Upward drilling automatic drainage device and coal seam gas pressure measuring method

Abstract

The invention discloses an ascending drill hole automatic drainage device and a coal seam gas pressure measuring method. The ascending drill hole automatic drainage device comprises a measuring pipe, a packing assembly, a connecting pipe and a floating ball assembly, and the measuring pipe is arranged in an ascending drill hole; the packing assembly is arranged between the ascending drill hole and the measuring pipe so as to seal a gap between the inner wall of the ascending drill hole and the outer wall of the measuring pipe; one end of the connecting pipe is connected with the lower end of the measuring pipe, a flow channel is formed between the measuring pipe and the connecting pipe, the other end of the connecting pipe is opened upwards, and a U-shaped sealing section is arranged in the middle of the connecting pipe and used for being filled with fluid media to block the lower end of the connecting pipe; the floating ball assembly is located on the side, close to the measuring pipe, of the sealing section, the floating ball assembly is arranged in the flow channel, the floating ball assembly has an open state and a closed state, when water in the measuring pipe flows to the connecting pipe, the floating ball assembly is in the open state so that the flow channel can be communicated, and when no water exists in the measuring pipe, the floating ball assembly is in the closed state so that the flow channel can be disconnected.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mines, and in particular relates to an automatic drainage device for an upward drilling hole and a method for measuring coal seam gas pressure. Background Art

[0002] Coal seam gas pressure is one of the important parameters for coal mine gas control work, and it is also one of the parameters for judging the danger of coal seam gas outburst. In the direct measurement method of underground coal seam gas pressure in related technologies, if water is found in some upward borehole pressure measuring tubes during the pressure measurement process, it will affect the pressure measurement results. After the pressure measurement work is completed, the amount of water released from the borehole should be measured when the meter head is removed, and the calculation and correction should be made based on the amount of water released and the drilling parameters. Affected by factors such as the operating experience of technicians and on-site tools, the measured volume or weight of accumulated water is not accurate, which ultimately leads to poor accuracy of the coal seam gas pressure measurement results, which has a great impact on the guidance of subsequent construction operations. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, an embodiment of the present invention provides an automatic drainage device for an upward drilling hole that can automatically discharge the accumulated water in a gas pressure measuring pipe hole.

[0005] The embodiment of the present invention also provides a method for measuring coal seam gas pressure.

[0006] The automatic drainage device for upward drilling according to the embodiment of the present invention comprises:

[0007] A measuring tube, the measuring tube being arranged in the upward borehole;

[0008] A packing assembly, the packing assembly being arranged between the upward borehole and the measuring tube to seal a gap between an inner wall of the upward borehole and an outer wall of the measuring tube;

[0009] A connecting pipe, one end of which is connected to the lower end of the measuring pipe, a flow channel is formed between the measuring pipe and the connecting pipe, the other end of the connecting pipe is opened upward, and the middle of the connecting pipe has a U-shaped sealing section, which is used to be filled with a fluid medium to seal the lower end of the connecting pipe;

[0010] A float assembly, wherein the float assembly is located on a side of the sealing section close to the measuring tube, the float assembly is arranged between the measuring tube and the connecting tube, or the float assembly is arranged in the flow channel, the float assembly has an open state and a closed state, when water flows from the measuring tube to the connecting tube, the float assembly is in the open state to make the flow channel conductive, and when there is no water in the measuring tube, the float assembly is in the closed state to disconnect the flow channel.

[0011] The automatic drainage device for upward drilling in the embodiment of the present invention automatically discharges the accumulated water, thereby ensuring the accuracy of the measurement results, avoiding inaccurate gas pressure measurement due to accumulated water, and avoiding inaccurate pressure correction due to inaccurate measurement of the water discharge volume.

[0012] In some embodiments, the float assembly includes:

[0013] A cylinder, wherein the cylinder has an inner cavity, the cylinder is connected between the measuring tube and the connecting tube, or the outer wall of the cylinder is sealed with the inner wall of the flow channel, the inner cavity is communicated with the flow channel, and the cross-sectional size of the inner cavity gradually decreases from the middle to both ends;

[0014] A float is arranged in the inner cavity, the float can move up and down in the inner cavity, and the outer diameter of the float is larger than the opening size at both ends of the inner cavity.

[0015] In some embodiments, annular grooves are provided on the wall surface of the cylinder at both ends of the inner cavity, and a sealing ring is provided in the annular groove.

[0016] In some embodiments, the upper port size of the inner cavity is larger than the lower port size of the inner cavity.

[0017] In some embodiments, an intermediate tube is provided between the measuring tube and the connecting tube, and the connecting tube is hung on a circumferential structure;

[0018] And / or, the sealing section is filled with water or emulsion.

[0019] In some embodiments, a pressure gauge is further included. The pressure gauge is located on a side of the float assembly away from the sealing section. The pressure gauge is connected to the flow channel to detect the pressure in the flow channel.

[0020] In some embodiments, the connecting tube has a first connection port and a second connection port at one end close to the measuring tube, the first connection port is connected to the measuring tube, the second connection port is connected to the pressure gauge, and the float assembly is located in the connecting tube.

[0021] In some embodiments, a height of a port of the connecting tube that is away from one end of the measuring tube in the vertical direction is lower than a height of a lower port of the float assembly.

[0022] In some embodiments, a screen tube is further included, wherein the screen tube is connected to an end of the measuring tube away from the connecting tube, and the screen tube is used to filter the fluid flowing into the measuring tube.

[0023] The method for measuring coal bed gas pressure according to the embodiment of the present invention comprises the following steps:

[0024] Drilling upholes in and out of coal seams for coal seam gas pressure measurement;

[0025] Arranging an automatic drainage device for an upward borehole as described in any of the above embodiments in the upward borehole;

[0026] Filling a fluid medium in the sealing section of the upward borehole automatic drainage device to isolate the inner cavity of the upward borehole from the external atmosphere;

[0027] Using the pressure gauge in the upward borehole automatic drainage device to obtain the gas pressure parameters in the upward borehole in real time;

[0028] When water flows out of the upward borehole, the water in the upward borehole can be automatically discharged through the upward borehole automatic drainage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of an automatic drainage device for upward drilling according to an embodiment of the present invention.

[0030] Figure 2 Schematic diagram of a connecting pipe and a float assembly according to an embodiment of the present invention.

[0031] Figure 3 It is a flow chart of a method for measuring coal seam gas pressure according to an embodiment of the present invention.

[0032] Reference numerals:

[0033] 1. Measuring tube; 11. Screen tube;

[0034] 2. Packing assembly; 21. First bladder bag; 22. Second bladder bag; 23. Grouting pipe;

[0035] 3. Connecting pipe; 31. Sealing section; 32. First connecting port; 33. Second connecting port;

[0036] 4. Float assembly; 41. Cylinder; 42. Float; 43. Upper port; 44. Lower port;

[0037] 5. Pressure gauge;

[0038] 6. Upward drilling. DETAILED DESCRIPTION

[0039] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0040] like Figure 1 and Figure 2 As shown, the automatic drainage device for upward drilling according to an embodiment of the present invention includes a measuring pipe 1, a sealing assembly 2, a connecting pipe 3 and a floating ball assembly 4.

[0041] The orifice of the upward borehole 6 faces downward, and the borehole extends from bottom to top or extends obliquely upward in the up-down direction. When water accumulates in the borehole, the water can flow out from the orifice of the borehole along the wall of the upward borehole 6. The measuring tube 1 is arranged in the upward borehole 6, and the sealing assembly 2 is arranged between the upward borehole 6 and the measuring tube 1 to seal the gap between the inner wall of the upward borehole 6 and the outer wall of the measuring tube 1. It should be understood that most sections of the measuring tube 1 penetrate into the upward borehole 6. In order to ensure the sealing between the outer wall of the measuring tube 1 and the wall of the upward borehole 6, a sealing assembly 2 can be arranged between the measuring tube 1 and the upward borehole 6 to achieve blocking and ensure that the water and gas in the upward borehole 6 are connected to the inner cavity of the measuring tube 1.

[0042] One end of the connecting pipe 3 is connected to the lower end of the measuring pipe 1, and a flow channel is formed between the measuring pipe 1 and the connecting pipe 3. The other end of the connecting pipe 3 is opened upward, and the middle part of the connecting pipe 3 has a U-shaped sealing section 31, which is used to fill the fluid medium to block the lower end of the connecting pipe 3. After the connecting pipe 3 and the measuring pipe 1 are connected and connected together, the water in the borehole can flow out of the flow channel, but because the connecting pipe 3 has a U-shaped sealing section 31, a part of water will be retained in the sealing section 31 to achieve the sealing of the flow channel so that the gas will not be discharged. When there is no water flowing out of the borehole, water or other fluid medium can be actively filled into the sealing section 31 so that it can seal the flow channel, and when there is water flowing out, it will not prevent automatic drainage.

[0043] The float assembly 4 is located on the side of the sealing section 31 close to the measuring tube 1. The float assembly 4 is arranged between the measuring tube 1 and the connecting tube 3, or the float assembly 4 is arranged in the flow channel. The float assembly 4 has an open state and a closed state. When water flows from the measuring tube 1 to the connecting tube 3, the float assembly 4 is in an open state to make the flow channel conductive. When there is no water in the measuring tube 1, the float assembly 4 is in a closed state to disconnect the flow channel. The float assembly 4 forms an automatic opening and closing valve in the flow channel. When there is water, the float assembly 4 automatically opens under the action of buoyancy. When there is no water, the float assembly 4 is not affected by buoyancy and automatically blocks the flow channel, isolating it from the outside atmosphere, so that the air pressure in the upward borehole 6 remains relatively independent, which is convenient for accurately measuring the gas pressure in the borehole.

[0044] The automatic drainage device for upward drilling in the embodiment of the present invention automatically discharges the accumulated water, thereby ensuring the accuracy of the measurement results, avoiding inaccurate gas pressure measurement due to accumulated water, and avoiding inaccurate pressure correction due to inaccurate measurement of the water discharge volume.

[0045] Another specific embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0046] like Figure 1 and Figure 2 As shown, the automatic drainage device for upward drilling according to an embodiment of the present invention includes a measuring pipe 1, a sealing assembly 2, a connecting pipe 3 and a floating ball assembly 4.

[0047] The opening of the upward borehole 6 faces downward, and the borehole extends from bottom to top or extends obliquely upward in the up-down direction. When water accumulates in the borehole, the water can flow out from the opening of the borehole along the hole wall of the upward borehole 6.

[0048] The measuring tube 1 is arranged in the upward borehole 6, and the packing assembly 2 is arranged between the upward borehole 6 and the measuring tube 1 to seal the gap between the inner wall of the upward borehole 6 and the outer wall of the measuring tube 1. It should be understood that most sections of the measuring tube 1 penetrate into the upward borehole 6. In order to ensure the sealing between the outer wall of the measuring tube 1 and the hole wall of the upward borehole 6, the packing assembly 2 can be arranged between the measuring tube 1 and the upward borehole 6 to achieve plugging and ensure that the water and gas in the upward borehole 6 are connected with the inner cavity of the measuring tube 1.

[0049] The sealing assembly 2 includes a first bag 21, a second bag 22 and a grouting pipe 23. The first bag 21 and the second bag 22 are arranged at intervals on the outer wall of the measuring tube 1. The grouting pipe 23 is connected with the first bag 21, the second bag 22 and the sealed space between the first bag 21 and the second bag 22. After the first bag 21 and the second bag 22 are tied and fixed on the measuring tube 1, the measuring tube 1 is placed in the upward borehole 6, and grouting is injected into the first bag 21, the second bag 22 and the sealed space between the first bag 21 and the second bag 22. After the slurry solidifies for 24 hours, the connecting pipe 3 and the float assembly 4 are installed.

[0050] A screen tube 11 is connected to one end of the deep-drilled hole of the measuring tube 1. The screen tube 11 is used to filter the fluid flowing into the measuring tube 1. For example, the screen tube 11 includes a tube body and a plurality of screen holes opened on the outer wall of the tube body, which is used to prevent stones from entering the measuring tube 1, but allows water to flow into the measuring tube 1.

[0051] The measuring tube 1 can be a tube made of metal materials such as stainless steel or cast iron, and has a certain strength. The upper and lower ends of the measuring tube 1 are provided with threaded sections for threaded connection with the screen tube 11 and the connecting tube 3 respectively.

[0052] One end of the connecting pipe 3 is connected to the lower end of the measuring pipe 1, and a flow channel is formed between the measuring pipe 1 and the connecting pipe 3. The other end of the connecting pipe 3 is opened upward, and the middle part of the connecting pipe 3 has a U-shaped sealing section 31, which is used to fill the fluid medium to block the lower end of the connecting pipe 3. After the connecting pipe 3 and the measuring pipe 1 are connected and connected together, the water in the borehole can flow out of the flow channel, but because the connecting pipe 3 has a U-shaped sealing section 31, a part of water will be retained in the sealing section 31 to achieve the sealing of the flow channel so that the gas will not be discharged. When there is no water flowing out of the borehole, water or other fluid medium can be actively filled into the sealing section 31 so that it can seal the flow channel, and when there is water flowing out, it will not prevent automatic drainage.

[0053] The measuring tube 1 and the connecting tube 3 can be directly connected together, but when the two are not easy to connect directly, an intermediate tube can be provided between the measuring tube 1 and the connecting tube 3. The intermediate tube can be a soft rubber tube, and the connecting tube 3 can be hung on the circumferential structure (coal seam roof). However, it is still necessary to ensure that some sections of the connecting tube 3 are U-shaped to form a sealing section 31, and the opening faces upward, so that the sealing section 31 can be filled with fluid media such as water and emulsion to seal the flow channel. Preferably, when there is no water, a mining emulsion is added to the sealing section 31. This liquid is not only not easy to evaporate and is non-toxic to the human body, but can also ensure good performance for a long time.

[0054] One end of the connecting pipe 3 close to the measuring pipe 1 has a first connecting port 32 and a second connecting port 33. The first connecting port 32 is connected to the measuring pipe 1, and the second connecting port 33 is connected to the pressure gauge 5. The pressure gauge 5 is used to obtain the pressure in the measuring pipe 1 after the accumulated water is discharged.

[0055] The float assembly 4 is located on the side of the sealing section 31 close to the measuring tube 1, and the float assembly 4 is arranged between the measuring tube 1 and the connecting tube 3, or the float assembly 4 is arranged in the flow channel. Specifically, the float assembly 4 includes a cylinder 41 and a float 42, the cylinder 41 has an inner cavity, the cylinder 41 is connected between the measuring tube 1 and the connecting tube 3, or the outer wall of the cylinder 41 is sealed with the inner wall of the flow channel, preferably, the float assembly 4 is located in the connecting tube 3, wherein the pressure gauge 5 is located on the side of the float assembly 4 away from the sealing section 31, and the pressure gauge 5 is connected to the flow channel to detect the pressure in the flow channel. The float 42 is a lightweight rubber ball, and the density of the float 42 is less than the density of water.

[0056] In this embodiment, the inner cavity is connected to the flow channel, and the cross-sectional size of the inner cavity gradually decreases from the middle to the two ends. The float 42 is arranged in the inner cavity, and the float 42 can move up and down in the inner cavity. The outer diameter of the float 42 is larger than the opening size at both ends of the inner cavity. The size of the upper port 43 of the inner cavity is larger than the size of the lower port 44 of the inner cavity.

[0057] In order to improve the sealing performance, annular grooves are provided on the wall surfaces of the cylinder 41 at both ends of the inner cavity, and sealing rings are provided in the annular grooves. In order to prevent the water level in the sealing section 31 from being too high, causing the float 42 to contact the water in the sealing section 31, in this embodiment, the height H1 of the port at the end of the connecting pipe 3 away from the measuring pipe 1 in the vertical direction is lower than the height H2 of the lower port 44 of the float assembly 4. Therefore, when no water flows out of the upward borehole 6, the water level in the sealing section 31 is lower than the lower port 44 of the inner cavity.

[0058] The float assembly 4 has an open state and a closed state. When water flows from the measuring tube 1 to the connecting tube 3, the float 42 is separated from the lower port 44 of the cylinder 41 under the action of water, and the float assembly 4 is in an open state to make the flow channel conductive. When there is no water in the measuring tube 1, the float 42 falls back to the lower port 44 of the cylinder 41 and is sealed with the cylinder 41, and the float assembly 4 is in a closed state to disconnect the flow channel. The float assembly 4 forms an automatically opened and closed valve in the flow channel.

[0059] In this embodiment, when there is water in the borehole, the water in the borehole enters the measuring tube through the screen tube, and then enters the connecting tube. As the accumulated water continues to increase, the lightweight rubber ball floats up due to the buoyancy, and the accumulated water enters the U-shaped sealing section and is discharged through the drain port of the connecting tube. Since the liquid level in the U-shaped sealing section is lower than the liquid level at the lower port of the cylinder, and the gas pressure in the borehole is greater than the atmospheric pressure, the liquid in the borehole can be smoothly discharged from the connecting tube. There is always liquid in the sealing section to form a liquid seal ring, which ensures the airtightness of the entire device to gas.

[0060] When there is no water in the borehole, coal seam gas enters the measuring tube through the screen tube and then enters the connecting tube. Under the action of gas pressure, the lightweight rubber ball is pressed on the lower port of the cylinder. The greater the pressure, the tighter the contact between the lightweight rubber ball and the lower port. In addition, an O-ring is provided in the lower port, which forms a good sealing device together with the rubber ball, forming the first gas sealing barrier. Even if there is a small amount of gas leakage, it can be sealed by the liquid sealing ring formed by the emulsion poured into the U-shaped sealing section in advance, thereby ensuring the gas sealing of the entire device.

[0061] like Figure 3 As shown, the coal bed gas pressure measuring method of the embodiment of the present invention comprises the following steps:

[0062] S101, drilling an ascending borehole for coal seam gas pressure measurement in the coal seam. According to actual needs, there can be one or more ascending boreholes, for example, multiple ascending boreholes are arranged in an array on the coal seam.

[0063] S102, arranging an automatic drainage device for an ascending borehole as described in any of the above embodiments in the ascending borehole. When there are multiple ascending boreholes, a group of automatic drainage devices for ascending boreholes is arranged in each ascending borehole to measure the gas pressure in each ascending borehole.

[0064] S103, fill the sealing section of the upward borehole automatic drainage device with fluid medium to isolate the inner cavity of the upward borehole from the outside atmosphere. In other words, it is necessary to fill the sealing section of the connecting pipe with fluid medium such as mining emulsion to achieve the plugging and sealing of the connecting pipe. At the same time, a seal is also formed between the float and the cylinder in the float assembly to ensure that the pressure in the upward borehole is not affected by the external air pressure. Even if some gas leaks from the seal between the float and the cylinder, it will be blocked by the fluid medium filled in the sealing section and will not leak out.

[0065] S104, using the pressure gauge in the upward borehole automatic drainage device to obtain the gas pressure parameters in the upward borehole in real time.

[0066] S105. When water flows out of the upward borehole, the water in the upward borehole can be automatically discharged through the upward borehole automatic drainage device.

[0067] In this embodiment, the emulsion is first poured into the U-shaped sealing section, because the evaporation rate of the emulsion is relatively low. If there is no water in the borehole, the emulsion can play a role of liquid sealing. If there is water in the upward borehole, the excess water can be drained out through the upward borehole automatic drainage device of this embodiment. During the whole process, the pressure measurement is always carried out in real time. This embodiment can automatically drain the water in the upward borehole in time, ensuring that the data measured by the pressure gauge in the upward borehole automatic drainage device is true and accurate data, and will not be affected by the water accumulation in the upward borehole.

[0068] This embodiment designs a device and method for draining a borehole for measuring gas pressure in an ascending coal seam. Compared with the solutions in the related art, this embodiment solves the problem that water is left in the ascending borehole, and the volume of the water cannot be accurately measured during the pressure measurement by unloading the meter, which ultimately leads to inaccurate gas pressure measurement results. This embodiment has a simple structure, is light and compact, does not require complex construction technology, is easy to install and disassemble, and is more popular.

[0069] In the description of the present invention, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and should not be understood as a limitation to the present invention.

[0070] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0071] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0072] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0073] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0074] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An automatic drainage device for upward drilling, characterized in that: include: A measuring tube, the measuring tube being arranged in the upward borehole; A packing assembly, the packing assembly being arranged between the upward borehole and the measuring tube to seal a gap between an inner wall of the upward borehole and an outer wall of the measuring tube; A connecting pipe, one end of which is connected to the lower end of the measuring pipe, a flow channel is formed between the measuring pipe and the connecting pipe, the other end of the connecting pipe is opened upward, and the middle of the connecting pipe has a U-shaped sealing section, which is used to be filled with a fluid medium to seal the lower end of the connecting pipe; A float assembly, wherein the float assembly is located on a side of the sealing section close to the measuring tube, the float assembly is arranged between the measuring tube and the connecting tube, or the float assembly is arranged in the flow channel, the float assembly has an open state and a closed state, when water flows from the measuring tube to the connecting tube, the float assembly is in the open state to make the flow channel conductive, and when there is no water in the measuring tube, the float assembly is in the closed state to disconnect the flow channel.

2. The automatic drainage device for upward drilling according to claim 1, characterized in that: The float assembly comprises: A cylinder, wherein the cylinder has an inner cavity, the cylinder is connected between the measuring tube and the connecting tube, or the outer wall of the cylinder is sealed with the inner wall of the flow channel, the inner cavity is communicated with the flow channel, and the cross-sectional size of the inner cavity gradually decreases from the middle to both ends; A float is arranged in the inner cavity, the float can move up and down in the inner cavity, and the outer diameter of the float is larger than the opening size at both ends of the inner cavity.

3. The automatic drainage device for upward drilling according to claim 2, characterized in that: Annular grooves are arranged on the wall surfaces of the cylinder at both ends of the inner cavity, and sealing rings are arranged in the annular grooves.

4. The automatic drainage device for upward drilling according to claim 2, characterized in that: The size of the upper port of the inner cavity is greater than the size of the lower port of the inner cavity.

5. The automatic drainage device for upward drilling according to claim 1, characterized in that: An intermediate tube is provided between the measuring tube and the connecting tube, and the connecting tube is hung on a circumferential structure; And / or, the sealing section is filled with water or emulsion.

6. The automatic drainage device for upward drilling according to claim 1, characterized in that: A pressure gauge is also included. The pressure gauge is located on a side of the float assembly away from the sealing section. The pressure gauge is connected to the flow channel to detect the pressure in the flow channel.

7. The automatic drainage device for upward drilling according to claim 6, characterized in that: The connecting tube has a first connecting port and a second connecting port at one end close to the measuring tube, the first connecting port is connected to the measuring tube, the second connecting port is connected to the pressure gauge, and the float assembly is located in the connecting tube.

8. The automatic drainage device for upward drilling according to claim 7, characterized in that: The height of the port of the connecting pipe away from the end of the measuring pipe in the vertical direction is lower than the height of the lower port of the float assembly.

9. The automatic drainage device for upward drilling according to claim 1, characterized in that: It also includes a screen tube, which is connected to one end of the measuring tube away from the connecting tube, and is used to filter the fluid flowing into the measuring tube.

10. A method for measuring coal seam gas pressure, characterized in that: The following steps are involved: Drilling upholes in and out of coal seams for coal seam gas pressure measurement; Arranging an automatic drainage device for an upward borehole as claimed in any one of claims 1 to 9 in the upward borehole; Filling a fluid medium in the sealing section of the upward borehole automatic drainage device to isolate the inner cavity of the upward borehole from the external atmosphere; Using the pressure gauge in the upward borehole automatic drainage device to obtain the gas pressure parameters in the upward borehole in real time; When water flows out of the upward borehole, the water in the upward borehole can be automatically discharged through the upward borehole automatic drainage device.

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