Coal seam reaming system using three-dimensional (3D) swirling water jet and reaming and fracturing method for permeability enhancement

Abstract

The invention relates to coalmine gas extraction and permeability enhancement equipment and technology, and discloses a coal seam reaming system using three-dimensional (3D) swirling water jet. The system is connected to a high-pressure rotary joint through a high-pressure hose provided with a stop valve by virtue of a high-pressure hydraulic pump station and is characterized by being connected to a high-pressure water jet drill stem through a drilling machine, wherein the front end of the high-pressure water jet drill stem is connected with a high-pressure water jet head with nozzle bases; and high-pressure swirling water jet nozzles are arranged on the nozzle bases. The invention further discloses a coal seam reaming and fracturing method for permeability enhancement using the 3D swirling water jet. In the coal seam reaming method using the 3D swirling water jet, coal is sheared so as to lower the hydraulic pressure loss, improve the cutting efficiency and increase the cracks and bore diameter of the coal; high-pressure water is injected so as to fracture the coal between a hydraulic reamed hole and control bored holes; and a coal seam is fully depressurized within a large range so as to shorten the pre-extraction time of the coal seam.

Description

technical field [0001] The invention relates to coal mine gas drainage anti-reflection equipment, in particular to a three-dimensional rotating water jet coal seam reaming system, and also to coal mine gas drainage technology, in particular to a method for comprehensively increasing coal seam air permeability through hydraulic reaming and fracturing. Background technique [0002] Due to the difficulty of pre-pumping the gas in high gas and low permeability coal seams, a large amount of gas gushes out during the mining operation of high gas and coal and gas outburst mines, which easily causes the gas in the working face to exceed the limit, and even induces coal and gas outburst ACCIDENT. With the development of high-efficiency and intensive coal production and the continuous increase of mining depth, this problem has increasingly restricted coal mine safety production. In the coal and gas outburst mines that do not have the protection layer mining conditions, the pre-extrac...

AI Technical Summary

Problems solved by technology

However, most of these methods have problems such as large amount of drilling construction, small effective range of influence, and long extraction time.

Although the high-pressure hydraulic reaming and slotting techniques have increased the pressure relief range of the coal body around the borehole and the area affected by drainage to a certain extent, they are only limited to one borehole to increase the area affected by drainage, and the increase is not large enough. This affects the application of hydraulic reaming and slotting technology in the drainage of interbedded boreholes

In addition to increasing the diameter of the drill bit, most of the commonly used reaming methods are realized by cutting the coal body with a circular jet generated by an automatic rotating nozzle. This jet method has the disadvantages of large water pressure loss, low cutting efficiency, and difficulty in slag removal. , It takes a long time to expand the hole and other disadvantages. When the hole is blocked, it is easy to cause the pressure in the hole to increase and cause the nozzle hole, which has certain safety hazards.

Hydraulic fracturing technology can realize the pressure relief of the coal seam within a certain range around the borehole, but at the same time, it produces high stress concentration, and the concentrated stress can reach 3 to 4 times the original stress, which has caused new problems for coal mine safety production. obstacle

In addition, due to the complex structure of outburst coal seams, soft coal quality, and large ground stress, it is often difficult to control the direction of fracturing, and it is difficult to remove the fracturing fluid after it is immersed in the coal body, and the formed coal seam fissures are quickly closed, which limits the wide application of this technology

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