Study on Key Parameters of Directional Long Borehole Layout in High‐Gas Working Face

Yan, Zhenguo; Wang, Yanping; Fan, Jingdao; Huang, Yuxin; He, Yanpeng

doi:10.1155/2021/5579967

Cited by 6 publications

(4 citation statements)

References 18 publications

(12 reference statements)

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“…The gas reserve law in coal mines in China shows the feature of three high (high plasticity structure of coal seam, high gas adsorption ability of coal seam, and high gas content of coal seam) and three low (low gas pressure of coal seam, low gas saturation of coal seam, and low rate of gas permeability of coal seam), which causes the effect of pre-mining gas extraction to be ineffective. Many scholars combine the development characteristics of mining-induced fissures with the migration law of pressure relief gas [6][7][8] and use high drainage roadways and high-level boreholes to extract pressure relief gas [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Application and Optimization of the Parameters of the High-Level Boreholes in Lateral High Drainage Roadway

et al. 2022

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The key parameters of high-level boreholes in high drainage roadways affect the gas treatment effect of the working face directly. Therefore, the layout parameters of high-level boreholes in the lateral high drainage roadway (LHDR) are determined and optimized as necessary. Based on the LHDR layout on the 2-603 working face of the Liyazhuang coal mine, the key technological requirements on high-level borehole parameters were analyzed and the distribution characteristics of the gas volume fraction in the coal roof were studied. The gas migration law in the mined-out areas was obtained and the layout locations of high-level boreholes were determined finally. The research demonstrates that the high-level boreholes lag the 2-603 working face distance and the position of the final borehole (the position of the final borehole in this paper refers to the distance between the final borehole and the roof) influence the stability of boreholes and the gas extraction effect. The distribution of the gas volume fraction from the intake airway to the return airway can be divided into the stable stage, slow growth stage, and fast growth stage. Influenced by the flow field in the mined-out areas, the mean volume fraction of the borehole-extracted gas has no obvious relationship with the gas volume fraction at the upper corner. According to the final optimization, the high-level borehole is determined as having a 15 m lag behind the working face and the position of the final borehole is 44 m away from the coal seam roof. These have been applied successfully in engineering practice.

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Section: Introductionmentioning

confidence: 99%

Application and Optimization of the Parameters of the High-Level Boreholes in Lateral High Drainage Roadway

et al. 2022

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“…Duan et al [17] determined the best drilling structure of the near-horizontal high directional long hole by analyzing the evolution process of the fracture in the mining area with the working face and achieved good results. Yan et al [18] proposed the optimization method and drilling method of directional long borehole arrangement in the surrounding rock based on the law of coalbed methane transport during the directional long borehole arrangement. Duan et al [19] analyzed the effect of locating directional drilling on the effectiveness of gas extraction from different layers and obtained the optimal location for different distance and height zones.…”

Section: Introductionmentioning

confidence: 99%

Determination and Application of Reasonable Levels for Highly Directional Long Boreholes in Deep Outburst Coal Seams

Zhang¹,

Zhang

Wang

et al. 2022

Geofluids

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In order to solve the problem that the gas in the upper corner is easy to exceed the limit in the mining process of the deep outburst coal seam. Based on the theory of “O-ring” and the distribution of stratigraphy in the field, the development law of mining fissures in the overlying rock layer during the workface retrieval was studied by combining theoretical calculation and FLAC3D numerical modeling. The research results show that the range of fissure development zone in 2913 working face is 14.2 to 33 m from the coal seam roof, and the high drilling arrangement can be in the stable rock layer of the roof. For siltstone-fine sandstone interaction stratum, measures such as opening branches to adjust the layer and lowering the casing to protect the hole wall can be taken to ensure the stability of the borehole and the smooth flow of gas extraction channels. Field application shows that the high directional long borehole has the advantages of long extension distance and wide coverage, the average value of extraction mix is 34.3 m3/min, and the average value of extraction pure is 0.4 mm3/min, which helps to prevent the gas overlimit in the upper corner during the workface recovery. The high directional long borehole has obvious economic and safety benefits over the traditional high hole and has important promotion value in coal mine gas management.

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“…Based on the selection of reasonable parameters of gas extraction borehole, through the study of overburden development, breakage distance, 'O' circle and other factors, and the upper corner gas concentration, extraction concentration and other indicators [13][14][15], many scholars at home and abroad have proposed the corresponding methods. An, FH [16] et al conducted a study on directional borehole for gas extraction from the upper and lower adjacent layers, which broadened the scope of application of directional borehole.…”

Section: Introductionmentioning

confidence: 99%

Determination of Gas Extraction Borehole Parameters in Fractured Zone on ‘Borehole in Place of Roadway’ Based on RSM-GRA-GA

et al. 2022

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Large-diameter gas extraction borehole is considered an effective method by which to realize coal mine methane exploitation and outburst prevention. Efficient gas extraction can be achieved by selecting the right borehole parameters. In this paper, by comparing several conventional objective weighting methods, the PCA was used to assign the weights to the research indices, the optimization objective was reduced from multi-dimensional to one-dimensional with the help of the gray correlation analysis. The study of gas extraction effect under different borehole parameters based on the response surface model. Numerical simulations were used to analyze the mixed volume of gas extraction, the pure volume of extraction and the concentration in the upper corner after extraction under different schemes. Finally, a genetic algorithm degree model was used to solve the solution and determine the optimal arrangement of borehole parameters. The study shows that (1) the weight shares of borehole stratum, borehole diameter and borehole spacing were 0.385, 0.285 and 0.33, respectively, in the reduced dimensional analysis of the PCA. (2) Using the results of improved gray correlation analysis as a comprehensive evaluation value to measure the effect of gas extraction, the optimal range of the model was 28–30 m borehole level, 190–210 mm borehole diameter and 5.5–6.5 m borehole spacing. (3) Using the genetic algorithm to solve the model, we obtained the borehole layer 28.79 m, borehole diameter 199.89 mm, borehole spacing 5.76 m. The borehole gas extraction effect was good under this parameter. The extraction mixed volume was 129.8 m3/min, the extraction pure volume was 9.16 m3/min, the upper corner concentration was 0.52%, and the prediction accuracy of the model was 97.8%.

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Study on Key Parameters of Directional Long Borehole Layout in High‐Gas Working Face

Cited by 6 publications

References 18 publications

Application and Optimization of the Parameters of the High-Level Boreholes in Lateral High Drainage Roadway

Application and Optimization of the Parameters of the High-Level Boreholes in Lateral High Drainage Roadway

Determination and Application of Reasonable Levels for Highly Directional Long Boreholes in Deep Outburst Coal Seams

Determination of Gas Extraction Borehole Parameters in Fractured Zone on ‘Borehole in Place of Roadway’ Based on RSM-GRA-GA

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