Hydraulic fracturing control method of cut tight roof/top coal

Abstract

The invention relates to a hydraulic fracturing control method of cut tight roof / top coal. The method comprises the following steps: constructing two rows of fracturing drill holes at intervals in the roof / top coal above an open-off cut by a drilling machine to a set depth, wherein one row of fracturing drill holes is close to a main upper of the open-off cut while the other row is close to an auxiliary upper of the open-off cut; constructing a row of anchor cable drill holes to the roof / top coal at the left and right ends of the open-off cut, respectively; or constructing rows of fracturing drill holes in different directions in a measure lane of the roof above the open-off cut; carrying out hydraulic fracturing on the drill holes, so that one or more cracks are generated on a rock body in a given plane to split the rock stratum to blocks or layers in certain shapes and sizes so as to damage the integrity of the rock and reduce the strength of the rock. Therefore, pressure of the roof in a large area and sudden extrusion of accumulated gases in a worked out section in an early mining stage on a coal face are prevented, air leak on the coal face is reduced, and the safety is ensured. Meanwhile, caving of top coal can be improved. The method is simple, convenient to construct, safe and reliable and good in effect.

Description

technical field [0001] The invention relates to a roof hydraulic fracturing method, in particular to a method for controlling hydraulic fracturing of a hard roof / top coal with cut holes. Background technique [0002] In many mining areas in my country (such as Yulin Shendong mining area, Datong mining area, etc.), there are hard roofs with high strength, large thickness, strong integrity, and no joints and fissures that occur directly on the coal seam or on the thinner direct roof. Since the roof of the coal mining face is supported by anchor cables + anchor rods + reinforced steel strips, the support strength is high, resulting in the overhang area of ​​the roof of the coal mining face during the initial mining period reaching several thousand square meters When the roof collapses in a large area, it is easy to squeeze out the gas accumulated in the goaf suddenly, causing the gas to exceed the limit and affecting the safe production of the working face; the roof collapse in t...

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Problems solved by technology

[0002] In many mining areas in my country (such as Yulin Shendong mining area, Datong mining area, etc.), there are hard roofs with high strength, large thickness, strong integrity, and no joints and fissures that occur directly on the coal seam or on the thinner direct roof. Since the roof of the coal mining face is supported by anchor cables + anchor rods + reinforced steel strips, the support strength is high, resulting in the overhang area of ​​the roof of the coal mining face during the initial mining period reaching several thousand square meters When the roof collapses in a large area, it is easy to squeeze out the gas accumulated in the goaf suddenly, causing the gas to exceed the limit and affecting the safe production of the working face; the roof collapse in the goaf is not timely , it is easy to cause air leakage from the side of the work facing the goaf, forming a safety hazard

[0003] In many coal mines, the hard or "two hard" (hard coal seam, hard roof) extra-thick coal seams are mined by fully mechanized caving. The phenomenon of gas exceeding the limit during the initial pressurization has affected the safe and normal recovery of the working face

In view of the problem of gas exceeding the limit during the initial mining period, the reasons are: (1) The poor caving performance of the top coal in the initial mining resulted in a large amount of coal left in the goaf; Insufficient conduction in the empty area, and the drainage effect of the high roof pumping lane did not appear; (3) The working face was pressed for the first time, and the old roof collapsed in a large area, and the gas was released and squeezed out concentratedly, causing the gas to exceed the limit at the working face

[0004] The safety management of traditional blasting caving is complex, involving the management and transportation of explosives and detonators, and the "one shot, three inspections" and "three-person chain firing system" must be strictly implemented for blasting; practice has shown that large-scale blasting instantaneously produces a large amount of CO, etc. Harmful gas has a huge impact on mine ventilation safety management, forming a safety hazard; and the economic cost of blasting is high

For high-gas mines, blasting caving should not be used due to the hidden danger of gas explosion induced by blasting sparks.

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