Inspection Method and Detection Equipment for Sealing Quality of Gas Drainage Boreholes

Abstract

An embodiment of the present invention provides a method and a detection device for inspecting the sealing quality of a gas drainage borehole. The method for inspecting the sealing quality of the gas drainage borehole includes obtaining an estimated value P0' of the original gas pressure of the coal seam; connecting the detection device to the borehole; introducing gas into the borehole through the detection device until the pressure in the borehole reaches P1, and then stopping introducing gas, where P1 is 0.4 to 0.8 times of P0'; obtaining the pressure change in the borehole after stopping introducing gas until the pressure change is less than 0.015 MPa within 2 to 4 consecutive days, then stopping obtaining the pressure change, and obtaining a pressure change curve according to the pressure change; and judging whether the sealing quality of the borehole is qualified according to the line type of the pressure change curve. The method for inspecting the sealing quality of the gas drainage borehole in the embodiment of the present invention judges whether the sealing quality of the borehole is qualified according to the line type of the obtained pressure change curve of the borehole, making the inspection result more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of mining, and particularly relates to a method for inspecting the sealing quality of gas drainage boreholes and a detection device. Background Art

[0002] Gas drainage is to drill boreholes into coal seams and gas accumulation areas, connect the boreholes to special pipelines, and use drainage equipment to drain the gas in the coal seams and goafs to the ground for utilization or discharge into the total return air current. By draining gas, the gas emission volume during mining can be reduced, gas overrun and accumulation can be prevented, and gas explosion and coal and gas outburst accidents can be prevented.

[0003] The sealing quality of gas drainage boreholes is the key to ensuring the gas drainage effect. In related technologies, in order to obtain the sealing quality of gas drainage boreholes, first, gas is supplied into the borehole, and then the value after the pressure stabilizes is obtained through a pressure gauge. This value is compared with a fixed judgment value of 0.05 MPa. If the measured value is greater than or equal to 0.05 MPa, the sealing quality is considered qualified. However, this inspection method ignores the influence of the original gas pressure of the coal seam and the maximum gas pressure that the borehole can seal on the sealing quality of the borehole, resulting in a large error between the inspection result and the actual sealing quality. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related technologies to some extent. For this purpose, an embodiment of the present invention provides a method for inspecting the sealing quality of gas drainage boreholes. The inspection method determines whether the sealing quality of the borehole is qualified according to the line type of the obtained pressure change curve of the borehole, making the inspection result more accurate.

[0005] An embodiment of the present invention also provides a detection device.

[0006] The method for inspecting the sealing quality of gas drainage boreholes according to the embodiment of the present invention includes:

[0007] Obtain an estimated value P0' of the original gas pressure of the coal seam;

[0008] Connect the detection device to the borehole;

[0009] Pass gas into the borehole through the detection device until the pressure in the borehole reaches an initial pressure P1, and stop passing the gas. The P1 is 0.4 times to 0.8 times of the P0';

[0010] After stopping passing the gas, start obtaining the pressure change in the borehole until the pressure change is less than 0.015 MPa continuously for 2 to 4 days, stop obtaining the pressure change, and obtain a pressure change curve according to the pressure change;

[0011] If in the pressure change curve, the pressure first decreases from P1 with the increase of time, then increases to a first fixed value or approaches the first fixed value, or the pressure first decreases from P1 with the increase of time, then increases to a peak value, and then decreases from the peak value to a second fixed value or approaches the second fixed value, and the second fixed value is greater than P1, or the pressure decreases from P1 to a third fixed value or approaches the third fixed value with the increase of time, then the sealing quality of the borehole is qualified.

[0012] If in the pressure change curve, the pressure decreases from P1 and approaches 0 MPa with the increase of time, then the sealing quality of the borehole is unqualified.

[0013] The inspection method for the sealing quality of the gas drainage borehole in the embodiment of the present invention obtains the pressure change curve within the time period when the pressure change of the borehole is less than 0.015 MPa continuously for 2 to 4 days after stopping the gas injection, and judges whether the sealing quality of the borehole is qualified according to the line type of the pressure change curve, making the inspection result more accurate.

[0014] In some embodiments, the borehole is located in the first working face of the coal seam, and P0’ is the measured average value of the gas pressure measurement points in the first working face, or P0’ is the measured average value of the gas pressure measurement points in the second working face of the coal seam.

[0015] In some embodiments, after stopping the gas injection, the pressure change in the borehole is obtained until the pressure change is less than 0.015 MPa continuously for 3 days, and then the pressure change acquisition is stopped.

[0016] In some embodiments, the third fixed value is greater than 0.1 MPa;

[0017] When the sealing quality of the borehole is unqualified, in the pressure change curve, the pressure decreases from P1 to less than 0.1 MPa with the increase of time.

[0018] In some embodiments, P1 is 0.5 times of P0’.

[0019] In some embodiments, the inspection method for the sealing quality of the gas drainage borehole further includes:

[0020] When the sealing quality of the borehole is unqualified, another borehole is drilled in the coal seam working face where the borehole is located, and the pressure change curve of the other borehole is obtained.

[0021] In some embodiments, the inspection method for the sealing quality of the gas drainage borehole further includes:

[0022] After connecting the detection device to the borehole, use soapy water to detect the airtightness of the detection device. When the airtightness of the detection device is qualified, introduce gas into the borehole through the detection device.

[0023] The detection device according to an embodiment of the present invention includes:

[0024] A borehole drainage pipe for extending into the borehole and sealingly connecting with the borehole;

[0025] An inflation device communicated with the borehole drainage pipe for supplying gas to the borehole drainage pipe;

[0026] A pressure acquisition device connected to the borehole drainage pipe for acquiring the pressure in the borehole.

[0027] The detection device according to an embodiment of the present invention supplies gas into the borehole through the inflation device and the borehole drainage pipe, and acquires the pressure change in the borehole through the borehole drainage pipe and the pressure acquisition device, so as to be able to inspect the sealing quality of the borehole through the detection device according to an embodiment of the present invention, thereby obtaining a more accurate inspection result through the inspection method for the sealing quality of the gas drainage borehole according to an embodiment of the present invention.

[0028] In some embodiments, the detection device further includes:

[0029] A multi-way joint having a first interface, a second interface, and a third interface. The first interface is communicated with the borehole drainage pipe, the second interface is communicated with the inflation device, and the third interface is communicated with the pressure acquisition device;

[0030] A first switching valve provided between the second interface and the inflation device for controlling the opening and closing of the second interface and the inflation device.

[0031] In some embodiments, the detection device further includes:

[0032] A gas drainage pipe. The multi-way joint further has a fourth interface, and the gas drainage pipe is communicated with the fourth interface;

[0033] A second switching valve provided between the gas drainage pipe and the fourth interface for controlling the opening and closing of the gas drainage pipe and the fourth interface. Description of the Drawings

[0034] Figure 1 is a schematic structural diagram of the detection device according to an embodiment of the present invention;

[0035] Figure 2 is the first pressure change curve according to an embodiment of the present invention;

[0036] Figure 3 is the second pressure change curve of the embodiment of the present invention;

[0037] Figure 4 is the third pressure change curve of the embodiment of the present invention;

[0038] Figure 5 is the fourth pressure change curve of the embodiment of the present invention;

[0039] Figure 6 is the fifth pressure change curve of the embodiment of the present invention;

[0040] Figure 7 is the sixth pressure change curve of the embodiment of the present invention.

[0041] Reference numerals:

[0042] 1. Borehole; 2. Borehole drainage pipe; 3. Inflation device; 4. Pressure acquisition device; 5. Multi-way joint; 6. First shut-off valve; 7. Gas drainage pipe; 8. Second shut-off valve; 9. Sealing section. Detailed implementation manners

[0043] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] Below, refer to the attached Figure 1 - attached Figure 7 Describe a method for inspecting the sealing quality of a gas drainage borehole and a detection device according to an embodiment of the invention.

[0045] As Figure 1 shown, the detection device of the embodiment of the present invention includes a borehole drainage pipe 2, an inflation device 3 and a pressure acquisition device 4.

[0046] The borehole drainage pipe 2 is used to extend into the borehole 1 and be sealingly connected to the borehole 1. Specifically, as Figure 1 shown, a borehole 1 is drilled in the coal seam working face. One end of the borehole drainage pipe 2 extends into the borehole 1. A sealing section 9 formed of a sealing material is provided in the borehole 1. The sealing section 9 surrounds the outer wall surface of the borehole drainage pipe 2 to sealingly connect the borehole drainage pipe 2 and the borehole 1.

[0047] The inflation device 3 is communicated with the borehole drainage pipe 2 to supply gas to the borehole drainage pipe 2. Specifically, as Figure 1 shown, the other end of the borehole drainage pipe 2 extends out of the borehole 1. The inflation device 3 is communicated with the other end of the borehole drainage pipe 2 so that the gas generated by the inflation device 3 is supplied into the borehole 1 through the borehole drainage pipe 2. Preferably, the inflation device 3 is an air pump.

[0048] The pressure acquisition device 4 is connected to the borehole drainage pipe 2 for acquiring the pressure inside the borehole 1. Specifically, as Figure 1 shown, the pressure acquisition device 4 communicates with the other end of the borehole drainage pipe 2 to acquire the pressure inside the borehole drainage pipe 2 through the pressure acquisition device 4, and further acquire the pressure inside the borehole 1. Preferably, the pressure acquisition device 4 is a pressure gauge or an on-line pressure monitoring device.

[0049] The detection device according to the embodiment of the present invention provides gas into the borehole through the inflation device and the borehole drainage pipe, and acquires the pressure change inside the borehole through the borehole drainage pipe and the pressure acquisition device, so as to be able to inspect the sealing quality of the borehole through the detection device according to the embodiment of the present invention, and thus obtain a more accurate inspection result through the inspection method for the sealing quality of the gas drainage borehole according to the embodiment of the present invention.

[0050] In some embodiments, the detection device according to the embodiment of the present invention further includes a multi-way joint 5 and a first switching valve 6. The multi-way joint 5 has a first interface, a second interface and a third interface. The first interface communicates with the borehole drainage pipe 2, the second interface communicates with the inflation device 3, and the third interface communicates with the pressure acquisition device 4. The first switching valve 6 is arranged between the second interface and the inflation device 3 for controlling the opening and closing of the second interface and the inflation device 3.

[0051] As Figure 1 shown, the multi-way joint 5 has a first interface, a second interface and a third interface. The first interface directly communicates with the other end of the borehole drainage pipe 2, the second interface communicates with the inflation device 3 through a hose, the third interface directly communicates with the pressure acquisition device 4, and the first switching valve 6 is arranged on the hose for controlling the opening and closing of the second interface and the inflation device 3. When the first switching valve 6 is opened, the gas generated by the inflation device 3 can enter the borehole drainage pipe 2 through the multi-way joint 5. When the first switching valve 6 is closed, the gas generated by the inflation device 3 cannot enter the borehole drainage pipe 2, and the gas inside the borehole drainage pipe 2 cannot return to the inflation device 3 either, so that the borehole 1 will not relieve pressure.

[0052] It can be understood that the structure of the detection device is not limited to having a multi-way joint. In other embodiments, the inflation device directly communicates with the other end of the borehole drainage pipe or communicates through a pipeline. A switching valve is arranged between the inflation device and the other end of the borehole drainage pipe, and the pressure acquisition device is arranged at the other end of the borehole drainage pipe.

[0053] In some embodiments, the detection device according to the embodiment of the present invention further includes a gas drainage pipe 7 and a second switching valve 8. The multi-way joint 5 further has a fourth interface, and the gas drainage pipe 7 communicates with the fourth interface. The second switching valve 8 is arranged between the gas drainage pipe 7 and the fourth interface for controlling the opening and closing of the gas drainage pipe 7 and the fourth interface.

[0054] AsFigure 1 As shown, a gas drainage pipe 7 is provided in the underground roadway. The multi-way joint 5 also has a fourth interface, which is connected to the gas drainage pipe 7. A second shut-off valve 8 is provided between the fourth interface and the gas drainage pipe 7. When the second shut-off valve 8 is opened, the fourth interface is connected to the gas drainage pipe 7. Since there is a certain negative pressure or low pressure in the gas drainage pipe 7, the gas in the borehole 1 can be extracted and discharged through the borehole drainage pipe 2. When the second shut-off valve 8 is closed, when the fourth interface is closed to the gas drainage pipe 7, the gas generated by the inflating device 3 can completely enter the borehole drainage pipe 2 through the multi-way joint 5. At the same time, the gas in the borehole drainage pipe 2 cannot enter the gas drainage pipe 7, so that the borehole 1 will not relieve pressure.

[0055] It can be understood that the structure of the detection device is not limited to Figure 1 As shown, in some other embodiments, the gas drainage pipe and the inflating device are respectively detachably connected to the borehole drainage pipe. When gas needs to be provided to the borehole, the inflating device is connected to the borehole drainage pipe. When the gas in the borehole needs to be discharged, the borehole drainage pipe is connected to the borehole drainage pipe.

[0056] It can be understood that the multi-way joint, the first shut-off valve and the second shut-off valve can also be a four-way valve.

[0057] Such as Figures 1-7 As shown, the method for inspecting the sealing quality of the gas drainage borehole in the embodiment of the present invention includes:

[0058] Obtain the estimated value P0' of the original gas pressure of the coal seam.

[0059] Connect the detection device to the borehole 1. Specifically, as Figure 1 shown, one end of the borehole drainage pipe 2 is extended into the borehole 1, and the borehole drainage pipe 2 and the borehole 1 are hermetically connected through the sealing section 9.

[0060] Pass gas into the borehole 1 through the detection device until the pressure in the borehole 1 reaches the initial pressure P1, and then stop passing gas. P1 is 0.4 times to 0.8 times of P0'. Specifically, as Figure 1 shown, open the first shut-off valve 6 and close the second shut-off valve 8, then start the inflating device 3 to pass gas into the borehole 1. The gas is preferably air or nitrogen. Obtain the pressure in the borehole 1 through the pressure acquisition device 4. When the pressure obtained by the pressure acquisition device 4 reaches the initial pressure P1, turn off the inflating device 3 and close the first shut-off valve 6 to stop passing gas into the borehole 1. P1 is 0.4 times to 0.8 times of P0', preferably 0.5 times.

[0061] After stopping the introduction of gas, the pressure change in the borehole 1 is obtained, until the pressure change is less than 0.015MPa for 2 to 4 consecutive days, then the pressure change is stopped, and a pressure change curve is obtained based on the pressure change. Specifically, after stopping the introduction of gas, the pressure change in the borehole 1 is observed and obtained through the pressure acquisition device 4 of the detection equipment, and the observation is stopped when it is found that the pressure change is less than 0.015MPa for 2 to 4 consecutive days, and then the pressure change curve is obtained based on the observed pressure change. Since the time when the pressure change is less than 0.015MPa for 2 to 4 consecutive days is uncertain, the time period from the beginning of obtaining the pressure change to the end of obtaining the pressure change is uncertain, which may be 2 to 4 consecutive days, or as long as 10 days or 15 days. Preferably, when obtaining the pressure change, the observation is stopped when it is found that the pressure change is less than 0.015MPa for 3 consecutive days.

[0062] If in the pressure change curve, the pressure first decreases from P1 as time increases, and then increases to the first fixed value or approaches the first fixed value, or the pressure first decreases from P1 as time increases, and then increases to a peak value, and then decreases from the peak value to a second fixed value or approaches the second fixed value, and the second fixed value is greater than P1, or the pressure decreases from P1 to a third fixed value or approaches the third fixed value as time increases, then the sealing quality of borehole 1 is qualified; if in the pressure change curve, the pressure decreases from P1 as time increases and approaches 0 MPa, then the sealing quality of borehole 1 is unqualified.

[0063] Specifically, Figure 2 In the pressure variation curve, the pressure first decreases from P1 as time increases, and then increases to the first fixed value or approaches the first fixed value. Figure 2 The first fixed value in is greater than P1. This indicates that the coal rock cracks around borehole 1 are not developed. After the gas is introduced into borehole 1, the gas first seeps into the gas pressure relief area of ​​the coal body around borehole 1. Therefore, the pressure first decreases from P1 as time increases. At the same time, the gas in the unpressure relief area of ​​the coal body forms a radial flow field and flows toward borehole 1. Therefore, the pressure increases to the actual value of the original gas pressure of the coal seam as the first fixed value, P0, or approaches P0. At this time, the maximum gas pressure that can be sealed by borehole 1 is Pmax>P0>P1, and the sealing quality of borehole 1 is higher than the qualified standard.

[0064] like Figure 3 As shown in the pressure variation curve, the pressure first decreases from P1 with the increase of time, and then increases to the first fixed value or approaches the first fixed value. Figure 3The first fixed value in it is less than P1. This indicates that the fractures in the coal and rock mass around Borehole 1 are not well-developed. After gas is introduced into Borehole 1, the gas first seeps into the gas pressure-relief zone of the coal around Borehole 1. Therefore, the pressure first decreases from P1 with the increase of time. At the same time, the gas in the unpressurized area of the coal mass forms a radial flow field flowing towards Borehole 1. Therefore, the pressure increases again to the actual value P0 of the original gas pressure of the coal seam or approaches P0. At this time, P1 > Pmax > P0, and the sealing quality of Borehole 1 is higher than the qualified standard.

[0065] As Figure 4 shown, in the pressure change curve, the pressure first decreases from P1 with the increase of time, then increases to the peak value, and then decreases from the peak value to the second fixed value or approaches the second fixed value, and the second fixed value is greater than P1. This indicates that after gas is introduced into Borehole 1, the gas first seeps into the gas pressure-relief zone of the coal around Borehole 1. Therefore, the pressure first decreases from P1 with the increase of time. At the same time, the gas in the unpressurized area of the coal mass forms a radial flow field flowing towards Borehole 1, and the pressure turns to increase again. When the pressure increases to be greater than the maximum gas pressure Pmax that Borehole 1 can seal, the seal of Borehole 1 fails, and part of the gas leaks from the seal. In other words, part of the gas leaks from the fractures of the seal section 9. Therefore, the pressure decreases from the peak value to Pmax as the second fixed value or approaches Pmax. At this time, P0 > Pmax > P1, and the sealing quality of Borehole 1 meets the qualified standard.

[0066] As Figure 5 shown, in the pressure change curve, the pressure decreases from P1 to the third fixed value or approaches the third fixed value with the increase of time. This indicates that after gas is introduced into Borehole 1, the gas first compensates for the gas pressure in the pressure-relief zone of the coal around Borehole 1, and then gradually migrates to the unpressurized area. Therefore, the pressure first decreases to P0, but since Pmax < P0, part of the gas is lost through the fractures of the seal section 9. Therefore, the pressure continues to decrease to Pmax as the third fixed value or approaches Pmax. At this time, P0 > Pmax, and Pmax is preferably > 0.1 MPa, and the sealing quality of Borehole 1 meets the qualified standard.

[0067] As Figure 6 and Figure 7 shown, in the pressure change curve, the pressure decreases from P1 and approaches 0 MPa with the increase of time. This indicates that after gas is introduced into Borehole 1, the gas is lost through the fractures of the seal section 9 or the surrounding rock, and the pressure rapidly decreases to 0 MPa or approaches 0 MPa. At this time, Pmax is preferably 0 MPa - 0.1 MPa, and the sealing quality of Borehole 1 is unqualified.

[0068] When the sealing quality of Borehole 1 is qualified, the second switch valve 8 can be opened to connect the gas extraction pipe 7 with the borehole extraction pipe 2, and the gas in Borehole 1 is extracted and discharged through the gas extraction pipe 7 for gas extraction operations.

[0069] It is understandable that the inspection method for the sealing quality of gas drainage boreholes in the embodiments of the present invention is not limited to using the detection equipment in the embodiments of the present invention. In some other embodiments, the equipment used in the inspection method can introduce gas into the borehole and can obtain the pressure inside the borehole.

[0070] The inspection method for the sealing quality of gas drainage boreholes in the embodiments of the present invention obtains the pressure change curve within the time period when the pressure change is less than 0.015 MPa within 2 to 4 consecutive days after stopping the gas injection into the borehole, and judges whether the sealing quality of the borehole is qualified according to the linear type or trend of the pressure change curve. The influence of the actual value P0 of the original gas pressure of the coal seam and the maximum gas pressure Pmax that the borehole can seal on the sealing quality of the borehole is considered during the judgment process. Therefore, the obtained inspection result is more accurate.

[0071] In some embodiments, borehole 1 is located in the first working face of the coal seam, and P0' is the measured average value of the gas pressure measurement points in the first working face, or P0' is the measured average value of the gas pressure measurement points in the second working face of the coal seam.

[0072] Specifically, the coal seam includes a first working face and a second working face. Borehole 1 is located in the first working face. The step of obtaining the estimated value P0' of the original gas pressure of the coal seam is specifically to obtain the measured average value of the gas pressure measurement points in the first working face as P0', or to obtain the measured average value of the gas pressure measurement points in the second working face as P0'. Preferably, the first working face and the second working face are adjacent working faces.

[0073] It is understandable that in some other embodiments, the estimated value P0' of the original gas pressure of the coal seam can also be estimated based on work experience and relevant parameters obtained during the construction process.

[0074] In some embodiments, the third fixed value is greater than 0.1 MPa. When the sealing quality of borehole 1 is unqualified, in the pressure change curve, the pressure decreases from P1 to less than 0.1 MPa as time increases.

[0075] Specifically, when Pmax ≤ 0.1 MPa, the sealing quality of borehole 1 is unqualified; when Pmax > 0.1 MPa, the sealing quality of borehole 1 is qualified. Therefore, the third fixed value is greater than 0.1 MPa. When the sealing quality of borehole 1 is unqualified, in the pressure change curve, the pressure decreases from P1 to less than 0.1 MPa as time increases.

[0076] It is understandable that the criterion for whether the sealing quality of the borehole is qualified is not limited to 0.1 MPa. In some other embodiments, the criterion is a value greater than 0.1 MPa.

[0077] In some embodiments, the method for inspecting the sealing quality of the gas drainage borehole according to the embodiments of the present invention further includes, when the sealing quality of borehole 1 is unqualified, drilling another borehole 1 in the coal seam working face where borehole 1 is located, and obtaining the pressure change curve of the other borehole 1.

[0078] Specifically, when the sealing quality of borehole 1 is unqualified, gas drainage operation cannot be carried out in this borehole 1. Therefore, another borehole 1 is drilled in the first working face where borehole 1 is located, and the pressure change curve of the other borehole 1 is obtained. If the sealing quality of the other borehole 1 is qualified, gas drainage operation is carried out through the other borehole 1. If the sealing quality of the other borehole 1 is unqualified, then the next borehole 1 is drilled and the pressure change curve of the next borehole 1 is obtained until the sealing quality of the drilled borehole 1 is qualified.

[0079] In addition, when the pressure change curve is as Figure 4 and Figure 5 shown, since the sealing quality of borehole 1 does not meet the qualified standard, the sealing quality of borehole 1 can be further improved, for example, increasing the length of the sealing section 9 so that the sealing quality of borehole 1 reaches higher than the qualified standard.

[0080] In some embodiments, the method for inspecting the sealing quality of the gas drainage borehole of the present invention further includes, after connecting the detection device to borehole 1, using soapy water to detect the airtightness of the detection device. When the airtightness of the detection device is qualified, gas is introduced into borehole 1 through the detection device.

[0081] Specifically, after sealing and connecting the borehole drainage pipe 2 and borehole 1, soapy water is respectively applied at the connection between the multi-way joint 5 and the borehole drainage pipe 2, the connection between the multi-way joint 5 and the pressure acquisition device 4, the connection between the multi-way joint 5 and the first switch valve 6, the connection between the multi-way joint 5 and the second switch valve 8, the connection between the first switch valve 6 and the inflation device 3, and the connection between the second switch valve 8 and the gas drainage pipe 7. The airtightness of the connection is detected by soapy water to detect the airtightness of the detection device. If the airtightness is qualified, gas is introduced into borehole 1 through the detection device. If the airtightness is unqualified, the detection device is reconnected, and the airtightness of the connection is repeatedly detected to detect the airtightness of the detection device until the airtightness is qualified.

[0082] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for distinction and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features.

[0083] In the present invention, unless otherwise clearly specified or limited, terms such as "installed", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection, an electrical connection, or communicable with each other; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0084] In the present invention, unless otherwise clearly specified or limited, a first feature being "on" or "under" a second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, a first feature being "above", "over" and "on top of" a second feature may be that the first feature is directly above or obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. A first feature being "under", "below" and "beneath" a second feature may be that the first feature is directly below or obliquely below the second feature, or merely means that the horizontal height of the first feature is less than that of the second feature.

[0085] In the present invention, terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0086] Although the above embodiments have been shown and described, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions, and variations made by those of ordinary skill in the art to the above embodiments are within the protection scope of the present invention.

Claims

1. A method for inspecting the sealing quality of a gas drainage borehole, characterized in that Including: Obtaining an estimated initial gas pressure P0' of the coal seam; Connecting the detection device to the borehole (1); Injecting gas into the borehole (1) through the detection device until the pressure in the borehole (1) reaches an initial pressure P1, and then stopping the injection of the gas, where P1 is 0.4 to 0.8 times of P0'; After stopping the injection of the gas, starting to obtain the pressure change in the borehole (1) until the pressure change is less than 0.015 MPa for 2 to 4 consecutive days, then stopping the acquisition of the pressure change and obtaining a pressure change curve based on the pressure change; If in the pressure change curve, the pressure first decreases and then increases to a first fixed value or approaches a first fixed value as time increases, at this time the quality of the borehole (1) is higher than the qualified standard, or, if the pressure first decreases and then increases to a peak value as time increases, and then decreases from the peak value to a second fixed value or approaches a second fixed value, and the second fixed value is greater than P1, at this time the quality of the borehole (1) meets the qualified standard; If in the pressure change curve, the pressure decreases from P1 and approaches 0 MPa as time increases, then the sealing quality of the borehole (1) is unqualified.

2. The inspection method for the sealing quality of gas drainage boreholes according to claim 1, wherein The borehole (1) is located in the first working face of the coal seam, and P0' is the measured average value of the gas pressure measurement points in the first working face of the coal seam, or P0' is the measured average value of the gas pressure measurement points in the second working face of the coal seam.

3. The inspection method for the sealing quality of gas drainage boreholes according to claim 1, characterized in that, After stopping the injection of the gas, starting to obtain the pressure change in the borehole (1) until the pressure change is less than 0.015 MPa for 3 consecutive days, then stopping the acquisition of the pressure change.

4. The inspection method for the sealing quality of gas drainage boreholes according to claim 1, characterized in that, P1 is 0.5 times of P0'.

5. The inspection method for the sealing quality of gas drainage boreholes according to claim 1, characterized in that, Also including: When the sealing quality of the borehole (1) is unqualified, drilling another borehole (1) in the coal seam working face where the borehole (1) is located, and obtaining the pressure change curve of the other borehole (1).

6. The inspection method for the sealing quality of gas drainage boreholes according to claim 1, characterized in that, Also including: After connecting the detection device to the borehole (1), using soapy water to detect the airtightness of the detection device, and when the airtightness of the detection device is qualified, injecting gas into the borehole (1) through the detection device.

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