CN108331609A - Bedding drilling, slotting, pressure relief and permeability increasing method - Google Patents

Abstract

The invention discloses a method for pressure relief and anti-reflection of bedding drilling slots, comprising the following steps: (1) according to the design requirements of bedding gas drainage drilling, using a high-pressure hydraulic slotting device to construct bedding gas drainage drilling , to form a drill hole; (2) Without retreating the drill, feed high-pressure water into the high-pressure hydraulic slotting device to perform rotary circular cutting on the coal body to form a disc-shaped slot; (3) After the disc-shaped slot is formed, retreat Drilling, without rotating the drill bit and drill pipe, radially cut the coal body to form radial slots; (4) Repeat steps (2) and (3) to form multiple disc-shaped slots in the same drill hole Groove and radial slit; (5) Repeat steps (1) to (4) to implement drilling and slit operations on other bedding holes respectively. The invention reduces the stress in the horizontal and vertical directions of the coal seam, improves the gas extraction concentration and flow rate in boreholes, and reduces the number of boreholes along the working face. The method is simple and easy to operate.

Description

The Method of Relieving Pressure and Increasing Permeability by Cutting Slits in Bedding Drilling

technical field

The invention relates to the technical field of gas drainage in coal mines, in particular to a method for pressure relief and permeability enhancement by slit drilling in bedding.

Background technique

Coal and gas outbursts and rock bursts in deep mining are very serious and common natural disasters that threaten the safe production of coal mines. According to incomplete statistics, gas dynamic disasters have occurred in more than 20 countries and regions. The total number of disasters is more than 50,000, and more than 35,000 people died. Among them, rock burst accidents are also increasing year by year. With the increase of mining depth, the gas pressure, gas content and ground stress of coal seams increase, and the outburst danger of outburst mines becomes more and more serious, which has become one of the main problems threatening the safe production of mining areas; in addition, the increase of mining depth, The increase of mine pressure will also bring problems such as rock burst and deep well geothermal.

Under the conditions of high-intensity development and mining in deep mines, dynamic disasters such as coal and gas outbursts and rock bursts may coexist in the same mine or in different areas of the coal seam. In order to improve the effect of pre-pumping gas and reduce the high ground stress, borehole drilling, deep hole controlled pre-splitting blasting, deep hole loosening blasting, high-pressure water jet reaming, hydraulic slits, hydraulic fracturing and composite measures were adopted for drilling along the bedding. Strengthen pressure relief and anti-reflection. Although these measures have achieved certain effects in improving the drainage rate of low-permeability and high-gas coal seams, there are obvious limitations. Some mines have adopted anti-permeability measures to induce accidents such as outbursts and tunnel collapses, and the effect is not good; in addition, continuous unloading of coal seams is not possible. It cannot fundamentally guarantee the safe and efficient production of the mining face.

Contents of the invention

In view of this, a method for pressure relief and anti-reflection of layer-by-layer drilling and slotting of the present invention overcomes the deficiencies in the prior art, and provides a continuous slotting method combining circumferential and radial hydraulic slotting, Realize the overall pressure relief and permeability enhancement of the coal seam in the coal mining face, reduce the number of drilling holes for gas drainage along the working face, reduce the vertical and horizontal stress levels of the coal seam, and ensure the safe and efficient recovery of the working face.

The method for pressure relief and anti-reflection of layer-by-layer drilling and slotting of the present invention comprises the following steps:

(1) According to the design requirements of bedding gas drainage boreholes, use high-pressure hydraulic slotting device to construct bedding gas drainage boreholes to form boreholes;

(2) Without retreating the drill, feed high-pressure water into the high-pressure hydraulic slotting device to perform rotary and circumferential cutting on the coal body to form disc-shaped slots;

(3) After the disc-shaped slit is formed, the drill is retracted, and the drill bit and the drill pipe are not rotated, and the coal body is radially cut to form a radial slit;

(4) Repeat step (2) and step (3), form a plurality of disk-shaped slits and radial slits in the same borehole, and terminate when apart from the opening point of the borehole 5-15m, complete a Group drilling slots along the bedding for pressure relief and anti-reflection work;

(5) Repeat steps (1) to (4) to perform drilling and slitting operations on other bedding boreholes respectively, so as to realize pressure relief and permeability enhancement of bedding boreholes in the mining face.

Further, in step (2), the radius of the disc-shaped slot formed is 2-3m, and the height is 40-100mm.

Further, in step (2), the following steps are specifically included when the coal body is rotated and circumferentially cut:

(2a) The high pressure water pressure is adjusted to 20-50MPa, and the cutting time is 5-10min to form a disc-shaped slot with a radius of 0.5-1m;

(2b) The high pressure water pressure is adjusted to 50-80MPa, and the slotting time is 3-5min to form a disc-shaped slot with a radius of 1-2m;

(2c) The high pressure water pressure is adjusted to 80-150MPa, and the slotting time is 1-3min to form a disc-shaped slot with a radius of 2-3m.

Further, in step (2), the drill rod and the drill bit of the high-pressure hydraulic seaming device keep rotating.

Further, the distance between adjacent disc-shaped slots is 1-6m.

Further, in step (3), the radius of the formed radial slot is 1-2m and the height is 30-80mm.

Further, in step (3), the drilling speed is 5-10min/m, and the high-pressure water pressure is maintained at 80-150MPa.

Further, in step (2), the drill rod moves back and forth during the process of retreating.

Furthermore, the rated pressure of the high-pressure hydraulic cutting device is 100-150 MPa, and the rated flow rate is 80-125 L/min.

Beneficial effects of the present invention:

The pressure relief and anti-reflection method of bed-by-bed drilling and slotting of the present invention does not return the drill after the bed-by-bed drilling is completed, and uses the ultra-high pressure hydraulic slotting device to rotate the circular cutting and step pressure to form disc-shaped slots, further retreating During the drilling process, the ultra-high pressure hydraulic slotting device is used without rotation and the drill is withdrawn at a slow speed of 5-10min/m to form radial cutting to form slots. Repeat the above steps until it is 5-15m away from the opening point, and the coal face coal is realized. Continuous and overall pressure relief and antireflection, which overcomes the shortcomings of the traditional method of bedding gas drainage drilling and segmental slotting with small range and discontinuous pressure relief and antireflection; the method of the present invention is simple, easy to operate, and has good drainage effect , which reduces the stress level of the coal body, and has a wide application value.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment:

Accompanying drawing 1 is the top view when the present invention is applied to drilling;

Accompanying drawing 2 is the left side view when the present invention is applied to drilling;

Accompanying drawing 3 is the schematic diagram of the slit operation of the borehole for bedding gas drainage of the present invention;

Accompanying drawing 4 is the schematic diagram of slotting and drilling layout of transportation trough and track trough in mining face.

Explanation of reference signs: 1—drilling hole; 2—disc-shaped slot; 3—radial slot; 4—coal body; 5—transportation slot; 6—track slot.

Detailed ways

As shown in the figure, the method for pressure relief and antireflection of layer-by-layer drilling and slotting in this embodiment includes the following steps:

(1) According to the design requirements of bedding gas drainage drilling, the bedding gas drainage drilling 1 is respectively constructed in the coal body 4 of the transportation trough 5 and the track trough 6 on the mining face, that is, the high-pressure hydraulic slotting device is used Construction bedding gas drainage borehole 1 is formed to form borehole 1; the length of the borehole is 80-180m; the high-pressure hydraulic slotting device can be the structure disclosed in CN 106150500 A, which will not be repeated here, and its rated pressure is 100- 150MPa, the rated flow rate is 80-125L/min.

(2) Without retreating the drill, feed high-pressure water into the high-pressure hydraulic cutting device to cut the coal body in a circular and circular direction to form a disc-shaped slot; the disc-shaped slot can reduce the stress in the horizontal direction of the coal seam and improve the air permeability of the coal seam ; The radius of the formed disc-shaped slot is 2-3m, and the height is 40-100mm. Specifically, the following steps are specifically included when the coal body is rotated and circumferentially cut: (2a) the high-pressure water pressure is adjusted to 20-50MPa, the cutting time is 5-10min, and a disc-shaped slot with a radius of 0.5-1m is formed; ( 2b) The high pressure water pressure is adjusted to 50-80MPa, and the slotting time is 3-5min to form a disc-shaped slot with a radius of 1-2m; (2c) The high-pressure water pressure is adjusted to 80-150MPa, and the slotting time is 1-3min , forming a disc-shaped slot with a radius of 2-3m. Moreover, during this process, the drill pipe and drill bit of the high-pressure hydraulic seaming device keep rotating, and the rotation of the drill pipe and drill bit ensures the smooth discharge of cuttings and avoids the phenomenon of drill sticking and pinching.

(3) After the disc-shaped slots are formed, the drill is retracted without rotating the drill bit and the drill pipe, and the radial slots are formed by cutting the coal body radially; the radial slots are equivalent to mining a layer of poles in the coal seam. The thin protective layer reduces the stress in the vertical direction of the coal seam and improves the gas permeability of the coal seam; the radial slot formed has a radius of 1-2m and a height of 30-80mm; the drilling speed is 5-10min/m, and the high-pressure water The pressure is kept at 80-150MPa; during this process, the drill pipe moves back and forth during the process of retreating to ensure the smooth discharge of cuttings in slotted slots, avoiding the occurrence of stuck and pinched drills.

(4) Repeat step (2) and step (3), form a plurality of disk-shaped slits and radial slits in the same borehole, and terminate when apart from the opening point of the borehole 5-15m, complete a Combine bedding drilling slots for pressure relief and antireflection; the distance between adjacent disc-shaped slots can be 1-6m; disc-shaped slots and radial slots are connected to each other in the bedding gas drainage drilling Coupling forms the overall pressure relief and permeability enhancement of the coal seam;

(5) Repeat steps (1) to (4) to perform drilling and slotting operations on other bedding boreholes respectively, so as to realize pressure relief and anti-reflection work of bedding boreholes of the entire coal body in the mining face; Design spacing construction.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (9)

1. A method for pressure relief and anti-reflection of bed-by-bed drilling slit, is characterized in that, comprises the following steps: (1) According to the design requirements of bedding gas drainage boreholes, use high-pressure hydraulic slotting device to construct bedding gas drainage boreholes to form boreholes; (2) Without retreating the drill, feed high-pressure water into the high-pressure hydraulic slotting device to perform rotary and circumferential cutting on the coal body to form disc-shaped slots; (3) After the disc-shaped slit is formed, the drill is retracted, and the drill bit and the drill pipe are not rotated, and the coal body is radially cut to form a radial slit; (4) Repeat step (2) and step (3), form a plurality of disk-shaped slits and radial slits in the same borehole, and terminate when apart from the opening point of the borehole 5-15m, complete a Group drilling slots along the bedding for pressure relief and anti-reflection work; (5) Repeat steps (1) to (4) to perform drilling and slitting operations on other bedding boreholes respectively, so as to realize pressure relief and permeability enhancement of bedding boreholes in the mining face. 2. The method for pressure relief and anti-reflection of layer-by-layer drilling slits according to claim 1, characterized in that: in step (2), the radius of the disc-shaped slit formed is 2-3m, and the height is 40-100mm. 3. The method according to claim 2, characterized in that, in step (2), when the coal body is rotated and circumferentially cut, it specifically comprises the following steps: (2a) The high pressure water pressure is adjusted to 20-50MPa, and the cutting time is 5-10min to form a disc-shaped slot with a radius of 0.5-1m; (2b) The high pressure water pressure is adjusted to 50-80MPa, and the slotting time is 3-5min to form a disc-shaped slot with a radius of 1-2m; (2c) The high pressure water pressure is adjusted to 80-150MPa, and the slotting time is 1-3min to form a disc-shaped slot with a radius of 2-3m. 4. The method for pressure relief and anti-reflection of bed-by-bed drilling and slotting according to claim 3, characterized in that: in step (2), the drill pipe and the drill bit of the high-pressure hydraulic slotting device keep rotating. 5 . The method for pressure relief and anti-reflection through bedding drilling slotting according to claim 3 , wherein the distance between adjacent disc-shaped slots is 1-6 m. 5 . 6. The method according to claim 3, characterized in that: in step (3), the radius of the formed radial slot is 1-2m, and the height is 30 -80mm. 7. The method according to claim 6, characterized in that: in step (3), the drilling speed is 5-10min/m, and the high-pressure water pressure is maintained at 80-150MPa . 8 . The method for pressure relief and antireflection of bedding drilling slotting according to claim 7 , characterized in that: in step (2), the drill pipe moves back and forth during the process of retreating. 9. The method according to claim 1, characterized in that: the rated pressure of the high-pressure hydraulic slotting device is 100-150 MPa, and the rated flow rate is 80-125 L/min.