Safety line method for the prediction of deep coal-seam gas pressure and its application in coal mines

2012 ◽  
Vol 50 (3) ◽  
pp. 523-529 ◽  
Author(s):  
Liang Wang ◽  
Yuan-ping Cheng ◽  
Lei Wang ◽  
Pin-kun Guo ◽  
Wei Li
Keyword(s):  
Coal Seam ◽  
Coal Mines ◽  
Gas Pressure ◽  
Coal Seam Gas ◽  
Line Method

scholarly journals Coal Seam Gas Extraction by Integrated Drillings and Punchings from the Floor Roadway considering Hydraulic-Mechanical Coupling Effect

Geofluids ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-10
Author(s):  
Chaojun Fan ◽  
Haiou Wen ◽  
Sheng Li ◽  
Gang Bai ◽  
Lijun Zhou
Keyword(s):  
Coal Seam ◽  
Coal Mines ◽  
Coupling Model ◽  
Gas Pressure ◽  
Gas Content ◽  
Engineering Practice ◽  
Gas Extraction ◽  
Coal Seam Gas ◽  
Mechanical Coupling ◽  
Gas Disasters

Owing to the exhaustion of shallow coal resources, deep mining has been occupied in coal mines. Deep buried coal seams are featured by the great ground stress, high gas pressure, and low permeability, which boost the risk of gas disasters and thus dramatically threaten the security about coal mines. Coal seam gas pressure and gas content can be decreased by gas extraction, which is the primary measure to prevent and control mine gas disasters. The coal mass is simplified into a continuous medium with dual structure of pores and fractures and single permeability. In consideration of the combined effects of gas slippage and two-phase flow, a hydraulic-mechanical coupling model for gas migration in coals is proposed. This model involves the equations of gas sorption and diffusion, gas and water seepage, coal deformation, and evolution of porosity and permeability. Based on these, the procedure of gas extraction through the floor roadway combined with hydraulic punching and ordinary drainage holes was simulated, and the gas extraction results were used to evaluate the outburst danger of roadway excavation and to verify the engineering practice. Results show that gas extraction can reduce coal seam gas pressure and slow down the rate of gas release, and the established hydraulic-mechanical coupling model can accurately reveal the law of gas extraction by drilling and punching boreholes. After adopting the gas extraction technology of drilling and hydraulic punching from the floor roadway, the remaining gas pressure and gas content are reduced to lower than 0.5 MPa and 5.68 m3/t, respectively. The achievements set a theoretical foundation to the application of drilling and punching integrated technology to enhance gas extraction.

scholarly journals The research of coal seam gas pressure and initial gas emission characteristics of borehole

2019 ◽  
Vol 7 (5) ◽  
pp. 1961-1969 ◽  
Author(s):  
Jianhua Zeng ◽  
Shixiang Tian ◽  
Guiyi Wu ◽  
Yunjun Zuo ◽  
Shiqing Xu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Gas Pressure ◽  
Emission Characteristics ◽  
Coal Seam Gas ◽  
Gas Emission

scholarly journals A New Method for the Measurement of Gas Pressure in Water-Bearing Coal Seams and Its Application

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xiao Cui ◽  
Jiayong Zhang ◽  
Liwen Guo ◽  
Xuemin Gong
Keyword(s):  
Coal Seam ◽  
Field Experiments ◽  
Water Pressure ◽  
Direct Methods ◽  
Gas Pressure ◽  
New Method ◽  
Well Testing ◽  
Coal Seams ◽  
Coal Seam Gas ◽  
Gas Disaster

Coal seam gas pressure is one of the fundamental parameters used to assess coal seam gas occurrence and is an important index in assessing the risk of gas disaster. However, the geological characteristics of coal seams become increasingly complex with increasing mining degree, thus decreasing the accuracy and success rate of direct methods for measuring gas pressure. To address such issues, we have developed a new method for direct measurement of gas pressure in water-bearing coal seams. In particular, we developed a pressure measurement device based on theoretical analysis and quantified the basic parameters of the device based on well testing. Then, we verified the applicability of our method based on comparative analysis of the results of field experiments and indirect measurements. Our results demonstrate that this new method can resolve the effects of water pressure, coal slime, and other factors on the estimation of gas pressure. The performance of this new method is considerably better than that of traditional methods. In particular, field test results demonstrate that our method can accurately and efficiently measure gas pressure in water-bearing coal seams. These results will be of great significance in the prevention and control of coal seam gas disaster.

scholarly journals Numerical Investigation of Complex Thermal Coal-Gas Interactions in Coal-Gas Migration

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Xiaoyan Ni ◽  
Peng Gong ◽  
Yi Xue
Keyword(s):  
Coal Seam ◽  
Variable Temperature ◽  
Gas Pressure ◽  
Gas Migration ◽  
Coal Seams ◽  
Coal Seam Gas ◽  
Coal Gas ◽  
Thermal Coal ◽  
Gas Seepage ◽  
Gas Interactions

Understanding the influence of temperature on the gas seepage of coal seams is helpful to achieve the efficient extraction of underground coal seam gas. Thermal coal-gas interactions involve a series of complex interactions between gas and solid coal. Although the interactions between coal and gas have been studied thoroughly, few studies have considered the temperature evolution characteristics of coal seam gas extraction under the condition of variable temperature because of the complexity of the temperature effect on gas drainage. In this study, the fully coupled transient model combines the relationship of gas flow, heat transfer, coal mass deformation, and gas migration under variable temperature conditions and represents an important nonlinear response to gas migration caused by the change of effective stress. Then, this complex model is implemented into a finite element (FE) model and solved through the numerical method. Its reliability was verified by comparing with historical data. Finally, the effect of temperature on coal permeability and gas pressure is studied. The results reveal that the gas pressure in coal fracture is generally higher than that in the matrix blocks. The higher temperature of the coal seam induces the faster increase of the gas pressure. Temperature has a great effect on the gas seepage behavior in the coal seams.

Numerical Simulation on the Influence of Mining-Induced Fractures Field on Gas Drainage and its Application

2011 ◽  
Vol 90-93 ◽  
pp. 477-484
Author(s):  
Shu Jing Zhang ◽  
Yong Wei Peng ◽  
Yong Jiang Yu
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Gas Flow ◽  
Underground Mining ◽  
High Strength ◽  
Gas Pressure ◽  
Comsol Multiphysics ◽  
Coal Seam Gas ◽  
Gas Drainage ◽  
Induced Fractures

In order to study the influence of mining-induced fractures field on gas drainage,the paper adopts software of numerical simulation COMSOL Multiphysics to simulate gas drainage of coal seam under the condition of high-strength underground mining. The main aspects can be seen as the following: (1) In the case without considering the fractures, gas drainage in single hole, the gas pressure distribution showed a funnel-type distribution in space along the drainage holes around. (2) The orientation and direction of fractures play a major role on the flow field of gas. In the region that exits fractures, the distribution of gas pressure has a clear fluctuation and adjustment.(3) The numerical simulation of coal seam gas drainage that considered the fracture of coal mining, was closer to the true gas flow.

Study of Sealing Technology of Downward & Permeable Borehole

2012 ◽  
Vol 524-527 ◽  
pp. 351-354 ◽  
Author(s):  
Zu Xiang Hu
Keyword(s):  
Coal Seam ◽  
Wall Rock ◽  
Gas Pressure ◽  
Good Effect ◽  
Time Sharing ◽  
Coal Seam Gas ◽  
Local Practice ◽  
Prediction And Prevention ◽  
Geological Conditions ◽  
Pressure Measure

In gas prediction and prevention , it is important for the Mine-managers to know coal-seam gas-pressure. Because of the limitation of geological conditions,some seam can not use upward bore to measure gas pressure,so using downward bore is essential, but coal-seam gas-pressure measure is difficult on the this condition(QixiangYu. 1992) . In order to resolve this problem, the way of “subsection and time-sharing hole sealing” is propounded in this paper.by using this method, the crevice water of wall rock is blockaded effectively and the influence of measure gas pressure by crevice water is avoided. It can provide guarantee to measure gas pressure under the complicated condition.By the local practice,good effect is achieved.

scholarly journals Research and Optimization of Gas Extraction by Crossing-Seam Boreholes from Floor Roadway

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Gang Li ◽  
Jiafei Teng
Keyword(s):  
Coal Seam ◽  
Gas Permeability ◽  
Gas Pressure ◽  
Gas Content ◽  
Gas Extraction ◽  
Gas Migration ◽  
Governing Equations ◽  
Coal Seam Gas ◽  
Gas Seepage ◽  
Gas Disaster

Deep coal seams are characterized by large stress, high gas pressure, and low permeability. The gas disaster threatens the safe production of coal mine seriously. Gas extraction by crossing-seam boreholes from floor roadway (GECMBFR) can reduce the pressure and content of coal seam gas, which is the main measure to prevent gas disaster. Considering the Klinkenberg effect, governing equations of gas adsorption/desorption-diffusion, gas seepage, and stress fields within the coal seam are established to form the seepage-stress coupling model. The governing equations are embodied into a finite element driven software to numerically simulate gas migration and fluid-solid coupling law in coal seam. On this basis, the process of gas extraction under different borehole spacings and diameters is simulated. The effects of these two key parameters on coal seam gas pressure, gas content, and gas permeability were analyzed. The borehole spacing and diameter were determined to be 5 m and 0.09 m, respectively. Combined with the actual situation of a mine, the process of gas extraction from floor roadway with different cross-sectional schemes, ordinary drilling boreholes and punching combined drilling boreholes, is comparatively analyzed. The results show that the gas extraction effect by ordinary drilling boreholes is lower than that of the punching combined drilling boreholes, and the extraction is uneven and makes it difficult to meet the standard. Hydraulic punching was carried out, and coal was washed out of the borehole, which expanded the contact area between the borehole wall and coal seam. The coal seam around the punching borehole is unloaded, which improves coal permeability and accelerates gas migration towards the borehole, thus promoting the efficiency of gas extraction. It is more reasonable to use punching combined drilling borehole scheme when implementing the GECMBFR technology.

The Application of Crossing and Grid Drainage Boreholes in Floor Tunnel for Coal Roadway Safety Tunneling

2014 ◽  
Vol 962-965 ◽  
pp. 1169-1174
Author(s):  
Hong Qing Zhu ◽  
Bei Fang Gu ◽  
Min Bo Zhang ◽  
Chao Yu ◽  
Zhen Zhang
Keyword(s):  
Coal Seam ◽  
Gas Pressure ◽  
Gas Content ◽  
Dynamic Phenomenon ◽  
Coal Seams ◽  
Coal Seam Gas ◽  
Technical Parameters ◽  
Coal Roadway ◽  
Roadway Safety ◽  
The Relationship

In order to reduce the danger of single coal seams outburst during the tunneling in coal roadway and ensure the tunneling of coal seams, this text analyzed the mechanism of crossing drilling against outburst; studied the area measures of floor tunnel crossing and grid drainage boreholes in coal roadway, Designed and optimized the drilling technical parameters; Analyzed the relationship between the drainage concentration and scalar; Calculated the maximum overlying coal seam gas to spare scalar quantity is 224300 m3 ;Used a variety of indicators to investigate the effect of outburst prevention. It shows that Gas content and gas pressure have significant lower than drainage. After the drainage up to standard, all the sensitive indexes is not overrun, during the coal roadway tunneling, it does not appears dynamic phenomenon. Solve the problem of mining imbalances, guaranteed the safety driving of roadway.

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