Analysis on Sealing Method and Sealing Materials of Gas Drainage Borehole

2013 ◽  
Vol 716 ◽  
pp. 485-489 ◽  
Author(s):  
Qing Ye ◽  
Zhen Zhen Jia ◽  
Yan Pi ◽  
Hai Zhen Wang
Keyword(s):  
Coal Seam ◽  
Gas Flow ◽  
Coal Mines ◽  
Polymer Foam ◽  
Gas Drainage ◽  
Rubber Ring ◽  
Advantages And Disadvantages ◽  
Materials Used ◽  
Drainage Effect ◽  
Sealing Materials

With the increase of gas drainage volume and gas drainage requirement of coal seam in China, more and more attention to gas drainage effect of coal seam is paid. The gas flow law and borehole sealing mechanism are briefly described, the borehole sealing technologies of different materials are analyzed and the requirements are obtained as follows: 1Sealing materials shall have permeability. 2Sealing materials shall have expansion. 3The strength and hardness of sealing material can not be too high. 4Sealing materials are compact; sealing materials shall have certain strength. 5Sealing materials can be obtained easily and their price shall be low. 6Sealing process is simple and is constructed easily. Finally, the high polymer foam sealing technology, the mechanical elastic sealing technology, borehole packer sealing technology, the new pressure grouting hole sealing technology, yellow clay borehole sealing technology and rubber ring (or capsule)-sealing fluid sealing technology are briefly analyzed, the advantages and disadvantages of the borehole sealing method and the sealing materials used in coal mines in China are summed up. The results can provides the reference for selection of borehole sealing methods and sealing materials of gas drainage in coal mines.

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.

scholarly journals Experimental Study on the Gas Flow Characteristics and Pressure Relief Gas Drainage Effect under Different Unloading Stress Paths

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Chaolin Zhang ◽  
Jiang Xu ◽  
Enyuan Wang ◽  
Shoujian Peng
Keyword(s):  
Coal Seam ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Gas Production ◽  
Gas Pressure ◽  
Coal Seam Gas ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Coal Temperature ◽  
Drainage Effect

Coal seam gas is a critical substance because it can be a source of a large quantity of clean energy as well as a dangerous source of risk. A pressure relief gas drainage is an effective and widely used method for coal seam gas recovery and gas disaster control in coal mines. A series of pressure relief gas drainage experiments were conducted using large-scale coal samples under different unloading stress paths in this study to explore the unloading stress paths. From the experimental results, the dynamic evolutions of gas pressure, coal temperature, and gas production were analyzed. The trends of gas pressure and coal temperature during pressure relief gas drainage were similar: dropping rapidly first and then slowly with time. Correspondingly, gas production was fast in the early stage of pressure relief gas drainage and became stable thereafter. Meanwhile, gas flow characteristics were significantly affected by the unloading stress paths. Gas pressure and coal temperature had the maximum descent by unloading stress in three directions simultaneously, and the unloading stress of the Z direction had the minimal impact when only unloading in one direction of stress. However, the influence of unloading stress paths on gas production was complex and time dependent. The difference coefficient parameter was proposed to characterize the influence degree of unloading stress paths on the pressure relief gas drainage effect. Eventually, the selection of unloading stress path under different situations was discussed based on time, which is expected to provide the basis for pressure relief gas drainage.

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 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 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.

scholarly journals A Numerical Study of Stress Distribution and Fracture Development above a Protective Coal Seam in Longwall Mining

Processes ◽  
2018 ◽  
Vol 6 (9) ◽  
pp. 146 ◽  
Author(s):  
Chunlei Zhang ◽  
Lei Yu ◽  
Ruimin Feng ◽  
Yong Zhang ◽  
Guojun Zhang
Keyword(s):  
Stress Distribution ◽  
Coal Seam ◽  
Gas Flow ◽  
Longwall Mining ◽  
Numerical Study ◽  
Stress Relief ◽  
Coal Industry ◽  
Gas Drainage ◽  
New Findings ◽  
Fracture Development

Coal and gas outbursts are serious safety concerns in the Chinese coal industry. Mining of the upper or lower protective coal seams has been widely used to minimize this problem. This paper presents new findings from longwall mining-induced fractures, stress distribution changes in roof strata, strata movement and gas flow dynamics after the lower protective coal seam is extracted in a deep underground coal mine in Jincheng, China. Two Flac3D models with varying gob loading characteristics as a function of face advance were analyzed to assess the effect of gob behavior on stress relief in the protected coal seam. The gob behavior in the models is incorporated by applying variable force to the floor and roof behind the longwall face to simulate gob loading characteristics in the field. The influence of mining height on the stress-relief in protected coal seam is also incorporated. The stress relief coefficient and relief angle were introduced as two essential parameters to evaluate the stress relief effect in different regions of protected coal seam. The results showed that the rock mass above the protective coal seam can be divided into five zones in the horizontal direction, i.e. pre-mining zone, compression zone, expansion zone, recovery zone and re-compacted zone. The volume expansion or the dilation zone with high gas concentration is the best location to drill boreholes for gas drainage in both the protected coal seam and the protective coal seam. The research results are helpful to understand the gas flow mechanism around the coal seam and guide industry people to optimize borehole layouts in order to eliminate the coal and gas outburst hazard. The gas drainage programs are provided in the final section.

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.

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.

scholarly journals Liquid CO2 phase transition fracturing technology and its application in enhancing gas drainage of coal mines

2020 ◽  
Vol 38 (9-10) ◽  
pp. 393-412
Author(s):  
Yingchun Fan ◽  
Botao Qin ◽  
Qun Zhou ◽  
Quanlin Shi ◽  
Dong Ma ◽  
...  
Keyword(s):  
Phase Transition ◽  
Coal Seam ◽  
Gas Permeability ◽  
Coal Mines ◽  
Control Unit ◽  
Maximum Energy ◽  
Gas Drainage ◽  
Technical Parameters ◽  
Airtight Container ◽  
Influence Radius

Liquid CO2 phase transition fracturing (LCO2-PTF) is an effective and economical technology used to improve the permeability of rock and coal. In this study, the working mechanisms of LCO2-PTF were analysed and relevant equipment was designed to develop and promote the application of this technology. It utilized phase transition equipment (PTE) consisting of a liquid gas container, control unit for the current and gas volume, heating tube, and other components. LCO2 blasting experiments were conducted in an airtight container to investigate the released energy, pressure, and other technical parameters. The application of LCO2-PTF for enhancing gas drainage in coal mines was then evaluated. The results of a blasting experiment showed a maximum energy of 947.12 kJ and revealed that the releasing pressure could be easily changed by varying the plate and heat tube. The releasing pressure remained unchanged within an initial distance and then decreased exponentially. The blasting products were gaseous CO2 and water vapor, with no sparks or flames. The surface temperature of the PTE ranged from 269.32 to 277.96 K. Application of LCO2-PTF in coal mines with low permeability showed gas drainage 3.38 times higher than that achieved with conventional technologies, with methane concentration increasing from 55 to 89%. The attenuation coefficient of gas emissions dropped by 94% and the gas permeability coefficient of the coal body increased more than 23 times after fracturing. The shockwave of the high-pressure gas promoted the development and extension of cracks. The influence radius of the pre-cracking coal seam was 8.1 m, which is 6.75 times that of the original coal seam. The experimental results and the engineering applications indicate that LCO2-PTF is a safe and effective technology to enhance gas drainage in coal mines.

Sign in / Sign up

Export Citation Format

Share Document