An internal circulation self-balancing coal seam gas parameter measuring device and method

Abstract

The present application belongs to the technical field of coal mine gas measurement. It relates to a kind of inner circulation self-balancing coal seam gas parameter measuring device and method, including inflation device, measuring device, sealing air bag and two steel pipes. The inflation device is connected with the sealing air bag through high-pressure hose. One end of the two steel pipes is equipped with a one-way valve, and the end extends into the closed air chamber from the sealing air bag outside the borehole. The other end of the two steel pipes is connected through high-pressure hose, forming a U-shaped channel that is unidirectionally communicated with the closed air chamber. The free gas desorbed from the coal body into the closed air chamber flows along the U-shaped channel until the circulating gas pressure reaches the desorption equilibrium pressure of coal seam gas. Based on the flow decay model in the process of borehole gas internal circulation self-balancing, and using automatic devices such as multi-channel parameter measuring instrument and storage pressure gauge as means, the present application realizes the integrated rapid measurement of coal seam gas pressure, borehole initial gas emission, borehole gas flow decay coefficient and coal seam permeability coefficient.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas measurement technology, and relates to an internal circulation self-balancing coal seam gas parameter measuring device and method. Background Technology

[0002] Currently, the most convenient and fastest method for measuring underground gas parameters is the DGC gas content measuring device. However, for coal seam gas pressure, initial borehole flow rate, and the permeability coefficient and borehole gas flow rate attenuation coefficient, which need to be indirectly calculated from the aforementioned parameters, a more traditional method is used: first, the coal seam gas pressure is measured, and then other parameters are calculated manually after the measurement is completed. There are two traditional methods for measuring coal seam gas pressure: active pressure measurement and passive pressure measurement. Passive pressure measurement has a long time cycle, while active pressure measurement cannot accurately predict the amount of gas injected, leading to uncertainties in the measurement cycle and accuracy. Both methods require significant manpower and resources for initial work such as grouting and sealing the borehole. After the pressure measurement is completed, a flow meter is installed to observe the change in borehole gas flow rate over time, further extending the entire work cycle. Summary of the Invention

[0003] In view of this, the present invention addresses the shortcomings of the prior art by providing an internal circulation self-balancing coal seam gas parameter measuring device and method.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] An internal circulation self-balancing coal seam gas parameter measuring device includes an air filling device, a measuring device, a sealing airbag, and two steel pipes.

[0006] The inflation device is connected to the sealing airbag via a high-pressure hose. The sealing airbag is placed in the coal seam borehole and is inflated to seal one end of the borehole, forming a closed air chamber inside the borehole. One end of each of the two steel pipes is equipped with a one-way valve, and this end extends from outside the borehole through the sealing airbag into the closed air chamber. The other ends of the two steel pipes are connected via a high-pressure hose, forming a U-shaped channel that communicates unidirectionally with the closed air chamber. The measuring device is located on the high-pressure hose connecting the two steel pipes and is used to detect the gas flow rate and pressure.

[0007] The free gas desorbed from the coal into the closed gas chamber circulates along the U-shaped channel until the pressure of the circulating gas reaches the equilibrium pressure of coal seam gas desorption.

[0008] Furthermore, the measuring device includes a storage pressure gauge, a multi-channel parameter measuring instrument, and a digital display system; the storage pressure gauge and the multi-channel parameter measuring instrument are both mounted on the high-pressure hose and are used to detect the gas pressure and flow rate within the U-shaped channel, respectively; the storage pressure gauge and the multi-channel parameter measuring instrument are both connected to the digital display system, which records and displays the detection results.

[0009] Furthermore, at least two of the sealing airbags are provided inside the borehole.

[0010] Furthermore, a valve is installed on the high-pressure hose connecting the two steel pipes to control the opening and closing of the U-shaped channel.

[0011] A method for determining coal seam gas parameters using an internal circulation self-balancing system includes the following steps:

[0012] The first step is to construct boreholes for measuring coal seam gas parameters: the borehole diameter and depth are determined in accordance with the standard "Direct Measurement Method of Coal Seam Gas Pressure in Underground Coal Mines".

[0013] The second step is to install the aforementioned internal circulation self-balancing coal seam gas parameter measuring device: After the coal seam gas parameter measuring borehole is completed, the uninflated sealing airbag and steel pipe are lowered into the borehole, with a reserved sealed air chamber length of not less than 2m.

[0014] The third step is to connect the device: connect the inflation device to the high-pressure hose on the sealing airbag, connect the two steel pipes through the high-pressure hose, and install the measuring device on the high-pressure hose between the two steel pipes.

[0015] Step 4: Inflate the sealing airbag: Open the inflation device to inflate the sealing airbag, seal the drill hole, and form a closed air chamber;

[0016] Step 5: Automatic data observation and statistics: Turn on the multi-channel parameter measuring instrument and the storage pressure gauge, and the measuring device will automatically observe and statistically analyze the data.

[0017] Step 6, Measurement and Acquisition of Coal Seam Gas Parameters: As free gas continuously circulates within the steel pipe until the gas pressure reaches equilibrium, the gas pressure within the measurement system gradually stabilizes. The stable pressure value recorded by the storage pressure gauge is the coal seam gas pressure in the target area. Simultaneously, the multi-channel parameter measuring instrument automatically records the instantaneous gas flow rate at different times. Recording automatically stops when the flow rate continuously decays to zero. Data is fitted according to the flow rate decay model during the borehole gas internal circulation self-balancing process, and then the borehole gas flow rate decay coefficient α and the initial borehole gas flow rate q0 can be obtained. Then, the coal seam permeability coefficient is calculated according to the coal seam permeability coefficient calculation method.

[0018] Furthermore, the flow rate decay model during the self-balancing process of borehole gas internal circulation is as follows:

[0019] q t =ξ·q0·e -αt

[0020] Where, q t The borehole gas flow rate after time t is m3 / min; α is the borehole gas flow rate attenuation coefficient, d -1 q0 is the initial gas flow rate in the borehole, in m 3 / min; t is time, d; ξ is the model correction coefficient.

[0021] Furthermore, the method for obtaining the flow decay model during the self-balancing process of borehole gas internal circulation is as follows: in areas where gas is stored in the same coal seam, the flow decay law under natural conditions and the flow decay law during the self-balancing process of borehole gas internal circulation are measured respectively. The relationship between the two flow decay laws is compared to obtain the model correction coefficient ξ. Then, the model correction coefficient ξ is substituted into the known decay model under natural conditions to correct and obtain the flow decay model during the self-balancing process of borehole gas internal circulation.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) This invention establishes a unidirectional U-shaped channel and utilizes the continuous desorption of coal gas. The gas pressure gradient formed between the U-shaped channels in the borehole causes the desorbed free gas to continuously circulate along the U-shaped channel until the circulating gas pressure reaches the coal seam gas desorption equilibrium pressure, thereby measuring the coal seam gas pressure.

[0024] (2) Based on the known attenuation model under natural conditions, this invention obtains the flow attenuation model in the self-balancing process of borehole gas internal circulation by modification, and combines automatic measurement methods such as multi-channel parameter measuring instrument and storage pressure gauge to realize the integrated rapid measurement of coal seam gas pressure, initial borehole gas outflow, borehole gas flow attenuation coefficient and coal seam permeability coefficient.

[0025] (3) The device in this invention can be reused, saving the cost of measuring coal seam gas parameters. At the same time, since it is a closed measurement, it can effectively prevent alarm over-limit problems caused by large gas outflow from the borehole during the measurement process.

[0026] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0028] Figure 1 This is a schematic diagram of the internal circulation self-balancing coal seam gas parameter measuring device of the present invention.

[0029] Figure 2 for Figure 1 A magnified view of a portion of the image.

[0030] Reference numerals: 1-Inflation device; 2-Storage pressure gauge; 3-Multi-channel parameter measuring instrument; 4-Valve; 5-High-pressure hose; 6-Reducing joint; 7-Steel pipe; 8-Sealing airbag; 9-Sealed air chamber; 10-One-way valve; 11-Coal body; 12-Drill hole; 13-Digital display system. Detailed Implementation

[0031] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0032] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0033] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0034] Please see Figures 1-2This is an internal circulation self-balancing coal seam gas parameter measuring device, comprising an air filling device 1, a measuring device, a sealing airbag 8, and two steel pipes 7. The air filling device 1 is connected to the sealing airbag 8 via a high-pressure hose 5. The sealing airbag 8 is located in a coal seam borehole 12. By filling the borehole with air, one end of the borehole 12 is sealed, forming a closed gas chamber 9 inside the borehole 12. One-way valves 10 are installed at one end of each of the two steel pipes 7, and this end extends from outside the borehole 12 through the sealing airbag 8 into the closed gas chamber 9. The other ends of the two steel pipes 7 are each equipped with a reducing joint 6. The two reducing joints 6 are connected by the high-pressure hose 5, forming a U-shaped channel that is unidirectionally connected to the closed gas chamber 9. A valve 4 is also installed on the high-pressure hose 5 connecting the two steel pipes 7 to control the opening and closing of the U-shaped channel.

[0035] The measuring device is installed on the high-pressure hose 5 connecting the two steel pipes 7, and is used to detect the gas flow and pressure; the free gas desorbed into the closed gas chamber 9 by the coal body 11 circulates along the U-shaped channel until the pressure of the circulating gas reaches the coal seam gas desorption equilibrium pressure.

[0036] In this embodiment, the measuring device includes a storage pressure gauge 2, a multi-channel parameter measuring instrument 3, and a digital display system 13. The storage pressure gauge 2 and the multi-channel parameter measuring instrument 3 are both mounted on the high-pressure hose 5 and are used to detect the gas pressure and flow rate in the U-shaped channel, respectively. The storage pressure gauge 2 and the multi-channel parameter measuring instrument 3 are both connected to the digital display system 13, and the detection results are recorded and displayed through the digital display system 13.

[0037] In this embodiment, two sealing airbags 8 are installed inside the drill hole 12.

[0038] A method for determining coal seam gas parameters using an internal circulation self-balancing system includes the following steps:

[0039] The first step is to construct borehole 12 for measuring coal seam gas parameters: the borehole diameter and depth of borehole 12 are determined in accordance with the standard "Direct Measurement Method of Coal Seam Gas Pressure in Underground Coal Mines"; the borehole diameter of borehole 12 is 94mm, the borehole inclination angle of borehole 12 is +6°, and the borehole depth of borehole 12 is 52m.

[0040] The second step is to install the aforementioned internal circulation self-balancing coal seam gas parameter measuring device: After the coal seam gas parameter measuring borehole 12 is completed, before lowering it, it is necessary to check whether the one-way valve 10 located at the end of the steel pipe 7 is installed properly and correctly. The installation direction of the one-way valve 10 should be consistent with the gas flow direction marked in the figure. The sealing depth is 50m. The uninflated sealing airbag 8 and the steel pipe 7 are lowered into the borehole 12. The inner sealing airbag 8 is 2m away from the bottom of the hole, and the outer airbag is 1m away from the opening of the hole.

[0041] Step 3: Connect the device. Connect the inflation device 1 to the high-pressure hose 5 on the sealing airbag 8. Connect the two steel pipes 7 through the high-pressure hose 5. At the same time, install the measuring device on the high-pressure hose 5 between the two steel pipes 7.

[0042] Step 4: Inflate the sealing airbag 8. Open the inflation device 1 to inflate the sealing airbag 8, sealing the drill hole 12 and forming a closed air chamber 9. During inflation, the sealing airbag 8 expands sequentially from the outside to the inside until the pressure data of the inflation device 1 no longer increases. After inflation is complete, use a portable instrument to check for air leakage at the hole opening. If leakage is found, the number of sealing airbags 8 should be increased.

[0043] Step 5: Automatic data observation and statistics: Turn on the multi-channel parameter measuring instrument 3 and the storage pressure gauge 2, and the measuring device will automatically observe and statistically analyze the data.

[0044] Step 6, Measurement and Acquisition of Coal Seam Gas Parameters: As free gas continuously circulates within steel pipe 7 until the gas pressure reaches equilibrium, the gas pressure within the measurement system gradually stabilizes. The stable pressure value recorded by the storage pressure gauge 2 is the coal seam gas pressure in the target area. Simultaneously, the multi-channel parameter measuring instrument 3 automatically records the instantaneous gas flow rate at different times. Recording automatically stops when the flow rate continuously decreases to zero. Data is fitted according to the flow rate attenuation model during the gas internal circulation self-balancing process in borehole 12, and then the gas flow rate attenuation coefficient α and the initial gas flow rate q0 of borehole 12 can be obtained. Then, the coal seam permeability coefficient is calculated according to the coal seam permeability coefficient calculation method.

[0045] The flow rate attenuation model during the self-balancing process of internal gas circulation in borehole 12 is as follows:

[0046] q t =ξ·q0·e -αt

[0047] Where, q t The borehole gas flow rate after time t is m. 3 / min; α is the gas flow rate attenuation coefficient of borehole 12, d -1 q0 is the initial gas flow rate in borehole 12, in m³. 3 / min; t is time, d; ξ is the model correction coefficient.

[0048] The method for obtaining the flow decay model during the self-balancing process of gas internal circulation b in borehole 12 is as follows: In areas where gas is stored in the same coal seam, the flow decay law under natural conditions and the flow decay law during the self-balancing process of gas internal circulation in borehole 12 are measured respectively. The relationship between the two flow decay laws is compared to obtain the model correction coefficient ξ. Then, the model correction coefficient ξ is substituted into the known decay model under natural conditions to correct and obtain the flow decay model during the self-balancing process of gas internal circulation in borehole 12.

[0049] This invention can achieve integrated and rapid measurement of coal seam gas pressure, initial borehole gas emission, borehole gas flow attenuation coefficient, and coal seam permeability coefficient in a short time, greatly improving the efficiency of coal seam gas parameter measurement.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A self-balancing internal circulation coal seam gas parameter measuring device, characterized in that: It includes an inflation device, a measuring device, a sealing airbag, and two steel pipes; The inflation device is connected to the sealing airbag via a high-pressure hose. The sealing airbag is placed in the coal seam borehole and is inflated to seal one end of the borehole, forming a closed air chamber inside the borehole. One end of each of the two steel pipes is equipped with a one-way valve, and this end extends from outside the borehole through the sealing airbag into the closed air chamber. The other ends of the two steel pipes are connected via a high-pressure hose, forming a U-shaped channel that communicates unidirectionally with the closed air chamber. The measuring device is located on the high-pressure hose connecting the two steel pipes and is used to detect the gas flow rate and pressure. The free gas desorbed from the coal into the closed gas chamber circulates along the U-shaped channel until the pressure of the circulating gas reaches the equilibrium pressure of coal seam gas desorption.

2. The internal circulation self-balancing coal seam gas parameter measuring device according to claim 1, characterized in that: The measuring device includes a storage pressure gauge, a multi-channel parameter measuring instrument, and a digital display system. The storage pressure gauge and the multi-channel parameter measuring instrument are both mounted on the high-pressure hose and are used to detect the gas pressure and flow rate within the U-shaped channel, respectively. The storage pressure gauge and the multi-channel parameter measuring instrument are both connected to the digital display system, which records and displays the detection results.

3. The internal circulation self-balancing coal seam gas parameter measuring device according to claim 1, characterized in that: At least two sealing airbags are provided inside the borehole.

4. The internal circulation self-balancing coal seam gas parameter measuring device according to claim 1, characterized in that: A valve is also installed on the high-pressure hose connecting the two steel pipes to control the opening and closing of the U-shaped channel.

5. A method for determining coal seam gas parameters using an internal circulation self-balancing system, characterized in that, Includes the following steps: The first step is to construct boreholes for measuring coal seam gas parameters: the borehole diameter and depth are determined in accordance with the standard "Direct Measurement Method of Coal Seam Gas Pressure in Underground Coal Mines". The second step is to install the internal circulation self-balancing coal seam gas parameter measuring device as described in any one of claims 1 to 4: after the coal seam gas parameter measuring borehole is completed, the uninflated sealing airbag and steel pipe are lowered into the borehole, with a reserved sealing air chamber length of not less than 2m. The third step is to connect the device: connect the inflation device to the high-pressure hose on the sealing airbag, connect the two steel pipes through the high-pressure hose, and install the measuring device on the high-pressure hose between the two steel pipes. Step 4: Inflate the sealing airbag: Open the inflation device to inflate the sealing airbag, seal the drill hole, and form a closed air chamber; Step 5: Automatic data observation and statistics: Turn on the multi-channel parameter measuring instrument and the storage pressure gauge, and the measuring device will automatically observe and statistically analyze the data. Step 6, Measurement and Acquisition of Coal Seam Gas Parameters: As free gas continuously circulates within the steel pipe until the gas pressure reaches equilibrium, the gas pressure within the measurement system gradually stabilizes. The stable pressure value recorded by the storage pressure gauge is the coal seam gas pressure in the target area. Simultaneously, the multi-channel parameter measuring instrument automatically records the instantaneous gas flow rate at different times. Recording automatically stops when the flow rate continuously decays to zero. Data is fitted according to the flow rate decay model during the borehole gas internal circulation self-balancing process, and then the borehole gas flow rate decay coefficient α and the initial borehole gas flow rate q0 can be obtained. Then, the coal seam permeability coefficient is calculated according to the coal seam permeability coefficient calculation method.

6. The method for determining coal seam gas parameters using an internal circulation self-balancing system according to claim 5, characterized in that: The flow rate attenuation model during the self-balancing process of borehole gas internal circulation is as follows: what t =ξ·q0·e -αt Where, q t The borehole gas flow rate after time t is m 3 / min; α is the borehole gas flow rate attenuation coefficient, d -1 q0 is the initial gas flow rate in the borehole, in m 3 / min; t is time, d; ξ is the model correction coefficient.

7. The method for determining coal seam gas parameters using an internal circulation self-balancing system according to claim 6, characterized in that, The method for obtaining the flow decay model during the self-balancing process of borehole gas internal circulation is as follows: In areas with the same coal seam gas occurrence, the flow decay law under natural conditions and the flow decay law during the self-balancing process of borehole gas internal circulation are measured respectively. The relationship between the two flow decay laws is compared to obtain the model correction coefficient ξ. Then, the model correction coefficient ξ is substituted into the known decay model under natural conditions to correct and obtain the flow decay model during the self-balancing process of borehole gas internal circulation.

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