Gas extraction drill hole sealing quality evaluation method and parameter testing device
By measuring the relative change rate ψ of the methane volume concentration of the drill hole under the preset extraction negative pressure, the problems of complexity and misjudgment of the existing gas extraction drill hole sealing quality evaluation method are solved, and high accuracy and low construction difficulty are achieved The sealing quality evaluation, determine the leakage position, and improves the gas extraction efficiency.
Patent Information
- Application Number
- CN202411405981.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-10
- Publication Date
- 2024-12-10
AI Technical Summary
The existing gas extraction drilling seal quality evaluation methods are complex and easy to misjudgment, and the construction is difficult, so it is impossible to accurately evaluate the quality of the drilling seal, especially when the gas outflow is large or small.
By measuring the relative change rate ψ of the volume concentration of the methane at the preset extraction negative pressure of the drilling hole, the quality of the drilling hole is judged, and the quality of the drilling hole is avoided, and there is no need to install a detection device in the hole, and the negative pressure regulation is performed directly at the hole and Determination.
It improves the accuracy and reliability of drilling seal quality evaluation, reduces construction difficulty, can scientifically evaluate drilling seal quality, and judges the leaking position, which improves gas extraction efficiency.
Smart Images
Figure CN119102596A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of gas extraction, and in particular relates to a gas extraction borehole sealing quality evaluation method and a parameter testing device. Background Art
[0002] Gas extraction drilling is currently the main engineering method for preventing and controlling gas disasters and developing coalbed methane resources in coal mines, accounting for more than 90% of the total gas extraction in coal mines. The sealing quality of gas extraction drilling holes is one of the key factors to ensure the effect of gas extraction.
[0003] There are several methods for evaluating borehole sealing quality in related technologies. One method is to evaluate the borehole sealing quality by measuring the gas extraction concentration in the extraction pipe related to the sealing section and at different positions of the borehole. During the construction process, it is necessary to install gas extraction points or sensors at different positions in the extraction pipe and the borehole, or to move fixed gas extraction devices and sensors in the extraction pipe for detection. This can more accurately determine the leakage position of the borehole sealing section and evaluate the borehole sealing quality. However, the borehole sealing quality may be misjudged due to a large or small amount of borehole gas outflow, and the construction process is complicated and the engineering workload is large. Summary of the invention
[0004] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, an embodiment of the present invention proposes a method for evaluating the sealing quality of a gas extraction borehole, which can improve the reliability of the evaluation of the sealing quality of the borehole, and does not require the installation of a detection device in the hole, thereby reducing the difficulty of construction.
[0005] The invention also proposes a gas extraction borehole sealing quality evaluation parameter testing device.
[0006] The gas extraction borehole sealing quality evaluation method of the embodiment of the present invention comprises the following steps: determining the original methane volume concentration of the borehole Under the preset extraction negative pressure P, gas extraction is performed on the borehole to measure the extracted methane volume concentration of the borehole. according to and The relative change rate ψ of the extracted methane volume concentration under the preset extraction negative pressure P is calculated; and the sealing quality of the borehole is judged according to the value of the relative change rate ψ of the extracted methane volume concentration.
[0007] In this embodiment, the sealing quality of the borehole is evaluated by calculating the relative change rate ψ of the extracted methane volume concentration under the preset extraction negative pressure P. The smaller the relative change rate ψ of the extracted methane volume concentration, the smaller the leakage of the borehole and the better the sealing quality of the borehole. The larger the relative change rate ψ of the extracted methane volume concentration, the greater the leakage of the hole and the worse the sealing quality of the borehole. This avoids the misevaluation of the borehole sealing quality caused by the high or low methane content in the gas stored in the coal body itself, and can improve the accuracy and reliability of the evaluation of the borehole sealing quality. In addition, when measuring the methane volume concentration, the negative pressure can be directly controlled at the borehole mouth and the extracted methane volume concentration can be measured. There is no need to install a detection device in the hole, which is conducive to reducing the difficulty of construction.
[0008] In this embodiment, the evaluation model for judging the sealing quality of the borehole according to the relative change rate ψ value of the extracted methane volume concentration is as follows: when ψ≤10, the borehole sealing quality is excellent; when 10<ψ≤30, the borehole sealing quality is good; when 30<ψ≤50, the borehole sealing quality is medium; when 50<ψ, the borehole sealing quality is poor.
[0009] In this embodiment, the leakage area of the sealing section of the borehole is divided into leakage in the pore 3 between the borehole sealing material and the borehole wall, leakage in the broken area of the borehole surrounding rock and leakage in the plastic area of the borehole surrounding rock. The gas extraction borehole sealing quality evaluation method also includes: determining the leakage position of the borehole.
[0010] In this embodiment, the method for evaluating the sealing quality of gas extraction boreholes also includes: measuring the leakage Q of the borehole under different preset extraction negative pressures P, and calculating the change rate η of the leakage, so as to judge the leakage position of the borehole according to the value of the change rate η of the leakage.
[0011] In this embodiment, the gas extraction borehole sealing quality evaluation method further includes: determining the borehole extraction mixing volume S under different preset extraction negative pressures P, wherein the borehole extraction mixing volume S is the sum of the borehole gas outflow volume Y and the gas leakage volume Q;
[0012] according to The air leakage Q is calculated by using S and the calculation formula of the air leakage Q is as follows:
[0013]
[0014] In this embodiment, the discrimination model of the leakage position of the sealing section is as follows: when η>1, it is leakage between the borehole sealing material and the borehole wall; when 0.01<η≤1, it is leakage in the broken area of the borehole surrounding rock; when η<0.01, it is leakage in the plastic area of the borehole surrounding rock.
[0015] In this embodiment, the discriminant model is set according to the following model:
[0016]
[0017] In the formula, Q s Q is the gas leakage in the plastic zone of the borehole surrounding rock; p Q is the gas leakage in the broken area of the surrounding rock of the borehole; k A is the air leakage between the drilling sealing material and the drilling hole wall; s A is the air leakage area of the plastic zone of the borehole surrounding rock; p A is the air leakage area of the surrounding rock crushing zone of the borehole; k K is the air leakage area between the borehole sealing material and the surrounding rock pores; s K is the plastic zone permeability of the borehole surrounding rock; p is the permeability of the broken area of the borehole surrounding rock; U is the circumference of the air leakage channel between the borehole sealing material and the surrounding rock pores; μ is the aerodynamic viscosity; L is the length of the borehole sealing section, P1 is the first preset extraction negative pressure, and P2 is the second preset extraction negative pressure.
[0018] In this embodiment, when the preset extraction negative pressure P value is set to three groups or more, the difference between two adjacent groups of the preset extraction negative pressure P is a fixed value H.
[0019] In this embodiment, the method for evaluating the sealing quality of gas extraction boreholes further includes: selecting the preset extraction negative pressure P for extraction according to the maximum extracted methane volume concentration or the minimum gas leakage under different preset extraction negative pressures P.
[0020] In this embodiment, a gas extraction borehole sealing quality evaluation parameter testing device is used for the above-mentioned gas extraction borehole sealing quality evaluation method. The gas extraction borehole sealing quality evaluation parameter testing device includes a negative pressure control component, a gas concentration measuring component and a flow measuring component. The negative pressure control component is connected to the borehole to be extracted, and the gas concentration measuring component and the flow measuring component are connected to the negative pressure control component through a gas measuring nozzle. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a flow chart of a method for evaluating the sealing quality of a gas extraction borehole according to an embodiment of the present invention.
[0022] Figure 2 It is a schematic structural diagram of a drilling sealing section according to an embodiment of the present invention.
[0023] Figure 3 It is a structural schematic diagram of a gas extraction borehole sealing quality evaluation parameter testing device according to an embodiment of the present invention.
[0024] Reference numerals:
[0025] 1. Borehole; 2. Borehole sealing material; 3. Pores between the borehole sealing material and the borehole wall; 4. Broken area of the borehole surrounding rock; 5. Plastic area of the borehole surrounding rock; 6. Coal body; 7. Extraction pipe; 8. Pressure regulating valve; 9. Pressure gauge; 10. Gas measuring nozzle. DETAILED DESCRIPTION
[0026] The 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.
[0027] In this embodiment, if Figure 1 As shown in the figure, the gas extraction borehole sealing quality evaluation method includes the following steps:
[0028] S100, determination of the original methane volume concentration in borehole 1
[0029] Specifically, when measuring the original methane volume concentration of borehole 1, close the negative pressure of extraction, wait until the pressure gauge shows positive pressure, and then measure the original methane volume concentration of the coal seam in borehole 1. Carry out determination.
[0030] S200, gas extraction is performed on borehole 1 under a preset extraction negative pressure P, and the extracted methane volume concentration of borehole 1 is measured
[0031] For example, the preset extraction negative pressure P may be 10Kpa, 20Kpa, 30Kpa or 40Kpa, etc. The value of the preset extraction negative pressure P may be set as required and is not limited here.
[0032] Specifically, when gas extraction is performed under the preset extraction negative pressure P, the extracted methane volume concentration is measured after the extraction is stable. To ensure the accuracy of the measured values.
[0033] S300, according to and Calculate the relative change rate ψ of the extracted methane volume concentration under the preset extraction negative pressure P.
[0034] Specifically, the calculation formula of the relative change rate ψ of the extracted methane volume concentration is as follows:
[0035]
[0036] By measuring and Substituting the value into the above formula, we can obtain the change rate of the extracted methane volume concentration ψ.
[0037] S400, judging the sealing quality of the borehole 1 according to the relative change rate ψ value of the extracted methane volume concentration.
[0038] The volume concentration of extracted methane under different preset extraction negative pressures P can be measured. The relative change rate ψ of the extracted methane volume concentration under different preset extraction negative pressures P is calculated to improve the accuracy of the evaluation.
[0039] In this embodiment, the sealing quality of borehole 1 is evaluated by calculating the relative change rate ψ of the extracted methane volume concentration under the preset extraction negative pressure P. The smaller the relative change rate ψ of the extracted methane volume concentration, the smaller the leakage of borehole 1 and the better the sealing quality of borehole 1. The larger the relative change rate ψ of the extracted methane volume concentration, the greater the leakage of the hole and the worse the sealing quality of borehole 1. This avoids the misevaluation of the sealing quality of borehole 1 due to the high or low methane content in the gas stored in the coal body itself, and can improve the accuracy and reliability of the evaluation of the sealing quality of borehole 1. In addition, when measuring the methane volume concentration, the negative pressure can be directly controlled at the orifice of borehole 1 and the extracted methane volume concentration can be measured. There is no need to install a detection device in the hole, which is conducive to reducing the difficulty of construction.
[0040] In this embodiment, the evaluation model for judging the sealing quality of the borehole 1 according to the value of the relative change rate ψ of the extracted methane volume concentration is as follows:
[0041] When ψ≤10, the sealing quality of borehole 1 is excellent;
[0042] When 10<ψ≤30, the sealing quality of borehole 1 is good;
[0043] When 30<ψ≤50, the sealing quality of borehole 1 is medium;
[0044] When 50<ψ, the sealing quality of borehole 1 is poor.
[0045] It can be understood that the better the sealing quality of borehole 1, the smaller the gas leakage in borehole 1, and the increase of extraction negative pressure has a smaller impact on the gas leakage. Therefore, the relative change rate of gas concentration extracted from borehole 1 is smaller; when the sealing quality of borehole 1 is poor, the gas leakage of borehole 1 is large, and the increase of extraction negative pressure has a greater impact on the gas leakage. Therefore, the larger the relative change rate ψ of the extracted methane volume concentration, the larger the relative change rate ψ of the extracted methane volume concentration. Dividing the sealing quality of borehole 1 into multiple levels according to the value of the relative change rate ψ of the extracted methane volume concentration is, which is more conducive to improving the scientificity and reliability of the evaluation results.
[0046] In this embodiment, the leakage area of the sealing section of the borehole 1 is divided into leakage in the pores 3 between the borehole sealing material and the borehole wall, leakage in the borehole surrounding rock crushing zone 4 and leakage in the borehole surrounding rock plastic zone 5. The gas extraction borehole sealing quality evaluation method also includes: determining the leakage position of the borehole 1.
[0047] It is understandable that while evaluating the sealing quality of the gas extraction borehole 1, the leakage position of the borehole 1 is judged, so that the leakage position can be processed in time when the sealing quality is poor.
[0048] In this embodiment, the method for evaluating the sealing quality of gas extraction boreholes also includes: measuring the leakage volume Q of borehole 1 under different preset extraction negative pressures P, and calculating the change rate η of the leakage volume of borehole 1, so as to judge the leakage position of borehole 1 according to the change rate η of the leakage volume of borehole 1.
[0049] Specifically, the specific method of measuring at different preset extraction negative pressures P is to extract gas from borehole 1 under the first extraction negative pressure P1 and measure the extracted methane volume concentration. and the gas leakage Q1 of borehole 1; under the second extraction negative pressure P2, gas extraction was performed on borehole 1 to measure the extracted methane volume concentration and the air leakage of borehole 1 Q2, P2>P1; Substitute the measured Q1 and Q2 into Calculate the change rate η of the gas leakage of borehole 1. Similarly, gradually increase the value of the preset extraction negative pressure P and measure the volume concentration of extracted methane and the gas leakage Q of borehole 1, and according to the measured methane volume concentration of the two adjacent groups and the gas leakage Q of borehole 1, calculate the relative change rate ψ of the extracted methane volume concentration and the change rate η of the gas leakage of borehole 1. The total number of groups measured can be set as needed and is not limited here.
[0050] It can be understood that due to the different material permeabilities of the borehole sealing material 2, the borehole surrounding rock crushing zone 4 and the borehole surrounding rock plastic zone 5, the change rates of leakage at different locations are different. Therefore, the location of the leakage can be inferred by calculating the change rate η of the leakage of the borehole 1.
[0051] In this embodiment, when the preset extraction negative pressure P value is set to three groups or more, the difference between two adjacent groups of preset extraction negative pressures P is a fixed value H.
[0052] For example, the difference H between the second preset extraction negative pressure P2 and the first preset extraction negative pressure P1 is 10 KPa, then the difference H between the third preset extraction negative pressure P3 and the second preset extraction negative pressure P2 is also 10 KPa, and so on.
[0053] It can be understood that setting the difference between two adjacent groups of preset extraction negative pressures P to a fixed value H can facilitate the comparison of the values of the change rate η of the leakage volume of multiple groups of boreholes 1, as well as the comparison of the values of the relative change rate ψ of the volume concentration of extracted methane of multiple groups, so as to improve the accuracy of the measurement results.
[0054] In this embodiment, the gas extraction borehole sealing quality evaluation method further includes:
[0055] The drilling extraction mixing volume S under different preset extraction negative pressures P is determined. The drilling extraction mixing volume S is the sum of the drilling gas outflow volume Y and the gas leakage volume Q of borehole 1. The air leakage Q of borehole 1 is calculated by using the formula of S and the air leakage Q of borehole 1 is as follows:
[0056]
[0057] Specifically, S=Y+Q and It can be concluded that Due to the preset extraction negative pressure P, the drilling extraction mixing volume S and the extraction methane volume concentration And the original methane volume concentration of the coal seam in borehole 1 can be measured, so the measured well extraction mixed volume S and methane volume concentration And the original methane volume concentration of the coal seam in borehole 1 By taking the calculation formula of the gas leakage Q of borehole 1, the gas leakage under the preset extraction negative pressure P can be obtained.
[0058] In this embodiment, the discriminating model of the leakage position of the sealing section of the borehole 1 is as follows:
[0059] When η>1, there is air leakage between the borehole sealing material 2 and the borehole wall; when 0.01<η≤1, there is air leakage in the broken zone of the borehole surrounding rock; when η<0.01, there is air leakage in the plastic zone of the borehole surrounding rock.
[0060] It can be understood that since the permeability of the plastic zone 5 of the borehole surrounding rock is much smaller than the permeability of the crushed zone 4 of the borehole surrounding rock, and the air leakage between the borehole sealing material and the borehole wall is similar to pipe flow, the flow capacity is much larger than the permeability of the crushed zone 4 of the borehole surrounding rock. As the pressure changes, the change in leakage volume is greater. Therefore, the location of the leakage can be judged based on η, which is more scientific and more reliable.
[0061] In this embodiment, the discrimination model is set according to the following calculation model of air leakage:
[0062]
[0063] In the formula, Q s Q is the gas leakage in the plastic zone of the borehole surrounding rock; pQ is the gas leakage in the broken area of the surrounding rock of the borehole; k A is the air leakage between the drilling sealing material and the drilling hole wall; s A is the air leakage area of the plastic zone of the borehole surrounding rock; p A is the air leakage area of the surrounding rock crushing zone of the borehole; k K is the air leakage area between the borehole sealing material and the surrounding rock pores; s K is the plastic zone permeability of the borehole surrounding rock; p is the permeability of the broken area of the borehole surrounding rock; U is the circumference of the air leakage channel between the borehole sealing material and the surrounding rock pores; μ is the aerodynamic viscosity; L is the length of the borehole sealing section, P1 is the first preset extraction negative pressure, and P2 is the second preset extraction negative pressure.
[0064] It should be noted that the first preset negative pressure P1 and the second preset negative pressure P2 are both fixed values set when negative pressure extraction is performed. When the leakage volume Q is measured, due to different leakage conditions, A s K s , A p K p and A k 3 / U is different, so the empirical value of η can be set based on the above-mentioned calculation model of the leakage volume and the change rate η of the leakage volume of the borehole 1.
[0065] In this embodiment, the gas extraction borehole sealing quality evaluation method further includes: selecting a preset extraction negative pressure P for extraction according to the maximum extracted methane volume concentration or the minimum gas leakage under different preset extraction negative pressures P.
[0066] It can be understood that under different preset extraction negative pressures P, if the extracted methane volume concentration is large or the gas leakage of borehole 1 is small, it means that the gas extraction effect is better when gas extraction is performed under this preset extraction negative pressure P. When the extraction target is gas resource utilization, the extraction negative pressure P when the extracted methane volume concentration is the largest is selected; when the extraction target is to improve the extraction efficiency and reduce the extraction reaching standard time, the extraction negative pressure P when the gas leakage is the smallest is selected.
[0067] In this embodiment, the gas extraction borehole sealing quality evaluation parameter testing device is used in the above-mentioned gas extraction borehole sealing quality evaluation method. Figure 3 As shown, the gas extraction borehole sealing quality evaluation parameter testing device includes a negative pressure control component, a gas concentration measuring component (not shown in the figure) and a flow measuring component (not shown in the figure). The negative pressure control component is connected to the extraction borehole, and the gas concentration measuring component and the flow measuring component are connected to the negative pressure control component through a gas measuring nozzle 10.
[0068] Specifically, Figure 3As shown, the negative pressure control component includes an extraction pipe 7, a pressure regulating valve 8 and a pressure gauge 9. The extraction pipe 7 is connected to the borehole 1. The pressure regulating valve 8 and the pressure gauge are both arranged on the extraction pipe 7. The negative pressure of the extracted gas is adjusted by the pressure regulating valve 8, and the pressure is observed and adjusted by the pressure gauge 9. A gas measuring nozzle 10 is also arranged on the extraction pipe 7. The gas concentration measuring component and the flow measuring component are respectively connected to the gas measuring nozzle 10. The gas concentration measuring component measures the volume concentration of methane through the gas measuring nozzle 10, and the flow measuring component measures the sum of the gas outflow volume Y and the gas leakage volume Q through the gas measuring nozzle 10. The specific structure and working principle of the gas concentration measuring component and the flow measuring component are conventional prior art and will not be described in detail here.
[0069] The gas extraction borehole sealing quality evaluation parameter testing device of the present invention is used for the above-mentioned gas extraction borehole sealing quality evaluation method, by respectively measuring the borehole methane volume concentration under different preset extraction negative pressures P. The borehole sealing quality is judged according to the relative change rate ψ of the volume concentration of methane extracted from the borehole after the negative pressure is increased or decreased, so as to avoid the misjudgment of the borehole sealing quality due to the large or small gas outburst of borehole 1. The reliability of the evaluation of the borehole sealing quality can be improved, and the relative change rate η of the leakage amount under different preset extraction negative pressures P can be calculated to determine the location of the leakage, so as to facilitate the rapid compensation of the borehole sealing quality.
[0070] In the description of the present invention, it is to be understood that 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”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, 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 therefore should not be understood as limiting the present invention.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] 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.
[0075] 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. A method for evaluating the sealing quality of a gas extraction borehole, characterized in that: The steps include: Determination of the original methane volume concentration in the borehole Under the preset extraction negative pressure P, gas extraction is performed on the borehole to measure the extracted methane volume concentration of the borehole. according to and Calculating the relative change rate ψ of the extracted methane volume concentration under the preset extraction negative pressure P; The sealing quality of the borehole is judged according to the relative change rate ψ value of the extracted methane volume concentration.
2. The gas extraction borehole sealing quality evaluation method according to claim 1, characterized in that: The evaluation model for judging the sealing quality of the borehole according to the relative change rate ψ value of the extracted methane volume concentration is as follows: When ψ≤10, the drilling sealing quality is excellent; When 10<ψ≤30, the drilling sealing quality is good; When 30<ψ≤50, the drilling sealing quality is medium; When 50<ψ, the drilling sealing quality is poor.
3. The method for evaluating the sealing quality of a gas extraction borehole according to claim 1, characterized in that: The leakage area of the sealing section of the borehole is divided into pore leakage between the borehole sealing material and the borehole wall, leakage in the broken area of the borehole surrounding rock and leakage in the plastic area of the borehole surrounding rock. The gas extraction borehole sealing quality evaluation method also includes: determining the leakage position of the borehole.
4. The method for evaluating the sealing quality of a gas extraction borehole according to claim 3, characterized in that: Also includes: The gas leakage Q of the borehole under different preset extraction negative pressures P is measured, and the change rate η of the gas leakage is calculated, so as to determine the gas leakage position of the borehole according to the value of the change rate η of the gas leakage.
5. The method for evaluating the sealing quality of a gas extraction borehole according to claim 4, characterized in that: Also includes: Determine the borehole extraction mixing volume S under different preset extraction negative pressures P, wherein the borehole extraction mixing volume S is the sum of the borehole gas outflow volume Y and the gas leakage volume Q; according to The air leakage Q is calculated by using S and the calculation formula of the air leakage Q is as follows:
6. The method for evaluating the sealing quality of a gas extraction borehole according to claim 4, characterized in that: The discriminant model of the leakage position of the sealing section is as follows: When η>1, there is air leakage between the drilling sealing material and the drilling hole wall; When 0.01<η≤1, there is gas leakage in the broken area of the surrounding rock of the borehole; When η<0.01, there is air leakage in the plastic zone of the surrounding rock of the borehole.
7. The method for evaluating the sealing quality of a gas extraction borehole according to claim 6, characterized in that: The discriminant model is set according to the following model: In the formula, Q s Q is the gas leakage in the plastic zone of the borehole surrounding rock; p Q is the gas leakage in the broken area of the surrounding rock of the borehole; k A is the air leakage between the drilling sealing material and the drilling hole wall; s A is the air leakage area of the plastic zone of the borehole surrounding rock; p A is the air leakage area of the surrounding rock crushing zone of the borehole; k K is the air leakage area between the borehole sealing material and the surrounding rock pores; s is the plastic zone permeability of the borehole surrounding rock; K p is the permeability of the broken area of the borehole surrounding rock; U is the circumference of the air leakage channel between the borehole sealing material and the surrounding rock pores; μ is the aerodynamic viscosity; L is the length of the borehole sealing section, P1 is the first preset extraction negative pressure, and P2 is the second preset extraction negative pressure.
8. The method for evaluating the sealing quality of a gas extraction borehole according to claim 4, characterized in that: When the preset extraction negative pressure P value is set to three groups or more, the difference between two adjacent groups of the preset extraction negative pressure P is a fixed value H.
9. The method for evaluating the sealing quality of a gas extraction borehole according to claim 4, characterized in that: Also includes: The preset extraction negative pressure P for extraction is selected according to the maximum extracted methane volume concentration or the minimum gas leakage under different preset extraction negative pressures P.
10. A gas extraction borehole sealing quality evaluation parameter testing device, characterized in that: A method for evaluating the sealing quality of a gas extraction borehole as described in any one of claims 1 to 9, wherein the device for testing the sealing quality evaluation parameters of a gas extraction borehole comprises a negative pressure control component, a gas concentration measuring component and a flow measuring component, wherein the negative pressure control component is connected to the borehole to be extracted, and the gas concentration measuring component and the flow measuring component are connected to the negative pressure control component via a gas measuring nozzle.