scholarly journals Influence of Deformation and Instability of Borehole on Gas Extraction in Deep Mining Soft Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xue-Bo Zhang ◽  
Shuai-Shuai Shen ◽  
Xiao-Jun Feng ◽  
Yang Ming ◽  
Jia-jia Liu
Keyword(s):  
Pressure Loss ◽  
Drainage System ◽  
Suction Pressure ◽  
Coal Seams ◽  
Gas Drainage ◽  
Soft Coal ◽  
Instability Modes ◽  
Deformation Instability ◽  
Effective Drainage ◽  
Drainage Effect

To study the effects of the three deformation instability modes of gas drainage borehole on gas drainage, the deformation instability mechanism of soft coal seams is analyzed, three deformation instability modes are proposed for soft coal seams, namely, complete holes, collapse holes, and plug holes, and a solid-fluid coupling model incorporating dynamic change of borehole suction pressure is established. The results of the study show the following. (1) When there is no borehole deformation (i.e., complete borehole), the suction pressure loss of drainage system in the borehole is very small, whose effect on gas drainage can be neglected. (2) In case of borehole collapse, the suction pressure loss is big at the collapse segment, and the total suction pressure loss of the drainage system in the borehole is bigger than that in the complete hole. However, it is smaller than the suction pressure of the drainage system and exerts limited effect on gas drainage. As the borehole collapse deteriorates, the effective drainage section of the borehole becomes smaller, while the suction pressure loss in the borehole increases continuously; thus, the gas drainage effect continuously worsens. (3) In case of plug hole, a continuous medium forms between the plug segment coal body and the surrounding coal seam, the plug segment drainage pressure turns into coal-bed gas pressure, and effective drainage length of the borehole shortens, seriously affecting the gas drainage effect. The study carries important theoretical guiding significance for improving gas drainage effect and effectively preventing gas disasters.

scholarly journals An integrated drilling, protection and sealing technology for improving the gas drainage effect in soft coal seams

2020 ◽  
Vol 6 ◽  
pp. 2030-2043
Author(s):  
Hong Li ◽  
Wei Wang ◽  
Yanwei Liu ◽  
Jinkui Ma ◽  
Hong Gao
Keyword(s):  
Coal Seams ◽  
Gas Drainage ◽  
Soft Coal ◽  
Drainage Effect

The Application of Gas Drainage Technology in the Workface of "Three Soft" Specially Thick Coal Seam

2012 ◽  
Vol 204-208 ◽  
pp. 3469-3475
Author(s):  
Guo Liang Lu ◽  
Chen Wang ◽  
Yao Dong Jiang ◽  
Hong Wei Wang
Keyword(s):  
Coal Seam ◽  
Production Process ◽  
Low Permeability ◽  
Gas Drainage ◽  
Thick Coal Seam ◽  
Mine Area ◽  
Soft Coal ◽  
Drainage Effect ◽  
Soft Coal Seam

In order to improve the gas drainage effect of "three soft" coal seam with low-permeability and eliminate the gas overrun in the upper corner and return air during the production process, this paper did an exploration on the comprehensive gas management on the fully mechanized caving face of gassy mines in Xuangang mine area and its application achieved a good result.

scholarly journals Gas Distribution Mechanism in Goaf during Combined Drainage of Upper Corner Buried Pipeline and Intubation for Thick Coal Seams

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Zhe Li ◽  
Fangtian Wang ◽  
Shuai Ren ◽  
Guannan Liu
Keyword(s):  
Buried Pipeline ◽  
Coal Seams ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Geological Conditions ◽  
Key Issues ◽  
Fluent Software ◽  
Gas Control ◽  
Drainage Effect ◽  
And Control

Abstract The prevention of gas overrun in the panel is one of the key issues on green mining. In this paper, a physical goaf model was established based on the geological production conditions of a coal seam in a coal mine in Henan Province, and the combined drainage technology by burying and spilling pipeline in the upper corner was proposed. The Fluent software was used to simulate the changes of gas mass fraction and flow field distribution when the gas is extracted from the goaf without the gas pipeline, with a single buried pipeline, and with the combination of buried and spilled pipelines. Analysis and simulation showed that in the absence of drainage pipelines, the gas concentrations in both the return airway and the upper corner are up to 1.2%, which failed to meet the gas prevention and control standard on the mine. In the case of gas drainage with a single buried pipeline, the average gas concentration in the return airway was 0.7%, and only the gas concentration in the upper corner was up to 1.1%, which failed to meet the gas control standards on the mine’s panel. However, the maximum gas concentration in the combined drainage was reduced from 1.1% to 0.6%, which indicates that the technology can greatly reduce gas concentration, but there is still a gap from the mine’s gas control standard. Therefore, the impacts of the lengths of pipelines buried in different goafs on the gas drainage effect in the goaf were studied, and it was concluded that the reasonable length of pipelines buried in the goaf under the geological conditions was 20 m. This technology not only solves the problem of gas overrun in the panel but also realizes the utilization of gas resources in the goaf. The research results are of guiding significance for pipeline laying and the drainage technology in the upper corners on the U-shaped ventilation panel.

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

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.

scholarly journals Study on gas drainage effect of hydraulic fracturing in soft coal seam

2020 ◽  
Vol 185 ◽  
pp. 01004
Author(s):  
Liangwei Li
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Gas Flow ◽  
Water Injection ◽  
Fracture Initiation ◽  
Gas Content ◽  
Gas Drainage ◽  
Soft Coal ◽  
Drainage Effect ◽  
Soft Coal Seam

Aiming at the difficulty of gas drainage by drilling along the seam in soft coal seam, the permeability of coal seam was increased by hydraulic fracturing test in the field, and the permeability and gas drainage parameters of coal seam before and after fracturing were studied. The results show that: ① The fracture initiation pressure of 3# coal seam in Guojiahe coal mine is 15~20MPa. When the water injection is 30~40m3, the fracturing radius is 15m, when the water injection is 50 ~ 60m3, the fracturing radius can reach 20m, when the water injection reaches 70m3, the fracturing radius can reach 30m; ② Driven by high pressure water, the gas in the fractured area migrates to the unfractured area, and the gas content in the fractured area decreases; ③ The attenuation coefficient of natural gas flow after fracturing is reduced by 50% compared with that before fracturing, and the permeability coefficient of coal seam after fracturing is increased by 50 times compared with that of original area; ④ The recovery concentration after fracturing is much higher than that before fracturing.

Drilling large diameter cross-measure boreholes to improve gas drainage in highly gassy soft coal seams

2015 ◽  
Vol 26 ◽  
pp. 193-204 ◽  
Author(s):  
Yabin Gao ◽  
Baiquan Lin ◽  
Wei Yang ◽  
Ziwen Li ◽  
Yuan Pang ◽  
...  
Keyword(s):  
Large Diameter ◽  
Coal Seams ◽  
Gas Drainage ◽  
Soft Coal

New Concept for a Thoracic Drainage System Using Magnetic Actuation

2019 ◽  
Vol 26 (6) ◽  
pp. 705-711
Author(s):  
Daisuke Taniguchi ◽  
Keitaro Matsumoto ◽  
Yoshihiro Kondo ◽  
Tomoshi Tsuchiya ◽  
Ikuo Yamamoto ◽  
...  
Keyword(s):  
Abdominal Cavity ◽  
Drainage System ◽  
Magnetic Actuation ◽  
Thoracic Cavity ◽  
Common Procedure ◽  
Thoracic Drainage ◽  
Drain Fluid ◽  
Laboratory Trial ◽  
General Surgeons ◽  
Effective Drainage

Objectives. Thoracic drainage is a common procedure to drain fluid, blood, or air from the pleural cavity. Some attempts to develop approaches to new thoracic drainage systems have been made; however, a simple tube is often currently used. The existing drain presupposes that it is placed correctly and that the tip does not require moving after insertion into the thoracic cavity. However, in some cases, the drain is not correctly placed and reinsertion of an additional drain is required, resulting in significant invasiveness to the patient. Therefore, a more effective drainage system is needed. This study aimed to develop and assess a new thoracic drain via a collaboration between medical and engineering personnel. Methods. We developed the concept of a controllable drain system using magnetic actuation. A dry laboratory trial and accompanying questionnaire assessment were performed by a group of thoracic and general surgeons. Objective mechanical measurements were obtained. Porcine experiments were also carried out. Results. In a dry laboratory trial, use of the controllable drain required significantly less time than that required by replacing the drain. The average satisfaction score of the new drainage system was 4.07 out of 5, indicating that most of the research participants were satisfied with the quality of the drain with a magnetic actuation. During the porcine experiment, the transfer of the tip of the drain was possible inside the thoracic cavity and abdominal cavity. Conclusion. This controllable thoracic drain could reduce the invasiveness for patients requiring thoracic or abdominal cavity drainage.

scholarly journals Permeability Enhancement Properties of High-Pressure Abrasive Water Jet Flushing and Its Application in a Soft Coal Seam

2021 ◽  
Vol 9 ◽  
Author(s):  
Xinzhe Zhang ◽  
Piotr Wiśniewski ◽  
Sławomir Dykas ◽  
Guojie Zhang
Keyword(s):  
High Pressure ◽  
Coal Seam ◽  
Water Jet ◽  
Gas Pressure ◽  
Theory And Practice ◽  
Abrasive Water Jet ◽  
Gas Drainage ◽  
Permeability Enhancement ◽  
Soft Coal ◽  
Soft Coal Seam

High-pressure abrasive water jet flushing (HPAWJF) is an effective method used to improve coal seam permeability. In this study, based on the theories of gas flow and coal deformation, a coupled gas-rock model is established to investigate realistic failure processes by introducing equations for the evolution of mesoscopic element damage along with coal mass deformation. Numerical simulation of the failure and pressure relief processes is carried out under different coal seam permeability and flushing length conditions. Distributions of the seepage and gas pressure fields of the realistic failure process are analyzed. The effects of flushing permeability enhancement in a soft coal seam on the gas drainage from boreholes are revealed by conducting a field experiment. Conclusions can be extracted that the gas pressure of the slotted soft coal seam is reduced and that the gas drainage volume is three times higher than that of a conventional borehole. Field tests demonstrate that the gas drainage effect of the soft coal seam is significantly improved and that tunneling speed is nearly doubled. The results obtained from this study can provide guidance to gas drainage in soft coal seams regarding the theory and practice application of the HPAWJF method.

Seepage through Earth Dams with Chimney Drain on Pervious Foundation

2012 ◽  
Vol 452-453 ◽  
pp. 538-542 ◽  
Author(s):  
Abdelkader Djehiche ◽  
Rekia Amieur ◽  
Mustafa Gafsi
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Drainage System ◽  
Earth Dam ◽  
Earth Dams ◽  
Drainage Systems ◽  
The Earth ◽  
Excess Water ◽  
Effective Drainage

This paper presents an experimental study of a homogenous earth dam. The work is focused to the search of solutions of problems encountered in the earth dams after their construction. One of the major problems is the choice and design of systems of drainage. The effective drainage system to prevent harmful accumulations of excess water is one of the most important roles of dams. Efficient drainage systems can improve the safety of earth dams. The paper presented herein reports the results obtained from the experimental study. Empiric relations have been obtained which can be help in the control of the flow rate in the chimney drain of the earth dams on pervious foundation, which can increase safety earth dams

Massive Hydraulic Fracturing to Control Gas Outbursts in Soft Coal Seams

2022 ◽  
Author(s):  
Shuaifeng Lyu ◽  
Shengwei Wang ◽  
Junyang Li ◽  
Xiaojun Chen ◽  
Lichao Chen ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Coal Seams ◽  
Soft Coal
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