Distribution of methane enrichment zone in abandoned coal mine and methane drainage by surface vertical boreholes: A case study from China

Feng, Guorui; Hu, Shengyong; Li, Zhen; Jiang, Haina; Zhang, Yuting; Xu, Guang; Wang, Zhuo; Kang, Lan

doi:10.1016/j.jngse.2016.07.045

Cited by 34 publications

(20 citation statements)

References 28 publications

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“…The gas from the goaf cannot be taken away by the fresh air in the roadway due to the fact that an eddy always forms in the upper corner when air flows through the right angle there. As a consequence, gas overruns in the upper corner of the coal face [1,2]. Additionally, a large-sized coal pillar between two U-type longwall panels is needed to support the overburden and protect the gateroad space [3], as shown in Figure 2c, which causes serious coal resources waste and potential risk of rock burst [4,5].…”

Section: Geological and Engineering Conditionsmentioning

confidence: 99%

Numerical Study on the Effectiveness of Grouting Reinforcement on the Large Heaving Floor of the Deep Retained Goaf-Side Gateroad: A Case Study in China

Zhang

Shimada

2018

Energies

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Abstract:To study the effectiveness of grouting reinforcement on a large heaving floor of the retained goaf-side gateroad (RGSG) at a 900 m depth in the Zhuji coal mine, a numerical model involving strain softening constitutive material was built. First, the simulated deformations of the RGSG were compared with field data to verify the reliability of the numerical model. Then, the dynamic distribution of the stress in the RGSG floor was examined to reveal the mechanism of floor heave. Finally, grouting reinforcement was proposed to control the RGSG floor, and the corresponding effectiveness was verified by improving the rock mechanics of the floor strata based on the results of numerical uniaxial compressive tests. The results demonstrated that a fairly good match was achieved between the field and numerical data, and the proposed FLAC3D (Fast Lagrangian Analysis of Continua) numerical model was an effective approach to study the stability of the deep RGSG. A variation of the ratio between horizontal stress to vertical stress in the floor strata was the root cause of floor heave in the deep RGSG. Ideally, the floor heave could be reduced by 41%, 62%, and 79% when the floor strata of 1 m depth were reinforced with grouting schemes I, II, and III, respectively.

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Section: Geological and Engineering Conditionsmentioning

confidence: 99%

Numerical Study on the Effectiveness of Grouting Reinforcement on the Large Heaving Floor of the Deep Retained Goaf-Side Gateroad: A Case Study in China

Zhang

Shimada

2018

Energies

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“…China has remained the world's largest coal producer for several years, and its coal production accounted for 47.7% of global coal production in 2015 (http://www.bp.com/statistical review). Nearly 90% of China's coal mines are underground, and 51% of them are highly gassy . With a continuously increasing demand for economic development, more and more coal mines have been mined out in the past few years in China.…”

Section: Introductionmentioning

confidence: 99%

“…crushing, and are not coal's intrinsic characteristics . In CMM drainage engineering, the seepage parameters of CH 4 flow in crushed coal are greatly affected by continuous excavation, and their gradual variation is apt to induce diverse methane enrichment, thus resulting in different recovery rates of gas extraction . Hence, it is important to take into account the CH 4 flow behaviors of crushed coal in caved zones under constant load of overburden strata.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, the Forchheimer equation fits the flow laws well. With continuous CMM drainage, the methane flow rate and mining gob pressure will inevitably decrease in the latter stages when drilling holes are abandoned or gas drainage is aborted . Up to now, the low‐speed methane flow behaviors under lower Re numbers are still not clearly understood.…”

Section: Introductionmentioning

confidence: 99%

“…Nearly 90% of China's coal mines are underground, and 51% of them are highly gassy. 2,3 With a continuously increasing demand for economic development, more and more coal mines have been mined out in the past few years in China. Unfortunately, due to the relative backwardness in mining technical conditions and the complicated geological conditions of coal seams, these mining gobs are usually mined out with lower recovery rates and contain a large amount of methane.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The correlation between crushed coal porosity and permeability under various methane pressure gradients: a case study using Jincheng anthracite

Feng

Jiang

et al. 2018

Greenhouse Gases

Self Cite

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As a greenhouse gas (GHG), methane (CH4) emitted from underground mines contributes 17% to total anthropogenic greenhouse gas emissions. Gas drainage is the main measure to resolve this problem, and knowledge of methane flow in surrounding coal and rocks greatly influences our thinking and handling strategies for reducing CH4 emissions. However, due to the lack of matched testing systems, current studies are generally confined to considering methane flow properties in porous and fractured coal and rocks, whereas methane flow behaviors in crushed coal have not been extensively studied and understood yet. In this study, the relationships between crushed coal porosity and permeability under various methane pressures are investigated using a self‐designed gas permeation testing system, and continuous measurements of methane pressure and flow rate have been conducted. The results show that the permeability properties of crushed coal are closely related to the coal porosity, methane pressure, and axial stress. Darcy flow transfers to slip flow in crushed coal in the latter stage of coal‐mine methane drainage in crushed coal, and the permeability of crushed coal has a magnitude of 10−12–10−11 m2, which is rather larger than that of porous and fractured coals. The pseudo‐threshold pressure gradient (TPG) decreases with the growth of porosity, and it is rather smaller than that of lower permeability reservoirs (LPR). With an increase in methane pressure, the permeability of crushed coal presents a logarithmic growth trend; by contrast, it displays an exponential growth trend with an increase in porosity. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Evaluation of closed gob methane sweet spots: A case study of the Tiefa mining area

Wang

Huang

Sang

et al. 2020

Energy Science & Engineering

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The coal seam gas development in closed gob zone is still in the exploratory stage in China, and potential evaluation and sweet spots selection are the key issues. This paper establishes a complete evaluation system for selecting sweet spots for closed gob methane extraction with surface wells in the Tiefa mining area to reduce the blindness of area selection. The one‐vote veto system, the comprehensive evaluation index system, and the AHP‐entropy combined weight model are used to screen and evaluate the closed gob zones in the Tiefa mining area. A total of twenty evaluation units are evaluated and the development potential of which is classified as three levels by the optimal segmentation method. The relationship between the results of the assessment and the closed gob methane resource is also discussed, as well as the combined weight distribution coefficient. The results show that the development potential of the block cannot be estimated simply by the closed gob methane resource because the consistency between the comprehensive evaluation value and the closed gob methane resource is poor. The size of the combined weight distribution coefficient has little effect on the comprehensive evaluation values and only affects the ranking of evaluation units in a small range.

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Distribution of methane enrichment zone in abandoned coal mine and methane drainage by surface vertical boreholes: A case study from China

Cited by 34 publications

References 28 publications

Numerical Study on the Effectiveness of Grouting Reinforcement on the Large Heaving Floor of the Deep Retained Goaf-Side Gateroad: A Case Study in China

Numerical Study on the Effectiveness of Grouting Reinforcement on the Large Heaving Floor of the Deep Retained Goaf-Side Gateroad: A Case Study in China

The correlation between crushed coal porosity and permeability under various methane pressure gradients: a case study using Jincheng anthracite

Evaluation of closed gob methane sweet spots: A case study of the Tiefa mining area

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