Coal and gas outburst control using uniform hydraulic fracturing by destress blasting and water-driven gas release

Yang, Wei; Lu, Changzheng; Si, Guangyao; Lin, Baiquan; Jiao, Xiangdong

doi:10.1016/j.jngse.2020.103360

Cited by 40 publications

(19 citation statements)

References 38 publications

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“…The low permeability of coal seam causes the low efficiency of traditional CBM development. Various methods of strengthening the CBM extraction have been applied, such as freeze-thaw damage mechanism, hydraulic slotting, hydraulic fracturing, and gas injection. − Gas injection can enhance the recovery of CBM, which is indeed an effective method by promoting methane desorption and maintaining reservoir pressure. − CO 2 and N 2 are often selected as injected gases to enhance CBM recovery because of its ancillary features and availability. It is essential to explore the CH 4 /CO 2 /N 2 adsorption properties on a coal seam for improving the recovery of CBM by CO 2 and N 2 injection.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Analysis of CH₄/CO₂/N₂ Adsorption on Anthracite Coal: Investigated by Molecular Simulation

et al. 2021

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The interpretation of gas adsorption behavior on a coal surface is an important theoretical basis for gas injection to enhance the recovery of coalbed methane. In order to further explore the adsorption properties of different gases (CH 4 /CO 2 /N 2 ) on the coal surface, the thermodynamic parameters of adsorption were revealed using a molecular simulation method. The results show that the Langmuir−Freundlich model is more accurate to represent gas adsorption on anthracite coal than the Langmuir model and Freundlich model, which reveal that the gas adsorption on the coal surface is heterogeneous. Also, thermodynamic parameters indicate that gas adsorption on anthracite coal is a thermodynamically spontaneous (ΔG < 0) and exothermic physisorption (0 < ΔH < 10 kcal/mol) process, and the gas molecules tend to be in an ordered state (ΔS > 0). According to adsorption affinity and thermodynamic parameters, the adsorption capacity of these three gases on a coal surface follows the sequence of CO 2 > CH 4 > N 2 . This research can provide foundational knowledge for further interpretation of gas adsorption behavior on a coal surface.

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Section: Introductionmentioning

confidence: 99%

Thermodynamic Analysis of CH₄/CO₂/N₂ Adsorption on Anthracite Coal: Investigated by Molecular Simulation

et al. 2021

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“…The technology of hydraulic perforation pressure relief and permeability enhancement is to release the coal body through the scouring effect of water flow, which reduces the stress of coal seam, increases the permeability, and releases the coal seam gas, thus eliminating the danger of coal seam outburst [40][41][42], and the experimental system established in reference [43] reveals the fluid solid coupling property of gas-bearing coal subjected to hydraulic slotting. The technology of hydraulic fracturing permeability enhancement is to inject highpressure water into the coal seam boreholes; under the pressure, the coal body around the borehole appears cutting cracks; and with the continuous injection of high-pressure water, the cracks gradually extend to the depth of the borehole, thus increasing the coal seam permeability [44,45]. Literature [46] explored the change rule of the compressive strength, elastic modulus, and Poisson's ratio of slotted coal samples with the slotting angle and found that the change rule, respectively, conforms to the Boltzmann function, logistic function, and quadratic function.…”

Section: Introductionmentioning

confidence: 99%

Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing

et al. 2022

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The No. 21 coal seam in the Zhengzhou mining area is a soft, three-layer, low-permeability coal seam prone to outbursts. The three-layer structure includes the coal seam and the roof and floor layers, which exhibit high gas contents and poor permeability. The dynamic hazards caused by coal and gas outbursts are very serious. A new permeability-increasing fracturing technique that combines hydraulic perforation and hydraulic fracturing was developed specifically for the geologic conditions of the gas-bearing No. 21 coal seam. Numerical simulations were developed to study the influence of the technique on the stress distribution and permeability of the coal around the borehole. In addition, the extracted borehole gas concentrations and extraction amounts at multiple sites were investigated before and after using the technique. The study shows that the permeability-increasing fracturing technique destroys the concentrated stress coal pillars via the development of fractures between boreholes in exposed hydraulically perforated coal. The coal stress within the zone with an effective increase in permeability decreased by 30%. Furthermore, the permeability in this zone increased by three times, and the average extracted gas concentration increased by over six times. The gas pressure in the No. 21 coal seam decreased from 1.1 MPa to 0.4 MPa, and the gas content decreased from 15.96 m3/t to 5.6 m3/t. All outburst prediction indexes measured on site did not exceed their respective limits. The technique not only effectively eliminated the dynamic hazards caused by coal and gas outbursts but also achieved efficient gas extraction in the Zhengzhou mining area.

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“…From the underground mining aspect, the coal mine water can be treated once coal mine water is generated during the coal cutting process [9,10]. At the working face, coal fines and powders are produced [11] and the ground water can be disturbed, so that the coal slurry is formed by mixing broken coals and water, especially for some waterabundant coal mines [10]. Many factors can affect the solid concentrations of the coal slurry.…”

Section: Introductionmentioning

confidence: 99%

Combined Treatments of Underground Coal Slurry: Laboratory Testing and Field Application

Zhang

Dong

Zhao

et al. 2021

Water

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During the coal mining process, underground water is generated from the longwall face. In the meantime, the coal cutting process would produce coal particles. Coal slurry is generated in the underground working site, especially for water abundant coal mines. The generated coal slurry is treated to prevent water pollution. Due to the extensively existing of the suspended solid, the traditional process method would often introduce new problems. In this study, laboratory testing was conducted to investigate the characteristics, including the particle size distribution of the coal sludge, coal slurry compositions, slurry viscosity and coal mine water quality. In order to improve the coal slurry treatment efficiency, based on the laboratory results, a novel combined treatment of underground coal slurry is proposed. First, the coarse grained coal slurry is process by a vibrating screening machine. Then, the coal slurry containing fine coal powders is processed through a settling pond. The sedimentation results of the coal solid materials are analyzed. The polymer flocculant is also added into the coal slurry to improve the sedimentation. These combined treats of the coal slurry significantly remove the suspended solid and improve the quality of the coal mine water. Based on the laboratory testing, the specific details of the field applications are designed. The key novelty of this paper is the underground background. All of these treatments are based on the underground environment and are capable of being applied in underground workings. From field applications and observations, these novel combined treatments of coal slurry in the underground site are effective. This study provides a novel method to treat the coal slurry, which has innovations from engineering aspect. These procedures are useful for the underground coal slurry treatment, especially for water-abundant coal mines. The normal coal production is guaranteed and less affected by the coal slurry discharge process. Meanwhile, the water pollution problem is much addressed and the damage of coal slurry to the environment is reduced.

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Coal and gas outburst control using uniform hydraulic fracturing by destress blasting and water-driven gas release

Cited by 40 publications

References 38 publications

Thermodynamic Analysis of CH₄/CO₂/N₂ Adsorption on Anthracite Coal: Investigated by Molecular Simulation

Thermodynamic Analysis of CH₄/CO₂/N₂ Adsorption on Anthracite Coal: Investigated by Molecular Simulation

Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing

Combined Treatments of Underground Coal Slurry: Laboratory Testing and Field Application

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Coal and gas outburst control using uniform hydraulic fracturing by destress blasting and water-driven gas release

Cited by 40 publications

References 38 publications

Thermodynamic Analysis of CH4/CO2/N2 Adsorption on Anthracite Coal: Investigated by Molecular Simulation

Thermodynamic Analysis of CH4/CO2/N2 Adsorption on Anthracite Coal: Investigated by Molecular Simulation

Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing

Combined Treatments of Underground Coal Slurry: Laboratory Testing and Field Application

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Thermodynamic Analysis of CH₄/CO₂/N₂ Adsorption on Anthracite Coal: Investigated by Molecular Simulation

Thermodynamic Analysis of CH₄/CO₂/N₂ Adsorption on Anthracite Coal: Investigated by Molecular Simulation