How sorption-induced matrix deformation affects gas flow in coal seams: A new FE model

Vast reserves of gas-bearing coal deposits are located in Queensland. Owing to the extremely low permeability and porosity of the coal, very low gas flow rates are normally encountered. In an effort to enhance the gas production to economic quantities and to degasify the coal to provide a safer mining environment, four experimental wells were drilled into coal seams near Blackwater, Queensland.Based on extensive laboratory testing of coal samples, computerised fracture design calculations were performed to determine a suitable stimulation programme. The wells were hydraulically fractured with up to 15 000 US gal of foamed stimulation fluid containing 75 per cent nitrogen. To prop open the induced fracture system, 15 000 lb of sand was pumped with the foam. The maximum concentration was eight pounds of 20-40 mesh sand per gallon of fluid. Gas production from the unstimulated wells was too low to measure. Early production data soon after the fracturing suggested a gas flow rate of approximately 50 Mcf/D.

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Mine Gas Flow in the Porous Massif and CFD Tool

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.362.38 ◽

2015 ◽

Vol 362 ◽

pp. 38-46

Author(s):

Pavel Staša ◽

Oldřich Kodym

Keyword(s):

Rock Mass ◽

Gas Flow ◽

Mining Activity ◽

Flow Modeling ◽

Coal Seams ◽

The Past ◽

Mining Conditions ◽

Reduce Risk ◽

Mine Gas ◽

Numerical Flow Modeling

There is a still dangerous effect in the form of methane leakage from coal seams in areas where mining activity still continuing or took place in the past. The issue of mining gas flow is still a matter that is necessary to pay attention and try to find new ways to solve this set of phenomena, no matter if it is the mining corridors or the flow in the rock massif. The number of measures to gradually reduce risk has been taken to protect the population. Nevertheless, the current situation is generally rated as serious as those risks still remain valid. Leakage of mine gases depend on many natural and technical mining conditions. With the closure of mines and thus the end of the ventilation situation considerably worse. This paper deals with the flow of dangerous mine gas, methane, through the rock mass using numerical flow modeling using CFD program Fluent. Using CFD codes can gain insight on the phenomenon under review and the results to take appropriate measures in the form of active or passive intervention.

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A numerical investigation of gas flow behavior in two-layered coal seams considering interlayer interference and heterogeneity

International Journal of Mining Science and Technology ◽

10.1016/j.ijmst.2021.05.003 ◽

2021 ◽

Author(s):

Ziwei Wang ◽

Yong Qin ◽

Teng Li ◽

Xiaoyang Zhang

Keyword(s):

Numerical Investigation ◽

Gas Flow ◽

Flow Behavior ◽

Coal Seams

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Influence of coal deformation on the Knudsen number of gas flow in coal seams

Energy ◽

10.1016/j.energy.2021.121161 ◽

2021 ◽

pp. 121161

Author(s):

Yinbo Zhou ◽

Hansheng Li ◽

Jilei Huang ◽

Ruilin Zhang ◽

Shijie Wang ◽

...

Keyword(s):

Knudsen Number ◽

Gas Flow ◽

Coal Seams ◽

Coal Deformation

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Research on the Effective Influence Radius of Hydraulic Reaming in Mining Seam

The Open Fuels & Energy Science Journal ◽

10.2174/1876973x01508010161 ◽

2015 ◽

Vol 8 (1) ◽

pp. 161-167

Author(s):

Li Peng ◽

Wang Kai ◽

Li Bo ◽

Jiang Yifeng ◽

Gou Jianqiang

Keyword(s):

Gas Flow ◽

Coupling Model ◽

Field Investigation ◽

Coal Mass ◽

Gas Content ◽

Coal Seams ◽

Gas Drainage ◽

Permeability Increase ◽

Influence Radius ◽

Drainage Effect

In Accordance with the present situations suggesting that the construction of the gas drainage boreholes in mining seam is sufficient and the gas drainage effect in low permeability coal seams does not yield perfectly, the hydraulic reaming technology in mining seam was proposed to increase the gas drainage efficiency. Through the gas flow method, the effective influence radius of hydraulic reaming was determined and the fluid-solid coupling model of gas drainage along boreholes after hydraulic reaming was established theoretically. Following this, the changes in the laws of gas content around the boreholes in the coal seam were simulated and analyzed. The results indicated that hydraulic reaming can effectively promote the stress-relief and permeability-increase of the coal mass around the boreholes, and the coal mass around the reaming boreholes can be divided into gas flow increase zone, gas flow delay attenuation zone and fast decay zone. The effective influence radius of hydraulic reaming was 5.5~6 m. The obtained simulation results were basically in accordance with the field investigation.

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Fracture evolution and gas transport laws of coal and rock in one kilometer deep coal mine with complicated conditions

Thermal Science ◽

10.2298/tsci180526126z ◽

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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