Liquid CO 2 high‐pressure fracturing of coal seams and gas extraction engineering tests using crossing holes: A case study of Panji Coal Mine No. 3, Huainan, China

2020 ◽  
Author(s):  
Xiaojiao Cheng ◽  
Hu Wen ◽  
Shixing Fan ◽  
Jian Chen ◽  
Xiaowei Zhai ◽  
...  
Keyword(s):  
High Pressure ◽  
Coal Mine ◽  
Gas Extraction ◽  
Coal Seams

scholarly journals Stability of Split-Level Gob-Side Entry in Ultra-Thick Coal Seams: A Case Study at Xiegou Mine

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 628 ◽  
Author(s):  
Junwen Zhang
Keyword(s):  
Coal Mine ◽  
Coal Pillar ◽  
Peak Stress ◽  
Coal Seams ◽  
Solid Coal ◽  
Stress Fluctuation ◽  
Pillar Mining ◽  
The Stability ◽  
Rock Specimens

Split-level longwall gob-side entry (SLGE) has been applied as a special form of small gate pillar mining (or non-coal pillar mining) in thick coal seams. The stability of the coal pillar directly affects the rationality of the layout of the SLGE. Starting from the mining-induced influence around the SLGE, this paper compares the mechanical properties of coal under different mining effects, and studies the rationality of “zero pillar” location against the Xiegou coal mine. The study shows that the key to success of the application of the SLGE is the existence of an intact zone within the triangular coal pillar in spite of double disturbances due to tunneling and coal mining extraction. Laboratory testing shows that the density and uniaxial compressive strength of rock specimens obtained from the triangular coal pillar are smaller than that from the other part of the panel which is concluded to be due to the varied degree of mining-induced influence. The numerical modeling results show that most of the triangular coal pillar is intact after extraction of the panel, and that the peak stress is located in the solid coal beyond the triangular coal pillar. The plastic zone of the triangular coal pillar is only about 1 m after the excavation of the tail gate of the next split-level panel. The physical modeling shows that the tail gate of the next panel is in the destressed zone with only a very small stress fluctuation during the extraction of the next panel. The study shows that the location of the SLGE at Xiegou coal mine is reasonable. SLGE is preferable for ultra-thick coal seams.

scholarly journals An Approach to Dynamic Disaster Prevention in Strong Rock Burst Coal Seam under Multi-Aquifers: A Case Study of Tingnan Coal Mine

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7287
Author(s):  
Xinxin Zhou ◽  
Zhenhua Ouyang ◽  
Ranran Zhou ◽  
Zhenxing Ji ◽  
Haiyang Yi ◽  
...  
Keyword(s):  
Rock Burst ◽  
Coal Mine ◽  
Water Inrush ◽  
Coal Seams ◽  
High Position ◽  
Integrated Method ◽  
Working Face ◽  
Strong Rock ◽  
And Control

In order to prevent the multi-dynamic disasters induced by rock burst and roof water inrush in strong rock burst coal seams under multi-aquifers, such as is the case with the 207 working face in the Tingnan coal mine considered in this study, the exhibited characteristics of two types of dynamic disasters, namely rock burst and water inrush, were analyzed. Based on the lithology and predicted caving height of the roof, the contradiction between rock burst and water inrush was analyzed. In light of these analyses, an integrated method, roof pre-splitting at a high position and shattering at a low position, was proposed. According to the results of numerical modelling, pre-crack blasting at higher rock layers enables a cantilever roof cave in time, thereby reducing the risk of rock burst, and pre-crack blasting at underlying rock layers helps increase the crushing degree of the rock, which is beneficial for decreasing the caving height of rock layers above goaf, thereby preventing the occurrence of water inrush. Finally, the proposed method was applied in an engineering case, and the effectiveness of this method for prevention and control of multi-dynamics disasters was evaluated by field observations of the caving height of rock layers and micro-seismic monitoring. As a result, the proposed method works well integrally to prevent and control rock burst and water inrush.

Development a New Classification for Assessing the Coal Mine Mechanization / Opracowanie nowej klasyfikacji dla oceny mechanizacji w kopalniach węgla

2013 ◽  
Vol 58 (1) ◽  
pp. 217-226 ◽  
Author(s):  
Hosseini Seyed Mehdi ◽  
Mikaeil Reza ◽  
Ataei Mohammad ◽  
Reza Khalokakaei
Keyword(s):  
Coal Mine ◽  
Underground Mines ◽  
Maximum Efficiency ◽  
Coal Production ◽  
Coal Seams ◽  
New Classification ◽  
Significant Cost ◽  
Cost Reductions ◽  
Good Medium

The coal mine mechanization is important to achieve optimum quality and maximum efficiency of coal production. Mechanization is an objective that can result in significant cost reductions and higher levels of profitability for underground mines. The potential of coal mine mechanization depends on some important factors Such as seam inclination and thickness, geological disturbances, seam floor conditions and roof conditions. These factors should be considered in coal mine mechanization analysis. In this study, the new classification was developed with the respect to the mentioned factors. Using this system the coal seam mechanization index (CSMi) of several types of coal seams was evaluated and classified into five categories; very good, good, medium, low and very low. As a case study, the mechanization of the Takht coal seams in Golestan area of Iran was investigated using this new classification system. The results show a low potential for mechanization in most of the Takht coal seams

Fuzzy Modeling for Coal Seams A Case Study for a Hard-Coal Mine

2005 ◽  
pp. 33-37
Author(s):  
José Antonio Martin ◽  
Teresa de Pedro ◽  
Carlos González ◽  
R. García ◽  
Luís Argüelles ◽  
...  
Keyword(s):  
Coal Mine ◽  
Fuzzy Modeling ◽  
Hard Coal ◽  
Coal Seams

scholarly journals A Sequential Approach for Integrated Coal and Gas Mining of Closely-Spaced Outburst Coal Seams: Results from a Case Study Including Mine Safety Improvements and Greenhouse Gas Reductions

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3023 ◽  
Author(s):  
Liang Cheng ◽  
Zhaolong Ge ◽  
Jiufu Chen ◽  
Hao Ding ◽  
Lishuang Zou ◽  
...  
Keyword(s):  
Coal Mining ◽  
Mine Safety ◽  
Coal Bed ◽  
Gas Extraction ◽  
Coal Seams ◽  
Sequential Approach ◽  
Coal Mine Safety ◽  
Working Face ◽  
Protective Seam

Closely-spaced outburst coal seams (COCS) is the main condition of coal seams in southwest China, and gas disasters are one of the major problems affecting coal mine safety. Mining a protective seam and pre gas extraction are the most safety way to improve the efficiency of mining under these conditions. However, low pre-mining gas extraction efficiency coupled with the close proximity of adjacent working faces is a problem. When mining at an old working face has been completed but the new working face is not yet ready to be mined, coal-bed gasses can flow into the new working face from adjacent seams and this commonly causes methane monitoring instruments to sound an alarm. These gas extraction difficulties lead to a conflict between mine safety and profit. To solve these problems, a sequential approach for integrated coal and gas mining of closely-spaced outburst coal seams is introduced in this paper. Two fundamental principles are proposed: (1) Fully coordinating the spatiotemporal relationships between gas extraction, roadway development, and coal mining to maximize both mine safety and coal and gas production; (2) Defining a mining sequence for outburst coal seams and choosing the coal seam with the weakest outburst risk as the protective seam. A system for comprehensive gas extraction in underground coal mines is divided into four stages for gas extraction: gas extraction before coal roadway tunneling, gas extraction before coal mining, gas extraction during coal mining, and gas extraction from the goaf after coal mining. The Songzao mining area, China, is used as a case study to demonstrate the effectiveness of this model, and it brings three major benefits: it improves underground coal mine safety with physical gas accidents decreased by 66.8%, it makes underground coal-bed methane (CBM) extraction more efficient with the average gas extraction rate were respectively 45.13 m3/t and 62.4%, the highest in China, and it reduces greenhouse gas emissions equivalent to 3.5 million tonnes of carbon dioxide. This study could be used as a valuable example for other coal deposits being mined under similar geological conditions.

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.

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