CN109944630B - A gas drainage method for low permeability thin coal seam working face - Google Patents

Abstract

The method for gas drainage in thin coal seam working face with low permeability proposed by the present invention divides the working face into adjacent mining roadway evaluation units, adjacent incision roadway evaluation units and working face middle evaluation units, and adopts different procedures for different evaluation units. The arrangement method of coal seam gas drainage drilling holes. Finally, the coal seam gas drainage drilling holes are connected with the gas drainage pipelines, and the coal seam gas is extracted from each evaluation unit in the working face under the action of negative pressure, and the construction of each evaluation unit is carried out. The gas inspection drilling hole is used to test the gas drainage effect. The method proposed by the invention better solves the problem that the gas drainage drilling hole is easily deviated to the roof or bottom plate due to the thin coal seam, poor gas permeability and large length of the working face, which leads to the failure of gas drainage. The problem of reaching the standard has improved the effective utilization rate of the gas drainage borehole and the gas drainage compliance rate of the coal seam in the middle of the working face, and ensured the safe recovery of the working face.

Description

A gas drainage method for low permeability thin coal seam working face

technical field

The invention relates to the technical field of coal mining, in particular to a gas extraction method for a thin coal seam working face with low gas permeability.

Background technique

Coal and gas outburst is one of the major disasters faced by coal mine safety production. With the increase in the intensity and depth of coal mining in my country, the danger of coal and gas outburst disasters is becoming more and more serious, which has a serious negative impact on the image of the coal industry.

The coal resources in southern my country are mainly thin coal seams, with high gas content and poor coal seam permeability. It takes a long time for the working face to reach the standard and it is difficult to extract. On the one hand, the reason is that the relatively short mining time in the incision area of the working face, on the other hand On the one hand, it is difficult to guarantee the construction quality of the gas drainage drilling holes in the middle area of the working face.

In the past, for gas extraction in low-permeability and thin coal seam mining working face, gas was usually extracted from the mining tunnels on both sides and the incision tunnel into the coal body of the working face before mining. However, this method is difficult to guarantee the working face. The effect of gas drainage in the middle of the coal seam, especially for the low permeability and thin coal seam working face, due to the difficulty of gas flow in the coal seam, the gas drainage is more difficult. The phenomenon of deviating to the roof or floor rock layer further reduces the drainage effect of bedding gas drainage drilling, which leads to poor gas drainage effect in the coal seam in the middle of the working face, and often causes the gas to exceed the limit in the working face during the mining period of the working face. , and even induce coal and gas outburst disasters in severe cases.

Therefore, in view of the problem of coal seam gas drainage in the working face with low permeability, thin coal seam and long length, it is necessary to design a more targeted and better gas drainage method to reduce the coal seam gas content, reduce the coal seam gas pressure, and weaken the coal seam gas. The danger of coal seam and gas outburst can improve the mining safety of the working face.

SUMMARY OF THE INVENTION

In order to achieve the above purpose, the present invention provides the following technical solutions: a low gas permeability thin coal seam working face gas extraction method, which comprises the following steps:

Step 1: Divide the area; the upper and lower sides of the working face are the mining lanes, and the right side of the working face is the cutting-hole lane. It is used to evaluate gas extraction separately in different areas;

Step 2: Construction of the first drill hole for gas drainage along the layer; firstly, for the evaluation unit of the adjacent mining roadway, the first drill hole for gas drainage along the layer is constructed. Hole 1; second, drill hole 1 for gas drainage along the floor during construction of the evaluation unit adjacent to the incision roadway, and drill hole 1 for gas drainage in the working face perpendicular to the roadway of the incision roadway;

Step 3: Construction of gas drainage tunnels; for the construction of gas drainage tunnels for the evaluation unit in the middle of the working face, while the tunnels of the mining tunnels on both sides of the working face are excavated, the tunnels of the mining tunnels are excavated to the interior of the working face with small rectangular sections. The gas extraction roadway is formed by excavating in the manner of excavation, the axis of the gas extraction roadway is perpendicular to the axis of the roadway of the mining roadway, the gas extraction roadway is excavated along the coal seam floor, and the head is located in the middle of the long side of the middle evaluation unit of the working face;

Step 4: construct the second drill hole for gas drainage along the bed; construct the second drill hole for gas drainage along the bed on the head end face of the gas drainage roadway. drill into;

Step 5: Pipeline connection; connect the above-mentioned bedding gas drainage hole 1 and bedding gas drainage hole 2 to the gas drainage pipeline, and drain the coal seam gas in each evaluation unit in the working face under the action of negative pressure. , the negative pressure in the gas extraction pipeline is not less than 13KPa, and the gas extraction pipeline is connected with the ground gas extraction system through the gas extraction roadway, the roadway of the mining roadway, and the roadway of the mining area;

Step 6: Construction of gas inspection holes; construction of gas inspection holes in each evaluation unit of the working face to check whether the gas pressure and residual gas content in each evaluation unit meet the standards.

Further, in step 1, the width of the working face is L, the length of the evaluation unit adjacent to the mining roadway and the evaluation unit in the middle of the working face are both 150-200m, and the width is L/3, and the length of the evaluation unit adjacent to the incision roadway is L/3. Both are L and the width is 100m.

Further, in step 2, the sealing length of the first layer of gas drainage drill hole in the adjacent mining roadway evaluation unit is 10-15m, the openings are located in the middle of the coal seam, arranged in a single row, and the hole spacing is 5-10m , the length of the first layer gas drainage hole in the evaluation unit adjacent to the mining roadway is L/3, and its diameter is 90-135mm; the sealing length of the first layer gas drainage hole in the adjacent mining roadway evaluation unit 10m, the openings are located in the middle of the coal seam, arranged in a single row, and the hole spacing is 3-5m. The length of the first drill hole for gas drainage in the evaluation unit of the adjacent incision roadway is 100m and its diameter is 90-135mm.

Further, in step 3, the gas extraction roadway is arranged in a "step" style, the cross-section of the gas extraction roadway is a rectangle, the width of the rectangle is 3.5m, the height is 2m, and the length of the gas extraction roadway is is L/3.

Further, in step 4, the second drill holes for gas drainage along the layer are arranged in a "fan shape" and drilled along the coal seam. The row spacing between the opening points is 0.5m to 1m, and the straight line distance between the end holes is 5 to 10m. The length of the second layered gas drainage hole is subject to the coverage evaluation unit. The diameter of the second hole is 90 to 135 mm.

Further, in step 6, the gas inspection hole is drilled parallel to the coal seam, the sealing length of the gas inspection hole is 10-15m, and the opening position of the hole is located at one of the adjacent two-layer gas drainage holes. The middle of the opening connecting line, or located in the middle of the opening connecting line of two adjacent layered gas drainage holes, the final hole position of the gas investigation hole is located at the end of the first two adjacent layered gas drainage holes. The middle part of the hole connecting line, or the middle part of the last hole connecting line of two adjacent gas drainage drill holes, the diameter of the gas investigation hole is 90-135mm.

Further, in step 6, when the gas pressure under investigation is less than 0.74MPa and the residual gas content is less than 8m ³ /t, it indicates that the extraction reaches the standard, and the coal seam in the evaluation unit can be safely mined; otherwise, it indicates that the extraction fails to meet the standard, and the coal seam in the evaluation unit is evaluated. It cannot be mined, and the extraction time needs to be extended until the extraction reaches the standard.

Compared with the prior art, the beneficial effects of the present invention are:

The method for gas drainage in the thin coal seam working face with low permeability proposed by the present invention divides the working face into an evaluation unit adjacent to the mining roadway, an evaluation unit adjacent to the incision roadway and an evaluation unit in the middle of the working face, and adopts different procedures for different evaluation units. The arrangement method of coal seam gas drainage drilling holes. Finally, the coal seam gas drainage holes are connected to the gas drainage pipelines, and the coal seam gas is extracted from each evaluation unit in the working face under the action of negative pressure, and the construction of each evaluation unit is carried out. Drilling holes for gas inspection to test the effect of gas drainage, especially for the evaluation unit in the middle of the working face, the construction gas drainage roadway and the second drilling hole for gas drainage along the floor are set up, which further ensures the gas drainage effect in the evaluation unit in the middle of the working face. The method of the invention better solves the problem that the gas drainage hole is easy to deviate to the roof or bottom plate due to the thin coal seam, poor gas permeability and long length of the working face, which leads to the substandard gas drainage, and improves the gas drainage hole efficiency. The effective utilization rate and the gas extraction compliance rate of the coal seam in the middle of the working face ensure the safe mining of the working face.

Description of drawings

Fig. 1 is the division plan of the gas drainage evaluation unit in the thin coal seam working face with low permeability;

Figure 2 is a plan view of the drilling arrangement for gas drainage in the working face evaluation unit;

Figure 3 is a plan view of the layout of the gas drainage boreholes in the gas drainage tunnel;

Figure 4 is a sectional view of the head-end face of the gas drainage roadway (section A-A in Figure 3);

In the picture: 1. working face; 2. mining roadway; 3. drilling hole 1 for gas drainage along the bed; 4. cutting hole; 5. roadway for gas drainage; Gas inspection drilling.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Please refer to Figures 1-4, the present invention provides a technical solution: a gas drainage method for low gas permeability thin coal seam working face, characterized in that it comprises the following steps:

Step 1: Divide the area; as shown in Figure 1, the upper and lower sides of the working face 1 are the mining lane 2, and the right side of the working face 1 is the cutting lane 4, and the working face 1 is divided into adjacent mining lane evaluation units (C, D, F, G, I, J), the adjacent incision lane evaluation unit (A) and the middle of the working face evaluation unit (B, E, H), to separately conduct gas extraction evaluation for different areas;

Step 2: Constructing the gas drainage drill hole 1 3 along the layer; firstly, constructing the gas drainage drill hole 1 3 along the layer for the evaluation unit adjacent to the mining roadway, and constructing the layer by layer in the working face 1 perpendicular to the roadway of the mining roadway 2 Gas drainage drill hole 1 3; secondly, for the evaluation unit adjacent to the cut-hole roadway, construct the floor-level gas drainage drill hole 1 3, and construct the floor-level gas drainage drill hole in the working face 1 perpendicular to the roadway of the cut-hole roadway 4. hole one 3;

Step 3: Construct the gas drainage tunnel 5; construct the gas drainage tunnel 5 for the evaluation unit in the middle of the working face. While the tunnels of the mining tunnel 2 on both sides of the working face 1 are excavated, the tunnels of the mining tunnel 2 are moved to the side of the working face 1. The gas extraction roadway 5 is formed by excavating with a rectangular small section in the interior. The axis of the gas extraction roadway 5 is perpendicular to the axis of the roadway of the mining roadway 2. The middle of the long side of the evaluation unit in the middle of the working face;

Step 4: constructing the second floor gas drainage hole 26; constructing the second floor gas drainage hole 26 on the head end face of the gas drainage roadway 5, and the second floor gas drainage hole 26 is in a "fan shape" layout, drilling along the coal seam;

Step 5: Pipeline connection; connect the above-mentioned bedding gas drainage hole 1 3 and bedding gas drainage hole 2 6 to the gas drainage pipeline, and drain each evaluation unit in the working face 1 under the action of negative pressure For medium coal seam gas, the negative pressure in the gas extraction pipeline is not less than 13KPa, and the gas extraction pipeline is connected to the ground gas extraction system through the gas extraction roadway 5, the roadway of the mining roadway 2, and the roadway of the mining area;

Step 6: Construction of gas inspection hole 7; construction of gas inspection hole 7 in each evaluation unit of working face 1 to check whether the gas pressure and residual gas content in each evaluation unit meet the standards.

Specifically, in step 1, the width of the working face 1 is L, the length of the evaluation unit adjacent to the mining roadway and the evaluation unit in the middle of the working face are both 200m, the width is L/3, and the length of the evaluation unit adjacent to the cutting roadway is both is L and the width is 100m.

Specifically, in step 2, the sealing length of the gas drainage drill hole 1 3 in the adjacent mining roadway evaluation unit is 15m, the hole is located in the middle of the coal seam, arranged in a single row, the hole spacing is 10m, and the adjacent mining hole is 10m. The length of the gas drainage drill hole-3 in the roadway evaluation unit is L/3, and its diameter is 135mm; The openings are located in the middle of the coal seam, arranged in a single row, and the hole spacing is 5m. The length of the bedding gas drainage hole-3 in the evaluation unit adjacent to the cut-out roadway is 100m and its diameter is 135mm.

Specifically, in step 3, the gas extraction roadway 5 is arranged in a "step" style, the cross-section of the gas extraction roadway 5 is a rectangle, the width of the rectangle is 3.5m, and the height is 2m. The length of the roadway 5 is L/3, and the axes of two adjacent gas extraction roadways 5 are 400m apart.

Specifically, in step 4, as shown in Figures 2 and 3, the gas drainage holes 26 along the bed are arranged in a "fan shape", and are drilled along the coal seam, and the length of the sealing hole is 15m, as shown in Figure 4, its opening The holes are arranged in three-flowered holes at the mouth, the row spacing between the opening points is 0.5m, and the straight line distance between the end holes is 10m. The diameter of the second-layer gas drainage hole 6 is 135mm.

Specifically, in step 6, the gas inspection hole 7 is drilled in parallel to the coal seam, the sealing length of the gas inspection hole 7 is 10 to 15 m, and the opening position of the gas inspection hole 7 is located in two adjacent layers of gas drainage holes The middle of the opening connection line of the first 3, or the middle of the opening connection line of the two adjacent gas drainage drill holes 2 6, the final hole position of the gas investigation drill hole 7 is located in the adjacent two adjacent layers of gas drainage. The middle part of the final hole connecting line of drill hole 1 3, or the middle part of the end hole connecting line of two adjacent layer gas drainage drill holes 2 6, the diameter of the gas inspection hole 7 is 90-135 mm.

Specifically, when the gas pressure under investigation is less than 0.74MPa and the residual gas content is less than 8m ³ /t, it indicates that the extraction standard is met, and the coal seam in the evaluation unit can be safely mined; Extend the extraction time until the extraction reaches the standard.

The method for gas drainage in the thin coal seam working face with low permeability proposed by the present invention divides the working face into an evaluation unit adjacent to the mining roadway, an evaluation unit adjacent to the incision roadway and an evaluation unit in the middle of the working face, and adopts different procedures for different evaluation units. The arrangement method of coal seam gas drainage drilling holes. Finally, the coal seam gas drainage holes are connected to the gas drainage pipelines, and the coal seam gas is extracted from each evaluation unit in the working face under the action of negative pressure, and the construction of each evaluation unit is carried out. Drilling holes for gas inspection to test the effect of gas drainage, especially for the evaluation unit in the middle of the working face, the construction gas drainage roadway and the second drilling hole for gas drainage along the floor are set up, which further ensures the gas drainage effect in the evaluation unit in the middle of the working face. The method of the invention better solves the problem that the gas drainage hole is easy to deviate to the roof or bottom plate due to the thin coal seam, poor gas permeability and long length of the working face, which leads to the substandard gas drainage, and improves the gas drainage hole efficiency. The effective utilization rate and the gas extraction compliance rate of the coal seam in the middle of the working face ensure the safe mining of the working face.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (3)

1. A low-permeability thin coal seam working face gas extraction method is characterized by comprising the following steps:

the method comprises the following steps: dividing regions; the upper side and the lower side of the working face (1) are mining roadways (2), the right side of the working face (1) is a cutting roadway (4), and the working face (1) is divided into a near mining roadway evaluation unit, a near cutting roadway evaluation unit and a working face middle evaluation unit for performing gas extraction evaluation on different areas in a separated mode;

the width of the working face (1) is L, the length of the evaluation unit close to the stoping lane and the length of the evaluation unit close to the middle of the working face are both 150-200 m, the width of the evaluation unit close to the stoping lane and the width of the evaluation unit close to the cutting lane are both 100m, and the width of the evaluation unit close to the cutting lane is L;

step two: constructing a bedding gas extraction drill hole I; firstly, constructing a bedding gas extraction drill hole I aiming at an evaluation unit close to a stoping roadway (2), and constructing a bedding gas extraction drill hole I towards the inside of a working face (1) by a roadway side perpendicular to the stoping roadway (2); secondly, constructing a first bedding gas extraction drill hole aiming at an evaluation unit close to the hole cutting lane (4), and constructing a first bedding gas extraction drill hole in a working face (1) by a lane wall perpendicular to the hole cutting lane (4);

step three: constructing a gas extraction roadway (5); the method comprises the steps that a gas extraction roadway (5) is constructed for a middle evaluation unit of a working face, the roadway of the recovery roadway (2) on two sides of the working face (1) is tunneled into the working face (1) to form the gas extraction roadway (5) in a rectangular small-section tunneling mode, the axis of the gas extraction roadway (5) is perpendicular to the axis of the roadway of the recovery roadway (2), the gas extraction roadway (5) is tunneled along a coal seam bottom plate, and the head of the gas extraction roadway is located in the middle of the long edge of the middle evaluation unit of the working face;

step four: constructing a bedding gas extraction borehole II (6); constructing a bedding gas extraction drill hole II (6) on the head end face of the gas extraction roadway (5), wherein the bedding gas extraction drill hole II (6) is arranged in a fan shape and drills along the coal bed;

step five: connecting pipelines; connecting the bedding gas extraction drill hole I and the bedding gas extraction drill hole II (6) with a gas extraction pipeline, extracting coal seam gas in each evaluation unit in the working face (1) under the action of negative pressure, wherein the negative pressure in the gas extraction pipeline is not less than 13KPa, and the gas extraction pipeline is connected with a ground gas extraction system through a gas extraction roadway (5), a roadway of a stoping roadway (2) and a roadway of a mining area;

step six: constructing a gas investigation borehole (7); constructing a gas investigation borehole (7) in each evaluation unit of the working surface (1) to investigate whether the gas pressure and the residual gas content in each evaluation unit reach the standard or not;

in the third step, the gas extraction roadway (5) is arranged in a stepping mode, the section of the gas extraction roadway (5) is rectangular, the width of the rectangle is 3.5m, the height of the rectangle is 2m, and the length of the gas extraction roadway (5) is L/3;

in the fourth step, the bedding gas extraction drill holes II (6) are arranged in a fan shape, the bedding gas extraction drill holes II are drilled along the coal seam, the hole sealing length is 10-15 m, the holes are arranged in a three-flower-hole arrangement mode, the row distance between the hole opening points is 0.5-1 m, the linear distance of the final hole point is 5-10 m, the length of the bedding gas extraction drill holes II (6) is based on the coverage evaluation unit, and the diameter of the bedding gas extraction drill holes II (6) is 90-135 mm;

and sixthly, the gas investigation drill hole (7) is drilled in parallel with the coal bed, the hole sealing length of the gas investigation drill hole (7) is 10-15 m, the hole opening position of the gas investigation drill hole is located in the middle of the hole opening connecting line of the first two adjacent bedding gas extraction drill holes or in the middle of the hole opening connecting line of the second two adjacent bedding gas extraction drill holes (6), the final hole position of the gas investigation drill hole (7) is located in the middle of the final hole connecting line of the first two adjacent bedding gas extraction drill holes or in the middle of the final hole connecting line of the second two adjacent bedding gas extraction drill holes (6), and the diameter of the gas investigation drill hole (7) is 90-135 mm.

2. The method for extracting the gas from the working face of the low-permeability thin coal seam according to claim 1, wherein in the second step, the hole sealing length of the bedding gas extraction drill hole I in the evaluation unit close to the stoping lane (2) is 10-15 m, the open holes are located in the middle of the coal seam and are arranged in a single row, the hole spacing is 5-10 m, the length of the bedding gas extraction drill hole I in the evaluation unit close to the stoping lane is L/3, and the diameter of the bedding gas extraction drill hole I is 90-135 mm; the hole sealing length of the bedding gas extraction drill hole I in the near-to-hole-cutting roadway evaluation unit is 10m, the open holes are located in the middle of the coal seam and are arranged in a single row, the hole spacing is 3-5 m, the length of the bedding gas extraction drill hole I in the near-to-hole-cutting roadway evaluation unit is 100m, and the diameter of the bedding gas extraction drill hole I is 90-135 mm.

3. The method for extracting the gas from the working face of the low-permeability thin coal seam according to claim 1, wherein in the sixth step, when the pressure of the detected gas is less than 0.74MPa and the content of the residual gas is less than 8m3/t, the extraction is up to the standard, the coal seam in the evaluation unit can be safely extracted, otherwise, the extraction is not up to the standard, the coal seam in the evaluation unit cannot be extracted, and the extraction time needs to be prolonged until the extraction is up to the standard.

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