Method for treating hard roof through hydraulic fracturing

Abstract

The invention discloses a method for treating a hard roof through hydraulic fracturing. The method comprises the following steps: (1) determining a stress state of the hard roof to be fractured; (2) selecting corresponding two different fracturing schemes according to the obtained stress state; (3) selecting drilling positions and drilling parameters and constructing fracturing drill holes; (4) carrying out hydraulic fracturing on the hard roof. The method has the advantage that the corresponding two different fracturing schemes can be adopted in accordance with the physical circumstance that terrestrial stresses are different. Compared with the former fracturing methods, the method has the advantages that the consideration is more comprehensive, the selection of fracturing methods is more flexible, the fracturing operation is more target-oriented, the forming of fractured cracks, which are beneficial to the weakening of hard roofs covering coal beds, is better facilitated, thus, the hard roofs are weakened, finally, the timely fracture of the hard roofs is achieved, the step pitch of roof weighting is shortened, the appearance of high mineral pressure of a working face is reduced, and the underground safe production of coal mines is facilitated.

Description

technical field [0001] The invention relates to a hard roof treatment technology, in particular to a method for hydraulic fracturing treatment of a hard roof. Background technique [0002] my country is rich in coal resources, and the conditions of coal seam occurrence are relatively complicated. The coal seams with hard roofs account for about one-third of the national coal mines, and they are distributed in more than 50% of the mining areas, such as Shanxi Datong mining area, Yangfangkou mining area, and Jincheng mining area; Beijing Chengzi Mine; Sichuan Tianchi Coal Mine; and Zaozhuang, Tonghua, Hegang, Shenfu, Dongsheng and other coal fields all have hard roofs. The hard roof is often difficult to fall during the mining process, resulting in a large area of ​​suspension, and it is easy to accumulate a large amount of energy to cause excessive stress concentration, which can easily lead to the appearance of strong mine pressure and impact rock pressure. Once it suddenly c...

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Problems solved by technology

Among them, the support method is a traditional passive method of supporting the hard roof, which cannot fundamentally control the hard roof, and can only prevent the sudden fall of the hard roof from the perspective of supporting the hard roof; the blasting method can cause the roof to break and collapse. Eliminate stress concentration and release the elastic energy accumulated on the roof, thereby reducing the possibility of rock burst and avoiding the hazards of large-area suspension of the hard roof. However, the blasting method has complicated construction procedures, high costs, pollutes the underground air, and may even cause gas explosions and coal It is unsafe due to gas outburst accidents; the water injection softening method is safer and can be operated in parallel underground, with little impact on production, but the simple water injection softening effect on sandstone or limestone that forms a hard roof is not obvious

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