Research on Gas Extraction Technology of Directional Long Borehole in Ultrathick Coal Seam

Li, Yaobin; Jiang, Tao; Guo, Xin

doi:10.1155/2022/6957896

Cited by 5 publications

(3 citation statements)

References 2 publications

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“…At present, various technologies are used to address high gas and low permeability coal seams, including mining protective layers [14,15], hydraulic slotting [16,17], hydraulic 2 of 19 fracturing [18][19][20][21], hydraulic punching [22,23], and intensive gas drainage drilling [24]. Protective layer mining is currently the most effective method to prevent coal and gas outbursts, which has been successful in field practice [15,25].…”

Section: Introductionmentioning

confidence: 99%

Double Unloading Gas Control Technology for Fracturing Soft Coal Seams in Overlying Key Strata

Xie,

Li,

Yan

et al. 2024

Applied Sciences

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Based on the ‘three highs and one low’ geological conditions of high gas pressure, high gas content, high ground stress, and low permeability in deep coal seams, this study proposes a dual method of hydraulic fracturing of key layers of overlying rock layers combined with pre-extraction of gas via large-diameter caving boreholes. The aim is to unload and dissipate the coal seam by fracturing the overlying key strata, allowing the stress and energy from the excavation working face to be transmitted and transferred to the deep coal seam. Additionally, large-diameter drilling effectively increases the effective drainage radius of the coal seam, resulting in a shorter extraction time. To validate this approach, a fracturing model and a gas extraction model were established for the key layers of the overlying rock layer using the engineering background of the 15,111 excavation working face of a mine in Shanxi. FLAC3D software v.6.0 was utilized to simulate the stress and energy changes of the coal seam before and after fracturing of the key layers, while COMSOL software v.6.0 was used to analyze the gas migration conditions, permeability, and effective drainage radius changes before and after drilling and caving drilling. The findings, combined with the engineering test results, conclude that key strata fracturing combined with large-diameter caving can effectively increase the permeability of coal seams and improve gas extraction. This study serves as a theoretical basis for guiding the design of gas drainage technology under the effects of coal seam pressure relief and permeability enhancement.

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Section: Introductionmentioning

confidence: 99%

Double Unloading Gas Control Technology for Fracturing Soft Coal Seams in Overlying Key Strata

Xie,

Li,

Yan

et al. 2024

Applied Sciences

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“…Aiming at the problem of gas control in the U-type ventilation working face of high-gas mines, Gao Hong et al [4][5][6] proposed a gas drainage technique combining a high-level suction roadway and a bottom-level suction roadway, which reduced the gas gushing to the working face. Li Jianwei, Gu Wangxin, et al [7,8] studied the distribution rules of plastic zones around boreholes with different apertures, which provided a basis for the selection of borehole diameters for gas drainage. Thanh et al [9][10][11][12][13][14] used different models to predict the CO 2 trapping index of deep saline aquifers and found that the developed models obtained excellent predictive performance.…”

Section: Introductionmentioning

confidence: 99%

Research on Gas Control Technology of “U+ Omni-Directional Roof to Large-Diameter High-Level Drilling Hole” at the End Mining Face of Multi-Source Goaf

Hong

Lei²

2023

Processes

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Aiming at the gas over-run problem in the upper corner of the “U-type ventilation” end-mining working face in the multi-source goaf of the #15 coal seam in the Phoenix Mountain Mine, site survey and numerical simulation methods were adopted, which showed that the maximum caving zone height of the #15 coal seam is 14.87 m, and the maximum height of the fissure zone is 51.63 m. On this basis, the gas control scheme of the “U+ omni-directional large-diameter high-level borehole along roof strike” in the end-mining working face was formulated. After adopting this scheme, the extracted gas concentration of each borehole will reach 5–20%, the gas extraction flow rate will reach 1 m3/min–2.5 m3/min, the gas concentration at the upper corner of the working face will be controlled below 0.54%, and the gas concentration in the return airway will be controlled below 0.35%, achieving the expected effect of gas control.

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“…In recent years, many researchers have conducted a lot of research on gas extraction technology. Li et al [12] numerically simulated the effect of different extraction parameters on directional drilling and showed through field tests that directional drilling is better than conventional drilling in operation. Qin et al, Shi et al, used the directional long borehole technique for deep coal seam gas extraction and achieved good results.…”

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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Research on Gas Extraction Technology of Directional Long Borehole in Ultrathick Coal Seam

Cited by 5 publications

References 2 publications

Double Unloading Gas Control Technology for Fracturing Soft Coal Seams in Overlying Key Strata

Double Unloading Gas Control Technology for Fracturing Soft Coal Seams in Overlying Key Strata

Research on Gas Control Technology of “U+ Omni-Directional Roof to Large-Diameter High-Level Drilling Hole” at the End Mining Face of Multi-Source Goaf

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

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