scholarly journals Study of Load Fluctuation Characteristics of PDC Bit during Gas Extraction Borehole in Soft Coal Seam

OALib ◽  
2017 ◽  
Vol 04 (06) ◽  
pp. 1-13
Author(s):  
Shifeng Wang ◽  
Xiaoming Han ◽  
Qiangqiang Zhang
Keyword(s):  
Coal Seam ◽  
Gas Extraction ◽  
Soft Coal ◽  
Load Fluctuation ◽  
Pdc Bit ◽  
Soft Coal Seam

scholarly journals Investigation of Large-Diameter Borehole for Enhancing Permeability and Gas Extraction in Soft Coal Seam

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yongwen Wang ◽  
Wanjun Yan ◽  
Zhongjiu Ren ◽  
Zhiqiang Yan ◽  
Ziwen Liu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Shear Failure ◽  
Large Diameter ◽  
Gas Content ◽  
Gas Extraction ◽  
Extraction Area ◽  
Damage Area ◽  
Soft Coal ◽  
Coal Deformation ◽  
Soft Coal Seam

The efficiency of gas extraction from the soft coal seam with ultralow permeability is low. Gas extraction with large-diameter borehole is proposed to deplete gas content for preventing gas outburst disaster in this study. The fractures around the large borehole will enhance the permeability in the damage area to promote gas extraction. We established a damage-stress-seepage coupling model for large-diameter borehole gas extraction in soft coal seam. This mathematical model contains governing equations of gases sorption and transport, coal deformation, and damage, reflecting the coupling responses between gas and coal seam. The model is solved by the finite element method to simulate the gas drainage large-diameter borehole through roadway. Distributions of elastic modulus, damage area, and maximum principal stress in soft coal seam with different borehole diameters including 94 mm, 133 mm, 200 mm, and 300 mm are analyzed. The gas pressure, gas content, and effective extraction area in soft coal seam are discussed. Results show that the shear failure zone appears around the large-diameter borehole, and its permeability rises sharply. This opens up the gas transport channel and is conducive to the rapid extraction. It is confirmed that gas extraction using large-diameter borehole (300 mm) can greatly improve the efficiency of the gas preextraction in soft coal seam by increasing gas extraction rate. These provide a foundation for guiding the operation of gas extraction with large borehole from the soft coal seam in the field.

The New Technology of Hydraulic Fracturing Soft Coal Rock Permeability Improvement

2014 ◽  
Vol 1030-1032 ◽  
pp. 1255-1259 ◽  
Author(s):  
Xue Xi Chen ◽  
Yan Ke Zhang ◽  
Yong Xu ◽  
Rui Qing Bi
Keyword(s):  
Coal Seam ◽  
New Technology ◽  
Water Injection ◽  
Injection Pressure ◽  
Field Application ◽  
Good Effect ◽  
Gas Extraction ◽  
Soft Coal ◽  
Coal Rock ◽  
Soft Coal Seam

According to the low intensity, good plasticity in soft coal seam, the effect of direct fracturing to increase permeability was not ideal, the new technology of hydraulic fracture soft coal rock was proposed, which increased coal seam permeability. Its technical principles and characteristics were researched. Water injection pressure was analyzed, including injection time, parameters of the technology and so on. Field application experiment and effect of inspection were conducted. The results showed that the concentration of gas extraction increased 4.3 times, and the gas extraction flow increased 6.2times. The technology has a good effect of fracturing and advantages in enlarging the released area and decreasing diffusion seepage resistance of coal seam. Most important, the technology has broad application prospects in soft coal seam.

scholarly journals Practice and Drilling Technology of Gas Extraction Borehole in Soft Coal Seam

2011 ◽  
Vol 3 ◽  
pp. 53-61 ◽  
Author(s):  
Ningping Yao ◽  
Xinsheng Yin ◽  
Yi Wang ◽  
Li Wang ◽  
Qianhui Ji
Keyword(s):  
Coal Seam ◽  
Gas Extraction ◽  
Soft Coal ◽  
Drilling Technology ◽  
Soft Coal Seam

The Adaptation Analysis of the Fully Mechanized Coal Mining Face of Huopu Mine’s Third Soft Coal Seam

2014 ◽  
Vol 1049-1050 ◽  
pp. 335-338 ◽  
Author(s):  
Fa Quan Liu ◽  
Xue Wen Geng ◽  
Yong Che ◽  
Xiang Cui
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Geological Condition ◽  
Soft Coal ◽  
Working Face ◽  
Mining Face ◽  
Soft Coal Seam ◽  
Working Resistance

To get the maximum coal in front of the working face of the 17# coal seam, we installed a longer beam which is 1.2m in length in the leading end of the original working face supports ZF3000/17/28, and know that working face supports’ setting load and working resistance are lower .We changed the original supports with shield supports ZY3800/15/33 that are adaptable in the geological condition and got the favorable affection.

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.

scholarly journals Research on Control of Rib Spalling Disaster in the Three-Soft Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Feng Cui ◽  
Tinghui Zhang ◽  
Xiaoqiang Cheng
Keyword(s):  
Coal Seam ◽  
Field Experiments ◽  
Simulation Experiment ◽  
Current Status ◽  
Soft Coal ◽  
Grouting Pressure ◽  
Working Face ◽  
Coal Wall ◽  
Soft Coal Seam ◽  
Seam Mining

Rib spalling disaster at the coal mining faces severely restricted the safe and efficient output of coal resources. In order to solve this problem, based on the analysis of the current status of rib spalling in the three-soft coal seam 1508 Working Face of Heyang Coal Mine, a mechanical model of sliding-type rib spalling was established and the main influencing factors that affect rib spalling are given. The mechanism of grouting technology to prevent and control rib spalling has been theoretically analyzed. A similarity simulation experiment is used to analyze the change law of roof stress under the condition of three-soft coal seam mining. The optimal grouting pressure is determined by a numerical simulation experiment. And, silicate-modified polymer grouting reinforcement materials (SMPGMs) are used in field experiments. After twice grouting operations in the 1508 Working Face, the coal wall was changed from the original soft and extremely easy rib spalling to a straight coal wall and the amount of rib spalling has been reduced by 57.45% and 48.43, respectively. And, the mining height has increased by 0.16 m and 0.23 m, respectively. The experimental results show that the rib spalling disaster of the three-soft coal seam has been effectively controlled.

scholarly journals Application of Sampling Method Based on Negative Pressure Pneumatic Conveying in Soft Coal Seam

2016 ◽  
Vol 34 (3) ◽  
pp. 473-478
Author(s):  
Hongtu Zhang ◽  
Jianping Wei ◽  
Yungang Wang ◽  
Zhihui Wen ◽  
Banghua Yao
Keyword(s):  
Coal Seam ◽  
Negative Pressure ◽  
Sampling Method ◽  
Pneumatic Conveying ◽  
Soft Coal ◽  
Soft Coal Seam

Coal and gas outburst mechanism of the “Three Soft” coal seam in western Henan

2010 ◽  
Vol 20 (5) ◽  
pp. 712-717 ◽  
Author(s):  
Dongji LEI ◽  
Chengwu LI ◽  
Zimin ZHANG ◽  
Yugui ZHANG
Keyword(s):  
Coal Seam ◽  
Coal And Gas Outburst ◽  
Gas Outburst ◽  
Soft Coal ◽  
Soft Coal Seam

scholarly journals Research and Application of Hydraulic Punching Pressure Relief Antireflection Mechanism in Deep “Three-Soft” Outburst Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Beifang Gu ◽  
Yanling Wu
Keyword(s):  
Coal Seam ◽  
Large Scale ◽  
Water Pressure ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Technical Problems ◽  
Soft Coal ◽  
Coal Rock ◽  
Outburst Coal Seam ◽  
Soft Coal Seam

To solve the problems of gas predrainage in deep seams with “three softs” and low-air permeability, hydraulic punching pressure relief antireflection technology is proposed on the basis of the research background of gas predrainage technology in Lugou Mine to alleviate technical problems, such as low gas drainage efficiency, in this mine. Through the analysis of the mechanism of hydraulic punching and coal breaking, combined with FLAC3D software, a hydraulic punching pressure relief antireflection model is established. Then, the fracture radii of coal rock are simulated and calculated. The results show that, under hydraulic punching with a water pressure of 10 MPa and coal outputs of 3 m3, 6 m3, 9 m3, and 12 m3, the fracture radii of coal and rock are 3.4 m, 4.8 m, 5.5 m, and 5.9 m, respectively. Using the software to fit the relationship between coal output V and hydraulic punching fracture radius R under the same water pressure, R = 2.32479 V0.3839 is obtained. The field test is carried out in the bottom drainage roadway of 32141 in Lugou Mine. The application effect is as follows: the gas concentration of hydraulic punching with a coal output of 3 m3 is twice that of ordinary drilling, and the coal output of hydraulic punching with a coal output of 6 m3 is four times that of ordinary drilling. The extraction concentration is four times that of ordinary drilling, and the extraction concentration of hydraulic punching with a coal output of 9 m3 is 6.4 times that of ordinary drilling. Combining the results of the numerical simulation and taking into account the actual construction situation on site, the coal output of water jetting from the borehole is 9 m3, and the fracture radius is 5.5 m. This outcome means that the effective half radius is 5.5 m, and the borehole spacing is 7.7 m. These values are the construction parameters for large-scale applications. This proposal provides effective technology and equipment for gas drainage in the deep three-soft coal seam. Consequently, it has promotion and reference significance for gas drainage in coal seam of the same geological type.

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