Mine Gas Research Articles

Cu-MOF attached with pyrene-cored probes as a highly sensitive indicator for carbon monoxide in coal mine gas: Synthesis and performance

As a toxic component in coal mine gas, CO has both acute and long-term damages to human health. Suitable CO probes satisfying the requirement for long-distance real-time monitoring in confined space are still underdeveloped. In this work, a series of fluorescent probes derived from pyrene were synthesized and coordinated onto [Cu3(BTC)2(H2O)3]n (H3BTC meant 1,3,5-benzenetricarboxylic acid) via a coordination bond with Cu2+. These probes were carefully analyzed, including their single crystal structure, absorption spectra, excitation spectra, and emission spectra. Their emission response towards CO gas was analyzed, with a sensing mechanism of probe release which was triggered by a dynamic wagging between the trans- and cis- configuration of –C = N–N = C– moiety upon photoexcitation. These probes were attached onto a classic MOF (metal-organic framework) [Cu3(BTC)2(H2O)3]n, which was confirmed by SEM, fluorescence microscopy, XRD, N2 adsorption/desorption, and TGA. The resulting composite samples (denoted as Pm@CuBTC) showed emission recovery upon trace amount CO (LOD = 0.005 % vs N2, 50 ppm), with a short response time of 31 s at room temperature. High sensing selectivity over competing species of alkane was observed, with stable signal for 5 days.

EVALUATION OF CONTINUOUS AND WATER ALTERNATING GAS (WAG) CO2 INJECTION ON X FIELD RECOVERY FACTOR

Indonesia is a country rich in natural resources. The wealth of Indonesia's natural resources is not only limited to agricultural and plantation products, but also from mineral and hydrocarbon mining or oil and gas. Indonesia's oil production has continued to decline in the last 10 years until the national consumption rate is much higher than national production. One of the causes of the decline in oil production in Indonesia is the condition of Indonesia's oil fields, which are currently mature fields. To overcome the problem of old fields that still have economic oil reserves, enhanced oil recovery (EOR) can be used. One of the EOR methods that can be used is the CO2 injection method using continuous and WAG injection schemes. The study was conducted in X field with oil-wet carbonate rock composition with waterdrive and fluid expansion driving mechanism. The basecase production scheme using 5 production wells produces a recovery factor of 34.3%, while continuous CO2 injection produces a recovery factor of 32%, and CO2-WAG produces a recovery factor of 42%. Continuous CO2 injection has the lowest recovery factor because early gas breaktrough occurs due to a large mobility ratio and causes gas fingering, hindering the oil production process. The most suitable injection method is CO2-WAG 1 cycle using a 1:1 ratio, CO2 injection volume of 6.661 MSCF/D, injection water volume of 37.4 MBBL/D with a recovery factor of 43.46%.

Analysis of the Formation Mechanism of Hydrogen Sulfide in the 13# Coal Seam of Shaping Coal Mine.

In order to accurately predict the law of occurrence and migration of hydrogen sulfide (H2S) in the underground and effectively solve the problem of excessive concentration of H2S gas, laboratory experiments on the content of various forms of sulfur in coal, sulfur isotopes, thermal evolution history, and coal seam water samples were carried out by applying the theories of coal mine geology, microbiology, and analytical chemistry, and based on the experimental results, the cause of H2S gas was explored. Through the analysis of the geological conditions of the coal seam mined, it can be seen that the coal mine experienced the alternation of marine and continental phases in the process of coal formation and that there was no magma intrusion. The experimental results showed that iron sulfide in coal accounts for 73.25% of the total sulfur, indicating that the coal seam was rich in pyrite. The results of the isotope test showed that the sulfur isotopes in coal samples were all negative, indicating that the sulfur isotope fractionation in coal was large, the loss was serious, and the coal seam was greatly affected by seawater. According to the experimental results of vitrinite reflectance, it can be concluded that the highest temperature during the thermal evolution of the coal seam is 108.12 °C, which has not reached the temperature condition of sulfate thermochemical reduction. Comparing the concentration of acid ions in coal seam water and tap water, it was found that the concentration of SO42- in coal seam water is low, while the concentration of HCO3- is high. According to the experimental results and theoretical analysis, the H2S gas in the high-sulfur coal mine was caused by microbial sulfate reduction. Finally, the transformation path of sulfur in the coal seam was deduced and analyzed. The results showed that sulfur in coal is positively correlated with H2S gas concentration.

Analysis of Leading Sectors in Driving the Economy of Majene Regency

West Sulawesi is the province with the lowest unemployment rate in Indonesia. Majene is a regency in West Sulawesi with increasing economic growth. This research aims to analyze the typology and leading sectors in Majene regency. This research uses the LQ, Shift Share, and Klassen Typology analysis methods. The data used is secondary data in the form of GRDP of Majene regency and West Sulawesi province for 2018-2022 which is sourced from the Central Statistics Agency (BPS). The analysis is carried out by determining the base sector, then determining the progressive sector, and finally formulating a sector typology using the Klassen Typology. The research results show that those included in the leading sectors are the mining sector, electricity and gas procurement, transportation, accommodation provision, information, financial services, real estate, government administration, educational services and other services. This sector has the potential to be developed. It is hoped that the results of this research can become the basis for an economic development strategy by looking at the potential of each sector typology

Tools available for methane recovery from mines belonging to C.E.H. Petroşani

Mine gas is present both in coals and in the surrounding rocks and basically consists of methane (some-times almost 100%) mixed with carbon dioxide (up to 5%) with nitrogen (a few percent) and traces of carbon monoxide. The genesis of mine gas can be related to the biochemical transformation of vegetation during the carbonization process. The degassing of coal bed has been established as an active method of reducing methane emissions due to the need to ensure the exploitation of the bed with high productivity and in safe conditions. The methane gas existing in the coal bed is captured through various types of drilling executed for this purpose, being directed through a system of pipes to the surface to the central degassing station from where it can be taken and directed for use for a specific purpose. From an economic point of view, it has been proven that methane recovery from coal mines is again a profitable activity for both the mining company and a possible investor. The volume of methane from the coal deposits in Jiu Valley is very large and can provide large quantities for the recovery of this gas. At the same time, there was already a market for this product in Jiu Valley made up of industrial and individual consumers.

A 3D Numerical Model for Improving Methane Drainage Efficiency in Underground Coal Mines Using the Cross‐Measure Borehole Method

The release of methane into the working area of coal mines can affect safety and production. Therefore, methane drainage reduces the risk of explosion and can be used as a fuel and energy source. One methane drainage method is cross‐measure borehole drilling, which involves drilling boreholes from tailgate roadways to the roof or floor layers of a mined seam. In this method, determining the appropriate distance between methane drainage stations has a significant impact on increasing the efficiency of operation and reducing drilling costs and the time required for drainage operations from each station. In this paper, a new 3D numerical model is developed for methane drainage from an underground coal mine to determine the suitable distance between methane drainage stations in the cross‐measure borehole method using COMSOL Multiphysics software. For this purpose, by considering the porous media flow module and the laws related to the movement of gas in the goaf, different numerical models for distances of 10, 15, 20, 25, and 30 m were simulated. The simulation results showed that by reducing the distance between methane drainage stations, the speed of gas flow in the borehole and the amount of gas removed from the boreholes in a similar period of time increase to an acceptable level. In addition, the implementation of this model in a case study showed that a distance of 10 m between drainage stations increases the efficiency of boreholes to approximately 20%. Numerical simulation in this study can provide basic support for the design of drainage boreholes and reduce the risk of gas in underground coal mines.

Pore-pressure and stress-coupled creep behavior in deep coal: Insights from real-time NMR analysis

Understanding the variations in microscopic pore-fracture structures (MPFS) during coal creep under pore pressure and stress coupling is crucial for coal mining and effective gas treatment. In this manuscript, a triaxial creep test on deep coal at various pore pressures using a test system that combines in-situ mechanical loading with real-time nuclear magnetic resonance (NMR) detection was conducted. Full-scale quantitative characterization, online real-time detection, and visualization of MPFS during coal creep influenced by pore pressure and stress coupling were performed using NMR and NMR imaging (NMRI) techniques. The results revealed that seepage pores and microfractures (SPM) undergo the most significant changes during coal creep, with creep failure gradually expanding from dense primary pore fractures. Pore pressure presence promotes MPFS development primarily by inhibiting SPM compression and encouraging adsorption pores (AP) to evolve into SPM. Coal enters the accelerated creep stage earlier at lower stress levels, resulting in more pronounced creep deformation. The connection between the micro and macro values was established, demonstrating that increased porosity at different pore pressures leads to a negative exponential decay of the viscosity coefficient. The Newton dashpot in the ideal viscoplastic body and the Burgers model was improved using NMR experimental results, and a creep model that considers pore pressure and stress coupling using variable-order fractional operators was developed. The model’s reasonableness was confirmed using creep experimental data. The damage-state adjustment factors ω and β were identified through a parameter sensitivity analysis to characterize the effect of pore pressure and stress coupling on the creep damage characteristics (size and degree of difficulty) of coal.

Проблематика теории и практики налога на сверхприбыль в России и за рубежом

The article deals with the problems of introducing a tax on excess profits in the Russian Federation in 2023. The excess profit tax is not a novelty of Russian lawmakers. The first such tax was introduced in the UK in 1915 during the First World War. The article examines the foreign experience of introducing the tax. The world practice indicates that the tax is introduced in emergency situations. Foreign countries have repeatedly resorted to replenishing their budgets through taxes on excess profits. The article highlights the experience in Denmark and Sweden, which introduced a tax on excess profits from the sale of weapons. It provides a brief historical background on the introduction of the tax in Australia and Norway for industrialists working in the oil and gas industry, mining, technology and pharmaceutical sectors. The historical documents of the US Congress are considered, and the speeches of leading economists and politicians who advocated and opposed the introduction of a tax in the United States in 1980. Further, based on the analysis of the revenues of the Russian budget, the need to introduce such a tax in the Russian Federation is justified. A forecast is made of the possible size of budget replenishment when this tax is introduced. The forecast is based on the analysis of annual reports of leading Russian companies for 2020 and 2021, published in open sources. The analysis made it possible to highlight the negative and positive aspects of the introduction of a tax on excess profits in our country. Separately, the author of the article considers the issue of the specifics of introducing a tax on excess profits in the Russian Federation, focusing on the fact that the oil and gas sector has been removed from the scope of the tax, which in the experience of foreign countries bears the main burden when paying the tax on excess profits. Analytical calculations are given, based on open annual reports of oil and gas companies, on the payment of tax if the oil and gas sector were included in the law on tax on excess profits. The arguments of opponents and supporters of the exclusion of the oil and gas sector are considered. The argument of official sources is given. The conclusion states that the possibility of making an interim payment for enterprises actually reduces the tax to 5 percent, instead of the declared 10 percent. And world experience shows that the tax rates on excess profits are significantly higher from 35 to 80 percent. Perhaps more attention should be paid to world experience, and the tax rate on excess profits should be increased.

Impact of External Atmospheric Pressure Changes on the Behavior of Gas Emission in Mines

With the rapid development of industry in China, the scale of coal mining continues to expand, leading to an increase in safety hazards and frequent accidents. Among these, gas overrun accidents account for a significant proportion, and changes in atmospheric pressure are a major factor affecting the outburst of coal mine gas. This paper takes a mine in Hebei Province, China, as the research object, combining on‐site data detection with numerical simulation methods to explore the influence of atmospheric pressure changes on underground air pressure and gas emission. The results show that changes in atmospheric pressure are synchronized with changes in underground air pressure, and the rate of change affects the amount of gas emitted. When the rate of pressure decrease is below 0.04 KPa/h, the impact is slower, and the peak time of gas emission is later than the time of minimum pressure. Simulation results indicate that the pressure difference caused by changes in atmospheric pressure is transferred to the underground air pressure, affecting the distribution of methane at the working face and the range of air leakage in the goaf. The greater the pressure difference, the higher the concentration of methane at the working face, the greater the air leakage in the goaf, and the more gas brought from the deep part of the goaf to the working face. These findings are of great significance for understanding the mechanism of gas emission and preventing gas accidents.

Identification of Hidden Hazard Risks of Coal Mine Gas Accidents based on SNA and Analysis of Action Path

Identification of Hidden Hazard Risks of Coal Mine Gas Accidents based on SNA and Analysis of Action Path

Research on Coal Mine Gas Monitoring System

Research on Coal Mine Gas Monitoring System

基于IAHP-未确知测度的煤矿瓦斯爆炸风险评估

基于IAHP-未确知测度的煤矿瓦斯爆炸风险评估

Optimization Design of Mining Tri-cone Bit Air Nozzle by CFD

Performance of the air nozzle of the mine tri-cone bit directly affects life of bit and rock breaking efficiency. The shape of air nozzle influences performance of mine tri-cone bit. It is necessary to optimize the shape of the air nozzle of tri-cone drill bits. The general specifications of gas mine tri-cone bit were analysed. Working condition and parameters of the air nozzle of the mine tri-cone bit were determined. A three-dimensional model of the air nozzle of the mine tri-cone bit was established. The characteristic geometry and range of air nozzle were determined. The performance index of air nozzle was proposed. An orthogonal experiment table of characteristic geometry of air nozzle was established. The ranking of influence weights of characteristic geometry was obtained. Key characteristic geometry which affects the performance of air nozzle was also obtained. This thesis work helps to improve the working performance of the gas nozzle of the three-cone bit. It can provide some reference ideas for the optimized design of the cone bit

The Effect of Work Motivation and Transformative Leadership on Freelancer Innovative Behaviour in the Oil and Gas Mining Industry Mediated by Absortive Capacity

The Effect of Work Motivation and Transformative Leadership on Freelancer Innovative Behaviour in the Oil and Gas Mining Industry Mediated by Absortive Capacity

Разработка методологии создания энергоэффективных вентиляторов для аппаратов воздушного охлаждения

Introduction. Increasing the competitiveness of enterprises in the mining and oil and gas sectors of the Russian economy in combination with industrial safety requirements actualizes the task of developing a methodology for creating energy-efficient fans for air cooling devices with a dominant nature-like proportionality. Research methods and materials. The research method for creating adaptive fans is based on the scientific hypothesis of a nature-like proportionality in the aerodynamics of the profiles of the impeller blades. The results of the research. In the course of research, it was established that the most significant source of increasing the efficiency of AVO fan installations is an increase in the aerodynamic quality of the profiles of the blades of their impellers as the range of angles of attack increases. Discussion of research results. The use of modifications of conformal transformations with the proposed hypothesis of nature-like proportionality makes it possible to solve the problem of improving the aerodynamic quality of the blade profiles. Conclusions of the article. The creation of fans based on the principle of nature-like proportionality makes it possible to adequately and simultaneously with minimal energy costs ensure the necessary parameters of the cooling air and the stable efficiency of heat exchangers. Suggestions for practical application and direction of future research. The research results can be obtained when creating and modernizing a wide class of high-speed axial fans.

Experimental study of coal and gas outburst processes influenced by gas pressure, ground stress and coal properties

With the continuous increase of mining depth, coal and gas outburst poses a significant threat to mining safety. Conducting research on the mechanisms of coal and gas outbursts contributes to understanding the evolutionary process of such incidents, thus enabling accurate prediction and prevention of coal and gas outbursts during mining operations. This paper has developed a comprehensive visual experimental system that is specifically tailored to simulate diverse coal body conditions, ground stress and gas pressures. By monitoring and analyzing the real-time progression of coal fissures during the outburst process, we can obtain valuable insights into the evolution and mechanisms of coal and gas outbursts. Additionally, this study introduces a method to determine the critical threshold for predicting coal and gas outbursts, and the critical gas pressure threshold for Jiulishan Coal Mine (Jiaozuo City, Henan Province, China) is established at 0.6 MPa.

Grouting solidification technology for fractured soft coal seams and its application in coalbed methane (coal mine gas) extraction

This article presents an effective method for improving the structure and performance of coal rock masses, thereby facilitating coalbed methane extraction—the grouting solidification technique. A systematic review is conducted on grouting solidification materials, process methods, evaluation techniques, and other related aspects. In conclusion, it is emphasized that the grouting solidification technique requires further refinement in its system, and its continued significance in the dynamically evolving energy and coal industry is underscored. This is crucial for ensuring the efficient development and sustainable utilization of coal and coalbed methane resources.

Exciting and Detecting Higher-Order Guided Lamb Wave Modes in High-Density Polyethylene Structures Using Ultrasonic Methods.

High-density polyethylene (HDPE) pipes are becoming increasingly popular, being used in various fields, such as construction, marine, petroleum, water transfer, process water, methane gas collection, oil and gas gathering, gas distribution systems, mining, acid and wet gas lines, offshore oil and gas and in nuclear power plants. Higher-order guided Lamb wave (UGW) modes can be used to detect various defects in complex structures. We will apply this methodology to one of the types of plastic-the structure of high-density polyethylene (HDPE). However, the excitation of UGW modes faces numerous challenges, especially when there is a need to identify which mode is excited. It is essential to note that, in the higher frequency range, multiple different higher-order modes can usually be excited. This can make it difficult to determine which modes have actually been excited. The objective of this research was to successfully excite and receive various higher-order UGW modes in high-density polyethylene structures using both ultrasonic single-element transducers and a phased array. Theoretical calculations were performed using a variety of methods: semi-analytical finite element (SAFE) method, 2D spatial-temporal spectrum analysis and finite element modeling (FEM). The results obtained from both measurements and simulations clearly demonstrate the possibility of efficiently exciting and receiving different Lamb wave modes possessing different phase velocities.

PENGARUH PENGUNGKAPAN ENTERPRISE RISK MANAGEMENT DAN KUALITAS LAPORAN KEUANGAN DENGAN UKURAN PERUSAHAAN SEBAGAI VARIABEL MODERASI PADA PERUSAHAAN PENERIMA CORPORATE IMAGE AWARD

This study aims to determine the effect of enterprise risk management disclosure on the quality of financial reports in companies receiving corporate image awards. This research was conducted on companies receiving the Corporate Image Award in the categories of national airlines, car tires, two-wheeled automotive, four-wheeled automotive, coal mining, oil & gas mining, and cement for the 2015-2019 period. This study uses purposive sampling technique and secondary analysis using quantitative methods. This observation uses the random effect method and multiple linear regression analysis which is used to test the hypothesis. The results of this study indicate that the disclosure of enterprise risk management has a negative effect on the quality of financial statements, and firm size can strengthen the effect of using enterprise risk management disclosures on the quality of financial statements.

Source apportionment of methane emissions from the Upper Silesian Coal Basin using isotopic signatures

Abstract. Anthropogenic emissions are the primary source of the increase in atmospheric methane (CH4) levels. However, estimates of anthropogenic CH4 emissions still show large uncertainties at global and regional scales. Differences in CH4 isotopic source signatures δ13C and δ2H can help to constrain different source contributions (e.g., fossil, waste, agriculture). The Upper Silesian Coal Basin (USCB) represents one of the largest European CH4 emission regions, with more than 500 Gg CH4 yr−1 released from more than 50 coal mine ventilation shafts, landfills, and wastewater treatment plants. During the CoMet (Carbon Dioxide and Methane Mission) campaign in June 2018 methane observations were conducted from a variety of platforms including aircraft and cars to quantify these emissions. Besides the continuous sampling of atmospheric methane concentration, numerous air samples were taken from inside and around the ventilation shafts (1–2 km distance) and aboard the High Altitude and Long Range Research Aircraft (HALO) and DLR Cessna Caravan aircraft, and they were analyzed in the laboratory for the isotopic composition of CH4. The airborne samples downwind of the USCB contained methane from the entire region and thus enabled determining the mean signature of the USCB accurately. This mean isotopic signature of methane emissions was -50.9±0.7 ‰ for δ13C and -226±9 ‰ for δ2H. This is in the range of previous USCB studies based on samples taken within the mines for δ13C but more depleted in δ2H than reported before. Signatures of methane enhancements sampled upwind of the mines and in the free troposphere clearly showed the influence of biogenic sources. We determined the source signatures of individual coal mine ventilation shafts using ground-based samples. These signatures displayed a considerable range between different mines and also varied for individual shafts from day to day. Different layers of the USCB coal contain thermogenic methane, isotopically similar to natural gas, and methane formed through biogenic carbonate reduction. The signatures vary depending on what layer of coal is mined at the time of sampling. Mean shaft signatures range from −60 ‰ to −42 ‰ for δ13C and from −200 ‰ to −160 ‰ for δ2H. A gradient in the signatures of subregions of the USCB is reflected both in the aircraft data and in the ground samples, with emissions from the southwest being most depleted in δ2H and emissions from the south being most depleted in δ13C, which is probably associated with the structural and lithostratigraphic history of the USCB and generation and migration processes of methane in the coal. The average signature of -49.8±5.7 ‰ in δ13C and -184±32 ‰ in δ2H from the ventilation shafts clearly differs from the USCB regional signature in δ2H. This makes a source attribution using δ2H signatures possible, which would not be possible with only the δ13C isotopic signatures. We assume that the USCB plume mainly contains fossil coal mine methane and biogenic methane from waste treatment, because the USCB is a highly industrialized region with few other possible methane sources. Assuming a biogenic methane signature between and −320 ‰ and −280 ‰ for δ2H, the biogenic methane emissions from the USCB account for 15 %–50 % of total emissions. The uncertainty range shows the need of comprehensive and extensive sampling from all possible source sectors for source apportionment. The share of anthropogenic–biogenic emissions of 0.4 %–14 % from this densely populated industrial region is underestimated in commonly used emission inventories. Generally, this study demonstrates the importance of δ2H-CH4 observations for methane source apportionment in regions with a mix of thermogenic and biogenic sources and, especially in our case, where the δ13C signature of the coal mine gas has a large variability.