scholarly journals Method for Determining the Coalbed Methane Content with Determination the Uncertainty of Measurements

2016 ◽  
Vol 61 (2) ◽  
pp. 443-456 ◽  
Author(s):  
Nikodem Szlązak ◽  
Marek Korzec
Keyword(s):  
Coalbed Methane ◽  
Coal Sample ◽  
Methane Content ◽  
Underground Mines ◽  
Methane Drainage ◽  
Uncertainty Of Measurements ◽  
Underground Coal Mines ◽  
Mining Works ◽  
Prevention Methods ◽  
Two Stages

AbstractMethane has a bad influence on safety in underground mines as it is emitted to the air during mining works. Appropriate identification of methane hazard is essential to determining methane hazard prevention methods, ventilation systems and methane drainage systems. Methane hazard is identified while roadways are driven and boreholes are drilled. Coalbed methane content is one of the parameters which is used to assess this threat. This is a requirement according to the Decree of the Minister of Economy dated 28 June 2002 on work safety and hygiene, operation and special firefighting protection in underground mines. For this purpose a new method for determining coalbed methane content in underground coal mines has been developed. This method consists of two stages - collecting samples in a mine and testing the sample in the laboratory. The stage of determining methane content in a coal sample in a laboratory is essential. This article presents the estimation of measurement uncertainty of determining methane content in a coal sample according to this methodology.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

scholarly journals Determination of Long Horizontal Borehole Height in Roofs and its Application to Gas Drainage

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2647
Author(s):  
Gang Wang ◽  
Cheng Fan ◽  
Hao Xu ◽  
Xuelin Liu ◽  
Rui Wang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Fracture Zone ◽  
Coalbed Methane ◽  
High Efficiency ◽  
Gas Drainage ◽  
Methane Drainage ◽  
Working Face ◽  
Variation Characteristics

Accurately determining the height of the gas-guiding fracture zone in the overlying strata of the goaf is the key to find the height of the long horizontal borehole in the roof. In order to determine the height, in this study we chose the 6306 working face of Tangkou Coal Mine in China as a research example and used both the theoretical model and discrete element method (DEM) numerical simulation to find the height of the gas-guiding fracture zone and applied the height to drill a long horizontal borehole in the roof of the 6303 working face. Furthermore, the borehole was utilized to deep into the roof for coalbed methane drainage and the results were compared with conventional gas drainage measures from other aspects. The height of the gas-guiding fracture zone was found to be 48.57 m in theoretical model based on the bulk coefficient and the void ratio and to be 51.19 m in the DEM numerical simulation according to the temporal and spatial variation characteristics of porosity. Taking both the results of theoretical analysis and numerical simulation into consideration, we determined that gas-guiding fracture zone is 49.88 m high and applied it to drill a long horizontal borehole deep into the roof in the 6303 working face field. Compared with conventional gas drainage measures, we found that the long horizontal borehole has the high stability, high efficiency and strong adaptability for methane drainage.

scholarly journals Gas Jet Coal-Breaking Behavior: An Elliptical Crushing Theoretical Model

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Gongda Wang ◽  
Yuanyuan Wang ◽  
Xin Yang ◽  
Xin Song
Keyword(s):  
Theoretical Model ◽  
Coalbed Methane ◽  
Clean Energy ◽  
Rock Breaking ◽  
Gas Jet ◽  
Rock Fracturing ◽  
Efficient Technology ◽  
Methane Drainage ◽  
Experimental Values ◽  
The Impact

Coalbed methane (CBM) is a source of clean energy and has been recovered in past decades all over the world. Gas dynamic disaster is the primary disaster in outburst coal, and methane drainage plays a key role in eliminating this danger. As an efficient technology, a gas jet is widely used in CBM development and methane drainage. In this work, the full impinging process of coal and rock fracturing by a supersonic gas jet was studied. To understand how jet parameters affect coal and rock fracturing results, an elliptical crushing theoretical model was proposed. In addition, a laboratory experiment was designed to examine the proposed model, and four key parameters affecting the fracturing results were studied. The results show that different from the monotonic variation of theoretical values, there is a turning point in the variation of experimental values under some parameters. Considering the influence of the depth and radius of the erosion pit, the rock-breaking effect is better when the nozzle size is 2.75 Ma. The optimal target distance is 30 mm, and the impact pressure of a gas jet should be continuously increased in order to achieve certain rock-breaking effects under the impact of the jet.

scholarly journals Modeling and prediction for gas production during coalbed methane drainage based on two indirect reservoir parameters

2018 ◽  
Vol 36 (6) ◽  
pp. 1424-1437 ◽  
Author(s):  
Mingjun Zou ◽  
Xiaochun Lv ◽  
Zhiquan Huang ◽  
Simin Wei ◽  
Miao Zhang ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Good Accuracy ◽  
Simulated Data ◽  
Gas Production ◽  
Methane Drainage ◽  
Modeling And Prediction ◽  
Cubic Polynomial ◽  
Southern Qinshui Basin ◽  
Two Parameters ◽  
Gas Production Prediction

Two indirect parameters influencing coalbed methane (CBM) drainage performances are proposed in this paper, which are effective desorption radius and difference between reservoir pressure and critical desorption pressure (DRPCDP). Variations of the two parameters during CBM drainage are investigated, which shows that they have a linear relationship. By using formula derivations, a theoretical model for gas production prediction is built. It suggests that the cumulative gas production is a product of square of effective desorption radius with DRPCDP, and there is also a cubic polynomial relationship between cumulative gas production and linear average DRPCDP. Furthermore, well PM01 located at southern Qinshui basin of China is selected as a case, and a commercial software is adopted to predict the gas production. Compared with the simulated and modeled cumulative gas productions, the simulated data match well with the modeled data, which indicates that the model has a good accuracy.

Wireless Sensor Network for Underground Mining Services Applications

2017 ◽  
pp. 504-530 ◽  
Author(s):  
Pankaj Kumar Mishra ◽  
Subhash Kumar
Keyword(s):  
Wireless Sensor Network ◽  
Sensor Network ◽  
Underground Mining ◽  
Underground Mines ◽  
Wireless Sensor ◽  
Maintenance Cost ◽  
Processing Unit ◽  
Central Processing ◽  
Underground Coal Mines ◽  
Logical Topology

Underground mines include a number of challenges due to their hostile milieu. Therefore, geotechnical and environmental monitoring mainly in underground coal mines have always been a critical task to ensure safe working conditions. If the monitoring device is cable based, then it requires an huge amount of cable deployment which can pose not only the high maintenance cost but difficulty in laying out the cable throughout the underground galleries. on the other hand, if it is direct wireless communication between sensing devices and the central processing unit, it is also not so feasible due to the crisscross, uneven and incline path. Therefore, Wireless Sensor Networks grab an opportunity to be deployed in such a hostile environment. Keeping in view, in the present chapter, attempts have been made to discuss the different aspects of wireless sensor network for underground coal mining services applications to overcome the various threats. Further, the best suited logical topology has been identified for the same.

scholarly journals Determining Coalbed Methane Content Structure

2019 ◽  
Vol 272 ◽  
pp. 022062
Author(s):  
T A Kiryaeva ◽  
V N Oparin ◽  
D A Yatsenko
Keyword(s):  
Coalbed Methane ◽  
Methane Content ◽  
Content Structure

The Effects of Posture and Technique on Forces Experienced When Hanging Continuous Miner Cable

1993 ◽  
Vol 37 (10) ◽  
pp. 779-783 ◽  
Author(s):  
Sean Gallagher ◽  
Christopher A. Hamrick ◽  
Mark S. Redfern
Keyword(s):  
Injury Risk ◽  
Underground Mines ◽  
Ground Reaction Forces ◽  
Shear Forces ◽  
Lateral Shear ◽  
Continuous Miner ◽  
Underground Coal Mines ◽  
Reaction Forces ◽  
Post Hoc ◽  
Resultant Forces

Analysis of lost-time back injuries in underground coal mines indicates that handling continuous miner cable places workers at high risk of injury. Manual hanging of this type of cable is a common lifting task in underground mines. This study was performed to assess the ground reaction forces associated with hanging cable in various postures and employing different methods of securing the cable. Seven experienced coal miners (mean age: 41.4 years ± 2.1) performed a series of 12 cable hanging tasks. Independent variables included a set of six posture/vertical space constraint conditions (LIFTCOND), and two techniques of securing the cable to the ceiling (METHOD). The dependent variables consisted of ground reaction forces measured using two force plates. LIFTCOND ( F5.66 = 21.31, p < 0.0001) and METHOD ( F1,66 = 10.89, p < 0.005) both significantly affected the magnitude of the peak resultant forces generated during the tasks. Post hoc analysis indicated that kneeling postures resulted in significantly lower forces than stooping for the same ceiling heights. Greater forces were associated with higher lifting conditions, attributable in part to the fact that higher lifts require more cable to be hoisted. Forces were also increased when subjects twisted baling wire to secure the cable, as compared to hanging it on a hook. An interaction between LIFTCOND and METHOD was identified with lateral shear forces - stooping conditions where the subjects twisted the cable with wire resulted in higher lateral shear forces. Results of this study will be used to develop recommendations to reduce back injury risk when handling cable.

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