Integration of vertical and in-seam horizontal well …
In that case, ventilation should be supported by other means of gas management, such as degasification using vertical or horizontal wells prior to coal mining (Karacan et al., 2011, Moore, 2012). A side benefit of degasification that is taken advantage of by most mine operators is to use or sell the produced gas as fuel.
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Physical, mechanical, and hydraulic properties of coal …
The physical, mechani cal, and hydraulic conductivity properties of CCR and FCR are critical. in designing coal refuse disposal dams and impoundments fo r both static and seismi c stability. This ...
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Horizontal Drilling
Coal mine degasification started in 1970s and it is an established practice by now in all gassy mines. A reduction of 50% in the in situ gas content was achieved in the Pittsburgh coal seam of United States. For highly gassy coal seams, the coal was first degassed by vertical wells and later by in-mine horizontal drillings.
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Stress and permeability modelling in depleted coal seams …
A mathematical model was developed to analyse stress and permeability distribution during CO 2 storage in depleted coal seam gas reservoirs. The model integrates the geomechanics, matrix shrinkage, and fluid flow behaviour of coal seams with wellbore trajectory effects. The performance of vertical and horizontal wells for CO 2 …
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Productivity Analysis of Draglines Operating in Horizontal and Vertical
In view of the importance of tandem operation, the present study has been undertaken in a large Indian opencast coalmine in order to critically investigate the horizontal and vertical tandem ...
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Horizontal Coalbed Methane Wells Drilled from Surface
Understanding the advantages and disadvantages of in-mine horizontal boreholes, and the benefits of degasification years in advance of mining if drilled from the surface, the U.S. Bureau of Mines drilled an experimental CBM horizontal well from the surface in 1978 in southwestern PA to degasify a coal area to be mined in the future …
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A comprehensive review of deep coalbed methane and
As mentioned earlier, the mechanical properties of deep coal seams under high in-situ stress are significantly different from those of shallow coal seams. With the increase of vertical stress, the hydraulic fractures gradually change from the horizontal to vertical direction, the direction and velocity of the multiphase flow in the fracture ...
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Fine Coal Centrifuge
Our Fine Coal Centrifuge range includes both vertical and horizontal scrolled basket style machines that use centrifugal force to separate surface water from coal. We offer two models: • FC1200 – vertical fine coal centrifuge • HFC1300-S2 – horizontal fine coal centrifuge. Fine coal centrifuges are largely used on coal mines, but their ...
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Solved The vertical and horizontal stresses at the middle of
Mechanical Engineering questions and answers. The vertical and horizontal stresses at the middle of a coal pillar are found to be 15 MPa and 3 MPa respectively. The shear stress is 2.5 MPa as shown in the figure below. Determine the stresses in X'-Y' coordinate system as shown in figures (a) and (b) and draw the diagram of the rotated ...
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Influences of Coal Seam Heterogeneity on Hydraulic …
Horizontal fractures mainly exist in shallow coal seams, and deep coal seams preferentially induce vertical fractures (Rahim and Holditch 1995; Ma et al. 2016). However, the underground field observations show that there are both horizontal hydraulic fractures and vertical hydraulic fractures in shallow coal seams, and even the vertical ...
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Multi-branched horizontal wells for coalbed …
Horizontal wells, such as multi-lateral and multi-branched horizontal wells (MBHWs) have been effectively used in the development of coalbed methane (CBM) …
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Solved Production of cloth requires two inputs: L workers
Economics. Economics questions and answers. Production of cloth requires two inputs: L workers and R tonnes of coal. The following diagram depicts the isocost associated with the production. You are also given that the wage cost is w= $20, the price of coal is p= $30 and the cost associated with the isocost is c= $180.
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Numerical study on the influence of coal-roof interface on …
Abstract. To extract coalbed methane (CBM) from tectonically deformed coal seams, a horizontal well was drilled in the roof of coal seam. Staged hydraulic fracturing …
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Three-dimensional time-varying large surface displacements in coal
Coal mining often leads to large surface displacements with high spatial gradients, which is beyond the detection ability of traditional InSAR. Surface displacements caused by underground coal mining occur in both the horizontal and vertical directions, but traditional InSAR only provides observations in the radar line of sight.
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Experimental investigation on the movement …
The results show that the horizontal coal is moved to the shield window and the vertical coal is moved downward in the first level, while that in the second level …
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Production performance analysis for horizontal wells …
The effects of related parameters such as storativity ratio, transfer coefficient, adsorption coefficient, ratio of vertical permeability to horizontal permeability, skin factor, horizontal well position in vertical …
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Productivity Analysis of Draglines Operating in Horizontal and Vertical …
The thickness of underlying coal seam ranged from 15 to 18 m. The draglines casted the overburden into previously cut void created after extraction of the underlying coal seam. 2.1 Description of Horizontal Tandem Operation in Mine 1. The cross-section and plan view of a typical horizontal tandem operation is illustrated in Figs. 1 and 2 ...
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Productivity Analysis of Draglines Operating in …
grained sandstone. The thickness of underlying coal seam ranged from 15 to 18 m. The draglines casted the overburden into previously cut void created after extraction of the underlying coal seam. 2.1 Description of Horizontal Tandem Operation in Mine 1 The cross-section and plan view of a typical horizontal tandem operation is illustrated in ...
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Analysis of main factors influencing the apertures of mining …
Main factors influencing the wide range of apertures (from 50 to 400 mm) of mining-induced horizontal fractures (Torezko-Snezhnyanskaya coal area, Ukraine) at traditional (without grout injection into bed separation) longwall coal mining were analysed. Apertures of these fractures were directly measured (using an original experimental …
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Coal seam gas reservoir characterisation based on high
Fig. 3 shows the location, trajectory, and coal tops of vertical and lateral wells used in this study. Horizontal well W-1 and vertical well W-2 both have resistivity-based image logs; Vertical wells VP-1 through VP-3 are producers, each connected to two laterals forming the chevron well groups typically used to produce the reservoir in the field.
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Multi-branched horizontal wells for coalbed methane …
If coal bed thicknesses are the same and L = r, then a horizontal wellbore will be in contact with 64% more rock volume.If L = 2r, then it will be in contact with 128% more volume. π is a mathematical constant and refers to the ratio of a circle's circumference to its diameter, equal to 3.14159.. Multi-branched horizontal coal bed wells (MBHW) …
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Technical advances in well type and drilling
The vertical well of a multibranch horizontal well is approximately 100 m away from the horizontal well. Once the two wells are connected in the coal seam, a …
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Production performance analysis for horizontal wells in composite coal
When the ratio of vertical permeability to horizontal permeability is small, the horizontal permeability is much larger than the vertical permeability. This results in great difficulty for gas to flow in vertical direction and consumes more energy when the well is producing at a constant gas rate.
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Glossary of Mining Terms
Haulage - The horizontal transport of ore, coal, supplies, and waste. The vertical transport of the same is called hoisting. Haulageway - Any underground entry or passageway that is designed for transport of mined material, personnel, or equipment, usually by the installation of track or belt conveyor.
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Drilling and Completion Technique Selection for …
In this technique (Fig. 3), a vertical well is drilled with the "vertical well, openhole underream, single seam" method described earlier. A target is then placed in the underream section, and the surface-to …
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Effects of fluid and proppant properties on proppant …
Currently, the mining depth of coal seams in China is less than 1000 m. Vertical stress is generally believed to be the minimum principal stress, which is about equal to the weight of the overlying strata. In the main coalbed methane mining areas in Qinshui Basin, China, the coal seam dip angle is less than 10° near the horizontal coal …
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Permeability changes in coal seams: The role of anisotropy
The vertical Young's modulus of the virtual material is identical to that of the tested coal cores E 3 = 2551 MPa, but the horizontal Young's modulus is set such as E/E 3 = 1.6. Third, for the sake of simplification, the anisotropy of mechanical properties is assumed to totally come from the inequality between E and E 3, so we set ν = ν 3 ...
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Drilling and completion technologies of coalbed …
The most important component of URRS may be the steering system, which can control the wellbore trajectory to turn from vertical to horizontal with an ultrashort …
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Technical advances in well type and drilling
The vertical production well is located in the lower part of the coal seam, and the horizontal well is downdip-drilled as a whole and connected to the vertical well. In North China, together with multibranch horizontal wells, U-shaped horizontal well groups are used to promote the overall development of CBM.
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A comprehensive review of deep coalbed methane …
The average daily CBM production from vertical wells ranges from (0.8–1.2) × 10 4 m 3 /d, while horizontal wells produce (2.5–5.5) × 10 4 m 3 /d on average (Chen, …
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