Mine Gas Research Articles

Study on the changes and transformation characteristics of intermediate liquid products in hydrogen sulfide production from lignite degraded by sulfate-reducing bacteria.

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, H2S 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 SO42- 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 H2S production, while amides stimulate nitrogen production. The process is divided into three stages: hydrolysis stage, H2S 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 H2S genesis.

Gas Fire Coupling Control of Goaf Based on Numerical Simulation

ABSTRACT In response to the problem that traditional gas control methods such as water injection and inert gas fire extinguishing are not effective and have a high level of risk in goaf, this study uses COMSOL software to establish a three-dimensional numerical simulation model of goaf, and combines air leakage intensity, oxygen concentration, and floating coal thickness to calculate the gas fire hazard area, in order to achieve effective control. The results show that the deviation between the data obtained from the numerical simulation and the actual measurement value is about 7 m, which proves that the given solution is reliable. The gas concentration of the wind lane and the upper corner is controlled below 1%, which proves that this method ensures the safety of the working environment. The above results show that the design method realizes the effective control of gas fire in the goaf, and provides reference for mine safety management and gas disaster control.

The Influence of Sales Growth, Profitability, Liquidity and Firm Size Towards Financial Distress

There are several models that can be used in analyzing a company's Financial Distress, the most widely used is the Altman model. The study aims to analyze and identify the influence of fundamental factors represented by ratios such as Sales Growth Analysis, ROA Ratio, Current Ratio, and Firm size on Financial Distress conditions. This research was conducted on financial statements of oil and gas mining sector. Data was collected using data panel with multiple linear regression technique analysis. Data was proceed using Eviews 12. The result show Sales growth, ROA, Current Ratio and TATO ratio have a partially significant effect on Financial Distress. Sales growth ROA, Current Ratio and TATO ratio together and a simultaneous have an effect on Financial Distress

TAX AVOIDANCE: AN AGENCY THEORY PERSPECTIVE

Tax Avoidance, or often known as tax avoidance, is an obstacle that has the potential to affect state cash revenue. This arises from the irresponsible behavior of corporate taxpayers who do not fulfill their obligations in paying their taxes, in practice often taking advantage of weaknesses or loopholes in tax regulations. The purpose of this research is to test the impact of transfer pricing, sales growth, capital intensity, and debt to equity ratio on tax avoidance in the oil, gas and coal mining industry listed on the IDX in 2019 – 2022. The method used in sampling is the purposive sampling method through a sample that has a total of 8 out of 19 oil, gas and coal mining industries in the IDX in 2019 – 2022. The variables used in this research are dependent (y) and independent (x) variables. The data analysis used in this research is multiple linear regression using the SPSS version 18 test tool. Based on the results of the analysis carried out, the researchers were able to draw conclusions that the variables transfer pricing, sales growth, capital intensity, and debt to equity ratio had a significant positive effect on tax avoidance, on the significance value of each independent variable (x), namely 0.001, 0.003, 0.042, and 0.010 where the value was smaller than 0.05.

Acoustic and thermal response characteristics and failure mode of gas-bearing coal–rock composite structure under loading

Exploring the characteristics of the instability and failure processes of gas-bearing coal and rock is crucial for monitoring and predicting mine gas accidents. Thus, a real gas environment was simulated based on a self-developed gas–solid coupling infrared observation system. The acoustic–thermal response characteristics and failure mode of the gas-bearing coal–rock composite structure were studied. The results showed the following: (1) From the plastic stage, the average infrared radiation temperature of the coal increased significantly. The variances of differential infrared temperature (VDIRT) of the combination and coal started to mutate approximately 30 s before the peak, and the b value of the combination began to fluctuate frequently, while the VDIRT of rock remained approximately 2.128 × 10−4 throughout the process. (2) When stress was about to peak, a clear temperature boundary formed between coal and rock. Acoustic emissions with high energy were mainly concentrated at the interface and inside the coal. (3) The early plastic stage was dominated by high-frequency, low-amplitude events. In the post-peak stage and late plastic stage, the proportion of events with 80–90 dB amplitude rose, and there was a significant increase in low-frequency, high-amplitude events. (4) As the loading proceeded, the density and area gradually increased and tended to move toward the shear crack region. The distribution range of the rise time/amplitude expanded from 0–12 ms/V at the beginning of the loading to the range of 0–60 ms/V in the post-peak stage.

Study on Prevention System Construction of Coal Mine Gas Accident

Study on Prevention System Construction of Coal Mine Gas Accident

Coal mine gas emission prediction based on multifactor time series method

The prediction of coal mine gas emission is an important indicator for ventilation systems reliability and a data basis for mine gas extraction design. The traditional gas emission prediction methods have weak universal applicability, and the existing prediction models are mostly based on single-factor time series prediction. To solve this problem, the gas emission prediction method based on Recursive Feature Elimination with cross-validation (RFECV) and Bidirectional Long and Short-Term Memory (Bi-LSTM) was proposed. Aiming at the problems of numerous influencing factors, strong nonlinear characteristics and time correlation, feature selection methods based on RFECV were applied. The RFECV method embedding of two base models, Ridge Regression (Ridge) and Random Forest (RF), obtained four gas emission prediction multifactor combinations. The predictive accuracy of different models was compared with multifactor combinations when the training set accounted for 60, 70 and 80 % of the total sample. The RMSE, MAE, R2, model stability, and running time of the RF-RFECV-Bi-LSTM model were 0.2455,0.1914,0.9897,0.9431 and 12.20 s, respectively. The result indicated that the constructed prediction model had high accuracy and reliability, which can be used as a basis for the accurate prediction of gas emission in multifactor time series.

Quantitative risk assessment of coal mine gas explosion based on a Bayesian network and computational fluid dynamics

A gas explosion is one of the most serious coal mine accidents. The complexity and dynamics of gas explosion accidents, resulting from both multiple risk factors and time-dependent physical parameters, necessitates the use of risk assessment techniques to analyze the accident. A quantitative risk assessment method is proposed for coal mine gas explosions based on a Bayesian Network (BN) and Computational Fluid Dynamics (CFD). The results show that, in addition to the problems of “low vigilance” and “substandard safety education”, the “irrational design of mine gas extraction” has become another major risk factor at the new stage of development of mine excavation technology. Three typical gas explosion areas are selected to analyze the possible consequences of an accident. Based on the probabilistic risk assessment model, time-dependent physical parameters such as accident conditions, location and time are analyzed. The probability of occurrence of time-dependent risk factors is quantified to calculate the risk values of the consequences of explosion accidents corresponding to different times. The proposed method helps to improve the calculation accuracy of updating the risk probability value over time and provides theoretical support for the risk analysis of coal mine gas explosion accidents.

Diatoms’ Diversity in the Assessment of the Impact of Diamond and Oil and Gas Mining on Aquatic Ecosystems of the Central Yakut Plain (Eastern Siberia, Yakutia) Using Bioindication and Statistical Mapping Methods

Diamond and oil and gas production carries risks to the aquatic ecosystem. In Eastern Siberia, on the territory of the Central Yakut Plain, mining development of the Yakut diamond-bearing province and Tas-Yuryakh oil and gas condensate field has been underway for several decades. But the problem of studying negative consequences in the region is covered only from the point of view of the impact on terrestrial ecosystems. The purpose of this study was to assess the impact of diamond and oil and gas production on the aquatic ecosystems of the region using the bioindicative properties of diatoms. The work used previously widely tested methods of ecological mapping, JASP, and species–environments relationship analysis. The results of chemical analysis of water showed that in oil and gas production areas, there is no pollution with petroleum products, but the concentration of silicon and zinc is increased. The study identified key pollutants in the Central Yakut Plain and demonstrated the effectiveness of diatoms as bioindicators. Elevated chloride levels were found in diamond mining areas, and increased copper levels were noted in oil production regions. In the diatom flora of the region, 144 species were identified, of which 137 are indicator species. Natural and anthropogenic clusters of environmental factors are identified, characterized by a specific effect on the species composition and taxonomic structure of diatom communities. The results obtained are suitable for assessing the level of anthropogenic impact on aquatic communities of photosynthetic microorganisms in permafrost conditions.

Analysis of Factors Affecting Emergency Response Linkage in Coal Mine Gas Explosion Accidents

To analyze the influencing factors of the emergency linkage of gas explosion accidents and their causal relationships, a method for analyzing the influencing factors of the emergency linkage of gas explosion accidents is proposed based on a hierarchical holographic model and Bayesian networks. Firstly, based on the hierarchical holographic model to determine the main influencing factors of the accident emergency linkage, we constructed the topological structure model of accident control, secondary disaster, and emergency rescue, and used the triangular fuzzy number to assess the a priori probability and conditional probability of the influencing factors. Next, the most likely factors affecting the accident emergency linkage are quickly identified by combining Bayesian diagnostic reasoning. Finally, sensitivity analysis is conducted to identify the key factors affecting the accident emergency linkage. The results show that the probability of normal operation of gas explosion accident emergency linkage is 78.1%, but when the coal mine environment changes, especially when multiple influencing factors occur simultaneously, the probability of normal operation of accident emergency linkage decreases significantly. Through causal analysis, the degree of influence on the operation of the accident emergency linkage in different situations can be deduced. Through diagnostic analysis, it can be seen that the emergency linkage operation is more sensitive to the two factors of the ventilation and smoke extraction system response and gas over limit, so it is necessary to pay attention to its important role in accident treatment. Meanwhile, the sensitivity analysis shows that the response of the ventilation and smoke extraction system, the accuracy of disaster sharing, the gas over limit, the technical level of the operators, and the team rescue experience are the key factors affecting the emergency response linkage in accidents. This study can provide theoretical guidance for the improvement of the emergency response linkage mechanism of coal mine gas explosion accidents as well as the decision-making of the accidents, minimize the losses of the accidents, and promote the sustainable development of the coal mining industry.

Enhancing coal seam gas pressure measurement accuracy and preventing leakage through dual chamber pressure balancing in borehole

Accurate measurement of coal seam gas pressure (CSGP) is critical to the evaluation of coal mine gas hazards and the potential of coal seam gas extraction. In this study, we investigate gas leakage from chambers and its influences on CSGP measurement results (MR) through numerical simulations. Furthermore, we propose, analyze and validate a novel method that balances gas pressure between two chambers, i.e. the measurement and regulation chambers, in a borehole. The results demonstrate that: (1) Traditional CSGP measurement method utilizing boreholes with a single chamber exhibit a gradual expansion of the gas pressure dropping region around the borehole, accompanied by an initial increase in chamber gas pressure followed by stabilization. The gas leakage process within the chamber undergoes three typical stages. (2) The increase of gas leakage lowers the MR value and raises the CSGP measurement error ratio (R). The relationship between MR, R and the stable value of gas leakage is nearly linear. (3) The proposed novel CSGP measurement method involves continuous gas injection into the regulation chamber to establish a dynamic gas pressure balance region between the two chambers. This approach minimizes gas leakage in the measurement chamber and accelerates gas pressure recovery. Maintaining dynamic pressure equality between the dual chambers is essential for minimizing R. (4) An automatic regulation unit is developed to achieve dynamic gas pressure balancing between the two chambers. With the novel method, R values remain below 3%, yielding higher CSGP measurement accuracy compared to alternative approaches.

Research on Gas Control Technology in Goaf Based on the Influence of Mining Speed

To comprehensively understand the influence of mining speed on gas emissions in goaf during coal seam extraction, enhance gas extraction efficiency in goaf, manage gas emissions at the working face, and ensure safety in the mining production process. This study focuses on the No. 3 mining area of Wangjialing Mine, employing numerical simulations to analyze the evolution of mining-induced fractures and the characteristics of gas distribution in the overburden at varying mining speeds. Furthermore, by integrating actual gas emission and extraction data at the production face, this study examines the quantitative relationship between mining speed and gas emissions in the goaf, identifying optimal regions for high-position borehole layouts and conducting borehole optimization design and investigation. The results of this study indicate that the initial caving step distance of the goaf roof increases with the advancement speed of the working face. Conversely, the maximum height of through fractures in the overburden decreases as the mining speed increases, while delamination fractures are minimally affected by the advancement speed. By categorizing and averaging data on goaf mining speed, the impact of initial and periodic pressure on gas emissions can be effectively mitigated, revealing a linear correlation coefficient of 0.94 between goaf gas emissions and mining speed. At varying mining speeds of the working face, the efficient extraction layer and horizontal distance parameters of gas extraction boreholes in the goaf conform to the linear equation y = ax ± b. Based on the research findings, an optimization design for mining face speed and high-level borehole parameters in the goaf was implemented. The average gas extraction rate of high-level directional boreholes reached 68% throughout the extraction period. Gas emissions at the working face were effectively controlled below 10 m3/min, with the maximum gas concentration at the upper corners and return airflow kept below 0.8%. This effectively managed gas emissions at the working face, ensuring safe production in the mine, providing a theoretical basis for identifying gas-rich areas in the mining-induced overburden, and enhancing gas extraction efficiency at the working face.

Upgrading low-concentration oxygen-bearing coal bed methane by dual-reflux vacuum swing adsorption

Fugitive methane (CH4) is a typical by-product of mining processes, which is commonly known as coal bed methane (CBM) or coal mine gas (CMG). The capture of these CH4 gases can simultaneously avoid greenhouse gas emissions and provide extra energy benefits. However, the explosion risk of low-concentration CBM (CH4 molar fraction ≤ 30%) requires strictly safe operating protocols to conduct the capture process. Dual reflux vacuum swing adsorption (DR-VSA) is a promising candidate with a vacuum operating condition which can lower the explosion risk and simultaneously reach CH4 enrichment and O2 removal targets in product and effluent streams. Herein, a low-concentration oxygen-bearing CBM (20% CH4, 16% O2 and 64% N2) can be upgraded to 69.7 mol% in the product gas while ensuring an effluent concentration of 2.5 mol% by the DR-VSA cycle using ionic liquidic zeolites (ILZ) as the adsorbents. A rigorous safety analysis has been conducted to investigate the explosion risk in the adsorption column and product tank, suggesting that the DR-VSA process is a safe technology for upgrading low-concentration oxygen-bearing methane.

Building MSME Competitiveness Through the Local Business Development Program in the Upstream Oil and Gas Working Area of the Rokan Block in Riau Province

This study examines the potential optimization of the Local Business Development (LBD) partnership program in the development of MSMEs in the upstream oil and gas work area of the Rokan Block, Riau Province. MSMEs in Indonesia, totaling 64.2 million units, play a crucial role in the economy by contributing 61.07% to GDP and absorbing 97% of the workforce. However, MSMEs face various challenges such as limited access to financing and low technical capabilities. Pertamina Hulu Rokan (PHR), through the LBD program, seeks to enhance the capabilities of local MSMEs in the oil and gas mining sector. This study uses the SEM-PLS analysis method to explain the relationship between partnership, entrepreneurial orientation, human resource capability, organizational learning, and the competitive advantage of MSMEs. Data were collected through questionnaires from 232 MSME owners registered in the LBD partnership program. The analysis results show that partnership, entrepreneurial orientation, and organizational learning significantly influence human resource capabilities and the competitive advantage of MSMEs. This research provides practical and theoretical guidelines for the implementation of the LBD-based partnership program, as well as deep insights for oil and gas companies, the government, and relevant stakeholders in enhancing the contribution of partnerships to MSME development. This study also bridges existing research gaps and empirical gaps and offers a new perspective on partnership theory with a local business development contract cooperation pattern supported by the upstream oil and gas company's partnership program.

Is TCR effective in reducing tax avoidance in Indonesia?

Thin capitalization is a tax avoidance technique using funding sources that prioritize debt over capital. Thin capitalization can be used as a technique to avoid taxes because there is a difference in treatment between debt and capital as a source of funding in tax regulations. Thin capitalization rule (TCR) is domestic tax system to reduce thin capitalization. This study aims to examine the effect of implementing thin capitalization rules on reducing tax avoidance in Indonesia. This study is a quantitative study. The data used are secondary data obtained from multinational companies listed on the IDX from 2013 to 2020 by excluding companies that are excluded from PMK-169: bank companies, financing institutions, insurance, reinsurance, operating in the oil and gas mining sector, companies whose entire income is subject to final tax, and infrastructure. The data analysis method used in this study is regression using the eviews 12.0 program. The results show that the implementation of thin capitalization rule (TCR) does not reduce tax avoidance. These results provide empirical evidence that the government need to consider using thin capitalization rule with the interest to Earnings Before Interest, Tax, Depreciation, and Amortization (EBITDA) rule mechanism rather than the Debt-to-Equity Ratio (DER) rule mechanism and arm’s length rule mechanism.

System simulation and parametric analysis of low-concentration coal mine gas fed SOFC-CHP with deoxygenation and enrichment pretreatment

Solid oxide fuel cell (SOFC) combined heat and power (CHP) can efficiently convert low-concentration coal mine gas (LC-CMG) into clean energy, avoiding the greenhouse effect of LC-CMG. Deoxygenation and methane enrichment pretreatment of LC-CMG can prevent explosion and anode oxidation risk. Herein, a chemical process model of LC-CMG fed SOFC-CHP system with the pretreatment was established to predict the performances under different operating conditions. Performance evaluation and exergy analysis were performed considering the use of oxygen-rich gas from the pretreatment at SOFC cathode. The effects of key operation parameters on system performances were investigated in terms of residual oxygen concentration, inlet methane concentration, fuel flow and fuel utilization. The results indicated that net electrical efficiency and heat supply efficiency can respectively reach 49.13 % and 23.90 % using LC-CMG of 15 % CH4 with enhancing effect of oxygen-rich gas at cathode. The decrease of methane concentration and the increase of residual oxygen concentration and flow rate caused the decreased electrical efficiency but the increased heat supply efficiency due to the enlargement of concentration polarization and heat supply. The optimal operation parameters were recognized by comprehensively considering diverse performance indicators. This work can guide system integration and operation optimization of LC-CMG fed SOFC-CHP.

About an Oil and Natural Gas Mining Treaty in the High Seas of the North Natuna Region with Economic, Legal and Environmental Aspects

This study thoroughly investigates the development of an oil and natural gas mining treaty in the high seas of the North Natuna region, focusing on overlapping Exclusive Economic Zone (EEZ) claims involving Indonesia, Vietnam, and China. Analyzing the geopolitical and economic implications, the research utilizes a comprehensive methodology, including policy document scrutiny and an extensive literature review. The findings underscore the significant potential of North Natuna’s natural resources, accentuating the determination of the three nations to assert their territorial claims. Notably, tension arises from China’s Nine Dash Line claim, challenging the UNCLOS 1982 arbitral tribunal decision. The study recommends a tripartite resolution, emphasizing a robust Code of Conduct agreement. Despite diplomatic efforts, this research stresses the need for strengthening the Code of Conduct and adopting a tripartite reconciliation approach to ensure the security and sovereignty of the North Natuna region. Enforcing rights through the International Arbitration Tribunal is crucial for lasting peace, stability, and the sustainable management of oil and natural gas activities.

A software for calculating coal mine gas emission quantity based on the different-source forecast method

The ability to predict gas emissions accurately is pivotal in managing gas control and ensuring safe mining operations. Existing internationally acknowledged gas control and prediction software does not cater to the specific conditions in Chinese coal mines. Hence, this paper introduces an object-oriented programming method to design a software tool for calculating the total gas emission quantity using the MATLAB application program designer runtime environment. The software incorporates an algorithm, data structure, framework, and module functions, all of which enable seamless integration and visualization of gas emission calculation software. This software tool mitigates the inefficiencies and inaccuracies associated with manual, different-source forecast methods. Based on the field data of the Hulonggou Coal Mine in Shanxi province, this technical software was used to predict the gas emission of the mine. The research results show that the predicted value of the technical software is close to the actual measured value. The differing estimates of the working face and coal mine output primarily account for the deviation between the tool's predicted gas emission value and the field-measured value. The underlying design logic of this technical software determines that it has good adaptability to mines with clear mining technology parameters and gas geological parameters. This study provides a valuable method for researchers and engineers seeking to improve gas emission calculation efficiency.

Status and Development of Coal Mine Gas Extraction Technology

Most of the coal seams in China are geologically old, well closed, with high gas content and high pressure, which are prone to coal and gas protrusion accidents. Coal mine gas extraction technology has been developed for a long period of time, and some extraction pressurization technologies have appeared in improving the effect of gas extraction. And in the research process of low permeability coal seam pressurization technology, hydraulic pressurization technology is gradually applied. In order to solve the problems encountered in the actual production, the development trend of gas extraction technology will be the up-and-down joint extraction, “three-area linkage” three-dimensional extraction, and coal and gas co-mining technology. However, there are some problems in gas extraction, such as theoretical research, extraction technology and popularization and application of technology and equipment, etc., and the research directions are also various

Research on the Critical Moisture Content of Frost Heaving in Gas-Containing Coal.

As the depth of coal seam mining increases, coal and gas outburst prevention and control face unprecedented challenges. In recent years, freezing outburst prevention technology has received attention and been applied in industry; this method mainly improves the strength of the coal body while reducing its energy storage. Research has shown that due to the influence of moisture content, frost heaving occurs in coal bodies during the cooling process, weakening the coal bodies' strength. Therefore, it is necessary to explore the effect of the moisture content on the coal body frost heave. This paper uses a research method that combines laboratory experiments, theoretical analysis, and numerical simulation to study the critical moisture content of frost heaving in gas-containing coal. The results showed that the coal sample can be divided into three stages during the cooling process: the cold shrinkage stage, frost heave stage, and stabilization stage. When the moisture content is greater than 7%, as the moisture content increases, the amount of ice increases accordingly, which causes an increase in the frost heave deformation of the coal sample and produces an obvious frost heave effect. Utilizing COMSOL simulation software, the deformation of gas-containing coal samples at different moisture levels is simulated. By combining the results with laboratory measurements, the critical moisture content for the frost heave in gas-containing coal is determined to be 6.6%.