Crossing hole mesh slotting and permeability increasing method

Abstract

The invention relates to a crossing hole mesh slotting and permeability increasing method. The method includes the following steps of S1, constructing crossing holes by a design depth in a to-be-excavated or to-be-mined working face by means of a drilling machine; S2, retreating a drilling stem, assembling a self-advancing type high-pressure hose in the drilled hole, introducing medium-pressure water in the self-advancing type high-pressure hose, bending the self-advancing type high-pressure hose by 90 degrees when the self-advancing type high-pressure hose advances to a designated position ofthe crossing holes, and constructing along-coal-seam drill holes distributed in the radial direction of the crossing holes around the crossing holes; S3, introducing high-pressure water into the self-advancing type high-pressure hose in the retreating process of the self-advancing type high-pressure hose after the along-coal-seam drill holes are constructed to cut a coal body around the along-coal-seam drill holes so as to generate a radial crack; S4, repeating the steps S2 and S3 to complete the mesh slotting and permeability of the crossing holes. The method is simple and convenient to operate and has wide application and popularization value, the effective influence range of the crossing holes is enlarged, the gas drainage rate is increased, the number of the crossing holes is greatlyreduced, and economic benefits are improved.

Description

technical field [0001] The invention relates to the technical field of gas drainage in coal mines, in particular to a method for increasing permeability through layer-penetrating drilling network slits. Background technique [0002] At home and abroad, the outburst prevention measures for outburst coal seam areas are mainly mining of protective layers, large-scale pre-pumping of coal seam gas, etc. Some seriously outburst mines even exploit soft rock as a protective layer for regional outburst prevention, which greatly reduces or eliminates outburst risks. For coal roadway excavation where the protective layer is the outburst coal seam when a single outburst coal seam or coal seam group is mined, the regional prevention of gas in the area to be excavated is carried out by drilling along the bedding or by using the bottom (top) slate roadway to construct the through-bed drilling and pre-extracting the coal roadway. For outburst measures, the bottom (top) slate roadway is gene...

AI Technical Summary

Problems solved by technology

The following problems exist in the pre-extraction drilling of gas in coal roadway strips: the range of pressure relief is small, and the effective radius of influence is generally less than 2.5m; the drilling volume is large and the efficiency is low, and each trench to be excavated generally requires thousands of drills Holes, such as the Huainan Mining Group stipulates that the gas pre-drainage drilling holes in the coal roadway strips should be less than 2MPa and the gas content should be less than 8m 3 / t, according to the arrangement within 10m×5m spacing of the final coal point (axis direction×axis vertical direction), gas pressure ≥ 2MPa or gas content ≥ 8m 3 / t, arranged within 5m×5m spacing of the final coal point

Although these measures have achieved certain effects in improving the recovery rate of low-permeability and high-gas coal seams, there are obvious limitations, such as the small pressure relief range of drilling holes, limited reduction in drilling engineering, and insignificant engineering benefits

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