperatures of 308, 313, and 318 K were measured. The adsorption phase density of supercritical methane was obtained by using the intercept method and model fitting, and the absolute adsorption capacity of methane was calculated. Simultaneously, the pore volume and specific surface area of the coal samples were tested, and the isothermal adsorption model for supercritical methane was studied and optimized. The results indicate that using mercury intrusion, low-temperature N 2 , and low-temperature CO 2 adsorption methods for testing coal sample pore structures allows for multiscale characterization of the coal pore structure. Based on the Gibbs excess adsorption theory, the phase density of methane obtained from the intercept method and model fitting effectively represent the isothermal adsorption curve of supercritical methane. By combination of the specific surface area and pore volume distribution of the coal with the absolute adsorption capacity of methane, the number of methane adsorption layers on the coal surface was calculated to be between 1.11 and 1.3 layers. This suggests that the isothermal adsorption model for supercritical methane on coal is not solely micropore filling or single molecular layer adsorption but primarily single molecular layer adsorption with concurrent micropore filling adsorption. Based on this adsorption mechanism, an L-DA isothermal adsorption model for supercritical methane on coal was established. The L-DA isothermal model shows good fitting results and effectively explains the adsorption characteristics of supercritical methane on coal., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The coal is affected by the latent heat of the phase change of in situ and migrating water and the exothermic heat of gas adsorbed by the coal during the freezing process, which leads to different temperatures at different locations and times inside the coal. Relying on the independently developed simulation platform for the freezing response characteristics of gas-containing coal, simulation experiments on the internal temperature change of the coal freezing process under different ambient cryogenic treatment temperatures were carried out, and the effects of the phase change latent heat of the in situ water and migrating water and the exothermic heat of gas adsorbed by the coal on the freezing coal temperature field were taken into account, so as to establish a temperature field model of the cryogenic treatment process of the coal under the influence of the thermal effect of the water and gas and construct the internal heat transfer model of the freezing coal with the aid of COMSOL. The internal heat transfer of frozen coal was constructed with the help of COMSOL, and the mathematical model of temperature field proposed in this paper was simulated and verified. The results show that the change in temperature with time in the coal cryogenic treatment process is consistent with the experimental law. It is generally divided into four stages: rapid decline, short stabilization, slow decline, and relative stability, and the maximum error between the simulation temperature and the experimentally measured temperature is 0.85 K. The rate of temperature decrease of coal during the cryogenic treatment process is accelerated with the decrease of ambient freezing temperature, and the duration of short stabilization of temperature is shortened in the stage of water phase change. The mathematical model proposed in this article can be used to simulate and characterize the temperature field distribution and changes during the cryogenic treatment process of water-containing gas-containing coal., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

CO is a hazardous and pollutant gas that can be produced in many scenarios of coal-related operations. The study mainly investigated CO production process and mechanism when coal is subject to external forces. The effects of coal type, particle size, temperature, and inlet atmosphere on CO production from coal body fragmentation were investigated through coal loading experiments. Materials Studio software was used to carry out coal macromolecular mechanics simulation and molecular dynamics simulation, and the gas production mechanism of coal under loading was explored at the molecular level. It was found that under air atmosphere, the low degree of deterioration, small particle size, and elevated temperature are all more likely to cause coal samples to fragment and decompose to produce CO. The carbonyl group in the molecular structure of coal is shed or broken free radical fragments react with oxygen which may lead to CO formation., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The changes and transformation laws of intermediate liquid-phase products during the anaerobic degradation of lignite by sulfate-reducing bacteria in the formation of hydrogen sulfide play an important role in supplementing and improving the existing theories on the genesis of hydrogen sulfide gas in coal mines. In this paper, H 2 S gas and key intermediate liquid-phase products produced during the anaerobic degradation of lignite by sulfate-reducing bacteria were detected and analyzed by gas chromatography and gas chromatography-mass spectrometry. The results showed that the process of hydrogen sulfide production from lignite degradation by sulfate-reducing bacteria can be roughly divided into four stages: slow production phase, rapid growth phase, steady production phase, and slight decline phase. In this reaction system, the SO 4 2- concentration showed a decreasing trend, the pH value showed an increasing trend, and the ORP value decreased and then slightly increased with time. Ten volatile component types were detected during the experiment: straight-chain alkanes, branched-chain alkanes, alcohols, aldehydes, ketones, olefins, amines, lipids, acids and phenols. The key components in the intermediate liquid phase products were straight chain alkanes, straight chain alkanes, acids, alcohols, phenols and amines. PAHs, alkanes, and phenols are closely related to H 2 S gas production stage, and decay stage. Liquid-phase intermediates play an important role in the formation process of coal mine BSR hydrogen sulfide and the mechanism of coal mine H 2 S gas production stage, and decay stage. Liquid-phase intermediates play an important role in the formation process of coal mine BSR hydrogen sulfide and the mechanism of coal mine H 2 S genesis., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The exploration potential within deep-water petroliferous basins holds great promise for oil and gas resources. However, the dearth of geochemical and isotopic data poses a formidable challenge in comprehending the intricate hydrocarbon charging processes, thereby impeding the comprehensive understanding of hydrocarbon accumulation mechanisms and models. Consequently, the establishment of robust source-reservoir relationships in deep-water petroliferous basins represents a pivotal challenge that significantly influences the exploration strategies and the comprehension of hydrocarbon enrichment dynamics within such basins. In this study, we introduce a novel approach, termed the "source-reservoir dynamic evaluation method," tailored to investigate reservoir accumulation models in deep-water petroliferous basins. This method uses basin simulation technology to recover the thermal evolution history and hydrocarbon generation and expulsion history of source rocks, and on this basis delimits the hydrocarbon kitchen range. At the same time, the maturity of source rocks corresponding to crude oil and natural gas in typical reservoirs is calculated. Then, when the thermal evolution degree of source rocks adjacent to the reservoir reaches this maturity, the corresponding geological period is the main charging period of hydrocarbon. As a typical deep-water petroliferous basin, the Santos Basin in Brazil has abundant oil and gas reservoirs under the thick salt rock, but there are still some fundamental problems such as unclear oil-gas accumulation process and model. Therefore, in this paper, the main charging periods of typical hydrocarbon reservoirs are determined based on the internal relationship between the thermal evolution history of the main source rocks and the maturity of crude oil and natural gas, and then the hydrocarbon accumulation process is analyzed and the dynamic accumulation model is established. Finally, the favorable prospecting direction is pointed out. The results show that the oil and gas in the Barra Velha Formation in the Santos basin are mainly derived from the Itapema Formation lacustrine shale source rock, and the source rock is mainly developed in the Eastern Sag of the Central Depression, and its main hydrocarbon generation period is from the deposition period of Florianopolis Formation to the deposition period of Santos Formation. The main hydrocarbon expulsion period was from the deposition period of the Santos Formation to the Early deposition of the Iguape Formation. The oil and gas in the Barra Velha Formation were mainly charged from the Late deposition period of the Santos Formation to the Early deposition period of the Iguape Formation. During this period, the hydrocarbon migrated vertically along the normal fault formed in the rift period to the trap of the adjacent inheritance structural highs and accumulated in the reservoir, which was dominated by the accumulation model of the "lower generation-upper reservoir-salt cap". Since the Barra Velha Formation has the characteristics of near-source accumulation, based on the hydrocarbon expulsion center and hydrocarbon expulsion intensity of the source rock of the Itapema Formation, the distribution ranges of 85% and 50% Pre-salt accumulation probability in the Santos basin were calculated by using the quantitative analysis model of the hydrocarbon distribution threshold. It is suggested that the next oil and gas exploration should be carried out in the paleo-structural highs and slope of Class I favorable area (the hydrocarbon accumulation probability is more than 85%) and Class II favorable area (the hydrocarbon accumulation probability is 85-50%)., (© 2024. The Author(s).)

In order to accurately and efficiently determine the effective drainage radius of the in-seam borehole, the advantages and disadvantages of the current effective drainage radius test methods are analyzed, and the method of combining the gas content field and numerical simulation calculation is proposed to accurately determine the effective drainage radius of the borehole, which is applied in the mine. The results show that the method combining gas content test and numerical simulation calculation has the advantages of a short measurement period and advanced means. The effective drainage radius of the borehole increases rapidly at the initial stage of gas drainage and then gradually slows, eventually reaching a limit value. The relationship between the effective drainage radius and drainage time follows a Langmuir function relationship. When the drainage time exceeds 300 days, the effect of the drainage time on the effective drainage radius becomes relatively small. The average error between the numerical simulation results of effective drainage radius and the field verification results of gas content is 2.2%, which validates the rationality of the constructed coal seam gas-solid coupling model. The research can provide theoretical references for accurately determining and reasonably laying out the effective drainage radius of the bedding borehole in the mining seam of the coal mine, which is of great practical significance for the safety production of the mine., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Existing ice particle jet surface treatment technology is prone to ice particle adhesion during application, significantly affecting surface treatment efficiency. Based on the basic structure of the jet pump, the ice particle air jet surface treatment technology is proposed for the instant preparation and utilization of ice particles, solving the problem of ice particle adhesion and clogging. To achieve efficient utilization of ice particles and high-speed jetting, an integrated jet structure for ice particle ejection and acceleration was developed. The influence of the working nozzle position (L d ), expansion ratio (n), and acceleration nozzle diameter ratio (D n ) length-to-diameter ratio (L n ) on the ice particle ejection and acceleration was systematically studied. The structural parameters of the ejector were determined using the impact kinetic energy of ice particles as the comprehensive evaluation index, and the surface treatment test was conducted to verify the results. The study shows that under 2 MPa air pressure, the ejector nozzle parameters of n = 1.5, D n  = 4.0, L d  = 4, and L n  = 0 mm can effectively eject and accelerate the ice particles. The aluminum alloy plate depainting test obtained a larger paint removal radius and resulted in a smoother aluminum alloy plate surface, reducing the surface roughness from 3.194 ± 0.489 μm to 1.156 ± 0.136 μm. The immediate preparation and utilization of ice particles solved the problems of adhesion and storage in the engineering application of ice particle air jet technology, providing a feasible technical method in the field of material surface treatment., (© 2024. The Author(s).)

The poor lighting environment in the underground coal mine is easy to cause the miners to have psychological irritability, which leads to the occurrence of accidents. In order to reduce the incidence of accidents and ensure the personal safety of miners. In this paper, different illumination levels are used as control variables. With the help of cognitive ability tests commonly used in psychology, accuracy(AC), reaction time(RT)and performance indicators(PI) are selected to describe how different illumination levels affect the psychological state of miners. The results show that: (1) In the two selected cognitive ability test tasks, when the illumination level is very low, the AC is not high and the RT is longer. As the illumination increases, the AC in the cognitive test task becomes higher and the RT becomes faster. The optimal value is reached at 200lux-300lux.At this time, the illumination level increases again, the AC value decreases, and the RT value increases. When the illuminance is lower than 200Lux, the results of the two tasks are not the same, but when 200Lux∼300Lux, the PI values are larger, and then increase the illuminance, the PI value decreases. (2)The regression analysis of three indicators and illuminance level was carried out, and the binary linear regression equation of different illuminance levels and PI/RT was established to monitor the influence of illuminance on the psychological state of miners. (3) Reasonable control of lighting environment can effectively promote the cognitive ability of miners in the work, and minimize the risk of coal mine accidents., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

In order to address the challenges of high gas outburst in both the adjacent layers and the coal seam itself faced by large mining faces, a study on the three-dimensional extraction of gas from different sources at a large mining face was conducted. Based on the research on the instability and failure characteristics of the overlying strata during mining and the gas outburst characteristics at the large mining face, a source-separated three-dimensional gas extraction system was established. A comprehensive gas management model for the large mining face, involving the extraction of gas from different sources, has been proposed. This model is suitable for gas management at large mining faces where there is a high gas emission in the adjacent layers and a complex structure of the coal seam. Through numerical simulations using FLAC 3D , the height of the "three zones" of the overlying strata and the range of the floor fracture zone at the large mining face were obtained, providing guidance for the layout of high-level drainage roadway, low-level drainage roadway, and floor drainage roadways. Following the coordinated layout of high-level drainage roadway, inclined high-level drainage roadway, and low-level drainage roadway, the reasonable optimization of gas extraction techniques in the coal seam, and the reasonable arrangement of floor rock predrainage roadways, the methane capture efficiency of the large 15115 mining face reached 87.5%. The methane concentrations at the upper corner and in the return airflow being below 0.8%. The methane concentration extracted from the coal seam boreholes is 2.9 times higher than that from the ordinary mining face after adopting "ordinary boreholes + large-diameter boreholes". This gas management model effectively addresses the gas-related challenges of the large mining face and improves the gas extraction rate, achieving harmonious mining and extraction of coal and methane., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

In order to investigate the electrical response characteristics of anthracite coal reservoirs and their correlation with water saturation, salinity, and porosity, the complex resistivity of Zhaogu No. 2 mine anthracite coal was measured across a frequency range of 1 Hz to 100 kHz. The experimental findings indicate that as water saturation, salinity, and porosity increase, the amplitude of both the real and imaginary components of the complex resistance of the coal sample gradually decreases, leading to a decrease in the dispersion degree and an increase in the interface polarization frequency. By analyzing the experimental data and studying the polarization mechanism of coal in a sodium chloride solution, this study proposed an enhanced model that integrates the aspects of the Cole-Cole model and the Warburg model to overcome the limitations of the traditional first-order model, which can fit only single-peak curves. The second-order series Cole-Cole model not only delves into microscopic mechanisms underlying the low-frequency polarization effect of coal samples but also provides a highly accurate fit for complex resistivity dispersion curves under varying conditions. This research offers both an experimental foundation and a theoretical framework for leveraging the electrical properties of anthracite coal reservoirs in assessing the pore structure and permeability of coal seams., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

With the high yield of many wells represented by Well JT1 in the Maokou Formation, has catalyzed a surge in exploration activities along the platform margin facies of the Maokou Formation in central Sichuan and further showed the significant exploration potential of the Maokou Formation in the northern slope. However, the fracture cave body of the Maokou Formation exhibits a high degree of development, strong longitudinal and horizontal heterogeneity, large formation pressure differences, and drilling events such as gas kicks and lost circulation occur frequently, which seriously affects the efficient implementation of drilling. Understanding the spatial distribution of the three-pressure in the formation can help better deal with and solve the above problems. Therefore, in order to help the safe, high-quality and rapid drilling of the Maokou Formation in the study area, and enhance the efficiency of oil and gas development, this paper explores the research on the prediction method of the three-pressure of jointing well-seismic data based on the geomechanical experimental data and the actual drilling data. In the process of prediction of pore pressure, this study found that the pore pressure and formation velocity in the study area have an exponential relationship. In order to enhance the applicability of the Filippone's method in the study area and improve the prediction accuracy of pore pressure, the linear relationship between pore pressure and formation velocity in the Filippone's method is modified to an exponential relationship, and a pore pressure prediction model suitable for the work area was established. Based on the Mohr-Coulomb criterion and Huang's model, the prediction models of collapse pressure and fracture pressure applicable to the study area were established, respectively. Then, the elastic parameters were obtained through pre-stack inversion, and the three-pressure bodies were calculated based on the elastic parameter bodies. The results indicate that: (1) The three-pressure prediction method of the jointing well-seismic data in this paper can predict the formation's longitudinal and transverse pressure anomaly zones in advance. (2) The Maokou Formation in the study area is characterized by abnormally high pressure, to balance the pressure of the high-ground formation, high-density drilling fluid is necessary. (3) The prediction results of three-pressure in this paper are highly consistent with the actual drilling engineering events, which verifies the reliability of the three-pressure prediction results presented in this study. The results of the study can provide a basis for decision-making in drilling geological design, such as the determination of drilling fluid density, the evaluation of borehole stability and other engineering problems that require support from three-pressure data., (© 2024. The Author(s).)

To investigate the characteristics of destabilization damage in coal-rock complexes. Mechanical property tests were conducted on coal, rock, and their complexes. An infrared thermal camera was employed to real-time monitor the infrared (IR) radiation response signals during the destabilization damage process. A numerical model of coal-rock destabilization damage was developed, and its validity was verified. Deformed stress fields and displacement contours were obtained during the destabilization damage process. Upon destabilization, numerous cracks form at the base of the "coal" section, extending towards the interface, resulting in the formation of a wave-like deformation region. The differentiation in infrared thermal images is more pronounced in the "coal" section compared to the "rock" section. A high-stress region is evident at the interface, resulting in an area of high stress differentials. However, the bottom of the "coal" section also exhibits a region with high stress differentials and a more pronounced tendency towards destabilization damage. Displacement contours revealed that numerous units at the bottom of the "coal" section had slipped and misaligned, leading to the accumulation of damage and an elevation in the local damage level. It is a crucial factor contributing to the notable phenomenon of IR thermal image differentiation., (© 2024. The Author(s).)