scholarly journals Gas Displacement Engineering Test by Combination of Low and Medium Pressure Injection with Liquid CO2 in High Gas and Low Permeability Coal Seam

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Hu Wen ◽  
Mingyang Liu ◽  
Gaoming Wei ◽  
Xiaowei Zhai ◽  
Shixing Fan ◽  
...  
Keyword(s):  
Coal Seam ◽  
Low Permeability ◽  
Gas Drainage ◽  
Technology System ◽  
Medium Pressure ◽  
Low Viscosity ◽  
Injection Process ◽  
Pressure Injection ◽  
Liquid Co2 ◽  
Drainage Effect

Mining high-gas coal seams in China has the characteristics mining of deep, high storage and low permeability, and low drainage efficiency, which seriously restrict the efficient prevention and control of mine gas disasters. Based on the characteristics of low viscosity and permeability, phase change pressurization, and strong adsorption potential energy of liquid CO2, the technology system of liquid CO2 displacement for high-gas and low-permeability coal seam was developed, and field industrial of low-pressure (0.5~2.5 MPa) and medium-pressure (2.5~15.0 MPa) combined injection test was carried out. In this test, the mode of injection followed by drainage was adopted, and the gas drainage effect was investigated for 30 days. The test results show that the effective influence radius of CO2 in this test is 20 m, and the liquid seepage radius is 5 to 7 m. After the injection of liquid CO2 into coal seam, the average gas drainage concentration and drainage purity of all drainage holes were increased by 3.2 and 3.4 times, respectively, and the gas promotion effect was significant. Taking the liquid CO2 low-medium-pressure displacement gas test area as the calculation unit, from the comprehensive benefit analysis, compared with the original drainage mode, the liquid CO2-combined pressure injection process can save 34.7% of the engineering cost and shorten the gas drainage standard time by 45.9%. Therefore, the application of this technology has important technical support and reference significance for the efficient management of gas in the same type of mine.

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 Study on Permeability Improvement Technology by Injecting Air into the Gas Drainage Borehole in Low-Permeability Coal Seam

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Li Hui ◽  
Guo Chengwei ◽  
Sun Yuanfang ◽  
Guo Shaoshuai
Keyword(s):  
Coal Seam ◽  
Gas Injection ◽  
Vertical Direction ◽  
Injection Pressure ◽  
Gas Content ◽  
Low Permeability ◽  
Gas Drainage ◽  
Working Face ◽  
Injection Technology ◽  
Time Required

Gas extraction cycle is too long in low-permeability coal seam. In order to solve the problem, the basic principle about gas drainage drilling for gas injection technology is studied to increase permeability. And the mathematical model is established. Gas is injected into the low-permeability coal seam by numerical simulation. The results indicate that the best condition is a negative pressure drainage at 26 kPa and a gas injection pressure at 0.6 MPa in the vertical direction and in the horizontal direction of the injection hole. In Shanxi Daping Coal Mine 3113 working face, the field test is implemented. As a result, the test is successful. During the 14 d gas injection constantly, gas content of coal seam is reduced from 12.33 m3/t to 7.12 m3/t, greatly reducing the risk of coal and gas outburst elimination time required.

Study and Application of Hydraulic Fracturing Technology to Increase Permeability in Soft and Low Permeability Coal Seam

2014 ◽  
Vol 700 ◽  
pp. 553-558
Author(s):  
Song Gao ◽  
Bu Chuan Wang ◽  
Wen Bin Wu
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Technical System ◽  
Low Permeability ◽  
Gas Drainage ◽  
Mine Area ◽  
Complete Set ◽  
Outburst Hazard

In order to improve gas drainage of soft and outstanding coal seam in Huainan mine area, for eliminating outburst hazard, hydraulic fracturing is applied at west one (13-1) rock cross-cut coal uncovering face. By analysising antireflection mechanism of hydraulic fracturing, hydraulic fracturing is designed and construct at rock cross-cut coal uncovering face, and then investigate the effect of hydraulic fracturing, at last it get a hydraulic fracturing complete set of technical system.

scholarly journals Determining the Layout Parameters of the Gas Drainage Roadway: A Study for Sima Coalmine China

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zhiliu Wang ◽  
Bo Liu ◽  
Yanhui Han ◽  
Zhaoyang Li ◽  
Yingjie Cao ◽  
...  
Keyword(s):  
Coal Seam ◽  
Fracture Zone ◽  
Calculation Method ◽  
Analytical Calculation ◽  
Horizontal Distance ◽  
Gas Drainage ◽  
Working Face ◽  
Scale Modelling ◽  
Modelling Experiment ◽  
Drainage Effect

To determine the layout parameters of the gas drainage roadway (GDR) serving for the working face, an analytical calculation method of fracture zone and the modelling experiment were adopted, and the overburden fissure induced by mining and the height of fracture zone were analyzed. For the research on the distribution of fracture zone by analytical calculation method, the multiple factors influencing the failure mode of strata and the height of fracture zone were considered. The #1207 working face in Sima mine was taken as an engineering background, and the layout parameters of GDR were given by analyzing the height of fracture zone. Combining the results obtained by analytical calculation and scale modelling experiment, the suggested height of GDR was 10.7–32.8 m away from the coal seam roof, and the projection distance of GDR in the horizontal was within the range of 0–35 m from the airway. By monitoring the gas drainage effects in different heights away from coal seam roof in #1207 working face and in different horizontal distances away from the ventilation roadway in the #1211 working face, the results showed that the optimal height was 17.5–22 m away from coal roof, and the optimal horizontal distance was 17–21 m away from airway for GDR. The gas drainage effect of GDR indicated that the proposed parameters are scientific and reasonable.

scholarly journals Experimental Study on Reasonable Spacing after Carbon Dioxide Presplitting in Low-Permeability Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zongyong Wei ◽  
Shugang Li ◽  
Haifei Lin ◽  
Botao Li ◽  
Yang Ding ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mines ◽  
Extraction Time ◽  
Shaanxi Province ◽  
Low Permeability ◽  
Efficient Production ◽  
Gas Drainage ◽  
Negative Exponential Function ◽  
Drainage Time ◽  
Drainage Radius

Gas disasters have been always a major hidden danger that affects mining safety in coal mines. Gas drainage by drilling is the fundamental method of gas control in coal mines. In view of the low-permeability coal seam, it is the basis of the safe and efficient production of the mine to take the measures of enhancing the permeability, improving the gas drainage efficiency, and shortening the drainage time. The 4−2 coal seam of the Jianxin coal mine in Shaanxi Province of China is a low-permeability coal seam. In order to obtain the reasonable hole spacing and the reasonable extraction time after the penetration enhancement, the pressure drop method is used to investigate the extraction radius. The results show that the gas pressure around the test hole decreases with time as a negative exponential function, and the effective radius of extraction increases with the increase of extraction time as a logarithmic function. Through the comparative analysis and variance analysis of the test data of the two drilling fields, it is proved that the data of the drainage radius of the two drilling fields are accurate and reliable. It is obtained that the reasonable spacing of the gas drainage holes is 8.10 m and the reasonable drainage time is 180 days after CO2 presplitting and permeability increase in the 4−2 coal seam of the mine.

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.

Research on Permeability of Coal Samples with and without the Effect of Supercritical CO2

2012 ◽  
Vol 455-456 ◽  
pp. 168-173
Author(s):  
Tao Yang ◽  
Bai Sheng Nie ◽  
Dong Yang ◽  
Ru Ming Zhang
Keyword(s):  
Experimental Study ◽  
Coal Seam ◽  
Low Permeability ◽  
Coal Seam Gas ◽  
Gas Drainage ◽  
Laboratory Conditions ◽  
Before And After ◽  
Order Of Magnitude ◽  
Volume Stress

To improve the low-permeability coal seam gas drainage and gas prevention and to seek the methods to improve the permeability of low-permeability coal, the experimental study on supercritical CO2 on coal was conducted in the laboratory conditions, and the experiment on pseudo-triaxial permeability testing for coal samples, with and without supercritical CO2, was conducted. The results show that due to the effect of supercritical CO2 on coal like physi-chemistry, the porosity of coal was changed, which markedly varied the permeability of coal samples before and after the effect of supercritical CO2; the permeability of the experimented coal samples was significantly higher than before, and average permeability increased by nearly an order of magnitude under the same volume-stress.

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