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Coal Engineering ›› 2023, Vol. 55 ›› Issue (7): 72-77.doi: 10.11799/ce202307012

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Gas drainage technology through long borehole segmented hydraulic fracturing in the medium-hard coal seam of Binchang mining area

  

  • Received:2022-04-25 Revised:2022-10-02 Online:2023-07-20 Published:2025-04-07

Abstract:

Taking No. 4 coal seam in the Binchang mining area as the research object, aiming at the problems existing in the construction process of long borehole segmented hydraulic fracturing in the medium-hard coal seam, such as long construction period, high accident rate, high risk, and poor economy, this paper uses the methods of experimental analysis, numerical simulation and system process optimization to study the new restrictor suitable for segmented fracturing in No. 4 coal seam, as well as the reasonable pump pressure. The improved fracturing technology was used to complete the hydraulic fracturing construction of 3 boreholes over 500m with a total of 22 sections. The range of pumping pressure is 7.56~9.70MPa with discharge volumes of 18.63~22.11m3/h, and all without accidents in the borehole. After the improvement, the duration of single hole hydraulic fracturing is reduced from 12 days to 7 ~ 8 days, the initial gas drainage volume of fracturing borehole is 1.29 and 1.38 times that of conventional mode, and the attenuation coefficient of gas drainage volume is reduced to 9.1% and 6.8% of conventional mode. The gas drainage effect of fracturing borehole has been greatly improved. The research results provide a new technical way for high-efficiency gas drainage in long directional drilling areas of the medium-hard coal seams.

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