CN109681262B - Method for improving gas drilling extraction concentration in broken coal body - Google Patents

Abstract

The invention discloses a method for improving the concentration of gas drilling in broken coal. The method firstly uses a small-diameter drill pipe to open holes to reduce coal fragmentation, and then uses liquid gel to make the gas around the drilled hole. The broken coal is condensed into one body, and then the large-diameter drill pipe is used to ream the hole. This method greatly reduces the generation of cracks around the hole and provides a basis for subsequent effective hole sealing; The fluid slurry is injected into the closed space formed by the sealing section, and the injected sealing slurry is always in a state of relatively constant pressure. Therefore, once new cracks appear around the borehole, the semi-fluid slurry can actively penetrate and automatically fill the cracks. , isolate the leakage channel, reduce the entry of air, thereby increasing the concentration of gas drainage.

Description

A method for improving gas drilling concentration in crushed coal

technical field

The invention relates to a method for gas drainage of coal body, in particular to a method for increasing the concentration of gas drilling in broken coal body, and belongs to the technical field of underground gas drainage.

Background technique

With the increase of coal mining depth, the gas problem of coal mines is becoming more and more serious, especially the gas control problem of high gas and low permeability coal seams, which has been seriously restricting the safe production of coal mines. Therefore, coal seam drilling gas drainage has been widely used as an important measure to prevent gas outburst, but in the process of gas drainage, there have always been various problems such as low drainage concentration, poor effect and short duration.

In order to improve the gas drainage effect of coal seam drilling, most outburst mines in my country use high negative pressure and large flow drainage systems, but this will inevitably lead to an increase in gas leakage and a decrease in gas drainage concentration, which not only does not shorten the effective gas drainage period , relieve the tension of mining replacement, but make the gas extraction concentration lower than 30% in the gas extraction pumping station, thus failing to meet the gas utilization conditions stipulated in the "Coal Mine Safety Regulations" and emptying the gas, which will have an impact on the environment.

In addition, the coal seam borehole is inevitably affected by various factors of in-situ stress during the coal seam borehole gas extraction, so that the fissures around the coal seam borehole continue to develop, and the outside air can easily enter the drainage from these fissures under the action of negative drainage pressure. The gas drainage concentration in the borehole decreases, which shortens the effective drainage period of the drainage hole and reduces the utilization rate of the drainage hole.

SUMMARY OF THE INVENTION

In order to overcome various deficiencies existing in the prior art, the present invention provides a method for increasing the concentration of gas drilling in broken coal, which can improve the drilling utilization rate and gas drainage concentration, and shorten the effective drainage period. It can alleviate the tension of excavation and replacement, and has the advantages of simple operation and low cost.

In order to achieve the above purpose of the invention, the present invention provides a method for improving the concentration of gas drilling in broken coal, comprising the following steps:

The first step is to use a drilling rig with a small diameter drill pipe to drill a gas drainage hole in the coal seam of the roadway according to the conventional drilling method. Then, the drainage hole will be preliminarily sealed, and the closed space formed by the hole will be filled with liquid. gel;

In the second step, when the liquid gel and the surrounding broken coal are tightly consolidated into one body, the drilling rig with a large diameter drill pipe is used to carry out reaming on the basis of the above-mentioned drilling;

The third step is to send the gas drainage pipe with the sealing device installed at both ends into the gas drainage hole, and the end of the gas drainage hole is located 1-2m behind the sealing section, and the gas drainage pipe is installed There are gas extraction valves; among them, a grouting pipe and a hydraulic gauge installation pipeline are installed on the left end hole sealer, a hydraulic pressure gauge is installed on the hydraulic gauge pipeline, a grouting pipe valve is installed on the grouting pipe, and the grouting pipe and The ends of the hydraulic gauge installation pipelines all lead to the inside of the sealing section of the gas drainage borehole;

Step 4: The hole sealers at both ends of the gas extraction pipe seal the holes again, so that the sealing section forms a sealed space, open the grouting pipe valve on the grouting pipe, and inject semi-fluid slurry into the sealing section until the hydraulic gauge shows When the number reaches the set stop grouting pressure value, close the grouting pipe valve;

The fifth step, when the hydraulic meter reading drops below the initial grouting pressure value, reopen the grouting pipe valve and inject semi-fluid slurry into the sealing section until the hydraulic meter reading reaches the set stop grouting pressure value; Repeat step 5 to ensure that the hydraulic pressure in the sealing section is always kept within a constant pressure range.

In this method, a small-diameter drill pipe is used to open holes to reduce coal fragmentation, and then liquid gel is used to condense the broken coal body around the drilled hole into a whole, and then a large-diameter drill pipe is used to ream the hole. This method greatly reduces the generation of cracks around the borehole and provides a basis for subsequent effective hole sealing; after the hole is sealed, the semi-fluid slurry is injected into the closed space formed by the sealing section with a certain pressure, and the injected hole sealing slurry is always in It is a relatively constant pressure state, so once a newly developed crack appears around the borehole, the semi-fluid slurry can actively infiltrate, automatically fill the crack, isolate the gas leakage channel, reduce the entry of air, and thus improve the gas drainage concentration.

Further, in the first step, the closed space formed by the drilled hole is filled with liquid gel at a pressure of not less than 1.5 MPa.

Further, in the fourth and fifth steps, the initial grouting pressure set by the hydraulic gauge is 0-2.5 MPa, and the stop grouting pressure is 3.5-4 MPa.

Further, the drilling rig for preliminary drilling in the first step uses a 30mm drill pipe; the drilling rig for reaming in the second step uses an 80mm drill pipe.

Further, the hole sealing device is a polyurethane sealing bag.

The liquid gel includes main material, auxiliary material and water, wherein the main material is a mixture of sodium bentonite and kaolin, and the auxiliary material is one or more mixtures of sodium tripolyphosphate, bandage and sodium chloride, and the main material is a mixture of sodium bentonite and kaolin. The mass ratio of raw materials plus auxiliary materials to water is 1:6 to 1:3.

The initial state of the liquid gel is a liquid flowing state, and it can form a solidified state at room temperature for a period of time, and has a certain adhesive force; sodium bentonite and kaolin can keep the slurry from running off, and have a certain lubricating effect, which is conducive to the penetration of the slurry. Filling cracks; excipients are easily complexed with metal ions to form soluble complexes, soften water, and have strong dispersing and suspending power for solid substances, thereby promoting the solidification of liquids, making fluid state liquid gel and broken coal. The body is tightly consolidated.

The semi-fluid slurry includes main material, auxiliary material and water, wherein the main material is a mixture of sodium bentonite and kaolin, and the auxiliary material is one or more of sodium silicate, lithium silicate, silicon dioxide and sodium chloride The mass ratio of the main material plus the auxiliary material to the water is 1:12 to 1:8.

The mixed semi-fluid slurry is a non-solidified, inorganic semi-fluid sealing slurry, and it will remain in a non-dehydrated state throughout the plugging period to maintain a certain fluidity; sodium-based bentonite and kaolin can keep the slurry from running off, And has a certain lubricating effect, which is conducive to the penetration of the slurry into the filling crack; the auxiliary material can keep the slurry to a certain degree of hydrophilicity; the cemented fluid will also play a certain elastic supporting role on the borehole wall, effectively improving the sealing section. It reduces the seepage flow of continuously acting hydrostatic water.

The invention firstly drills through a small-diameter drill pipe, and injects liquid gel into the sealing section to pretreat the crushing medium, so that the liquid gel and the crushed coal body are tightly consolidated, and then the large-diameter drill pipe is used to expand the hole, The cracks in the coal body are broken within a radius of 1m to reduce the generation of reaming and plug the borehole; then use a polyurethane sealing bag to seal the borehole, and inject semi-fluid slurry under a certain pressure to seal the hole. It is always in a state of relatively constant pressure, so once newly developed cracks appear around the borehole, the slurry liquid can actively infiltrate, automatically fill the cracks, isolate the gas leakage channel, reduce the entry of air, and thus improve the gas drainage concentration; and During the entire drainage process, the slurry in the sealing section is not dehydrated and remains in a semi-fluid state, so as to achieve a good sealing effect, realize dynamic sealing of new cracks in gas drainage holes, and greatly improve the gas drainage concentration.

Description of drawings

Fig. 1 is the schematic diagram of the implementation process of the present invention;

In the picture: 1. Gas drainage hole, 2. Sealing section, 3. Gas drainage pipe, 4. Grouting pipe, 5. Hole sealing device, 6. Hydraulic gauge, 7. Gas, 8. Semi-fluid slurry , 9, gas extraction valve, 10, grouting pipe valve, 11, liquid gel; 12, hydraulic gauge installation pipeline.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, a method for increasing the concentration of gas drilling in a broken coal body includes the following steps:

The first step is to use a drilling rig with a 30mm small diameter drill pipe to drill a gas extraction hole 1 in the roadway coal seam according to the conventional drilling method, and use a hole sealer 5 with a polyurethane sealing bag installed at both ends to perform preliminary sealing of the hole. A closed space is formed, and the closed space formed by the drilling is filled with liquid gel 11 at a pressure of not less than 1.5MPa;

Described liquid gel 11 comprises main material, auxiliary material and water, wherein main material is the mixture of sodium bentonite and kaolin, and auxiliary material is one or more mixtures in sodium tripolyphosphate, bandage, sodium chloride, The mass ratio of the main material plus the auxiliary material to the water is 1:6 to 1:3.

The initial state of the liquid gel is a liquid flowing state, and it can form a solidified state at room temperature for a period of time, and has a certain adhesive force; sodium bentonite and kaolin can keep the slurry from running off, and have a certain lubricating effect, which is conducive to the penetration of the slurry. Filling cracks; excipients are easily complexed with metal ions to form soluble complexes, soften water, and have strong dispersing and suspending forces for solid substances, thereby promoting the solidification of liquids, making fluid state liquid gel and drilling. The surrounding crushed coal is tightly consolidated.

The second step, about half a day later, when the liquid gel is tightly consolidated with the surrounding broken coal body, remove the hole sealer 5, and use a drilling rig with a large diameter drill pipe of 80mm to carry out reaming on the basis of the above drilling. ;

The third step is to send the gas drainage pipe 3 with the polyurethane sealing bags installed at both ends into the gas drainage hole 1, and the end of the gas drainage hole is located 1-2m behind the sealing section 2, and the gas drainage The gas extraction valve 10 is installed on the production pipe 3; wherein, the grouting pipe 4 and the hydraulic gauge installation pipeline 12 are simultaneously installed on the left end hole sealer, the hydraulic gauge 6 is installed on the hydraulic gauge pipeline 12, and the grouting pipe 4 A grouting pipe valve 10 is installed;

The fourth step, the polyurethane sealing bags at both ends of the gas extraction pipe 3 react and expand to seal the holes again, so that the sealing section 2 forms a sealed space, open the grouting pipe valve 10 on the grouting pipe 4, and inject into the sealing section 2 When the semi-fluid slurry 8 reaches the set stop grouting pressure value, close the grouting pipe valve 10;

The initial grouting pressure set by the hydraulic gauge 6 is 0-2.5MPa, and the stop grouting pressure is 3.5-4MPa.

The fifth step, when the reading of the hydraulic gauge 6 drops below the initial grouting pressure value, reopen the grouting pipe valve 10 and inject the semi-fluid slurry 8 into the sealing section 2 until the reading of the hydraulic gauge 6 reaches the set stop. Grouting pressure value; repeat step 5 to ensure that the hydraulic pressure in the sealing section 2 is always maintained within a constant pressure range.

Described semi-fluid slurry 8 comprises main material, auxiliary material and water, wherein main material is the mixture of sodium bentonite and kaolin, auxiliary material is one or both in sodium silicate, lithium silicate, silicon dioxide, sodium chloride For the above mixture, the mass ratio of the main material plus the auxiliary material to the water is 1:12 to 1:8.

The mixed semi-fluid slurry is a non-solidified, inorganic semi-fluid sealing slurry, and it will remain in a non-dehydrated state throughout the plugging period, thereby maintaining a certain fluidity; sodium-based bentonite and kaolin can keep the slurry from running off, And it has a certain lubricating effect, which is conducive to the penetration of the slurry into the filling cracks; the auxiliary materials can keep the slurry to a certain degree of hydrophilicity; the cemented fluid can also play a certain elastic supporting role on the borehole wall, effectively improving the sealing section. It reduces the seepage flow of continuously acting hydrostatic water.

Claims (5)

1. A method for improving the gas drilling extraction concentration in a broken coal body is characterized by comprising the following steps:

the method comprises the following steps of firstly, constructing a gas extraction drill hole (1) on a roadway coal seam by adopting a drilling machine with a small-diameter drill rod according to a conventional drilling method, then carrying out primary hole sealing on the gas extraction drill hole, filling a liquid gel (11) into a closed space formed by the gas extraction drill hole at a pressure of not less than 1.5MPa, wherein the liquid gel (11) comprises a main material, an auxiliary material and water, the main material is a mixture of sodium bentonite and kaolin, the auxiliary material is a mixture of one or more than two of sodium tripolyphosphate, sand stretching and sodium chloride, and the mass ratio of the mass of the main material and the auxiliary material to the mass of the water is 1: 6-1: 3;

secondly, when the liquid gel (11) is tightly and integrally solidified with the surrounding crushed coal body, reaming is carried out on the basis of the gas extraction drill hole (1) by utilizing a drilling machine with a large-diameter drill rod;

thirdly, sending the gas extraction pipe (3) with the hole packers (5) arranged at two ends into the gas extraction drill hole (1), wherein the tail end of the gas extraction drill hole is located 1-2 m behind the hole packer section (2), and the gas extraction pipe (3) is provided with a gas extraction valve (10); the left end hole sealing device is simultaneously provided with a grouting pipe (4) and a hydraulic gauge mounting pipeline (12), the hydraulic gauge (6) is mounted on the hydraulic gauge mounting pipeline (12), a grouting pipe valve (10) is mounted on the grouting pipe (4), and the tail ends of the grouting pipe (4) and the hydraulic gauge mounting pipeline (12) are respectively led into the hole sealing section (2) of the gas extraction drill hole (1);

fourthly, hole sealing is carried out on hole sealers (5) at two ends of the gas extraction pipe (3) again, so that a sealed space is formed on the hole sealing section (2), a grouting pipe valve (10) on the grouting pipe (4) is opened, semi-fluid slurry (8) is injected into the hole sealing section (2), and the grouting pipe valve (10) is closed until the indication number of the hydraulic gauge (6) reaches a set grouting stop pressure value;

fifthly, when the reading of the hydraulic meter (6) is lower than the initial grouting pressure value, the grouting pipe valve (10) is restarted to inject semi-fluid slurry (8) into the hole sealing section (2) until the reading of the hydraulic meter (6) reaches the set grouting stop pressure value; and step five is repeated to ensure that the hydraulic pressure in the hole sealing section (2) is always kept in a constant pressure range.

2. The method for improving the gas drilling extraction concentration in the crushed coal body according to claim 1, wherein in the fourth step and the fifth step, the initial grouting pressure value set by the hydraulic gauge (6) is 0-2.5 MPa, and the stopping grouting pressure value is 3.5-4 MPa.

3. The method for improving the gas extraction concentration in the gas drilled hole in the crushed coal body according to claim 1 or 2, wherein a drill rig for performing primary drilling in the first step adopts a drill rod with the diameter of 30 mm; the drill rig for reaming in the second step uses a drill rod of 80 mm.

4. The method for improving the gas extraction concentration in the gas drilling hole in the crushed coal body according to claim 1 or 2, wherein the hole packer (5) is a polyurethane hole-sealing bag.

5. The method for improving the gas drilling extraction concentration in the crushed coal body according to claim 4, wherein the semifluid slurry (8) comprises a main material, an auxiliary material and water, wherein the main material is a mixture of sodium bentonite and kaolin, the auxiliary material is one or a mixture of more than two of sodium silicate, lithium silicate, silicon dioxide and sodium chloride, and the mass ratio of the main material to the auxiliary material to the water is 1: 12-1: 8.

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