CN111734346A

CN111734346A - Magnetorheological hole protection method for long coal seam drilled hole

Info

Publication number: CN111734346A
Application number: CN202010659108.7A
Authority: CN
Inventors: 胡千庭; 李全贵; 宋明洋; 梁运培; 邹全乐; 罗永江; 姜志忠; 胡良平; 毛树人; 张跃兵; 武晓斌; 邓羿泽
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2020-07-09
Filing date: 2020-07-09
Publication date: 2020-10-02
Anticipated expiration: 2040-07-09
Also published as: CN111734346B

Abstract

The invention discloses a magnetorheological hole protection method for long coal seam drilled holes, which is suitable for protecting the drilled holes of a soft coal seam, avoiding hole collapse of the drilled holes and prolonging the service life of a single drilled hole. Firstly, drilling a through layer of a coal seam by using a roadway side, normally drilling, and pulling out a drill rod to form a hole; inserting a working pipe and a passage pipe into the hole, injecting magnetorheological fluid into the long drill hole through the working pipe, closing a valve of the passage pipe, penetrating part of surrounding rock around the hole by the magnetorheological fluid, and then discharging redundant magnetorheological fluid; the series permanent magnet rods are inserted into the long drill holes from the passage pipe, the stable magnetic field is established in the surrounding rock to solidify the magnetorheological fluid, the long drill holes are normally used, after the long drill holes are used, the series permanent magnet rods are drawn out, the surrounding rock is restored to the original shape, effective protection can be provided for the long drill holes of the soft coal seam, and the permanent magnet rods can be repeatedly used.

Description

Magnetorheological hole protection method for long coal seam drilled hole

Technical Field

The invention belongs to the technical field of coal mine safety, and particularly relates to a magnetorheological hole protection method for coal seam drilling.

Background

The coal bed in China has complex geological conditions and the soft coal bed is generally developed. The mining difficulty of a soft coal seam of a coal mine is high, factors such as gas disasters, rib caving and coal dust restrict the mining efficiency of the soft coal seam, so that the coal seam needs to be modified, wherein drilling holes are drilled in the coal seam most commonly, and measures are taken. The coal seam long drill hole can effectively relieve pressure and increase permeability of the coal seam, the drilling efficiency is high, and the gas extraction quantity is concentrated, the extraction efficiency is high and the attenuation period is long in the gas extraction project.

The existing protection method for long coal seam drilling mainly depends on the stability of rock surrounding a drilling hole, a method for supporting soft coal drilling by using a mechanical structure of a lower casing pipe and improving a drilling process, and the service time of the drilling is prolonged as much as possible. The methods have the problems that the hole protection effect is uncertain, the pipe body is disconnected and left in a coal seam or the structure is complex, the realization is difficult, and the economic cost is high.

Magnetorheological fluids are suspensions of micrometer-sized, magnetically polarized particles dispersed in a non-magnetic liquid (mineral oil, silicone oil, etc.). Under the condition of zero magnetic field, the magnetorheological fluid is liquid with good fluidity and small apparent viscosity; under the action of strong magnetic field, the apparent viscosity can be increased by more than two orders of magnitude in a short time (millisecond level), and the solid-like characteristic is presented; moreover, the change is continuous and reversible, namely, the magnetic field is removed and the original state is recovered. The invention solves the problem of hole protection of long drilling holes of the coal seam by utilizing the physical phenomenon of magnetic rheology.

A long borehole as referred to herein is a borehole having a length of more than 500 m.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to solve the technical problem of providing a magnetorheological hole protection method for long coal seam drilled holes, which protects the long drilled holes in the coal seam by changing external conditions, avoids the problems of drill jamming and screen pipe lowering caused by hole collapse and hole collapse of the drilled holes and is beneficial to long drilling engineering implementation.

The technical problem to be solved by the invention is realized by the technical scheme, which comprises the following steps:

step 1, drilling a long drill hole on a coal seam by a roadway side, inserting a working pipe and a passage pipe after the drill hole is finished, grouting and sealing holes in an orifice of the long drill hole, connecting the outer section of the passage pipe with a bent pipe, and arranging a valve on the bent pipe;

step 2, injecting magnetorheological fluid into the long drill hole through the working pipe, closing a valve of the access pipe, maintaining for at least 30min after the injection pressure is increased and exceeds 10MPa, partially permeating the magnetorheological fluid into the periphery of the long drill hole of the coal seam, and then discharging redundant magnetorheological fluid through the access pipe;

step 3, detaching the bent pipe, inserting the series permanent magnet rod into the long drill hole from the passage pipe, reinstalling the bent pipe, closing the valve and closing the passage pipe;

and 4, transforming and constructing the coal bed by using the working pipe through long drilling holes, and drawing out the series permanent magnet rods after construction is finished so as to be used for the next time.

As the magnetorheological fluid permeates into the surrounding rock around the long drill hole, the magnetorheological fluid is converted into solid by applying a magnetic field through the series permanent magnet rods, the long drill hole surrounding rock is solidified, and the long drill hole is normally used; and after the long drilling is finished, the series permanent magnet rods are drawn out, and the surrounding rock is restored to the original form.

Compared with the prior art, the invention has the technical effects that: the method is simple to use, can controllably protect the long drilling hole, and the permanent magnet rod material can be repeatedly used, so that a new technical idea is provided for protecting the long drilling hole of the coal seam.

Drawings

The drawings of the invention are illustrated as follows:

FIG. 1 is a layout diagram of one embodiment of the present invention;

fig. 2 is a schematic structural diagram of a single permanent magnet rod in the method.

In the figure: 1. a coal seam; 2. permanent magnet rods are connected in series; 3. a valve; 4. a working pipe; 5. sealing holes; 6. a passage tube; 7. long drilling; 8. bending the pipe; 201. a permanent magnet bar; 202. a strong permanent magnet; 203. a pin.

Detailed Description

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

as shown in fig. 1, the present embodiment includes the following steps:

step 1, drilling a long drilling hole 7 from a roadway side to a coal seam 1, inserting a working pipe 4 and a passage pipe 6 after drilling is completed, grouting a hole opening of the long drilling hole 7 for hole sealing 5, wherein the length of the passage pipe 6 is longer than that of the hole sealing 5 by 20cm, the passage pipe 6 is kept smooth in the construction process, and the passage pipe 6 is prevented from being blocked in hole sealing construction; the outer section of the passage pipe 6 is connected with a bent pipe 8, and a valve 3 is arranged on the bent pipe. The lane side refers to a side wall of a roadway and comprises a lane side of a coal seam roadway or a floor roadway.

The working pipe 4 is used for model selection according to specific long drilling hole reconstruction coal seam engineering and can be a gas extraction sieve pipe, a coal seam water injection pipe or the like. The compressive strength of the elbow 8 and the valve 3 reaches 15 MPa.

And 2, injecting magnetorheological fluid into the long drill hole 7 through the working pipe 4, closing the access pipe valve 3, maintaining for 30min after the injection pressure is increased and exceeds 10MPa, partially permeating the magnetorheological fluid into the periphery of the coal seam long drill hole, and then discharging redundant magnetorheological fluid through the access pipe 6.

The magnetic rheological liquid is prepared by dispersing carboxyl iron powder particles in mineral oil, and mixing with water.

And 3, detaching the bent pipe 8, inserting the series permanent magnet rod 2 into the long drilled hole 7 from the passage pipe 6, reassembling the bent pipe 8, closing the valve 3 and closing the passage pipe 6.

As shown in fig. 1 and 2, the series permanent magnet rod 2 is formed by connecting a plurality of sections of permanent magnet rods 201 through pins 203, and the pin connection positions can freely rotate; the permanent magnet pole 201 is a cuboid rod-shaped structure, a strong permanent magnet 202 is embedded in the pole body of the permanent magnet pole 201, one end of the permanent magnet pole 201 is a round-head thin slice, the other end of the permanent magnet pole is a jaw arc-shaped slice, pin holes are formed in the round-head thin slice and the jaw arc-shaped slice, and the round-head thin slice of the previous permanent magnet pole and the jaw arc-shaped slice of the next permanent magnet pole are connected through a pin 203 and are repeated in sequence.

The total length of the permanent magnet rod is 50cm, the lengths of the round head thin sheet and the jaw arc sheet are both 5cm, and the length of the strong permanent magnet is 30cm and is positioned in the middle of the rod body.

And 4, performing transformation construction on the coal seam 1 through the long drill holes 7 by using the working pipe 4, wherein the transformation construction mainly comprises coal seam transformation such as gas extraction and coal seam permeability increase by hydraulic fracturing, wherein protected drill holes are used for gas extraction in most cases, and the series permanent magnet rods 2 are extracted after the construction is finished for the next use.

Claims

1. A magnetorheological hole protection method for long coal seam drilled holes is characterized by comprising the following steps:

step 1, drilling a long drill hole (7) from a roadway side to a coal seam (1), inserting a working pipe (4) and a passage pipe (6) after drilling is finished, grouting and sealing holes (5) at an orifice of the long drill hole (7), connecting an outer section of the passage pipe (6) with an elbow (8), and arranging a valve (3) on the elbow;

step 2, injecting magnetorheological fluid into the long drill hole (7) through the working pipe (4), closing the access pipe valve (3), maintaining for at least 30min after the injection pressure is increased and exceeds 10MPa, partially permeating the magnetorheological fluid into the periphery of the long drill hole of the coal seam, and then discharging the redundant magnetorheological fluid through the access pipe (6);

step 3, unloading the bent pipe (8), inserting the series permanent magnet rod (2) into the long drill hole (7) from the passage pipe (6), reinstalling the bent pipe (8), closing the valve (3) and closing the passage pipe (6);

and 4, transforming and constructing the coal seam (1) by using the working pipe (4) through the long drilling hole (7), and drawing out the series permanent magnet rod (2) after construction is finished so as to be used for the next time.

2. The magnetorheological hole protection method for the long drilled holes in the coal seam according to claim 1, which is characterized in that: the magnetorheological fluid is prepared by uniformly dispersing carboxyl iron powder particles in mineral oil, and adding water for mixing.

3. The magnetorheological hole protection method for the long drilled holes in the coal seam according to claim 1, which is characterized in that: the length of the passage pipe (6) is longer than that of the hole sealing pipe (5) by 20cm, and the working pipe (4) is a gas extraction sieve pipe or a coal seam water injection pipe.

4. The magnetorheological hole protection method for the long drilled holes in the coal seam according to claim 1, which is characterized in that: the compressive strength of the elbow (8) and the valve (3) reaches 15 MPa.

5. The magnetorheological hole protection method for the coal seam long drilled hole according to the claim 1, the claim 2, the claim 3 or the claim 4, which is characterized in that: the series permanent magnet rods (2) are formed by connecting a plurality of sections of permanent magnet rods (201) through pins (203), and the pin connecting positions can freely rotate; the permanent magnet rod (201) is of a cuboid rod-shaped structure, a strong permanent magnet (202) is embedded in a rod body of the permanent magnet rod (201), one end of the permanent magnet rod (201) is a round-head thin sheet, the other end of the permanent magnet rod is a jaw arc sheet, and pin holes are formed in the round-head thin sheet and the jaw arc sheet.

6. The magnetorheological hole protection method for the long drilled holes in the coal seam according to claim 4, which is characterized in that: the total length of the permanent magnet rod (201) is 50cm, the lengths of the round head thin sheet and the jaw arc sheet are both 5cm, and the length of the strong permanent magnet is 30cm and is positioned in the middle of the rod body.