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) …
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 ...
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 …
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 …
A semi-analytical model for the transient pressure behaviors …
1. Introduction. Coal seam gas reservoirs generally consist of two components: (1) small-diameter pores, providing storage space for coalbed methane (CBM) and (2) natural fractures, not only acting as storage space, but connecting pores in matrix and supplying flow channels for fluid, which can be described by a double-porosity …
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 ...
Global trends in coal mine horizontal stress …
The magnitude of the horizontal stress increases with depth, at rates that range from 0.8 to 2.0 times the vertical stress, just as the WSM "critically stressed crust" model predicts. …
Evaluation of the synergy degree of industrial de-capacity …
Finally, based on the quantitative analysis of 264 coal policy documents of the central and local governments from 2009 to 2020, this study reveals the current situation and fluctuation characteristics of the synergy degree of the de-capacity policies from four angles: horizontal, vertical, temporal, and comprehensive synergies.
Experimental research of flow patterns and pressure signals …
The horizontal dense phase conveying system of pulverized coal is characterized by variable flow. The amplitude of variation in pulverized coal flow was relatively small in case 1 ( Cs = 0.43–0.59) and case 7 ( Cs = 0.23–0.28); the flow with high or low solid concentration changed a little in the conveying process.
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 ...
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 ...
Statistical analysis of underground stress measurements …
The vertical stress is driven by the gravitational load of the overburden strata. Horizontally bedded strata of different stiffness compress fully until they are able to carry the full overburden weight. The vertical stress will therefore be the same in all types of rock or coal strata. On the other hand, a.
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, …
Cbm Coal Fracture Orientation In Vertical And Horizontal
The cleat system orientation and cleat intensity were verified from electrical images in the horizontal wellbores, and image analysis and interpretation resulted in calibrating these results to production rates. Static image normalization in the vertical wells was used as a benchmark to reference the images to the coal quality.
A thermo-mechanical simulation for the stability analysis of a
The M2 coal seam in Mazino coal deposit (Iran) is selected for investigating the stability analysis of horizontal well. The thickness of M2 coal seam is 3.5 m [33]. The horizontal wells are drilled in the coal seam and the sandstone layer is located at the roof and floor of M2 coal seam.
Experimental investigation on the movement mechanism of top coal …
In the vertical direction, the coal at two mark points descended obviously. The coal at b mark point is located on the roof and the displacement is small for the roof is less collapsed during the coal caving process. The displacement in both horizontal and vertical is approximately 40 mm.
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.
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.
Solved Identify the incorrect answer concerning horizontal
An example of vertical integration would be if Standard Oil purchased a railroad. An example of horizonal intergration is Andrew Carnegie Steel purchased a coal mine. Horizontal and vertical integration were used by monopolies to control costs and destroy competition. Vertical integration combined different but related industries under one ...
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 …
Productivity Analysis of Draglines Operating in …
Irrespective of the mode of operation (horizontal or vertical tandem), the study moots the concept of computation of the weighted cycle time and overall cycle time vis-à-vis swing angle variation for the draglines …
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.
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) …
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.
Horizontal peeler vs. vertical peeler – which type to select?
The task for one or the other machine type is the same – but there are important parameters that have an impact on the decision for either the vertical or the horizontal peeler centrifuge. Important criteria for the selection of a horizontal or a vertical peeler centrifuge can be divided into three categories: installation, process, economy.
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 …
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.
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 …
Numerical simulation on dense phase pneumatic …
The dosing hopper (3) was suspended on three load cells (2), by which the pulverized coal mass flow rate was measured. The EJA 430A differential pressure transducers (11) were used to measure the pressure drops of sections in horizontal pipe, vertical pipe and two bends.
Estimating the anisotropy of the vertical transverse isotropy coal …
Coal seams exhibiting nearly horizontal bedding, and fractures can be characterized as transversely isotropic media with a vertical axis of symmetry, known as vertical transverse isotropy coal seams. The resulting anisotropy cannot be overlooked in high-precision seismic velocity analysis, migration imaging and pre-stack inversion.
