CN116816425A - Method for intercepting and extracting gas by directional long-drilling bottom plate - Google Patents

Abstract

The invention relates to the technical field of coal mine underground safety, and is a method for intercepting and extracting gas with a directional long borehole floor. Position, determine the drilling layout during coal seam floor interception extraction according to the length of the working face and the scope of treatment, determine the drilling spacing and number; select the drilling rig according to the drilling design requirements, and use the drilling rig to complete the drilling construction; after the construction is completed, intercept the floor The flow rate, negative pressure, concentration, daily extraction volume, and pure extraction volume of boreholes and mixed boreholes are tracked daily, and then the pressure relief gas extraction volume of the protected layer and the residual gas content of the protected layer are investigated. , check whether the extraction effect is achieved. This method can effectively reduce the outburst risk of outburst coal seams and prevent the gas from exceeding the limit in the mining working face of protected seams. The higher concentration of gas extraction can be used as power generation fuel, which has good environmental and economic value.

Description

A method for intercepting and draining gas with directional long borehole floor

Technical field

The invention relates to the technical field of underground coal mine safety, in particular to a method for intercepting and extracting gas with a directional long borehole floor.

Background technique

In coal mines, gas is a common harmful gas. Coal and gas outbursts are extremely complex coal and rock dynamic disasters. Too high concentrations can cause coal mine accidents. If a coal and gas outburst accident occurs, it will not only interrupt coal mine production. , the mine will stop production, causing economic losses in production, and may also trigger a mine gas explosion, causing serious damage to the mine facilities, and may lead to more casualties. Therefore, controlling coal and gas outbursts is an important part of coal mine production safety. Traditional gas drainage methods are mainly carried out through vertical drilling or horizontal drilling, but these methods have some problems, such as low drainage efficiency, gas leakage, and inability to replace mining.

Contents of the invention

In order to solve the above problems, the present invention proposes a method for intercepting and extracting gas with a directional long borehole floor, which can not only effectively reduce the risk of outburst coal seams, prevent the gas from exceeding the limit in the mining working face of the protective seam, but also prevent higher concentrations of gas. Drainage can be used as fuel for power generation, which has good environmental and economic value.

In order to achieve the above objects, the technical solution adopted by the present invention is:

A directional long borehole floor interception and gas extraction method includes the following steps:

Determine the layout range of gas drainage boreholes;

Determine the location of the drilling site based on the tunnel conditions and the drilling layout range determined through research, determine the drilling layout in the coal seam floor interception extraction based on the length of the working face and the treatment scope, and determine the drilling spacing and number;

Select a drilling rig according to the drilling design requirements and use the drilling rig to complete the drilling construction;

After the construction is completed, daily data tracking is carried out on the flow rate, negative pressure, concentration, daily extraction volume, and pure extraction volume of the floor interception boreholes and mixed boreholes, and then the pressure relief gas extraction volume and amount of the protected layer are The residual gas content of the protected layer will be inspected to see whether the drainage effect is achieved.

As an option, collect data and information on the evolution of floor cracks after the protective layer is mined, and collect the spatiotemporal evolution characteristics of cracks and gas-rich areas during the stress redistribution process to obtain the characteristics of floor cracks and gas-rich areas, thereby determining The layout range of gas drainage boreholes.

Preferably, the construction layer of the directional long borehole should be selected to be an adjacent coal seam as a protective layer for another coal seam.

Preferably, the drilling site layout should consider factors such as the thickness and inclination of the coal seam, the gas content and flow rate of the coal seam, and the efficiency and safety of gas extraction. The distance between gas extraction drilling sites shall not be less than 300 meters.

Preferably, the drilling site design should set the drilling site in a rectangular shape, with the size determined according to the actual situation. It is required that the bottom plate of the drilling site is completely hardened, with a hardened thickness of about 0.3m, and a water tank is left in the drilling site.

Preferably, for the directional long drilling design, the number of drilling holes in each drilling site should be controlled at 4-6, and the drilling arrangement spacing is 15m, 20m or 25m;

For the directional long borehole design, the opening height, aperture and azimuth angle of each borehole should be consistent.

Preferably, a dust removal device and a push-in local ventilator are used during drilling construction. The air outlet of the dust removal device is located 10m-20m behind the air outlet of the push-in local ventilator.

Preferably, the maximum drilling depth of the selected drilling rig should be greater than the design drilling depth.

The beneficial effects of using the present invention are:

This method can accurately analyze the structural characteristics of coal seam pores and fissures, and is helpful in determining the construction layers, spacing and quantity of directional long boreholes;

This method uses numerical simulation technology to study the gas drainage rules of downward directional boreholes under water column conditions of different heights, which can optimize the layout of boreholes and improve gas drainage efficiency.

This method can timely evaluate the gas drainage effect, adjust and optimize the gas drainage plan by tracking the data of floor interception boreholes and hybrid boreholes. At the same time, this method can be used to carry out operations under dry, wet, saturated water and water column conditions of different heights. The coal gas desorption experiment can deeply study the characteristics of coal gas desorption and provide scientific basis for gas control.

Generally speaking, this method uses a new directional long borehole floor interception and drainage method to control the dangerous area of gas outburst, optimizes the drilling layout plan, and effectively reduces the coal cost while improving the drainage efficiency and ensuring safety. It highlights the danger of gas and effectively guarantees the production safety and production plan of the mine. At the same time, experiments based on this method also provide experimental methods for gas control.

Description of the drawings

Figure 1 is an overall design diagram of the method for intercepting and extracting gas with a directional long borehole floor according to the present invention. .

Figure 2 is a cross-sectional view of the drilling design of the present invention.

Figure 3 is a plan view of the drilling design of the present invention.

Figure 4 is a perspective view of the drilling design of the present invention.

Reference signs include:

1-3# coal seam; 2-5# coal seam; 3-1# drilling field; 4-2# drilling; 5-roadway.

Detailed ways

In order to make the purpose, technical solution and advantages of this technical solution clearer, this technical solution will be further described in detail below in conjunction with specific implementation modes. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present technical solution.

As shown in Figures 1 to 4, this embodiment proposes a directional long borehole interception and gas extraction method.

In this case, 3# coal seam 1 is used as a protective layer to control gas in 5# coal seam 2, and the distance between the two coal layers is about 20m. First, based on the mine data, we studied the evolution rules of floor cracks after the upper protective layer was mined, as well as the spatiotemporal evolution characteristics of cracks and gas enrichment areas during the stress redistribution process. Based on the understanding of floor cracks and gas enrichment areas, we initially determined the efficient gas pumping method. The layout range of mining boreholes. Then predict the amount of gas outflow from the working face to determine the number and diameter of the designed boreholes; select the construction layer based on the relationship between the 3# coal seam 1 and 5# coal seam 2 layers and the lithology analysis results of the 3# coal seam 1 floor.

Finally, two drilling fields were designed according to the layout scope. The 1# drilling field 3 and the 2# drilling field 4 were respectively arranged in the lane 5 of the 3# coal seam 1. Each drilling field contains 5 boreholes. There are two drilling sites arranged in this case. The 1# drilling site 3 is located 906 meters outward from the cutting hole of the working surface, and the 2# drilling site 4 is located 1282 meters outward from the cutting hole of the working surface. The drilling site is rectangular, with specifications: long 12 meters, depth 5 meters, height 3 meters; at the same time, the bottom plate is completely hardened, with a hardened thickness of 0.3m; the width of the ditch in the drilling site is 0.3m*depth 0.2m, and the ditch is hardened with cement. A water tank is constructed near the drilling site, with dimensions of net length 1.5m*net width 0.8m*net depth 0.6m. The inside of the water tank is built with bricks and cement mortar is plastered and hardened.

As a preferred option, the distance between the auxiliary air inlet tunnels in the drill hole 3 of the 1# drilling site is 15m, 30m, 50m, 75m, and 100m (the drilling arrangement spacing is 15m, 20m, 25m), and the vertical distance between the final hole and the roof of the 5# coal seam 2 is 1.5 m, 2m, 3m, 5m, 7m, the hole diameter is 120mm, the target orientation is 190°, the design hole depth is 491-524m, and the project volume is 2528m.

As a preferred option, the auxiliary air inlet tunnel distance within the 4th drilling hole in the 2# drilling site is 30m, 50m, 75m, 100m, 120m (the drilling arrangement spacing is 20m, 25m, 25m), and the vertical distance between the final hole and the roof of the 5# coal seam 2 is 4m. , 4m, 5m, 5m, 5m, the hole diameter is 120mm, the target orientation is 190°, the design hole depth is 461-587m, and the total project volume is 2606m.

Drilling site 1#3 has 5 bottom plate interception directional drilling holes. Each hole has a separate metering device and a mixed drilling metering device. The mine measures the flow, negative pressure and concentration of the 5 floor intercepting drilling holes and mixed drilling holes every day. , daily extraction volume and pure extraction volume for daily data tracking. Through the data analysis of 5 single holes in 1# drilling field 3 and the mixed measurement in 1# drilling field 3, the extraction concentration, single hole drainage negative pressure, flow rate and daily drainage scalar of the mixed drilling were obtained, and Draw a borehole drainage line chart for the drainage situation of each borehole. Analyze each borehole according to the drainage line chart, and calculate the pressure relief gas extraction rate of 1# drill field 3 versus 5# coal seam 2. Calculate The residual gas content of the gas is used to comprehensively evaluate the drainage effect and existing problems of drill field 1#3.

Through the analysis of the extraction effect of No. 1 Drilling Site 3 and the summary of construction experience, it was found that there are problems such as the small offset distance from the auxiliary air inlet tunnel and the phenomenon of hole blocking. According to the problems existing in drilling field 3, the internal staggered auxiliary air inlet distance parameter of drilling field 4 in drilling field 2 was appropriately increased. At the same time, during the construction of drilling field 4 in #2, after the completion of each drilling construction, Lower the flower tube to prevent hole clogging, and use a corresponding type of drilling rig to perform directional long drilling construction. After the construction is completed, the mine conducts daily data tracking on the flow rate, negative pressure, concentration, daily extraction volume, and pure extraction volume of the 10 floor interception boreholes and hybrid boreholes. The results were obtained through data analysis of 10 single holes in the two drilling sites and mixed measurement in the two drilling sites. Then, the pressure relief gas extraction volume of the protected layer and the residual gas content of the protected layer were inspected to see whether they reached Extraction effect.

The above contents are only preferred embodiments of the present invention. For those of ordinary skill in the art, based on the ideas of this technical content, many changes can be made in the specific implementation modes and application scope, as long as these changes do not deviate from the concept of the present invention. All fall within the protection scope of this patent.

Claims (8)

1. A directional long borehole bottom plate interception and gas extraction method, which is characterized by: including the following steps: Determine the layout range of gas drainage boreholes; Determine the location of the drilling site based on the tunnel conditions and the drilling layout range determined through research, determine the drilling layout in the coal seam floor interception extraction based on the length of the working face and the treatment scope, and determine the drilling spacing and number; Select a drilling rig according to the drilling design requirements and use the drilling rig to complete the drilling construction; After the construction is completed, daily data tracking is carried out on the flow rate, negative pressure, concentration, daily extraction volume, and pure extraction volume of the floor interception boreholes and mixed boreholes, and then the pressure relief gas extraction volume and amount of the protected layer are The residual gas content of the protected layer will be inspected to see whether the drainage effect is achieved. 2. The directional long borehole floor interception and gas extraction method according to claim 1, characterized by: collecting data and information on the evolution of floor cracks after the protective layer is mined, and collecting cracks and gas content during the stress redistribution process. The spatiotemporal evolution characteristics of the concentration area can be obtained to obtain the characteristics of floor fissures and gas enrichment areas, thereby determining the layout range of gas drainage boreholes. 3. The directional long borehole floor interception and gas extraction method according to claim 1, characterized in that: the selection of the construction layer of the directional long borehole should select an adjacent coal seam as a protective layer of another coal seam. 4. The directional long borehole floor interception and gas extraction method according to claim 1, characterized in that: the drilling site layout should consider the thickness and inclination of the coal seam, the gas content and flow rate of the coal seam, and the efficiency of gas drainage. For safety and other reasons, the distance between gas extraction drilling sites shall not be less than 300 meters. 5. The directional long borehole floor interception and gas extraction method according to claim 1, characterized in that: the drilling site design should set the drilling site as a rectangle, the size should be determined according to the actual situation, and the drilling site floor is required to be fully hardened. , the hardened thickness is about 0.3m, and a water tank is left at the drilling site. 6. The directional long borehole bottom plate interception and gas extraction method according to claim 1, characterized in that: in the directional long borehole design, the number of boreholes in each drilling site should be controlled at 4-6, and the borehole layout Spacing is 15m, 20m or 25m; For the directional long borehole design, the opening height, aperture and azimuth angle of each borehole should be consistent. 7. The directional long borehole bottom plate interception and gas extraction method according to claim 1, characterized in that: a dust removal device and a press-in local ventilator are used during the drilling construction, and the air outlet of the dust removal device is arranged in the press-in 10m-20m behind the air outlet of the local ventilator. 8. The directional long borehole bottom plate interception and gas extraction method according to claim 1, characterized in that the maximum drilling depth of the selected drilling rig should be greater than the design drilling depth.