06/02015 Influence of geotechnical factors on gas flow experienced in a UK longwall coal mine panel

2006 ◽  
Vol 47 (5) ◽  
pp. 312
Keyword(s):  
Coal Mine ◽  
Gas Flow

Study on Original Coal Seam Permeability Coefficient

2011 ◽  
Vol 361-363 ◽  
pp. 179-182
Author(s):  
Zi Wen Dong ◽  
Qing Jie Qi ◽  
Nan Hu ◽  
Chang Fu Xu ◽  
Hui Niu
Keyword(s):  
Coal Seam ◽  
Water Flow ◽  
Coal Mine ◽  
Permeability Coefficient ◽  
Gas Flow ◽  
Radial Flow ◽  
Gas Permeability ◽  
Coal Seam Gas ◽  
Flow Method

In the case of gas radial flowing in layer-though boring, use the method of draining water gathering gas measured the Gas flow of borehole that there is water flow out from drilling Sometimes,the coal seam gas permeability coefficient is calculated using"Radial Flow Method"and"Optimizing Method,found out the range of 5-3 original coal seam Hongmiao coal mine permeability coefficient is0.007~0.008 m2/(MPa2·d).

Influence of geotechnical factors on gas flow experienced in a UK longwall coal mine panel

2006 ◽  
Vol 43 (3) ◽  
pp. 369-387 ◽  
Author(s):  
D.N. Whittles ◽  
I.S. Lowndes ◽  
S.W. Kingman ◽  
C. Yates ◽  
S. Jobling
Keyword(s):  
Coal Mine ◽  
Gas Flow

scholarly journals Characteristics of Bituminous Coal Permeability Response to the Pore Pressure and Effective Shear Stress in the Huaibei Coalfield in China

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Lei Zhang ◽  
Zhiwei Ye ◽  
Mengqian Huang ◽  
Cun Zhang
Keyword(s):  
Shear Stress ◽  
Pore Pressure ◽  
Coal Mine ◽  
Gas Flow ◽  
Bituminous Coal ◽  
Stress Conditions ◽  
Coal Permeability ◽  
Gas Seepage ◽  
Shear Slip ◽  
Huaibei Coalfield

The coal permeability is known to be influenced by the pore pressure and effective stress in coal mines. In this study, the characteristics of the bituminous coal permeability response to the pore pressure and effective shear stress in the Xutuan coal mine in Huaibei Coalfield in China were investigated under different stress conditions. For this purpose, gas seepage tests with various stress levels were conducted via the original gas flow and displacement testing apparatus using bituminous coal samples from the Xutuan coal mine. The pore pressure effect on the permeability under different stress conditions was assessed by varying the pore pressure in coal samples and simulating different in situ stresses. The axial and radial pressures were controlled to study the response of coal permeability to the effective shear stress. The experimental results revealed that with an increase in pore pressure, the permeability of coal in different stress environments firstly drops and then rises. The permeability increased gradually with the effective shear stress, which trend became more pronounced when the effective shear stress exceeded zero. In case of the axial pressure exceeding the radial one, the cross shear slip was observed, for which the permeability of coal samples increased with the effective shear stress. In the opposite case, the separated shear slip was observed, with the reverse trend.

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.

TEM evaluation of graded SixGe1-x heterolayers

1991 ◽  
Vol 49 ◽  
pp. 894-895
Author(s):  
N. David Theodore ◽  
Mamoru Tomozane ◽  
Ming Liaw
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Gas Flow ◽  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Dark Field ◽  
Bipolar Transistors ◽  
Structural Quality ◽  
Weak Beam ◽  
Transmission Electron ◽  
And Behavior

There is extensive interest in SiGe for use in heterojunction bipolar transistors. SiGe/Si superlattices are also of interest because of their potential for use in infrared detectors and field-effect transistors. The processing required for these materials is quite compatible with existing silicon technology. However, before SiGe can be used extensively for devices, there is a need to understand and then control the origin and behavior of defects in the materials. The present study was aimed at investigating the structural quality of, and the behavior of defects in, graded SiGe layers grown by chemical vapor deposition (CVD).The structures investigated in this study consisted of Si1-xGex[x=0.16]/Si1-xGex[x= 0.14, 0.13, 0.12, 0.10, 0.09, 0.07, 0.05, 0.04, 0.005, 0]/epi-Si/substrate heterolayers grown by CVD. The Si1-xGex layers were isochronally grown [t = 0.4 minutes per layer], with gas-flow rates being adjusted to control composition. Cross-section TEM specimens were prepared in the 110 geometry. These were then analyzed using two-beam bright-field, dark-field and weak-beam images. A JEOL JEM 200CX transmission electron microscope was used, operating at 200 kV.

Electron Microscopy/Diffraction Study of the Ternary Mn-Er-S System

1990 ◽  
Vol 48 (1) ◽  
pp. 76-77
Author(s):  
A. R. Landa Canovas ◽  
L.C. Otero Diaz ◽  
T. White ◽  
B.G. Hyde
Keyword(s):  
Electron Microscopy ◽  
Gas Flow ◽  
Graphite Crucible ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Alumina Crucible ◽  
X Ray ◽  
Intermediate Phases ◽  
Twin Band ◽  
Ar Gas

X-Ray diffraction revealed two intermediate phases in the system MnS+Er2S3,:MnEr2S4= MnS.Er2S3, and MnEr4S7= MnS.2Er2S3. Their structures may be described as NaCl type, chemically twinned at the unit cell level, and isostructural with CaTi2O4, and Y5S7 respectively; i.e. {l13} NaCl twin band widths are (4,4) and (4,3).The present study was to search for structurally-related (twinned B.) structures and or possible disorder, using the more sensitive and appropiate technigue of electron microscopy/diffraction.A sample with nominal composition MnEr2S4 was made by heating Mn3O4 and Er2O3 in a graphite crucible and a 5% H2S in Ar gas flow at 1500°C for 4 hours. A small amount of this material was thenannealed, in an alumina crucible, contained in sealed evacuated silica tube, for 24 days at 1100°C. Both samples were studied by X-ray powder diffraction, and in JEOL 2000 FX and 4000 EX microscopes.

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