Cross-layer drilling combined gas extraction device under mining condition of upper protective layer

Abstract

The utility model discloses a crossing drilling combined gas extraction device under an upper protective layer exploitation condition, which comprises an extraction pipe coaxially arranged in a drilling hole, an upper bag plugging device and an orifice plugging device are arranged on the extraction pipe, the upper bag plugging device is positioned between an upper protective layer and a protected layer, and the orifice plugging device is positioned between the upper protective layer and the protected layer. The orifice plugging device is located between a protected layer and a drill hole orifice, a conical pipe is arranged at the upper end of the extraction pipe, a constant-pressure opening extraction valve is arranged on the extraction pipe and located between the upper bag plugging device and the orifice plugging device, and the extraction pipe is connected with a positive-pressure gas injection assembly and a negative-pressure extraction assembly. According to the utility model, on the premise of not influencing the gas extraction effect and not additionally constructing drill holes, the extraction drill holes of the upper protective layer can still serve the gas extraction work of the protected layer, and gas extraction can be carried out on the upper coal seam and the lower coal seam independently in sequence, so that the separate source metering of the pre-extracted gas of the two coal seams is realized, and the gas extraction efficiency is improved. Reliable data are provided for gas extraction standard-reaching evaluation work, and meanwhile the underground extraction work efficiency is greatly improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of coal mine gas disaster prevention and control, and particularly relates to a combined gas drainage device for cross-layer boreholes under the condition of upper protective layer mining. Background Technique

[0002] For the treatment of coal mine gas disasters, the combined mining of the upper protective layer and the drainage of the depressurized gas in the protected coal seam has become a regional gas disaster treatment technology that is preferentially used in coal mines in China. At present, when draining the gas in the cross-layer boreholes underground, the upper protective layer and the protected coal seam are usually drained simultaneously. Since the gas source of the drainage boreholes cannot be distinguished, when evaluating whether the gas drainage parameters meet the standards, it is necessary to select other sampling methods or arrange other measuring points. After the upper protective layer is mined, the stress balance state of the roof and floor of the protected coal seam is broken. Due to the depressurization effect, a large amount of coal seam gas is desorbed. Before the protected coal seam is mined, it is still necessary to construct drainage boreholes to drain the gas. At this time, the surrounding rock at the bottom of the cross-layer borehole becomes a goaf due to the mining of the upper protective layer, and this borehole cannot be used to pre-drain the gas in the protected coal seam. This current situation cannot achieve the separate-source gas drainage of the upper protective layer and the protected coal seam, which brings various difficulties to the evaluation work of the drainage compliance of each coal seam, and the repeated utilization rate of the boreholes is low, affecting the efficiency of underground gas treatment work. Content of the Utility Model

[0003] In order to solve the above problems existing in the prior art, the utility model provides a combined gas drainage device for cross-layer boreholes under the condition of upper protective layer mining, which only needs to be installed once, first drains the gas in the upper protective layer, and then switches to drain the gas in the protected coal seam, is convenient to operate, and the whole drainage device can be reused.

[0004] To solve the above technical problems, the utility model adopts the following technical scheme: A combined gas drainage device for cross-layer boreholes under the condition of upper protective layer mining, including a drainage pipe coaxially installed in the borehole. An upper bladder plugging device and an orifice plugging device are arranged on the drainage pipe. The upper bladder plugging device is located between the upper protective layer and the protected coal seam, and the orifice plugging device is located between the protected coal seam and the borehole orifice. The upper end of the drainage pipe is provided with a conical pipe with a thin upper part and a thick lower part in an integral structure. A constant-pressure opening drainage valve is arranged on the drainage pipe between the upper bladder plugging device and the orifice plugging device. A positive-pressure gas injection assembly and a negative-pressure drainage assembly are connected to the lower side of the borehole orifice on the drainage pipe.

[0005] The upper bladder plugging device includes two upper expansion bladders arranged at intervals up and down. The orifice plugging device includes two lower expansion bladders arranged at intervals up and down. The two upper expansion bladders and the two lower expansion bladders are connected in series by an injection pipe parallel to the drainage pipe. The injection pipe is provided with injection holes respectively communicating with the interiors of the two upper expansion bladders and the two lower expansion bladders. The lower end of the injection pipe extends out of the borehole and is connected to an injection pump. An injection valve and a pressure gauge are installed on the injection pipe.

[0006] The constant-pressure opening drainage valve includes a sleeve coaxially sleeved on the drainage pipe. There is an annular cavity between the inner circle of the sleeve and the outer circle of the drainage pipe. Annular blanking plates are respectively provided at the upper and lower ports of the annular cavity. A number of air-permeable small holes communicating with the annular cavity are opened on the drainage pipe, and a number of bursting valves are provided on the sleeve.

[0007] The positive-pressure gas injection assembly includes an air pump. The air pump is connected to the side of the drainage pipe through a positive-pressure gas pipe. A number of first air holes located inside the positive-pressure gas pipe are opened on the drainage pipe, and a first valve is provided on the positive-pressure gas pipe.

[0008] The negative-pressure drainage assembly includes a drainage negative-pressure pump. The air inlet of the drainage negative-pressure pump is connected to the side of the drainage pipe through a negative-pressure gas pipe. A number of second air holes located inside the negative-pressure gas pipe are opened on the drainage pipe, and a second valve is provided on the negative-pressure gas pipe. The air outlet of the drainage negative-pressure pump is connected to the gas drainage pipeline in the coal mine underground.

[0009] A third valve is provided at the lower end of the drainage pipe. A rubber sealing ball is placed above the third valve inside the drainage pipe. The diameter of the rubber sealing ball is equal to or slightly larger than the inner diameter of the drainage pipe.

[0010] Adopting the above technical solution, compared with the prior art, the utility model has the following beneficial effects:

[0011] (1) The conical pipe forms a conical structure with a narrow upper part and a wide lower part after being reduced in diameter at the upper end of the drainage pipe, which is used to limit the upward movement of the rubber sealing ball and separate it from the drainage pipe when gas is drained from the protected coal seam.

[0012] (2) Through the pressure gauge, it can be monitored at any time whether the two upper expansion bladder bags and the two lower expansion bladder bags are leaking air or depressurizing, which is convenient for timely opening the air injection pump to replenish pressure for the four expansion bladder bags, improving the hole sealing quality and reliability.

[0013] (3) The four expansion bladder bags are all of an inner and outer double-layer structure, ensuring their sealing performance and durability. The inner layer is made of elastic non-woven fabric, and the outer layer is made of wear-resistant rubber material. The inner layer is made of elastic non-woven fabric.

[0014] (4) After the bursting valve in the constant-pressure opening drainage valve is opened by positive-pressure air, the communication with the drainage pipe can be realized, and the gas drainage from the protected coal seam is convenient to operate and safe and reliable.

[0015] (5) A number of conventional gas drainage pipes need to be arranged between the upper protected coal seam and the protected coal seam. The length of a single gas drainage pipe is 2m, and the number of pipes arranged depends on the distance between the upper and lower coal seams.

[0016] (6) The two upper expansion bladder bags and the two lower expansion bladder bags can control the hole sealing through gas injection, so this device can be reused.

[0017] (7) The most ideal arrangement positions of the two upper expansion pockets are that one upper expansion pocket on the upper side is located 0.5 - 1 m downward from the bottom plate of the upper protective layer, and one upper expansion pocket on the lower side is located 0.5 - 1 m upward from the roof of the protected layer.

[0018] (8) The diameter of the conical pipe gradually decreases from the extraction pipe to prevent the movement of the rubber sealing ball. To ensure both the hole - sealing effect and the smoothness of the negative - pressure outlet, the diameter should not be overly contracted. The upper port of the conical pipe should be reduced to about 80% of the original to ensure the extraction efficiency.

[0019] (9) The rubber sealing ball is made of silica gel with relatively high elasticity. The diameter of the rubber sealing ball is slightly larger than the inner diameter of the extraction pipe. Therefore, the resistance between the rubber sealing ball and the pipe wall is large, and a relatively large driving force is required to move the rubber plug. It should be ensured that when the pressure is 20 - 30 times the maximum extraction pressure (about 0.3 - 0.5 MPa), it is possible to overcome the moving resistance of the rubber sealing ball. In this way, when extracting the protected layer, the friction between the rubber sealing ball and the extraction pipe can still keep the rubber sealing ball stable.

[0020] (10) The rubber sealing ball is pre - placed inside the lower end of the extraction pipe, which reduces the time for switching from extracting the upper protective layer to extracting the protected layer and also avoids the loss of the rubber sealing ball.

[0021] (11) To avoid the extraction negative pressure and the pressure for pushing the rubber sealing ball from triggering the bursting valve, the bursting threshold is set to 100 times the maximum extraction negative pressure, about 1.5 Mpa.

[0022] (12) There are two lower expansion pockets outside the extraction pipe at the orifice. After being inflated by the air - injection pump, they can produce two - stage seals at the orifice, improving the hole - sealing effect at the orifice.

[0023] (13) Instead of opening a large hole inside the positive - pressure gas pipe on the extraction pipe, there are several first air holes; instead of opening a large hole inside the negative - pressure gas pipe on the extraction pipe, there are several second air holes. This structure prevents the rubber sealing ball from being stuck when moving upward inside the extraction pipe.

[0024] In summary, the utility model can, without affecting the gas extraction effect and without additional drilling construction, enable the extraction boreholes in the upper protective layer to still serve the gas extraction work in the protected layer, and can separately extract gas from the upper and lower coal seams successively. It not only realizes the separate - source metering of the two coal seams under the condition of mining the upper protective layer, provides reliable data for the gas extraction compliance evaluation work, but also greatly improves the underground extraction work efficiency and saves the labor, material and financial expenditures of the coal mine. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the utility model when extracting the upper protective layer;

[0026] Figure 2 It is a schematic structural diagram of the process of extracting the protected layer when the rubber ball of the present utility model moves up to the conical tube.

[0027] Figure 3 It is a schematic diagram of the application scenario of the present utility model. Specific embodiments

[0028] The following further describes in detail the embodiments of the present utility model in conjunction with the drawings and embodiments.

[0029] As Figures 1 - 3 shown, the cross-layer borehole combined gas drainage device under the condition of extracting the upper protected layer of the present utility model includes a drainage pipe 2 coaxially installed in the borehole 1. An upper bladder plugging device and an orifice plugging device are provided on the drainage pipe 2. The upper bladder plugging device is located between the upper protected layer 24 and the protected layer 25, and the orifice plugging device is located between the protected layer 25 and the orifice of the borehole 1. A conical tube 3 with a thinner upper part and a thicker lower part is provided at the upper end of the drainage pipe 2. A constant-pressure opening drainage valve is provided on the drainage pipe 2 between the upper bladder plugging device and the orifice plugging device. A positive-pressure gas injection assembly and a negative-pressure drainage assembly are connected to the lower side of the orifice of the borehole 1 on the drainage pipe 2. Both the upper protected layer 24 and the protected layer 25 are coal seams, and the upper protected layer 24 is located above the protected layer 25.

[0030] The upper bladder plugging device includes two upper expansion bladders 4 arranged at intervals up and down. The orifice plugging device includes two lower expansion bladders 5 arranged at intervals up and down. The two upper expansion bladders 4 and the two lower expansion bladders 5 are connected in series by an injection gas pipe 6 parallel to the drainage pipe 2. The injection gas pipe 6 is provided with injection holes respectively communicating with the interiors of the two upper expansion bladders 4 and the two lower expansion bladders 5. The lower end of the injection gas pipe 6 extends out of the borehole 1 and is connected to an injection gas pump 7. An injection gas valve 8 and a pressure gauge 9 are installed on the injection gas pipe 6.

[0031] The constant-pressure opening drainage valve includes a sleeve 10 coaxially sleeved on the drainage pipe 2. There is an annular cavity between the inner circle of the sleeve 10 and the outer circle of the drainage pipe 2. Annular plugging plates 11 are provided at the upper port and the lower port of the annular cavity respectively. The drainage pipe 2 is provided with a plurality of air-permeable small holes 12 communicating with the annular cavity. A plurality of blasting valves 13 are provided on the sleeve 10.

[0032] The positive-pressure gas injection assembly includes an air pump 14. The air pump 14 is connected to the side of the drainage pipe 2 through a positive-pressure gas pipe. The drainage pipe 2 is provided with a plurality of first air holes 16 located inside the positive-pressure gas pipe 15. A first valve 17 is provided on the positive-pressure gas pipe 15.

[0033] The negative pressure extraction assembly includes an extraction negative pressure pump 18. The air inlet of the extraction negative pressure pump 18 is connected to the side of the extraction pipe 2 through a negative pressure gas pipe 19. A number of second air holes 20 are provided on the extraction pipe 2 inside the negative pressure gas pipe 19. A second valve 21 is provided on the negative pressure gas pipe 19. The air outlet of the extraction negative pressure pump 18 is connected to the gas extraction pipeline in the coal mine underground.

[0034] A third valve 22 is provided at the lower end of the extraction pipe 2. A rubber sealing ball 23 is placed above the third valve 22 inside the extraction pipe 2. The diameter of the rubber sealing ball 23 is equal to or slightly larger than the inner diameter of the extraction pipe 2.

[0035] The specific working process of the present utility model is as follows: Collect data information such as the formation columnar section diagram, the design drawing of the cross-cut borehole 1, etc., and understand the key parameters such as the thickness and spacing of the upper protective layer 24 and the protected layer 25, and the depth of the borehole 1. Construct the cross-cut borehole 1 in the roadway. After the construction of the cross-cut borehole 1 is completed, clean the debris and other blockages in the borehole 1 to ensure that the borehole 1 is unobstructed; Push the extraction pipes 2 into the borehole 1 one by one. After the upper bag plugging device, the orifice plugging device and the constant pressure opening extraction valve reach the designated positions respectively, open the gas injection valve 8, start the gas injection pump 7, and inject air into the two upper expansion bags 4 and the two lower expansion bags 5 simultaneously through the gas injection pipe 6. After the two upper expansion bags 4 and the two lower expansion bags 5 expand radially, the borehole 1 is plugged and the extraction pipe 2 is fixed at the same time. After the pressure gauge 9 reaches the set pressure, turn off the gas injection pump 7 and the gas injection valve 8 to complete the hole sealing. When the reading of the pressure gauge 9 decreases, open the gas injection valve 8, start the gas injection pump 7, and inject air into the two upper expansion bags 4 and the two lower expansion bags 5 again for air supplement and pressure boost to maintain a good hole sealing effect.

[0036] First, carry out gas extraction on the upper protective layer 24. Open the extraction negative pressure pump 18. The gas in the upper protective layer 24 enters the extraction pipe 2 through the conical pipe 3 and is finally pumped to the gas extraction pipeline in the coal mine underground.

[0037] After the gas drainage of the upper protective layer 24 is completed, first close the drainage negative pressure pump 18 and the second valve 21, then open the third valve 22. Insert a long rod into the lower port of the drainage pipe 2, and the long rod pushes the rubber sealing ball 23 to move upward along the drainage pipe 2. When the rubber sealing ball 23 moves above the first air hole 16, close the third valve 22, open the first valve 17, and start the air pump 14. The air pump 14 injects positive pressure air into the drainage pipe 2 to drive the rubber sealing ball 23 to continue moving upward along the drainage pipe 2 until the rubber ring moves to the conical pipe 3 at the uppermost end of the drainage pipe 2. Blocked by the conical pipe 3, the rubber sealing ball 23 seals the conical pipe 3. The air pump 14 continues to increase the pressure. When the pressure in the drainage pipe 2 is greater than the bursting threshold of the bursting valve 13 (about 1.5 Mpa, 100 times the maximum drainage negative pressure), the bursting valve 13 opens. Then close the air pump 14 and the first valve 17, and then open the second valve 21 and the drainage negative pressure pump 18 to conduct gas drainage on the protected layer 25. The gas in the protected layer 25 enters the annular cavity through the air permeable small holes 12 on the drainage pipe 2, then enters the drainage pipe 2 through the opened bursting valve 13, and finally is pumped into the coal mine underground gas drainage pipeline.

[0038] The above embodiments illustrate the basic principles and features of the present invention. However, the above only illustrates the preferred embodiments of the present invention and is not limited by the described embodiments. Those of ordinary skill in the art, inspired by this patent, can also make many forms of deformation and improvement without departing from the purpose of the present invention and the scope protected by the claims. These all fall within the protection scope of the present invention. Therefore, the patent and protection scope of the present invention shall be subject to the appended claims.

Claims

1. The cross - seam borehole combined gas drainage device under the condition of upper protective layer mining, characterized in that: It includes a gas drainage pipe coaxially installed in a borehole. An upper bladder plugging device and an orifice plugging device are provided on the gas drainage pipe. The upper bladder plugging device is located between the upper protective layer and the protected layer, and the orifice plugging device is located between the protected layer and the borehole orifice. A conical pipe with a thinner upper part and a thicker lower part in an integrated structure is provided at the upper end of the gas drainage pipe. A pressure-fixed opening gas drainage valve is provided on the gas drainage pipe between the upper bladder plugging device and the orifice plugging device. A positive-pressure gas injection assembly and a negative-pressure gas drainage assembly are connected to the lower side of the borehole orifice on the gas drainage pipe.

2. The cross - seam borehole combined gas drainage device under the condition of upper protective layer mining according to claim 1, characterized in that: The upper bladder plugging device includes two upper expansion bladders arranged at intervals up and down. The orifice plugging device includes two lower expansion bladders arranged at intervals up and down. The two upper expansion bladders and the two lower expansion bladders are connected in series through an injection gas pipe parallel to the gas drainage pipe. Injection holes communicating with the interiors of the two upper expansion bladders and the two lower expansion bladders respectively are provided on the injection gas pipe. The lower end of the injection gas pipe extends out of the borehole and is connected to an injection gas pump. An injection gas valve and a pressure gauge are installed on the injection gas pipe.

3. The cross - seam borehole combined gas drainage device under the condition of upper protective layer mining according to claim 1, characterized in that: The pressure-fixed opening gas drainage valve includes a sleeve coaxially sleeved on the gas drainage pipe. There is an annular cavity between the inner circle of the sleeve and the outer circle of the gas drainage pipe. Annular blanking plates are provided at the upper port and the lower port of the annular cavity respectively. A number of air-permeable small holes communicating with the annular cavity are opened on the gas drainage pipe. A number of bursting valves are provided on the sleeve.

4. The cross - seam borehole combined gas drainage device under the condition of upper protective layer mining according to claim 1, characterized in that: The positive-pressure gas injection assembly includes an air pump. The air pump is connected to the side of the gas drainage pipe through a positive-pressure gas pipe. A number of first air holes located inside the positive-pressure gas pipe are opened on the gas drainage pipe. A first valve is provided on the positive-pressure gas pipe.

5. The cross - seam borehole combined gas drainage device under the condition of upper protective layer mining according to claim 1, characterized in that: The negative-pressure gas drainage assembly includes a gas drainage negative-pressure pump. The air inlet of the gas drainage negative-pressure pump is connected to the side of the gas drainage pipe through a negative-pressure gas pipe. A number of second air holes located inside the negative-pressure gas pipe are opened on the gas drainage pipe. A second valve is provided on the negative-pressure gas pipe. The air outlet of the gas drainage negative-pressure pump is connected to the gas drainage pipeline in the coal mine underground.

6. The cross - seam borehole combined gas drainage device under the condition of upper protective layer mining according to claim 1, characterized in that: A third valve is provided at the lower end of the gas drainage pipe. A rubber sealing ball is placed above the third valve inside the gas drainage pipe. The diameter of the rubber sealing ball is equal to or slightly larger than the inner diameter of the gas drainage pipe.

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