scholarly journals DETERMINATION OF METHANE DESORPTION ZONE FOR THE DESIGN OF A DRAINAGE BOREHOLE PATTERN (CASE STUDY: E4 PANEL OF THE TABAS MECHANIZED COAL MINE, IRAN)

2021 ◽  
Vol 36 (1) ◽  
pp. 61-75
Author(s):  
Ali Hosseini ◽  
Mehdi Najafi
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Methane Emissions ◽  
Gas Content ◽  
Coal Seams ◽  
Mining Operations ◽  
Methane Drainage ◽  
Tabas Coal Mine ◽  
Drainage Borehole

Underground coal mining is known as one of the major sources of methane emissions which mainly occurs after underground coal extraction. Rock strata in-situ methane can potentially be the most significant hazard in coal mining operations. To prevent or minimize the risks of methane emissions, methane drainage approaches have been adopted by coal mines. Rock mass methane drainage is the most efficient and effective approach toward controlling methane hazards as it prevents and reduces the frequency of methane emissions, outflows into the working area and sudden outbursts of methane and rocks. The method includes drilling boreholes from the tailgate side to the unstressed zone in the roof and floor strata above and below a working coal seam. The coal seam gas content in Tabas Parvadeh I is estimated to be about 16 m3 /t, which is relatively high. Based on exploration data, five distinct coal seams have been identified (B1, B2, C1, C2 and D) at the coal deposit and currently C1 is being worked. Considering the high value of C1 gas content and surrounding rocks, the Methane Drainage System (MDS) has been utilized for gas drainage. This paper tries to determine the desorption area which is essential and helpful for the selection of an effective drilling pattern into the adjacent coal seams. In this study, the methane drainage zone in the E4 panel of the Tabas coal mine was calculated using experimental equations and a drainage borehole pattern was determined.

The Study on Roadway Layout in Coordination of Mining Coal Seams Base on Failure of Floor Strata

2014 ◽  
Vol 889-890 ◽  
pp. 1362-1374 ◽  
Author(s):  
Yong Zhang ◽  
Chun Lei Zhang ◽  
Chun Chen Wei ◽  
Ya Dong Liu ◽  
Shi Qing Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Simulation Software ◽  
Coal Seams ◽  
Group Coordination ◽  
Mining Coal ◽  
Two Sides

In order to make sure the reasonable roadway layout in lower seam of close coal mining group coordination in Lijiahao coal mine, firstly, applying the theoretical analysis and geological radar detection to get the influence depth of mining from the up coal seam 2-2 to the floor is about 20m, the results show that the thickness of complete strata is about 15m, then determining to use the outward alternate entries in lower seam roadway by using theoretical analysis. At last, determining the distance of outward alternate entries is 12-14m by using FLAC3D numerical simulation software to simulate the change of stress and displacement in roof floor and two sides of roadway.

scholarly journals Fracture evolution and gas transport laws of coal and rock in one kilometer deep coal mine with complicated conditions

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 907-915
Author(s):  
Jianguo Zhang ◽  
Man Wang ◽  
Yingwei Wang
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Fracture Zone ◽  
Gas Flow ◽  
Gas Transport ◽  
Enhancement Effect ◽  
Gas Extraction ◽  
Coal Seams ◽  
Long Distance

As coal mining gradually extends deeper, coal seams in China generally show high stress, high gas pressure and low permeability, bringing more difficulty to coal mining. Therefore, in order to strengthen gas extraction, it is necessary to carry out reservoir reconstruction after deep coal seams reached. In this paper, the distribution and evolution laws of fracture zone overlaying strata of J15 seam in Pingdingshan No. 10 coal mine after excavation were studied by combining similar simulation and numerical simulation, meanwhile, the gas transport law within fracture zone was numerically simulated. The results show that the fracture zone reaches a maximum of 350 mm in the vertical direction and is 75 mm away from W9,10 coal seams in vertical distance. Since W9,10 coal seams are in an area greatly affected by the bending zone of J15 coal seam under the influence of mining, the mining of J15 coal seam will exert a strong permeability enhancement effect on W9,10 coal seams. The J15 coal seam can act as a long-distance protective layer of W9,10 coal seams to eliminate the outburst danger of the long-distance coal seams in bending zone with coal and gas outburst danger, thereby achiev?ing safe, productive and efficient integrated mining of coal and gas resources. The gas flux of mining-induced fractures in the trapezoidal stage of mining-induced fracture field is far greater than that in the overlaying stratum matrix. The horizontal separation fractures and vertical broken fractures within the mining-induced fracture field act as passages for gas-flow. Compared with gas transport in the overlaying stratum matrix, the horizontal separation fractures and vertical broken fractures within the mining-induced fracture field play a role in guiding gas-flow. The research results can provide theoretical support for the arrangement of high-level gas extraction boreholes in roof fracture zones.

scholarly journals Speculum Observation and Trajectory Measurement in Gas Extraction Drilling: A Case Study of Changling Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Enbiao Zhao ◽  
Kangnan Li ◽  
Xin Yang ◽  
Nan Deng
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Efficient Production ◽  
Drilling Process ◽  
Coal Seams ◽  
Adjacent Layer ◽  
Gas Drainage ◽  
High Level ◽  
Trajectory Measurement ◽  
Drainage Borehole

Coal will still be China’s basic energy for quite a long time. With the increase of mining depth, gas content and pressure also increase. The problems of gas emission and overrun affect the safety and efficient production of coal resource to a certain extent. In this work, the field test of gas drainage borehole peeping and trajectory measurement in coal seam of Changling coal mine are carried out. These coal seams include C5b coal seam, upper adjacent C5a coal seam, C6a coal seams, C6c in lower adjacent strata, and C5b coal seam in high-level borehole. The view of gas drainage borehole peeping and trajectory measurement in the working seam, upper adjacent layer, lower adjacent layer, and high position are obtained. It is found that the hole collapses at the position of about 20 m in both adjacent strata and high-level boreholes, and there are a lot of cracks in the high-level boreholes before 12 m. The deviation distance of high-level borehole is large, and the actual vertical deviation of upper adjacent layer is small. Finally, the strategies to prevent the deviation of drilling construction are put forward. It includes four aspects: ensuring the reliability of drilling equipment, reasonably controlling the drilling length, standardizing the drilling, and reasonably selecting the drilling process parameters.

scholarly journals Control of the Internal and External Staggered Distance of Coal Mining Face to the Water-Conducting Fissures in the Overlying Strata of the Near Coal

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhiyuan Jin ◽  
Tao Peng
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Coal Mine ◽  
Calculation Formula ◽  
Coal Seams ◽  
Coal Face ◽  
Geological Conditions ◽  
Mining Face ◽  
Seam Mining ◽  
Water Proof

In Northwest China, rainfall is low, water resources are scarce, and the ecological environment is fragile. For shallow-buried and close-spaced coal seams with a thickness of upper coal bed >60∼70 m, the water-conducting fissures of the overlying rock will not penetrate the water-isolating layer after the upper coal seam is mined; the internal and external gap angles of the water-conducting fissures are not generated from the water-isolating layer. We set out to explore the critical internal and external dislocations for the second significant development of water-conducting fissures in the overlying rock after coal mining under control. A calculation model for the critical internal and external staggered distances of coal mining face in shallow-buried and close-spaced coal seams is established, the calculation formula is given, and the calculation formula for the critical seam mining ratio under the condition of internal staggered mining mode is given. Numerical simulation performed by UDEC methods: taking the overburden strata in the shallow-buried and close-spaced coal seam mining area of Shigetai Coal Mine as a prototype, it was verified that the critical internal and external offsets of the coal mining face in shallow-buried and close-spaced coal seams have a significant effect on the overlying water flow cracks in the mining of the lower coal seam. For the feasibility of developmental control, according to the engineering geological conditions of Shigetai, through the calculation method of external staggered distance, it is concluded that the distance of the open cut of the lower coal face and the upper coal face is only 21∼27 m, which is much smaller than the water barrier. It does not produce the critical distance of the water-conducting cracks. Therefore, in the process of mining the lower coal seam, the water-proof layer will produce water-conducting cracks, lose its water-proof performance, and cause water loss. This is also the cause of the water inrush accident in Shigetai Coal Mine.

Methane content and relative methane releasability versus occurrence depth of coal seams in Mạo Khê mine

2020 ◽  
pp. 26-37
Author(s):  
Dik Thang Fam ◽  
Tuan An’ Fan ◽  
K. S. Kolikov
Keyword(s):  
Coal Mining ◽  
Mine Drainage ◽  
Mining Industry ◽  
Methane Content ◽  
Gas Content ◽  
Coal Seams ◽  
Methane Drainage ◽  
Geological Conditions ◽  
Coal Reserves ◽  
Full Conversion

Methane is one of the critical safety concerns in the modern coal mining industry. The current outputs per coal faces induce risk of explosion even at low gas content of coal. Methane drainage is an obligatory component of a coal mining technology; it enables full conversion of coal resources into coal reserves, safe operation of coal mine and utilization of coal methane. The approaches to introduction of norms on methane concentration in return ventilation air and to rating of coal mines by the gas criterion in the leading coal-producing countries are reviewed. Based on the analysis of underground measurements, the content and relative releasability of are estimated as functions of the occurrence depth of coal seams in Mạo Khê mine. The methane content-occurrence depth curves are obtained. Considering the geological conditions of the mine, the promising degassing technologies based on enhancement of coal permeability are discussed, and the required modification of standards to be imposed on geological exploration data for the purpose of introduction of new methane content prediction methods is described. The main problems of pre-mine drainage of methane are examined. The urgent nature of methane drainage in Mạo Khê mine is validated.

scholarly journals Determination of methane content and methane released when exploiting longwall at different levels at 13.2 seams, Khe Cham coal mine, Vietnam

2020 ◽  
Vol 211 ◽  
pp. 03017
Author(s):  
Van Thinh Nguyen
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Methane Emissions ◽  
Methane Content ◽  
Methane Drainage ◽  
Gas Explosions ◽  
Two Factors ◽  
The Relationship ◽  
Different Levels

Khe Cham coal mine is managed by Ha Long Coal Company TKV. Currently, Khe Cham coal mine is exploited from the ground up to 350 and is ranked III for methane. In 2008, a methane explosion at -168 level of the 13.2 coal seam of Khe Cham coal mine occurred, injuring 16 people and killing 8. In order to avoid gas explosions at mines like 2008, it is necessary to have appropriate solutions to eliminate methane accumulation in the pit paths. We have studied to determine the relationship between the level of methane emissions with the methane content in the coal seam and the bazaar’s mining output because of the methane content in the coal seam and coal mining output. These are the two factors that greatly affect the release of methane from the longwall. The paper used practical measurement, sampling, and analysis methods to determine the level of methane emissions from longwalls at different extraction levels of the 13.2 coal seam and determine the relationship between the methane drainage and the methane content in the coal seam and the exploitation output of the longwall. This relationship is expressed by the equation y = a.x2 + b.x + c (Fig. 2 and Fig. 3). The results will help with planning for mining and have specific solutions for diluting methane in the mine’s pit lines

scholarly journals Methane Content Estimation in DuongHuy Coal Mine

2018 ◽  
Vol 35 ◽  
pp. 01005 ◽  
Author(s):  
Van Thinh Nguyen ◽  
Waldemar Mijał ◽  
Vu Chi Dang ◽  
Thi Tuyet Mai Nguyen
Keyword(s):  
Experimental Data ◽  
Coal Mining ◽  
Coal Mine ◽  
Coal Mines ◽  
Methane Content ◽  
Underground Coal Mining ◽  
Coal Seams ◽  
Underground Coal Mine ◽  
Different Depths ◽  
Quang Ninh

Methane hazard has always been considered for underground coal mining as it can lead to methane explosion. In Quang Ninh province, several coal mines such as Mạo Khe coal mine, Khe Cham coal mine, especially Duong Huy mine that have high methane content. Experimental data to examine contents of methane bearing coal seams at different depths are not similar in Duong coal mine. In order to ensure safety, this report has been undertaken to determine a pattern of changing methane contents of coal seams at different exploitation depths in Duong Huy underground coal mine.

A Review of Technical Potential for Coal Production and Coal Degasification – A Conventional Source of Methane – In Nigeria

2003 ◽  
Vol 14 (1) ◽  
pp. 59-67
Author(s):  
Adepo Jepson Olumide ◽  
Ayodele Charles Oludare ◽  
Balogun Olufemi
Keyword(s):  
Coal Seam ◽  
Fossil Fuels ◽  
Underground Mining ◽  
Simple Calculation ◽  
Gas Content ◽  
Gelling Agent ◽  
Coal Bed ◽  
Natural State ◽  
Mining Operations ◽  
Inorganic Matter

Coal, a solid fuel in its natural state has been identified as one of the world's major fossil fuels. It is a compact, stratified mass of mummified plant debris interspersed with smaller amounts of inorganic matter buried in sedimentary rocks. The use of coal as an energy source can be dated back to the prehistoric times. Methane is associated with many if not all coal seams, and is the dreaded “fire damp” responsible for many pit explosions. Coal mines are designed to vent as much methane as possible. It is present in the pores of coal under pressure, released during mining operations and can be extracted through vertical well bores. This paper highlights the fact that pipeline- quality methane can be extracted economically from coal seems before and during underground mining operations. The stimulation method involves hydraulic fracturing of the coal seam by using water, sand and, a gelling agent in a staged and alternating sand/and no sand sequence. The purpose is to create new fractures in the coal seam(s). The cleating of the coal helps to determine the flow characteristics of the coal formation and is vital in the initial productivity of a coal-methane well. The simple calculation of gas-in-place is achieved by multiplying the gas content of the coal by net coal thickness, the density, and the aerial extent of the drainage. The method is claimed to be suitable for use in Nigeria and potential sites for coal bed methane extraction in Nigeria are identified.

scholarly journals Study on Reservoir Properties and Critical Depth in Deep Coal Seams in Qinshui Basin, China

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Guiqiang Zheng ◽  
Bin Sun ◽  
Dawei Lv ◽  
Zhejun Pan ◽  
Huiqing Lian
Keyword(s):  
Coal Seam ◽  
Step Change ◽  
Gas Content ◽  
Burial Depth ◽  
Critical Depth ◽  
Coal Seams ◽  
Reservoir Properties ◽  
Qinshui Basin ◽  
Geological Conditions ◽  
Change Characteristics

Coalbed methane (CBM) reservoir properties and relationship of properties with burial depth were studied based on the data derived from 204 deep CBM production wells in Qinshui Basin, China. Through the study, it is found that permeability and porosity decrease with the increase of burial depth and the decreasing trend shows step-change characteristics at a critical burial depth. They also show divisional characteristics at certain burial depth. Gas content, geostress, and geotemperature increase with the increase of burial depth, and the increasing trend shows step-change characteristics and also have divisional characteristics at certain burial depth. Based on the previous study on the reservoir property changes with burial depth, three series of critical depth using different parameters are obtained through simulating the critical depth using the BP neural network method. It is found that the critical depth is different when using different parameters. Combined the previous study with the normalization of three different parameter types, the critical depth in Qinshui Basin was defined as shallow coal seam is lower than 650 m and transition band is 650–1000 m, while deep coal seam is deeper than 1000 m. In deep coal seams, the geological conditions and recovery becomes poor, so it can be defined as unfavorable zones. Therefore, other development means, for example, CO2 injection, need to be used to accelerate the deep coal methane development.

scholarly journals CBM Resources Estimations for the Development of Coal Mine Methane in the Asturian Central Basin, Spain

Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1404
Author(s):  
Pablo Cienfuegos-Suárez ◽  
Efrén García-Ordiales ◽  
Diego Alonso-Fernández ◽  
Jorge Enrique Soto-Yen
Keyword(s):  
Coal Mine ◽  
Coalbed Methane ◽  
Technological Development ◽  
Gas Content ◽  
Central Basin ◽  
Economic Interest ◽  
Coal Seams ◽  
Coal Basin ◽  
Coal Mine Methane ◽  
Made In

New technological development and a best knowledge of the basin allow to have justified expectation to find coalbed methane reserves. Measurements of gas content in unexploited coal seams are made in order to estimate the CBM could revive the economic interest of the Asturian Central Coal Basin (ACCB). According to first estimations based on the studies accomplished, the minimum resources of coalbed methane in the whole of the Asturian Central Coal Basin are in the order of 25,000 Mm3 and the gas content of the coal seams range from 6 m3 to 14 m3/t. The introduction should briefly place the study in a broad context and define the purpose of the work and its significance.

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