Volume-variable buffer pressure relief zero-overrun blowout prevention method for gas extraction drill hole

Abstract

The invention relates to the technical field of gas extraction, and particularly discloses a variable-volume buffer pressure relief zero-overrun blowout prevention method for a gas extraction drill hole, which comprises the following steps of: mounting a volume buffer at a drill hole opening, and acquiring gas extraction parameters of gas extraction corresponding to each extraction period in real time through various monitoring instruments; wherein the gas extraction parameters of the gas extraction corresponding to each extraction time period comprise gas pressure, gas concentration, gas flow, environment temperature and water level data of the gas extraction corresponding to each extraction time period. According to the method, gas pressure, gas concentration, gas flow, environment temperature and water level data of gas extraction corresponding to each extraction time period are comprehensively analyzed to obtain gas pressure abnormity evaluation coefficients of gas extraction corresponding to each extraction time period, and the gas pressure abnormity evaluation coefficients are used for evaluating gas pressure extraction states of gas extraction corresponding to each extraction time period. Therefore, the abnormal state of the gas pressure in the gas extraction process can be early warned in advance, and the safety of the gas pressure in the gas extraction process is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of gas extraction, and in particular to a gas extraction drilling hole variable capacity, buffer pressure relief and zero over-limit blowout prevention method. Background Art

[0002] Gas extraction drilling refers to the process of drilling holes in coal seams and gas accumulation areas in order to reduce the amount of gas outflow in coal seams and goafs during coal mining, prevent gas over-limit and accumulation, and prevent gas explosions and coal and gas outburst accidents. These boreholes are connected to gas extraction equipment through special pipelines, so that gas can be extracted to the ground for use or discharged into the total return air flow.

[0003] Gas over-limit is a major safety hazard in coal mine production, which can easily lead to serious accidents such as gas explosions. In the process of gas extraction, if the borehole design is unreasonable or poorly managed, it may cause a large amount of gas to gush out, exceeding the safe concentration limit. For this reason, we have proposed a method of variable volume, buffer pressure relief and zero over-limit blowout prevention for gas extraction boreholes. The variable volume and buffer pressure relief design can automatically adjust the volume and pressure relief speed of the borehole according to the changes in gas pressure and flow during the extraction process, maintaining the stability and efficiency of the extraction system. Summary of the invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a gas extraction drilling variable capacity, buffer pressure relief and zero over-limit blowout prevention method to solve the above-mentioned technical defects.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a gas extraction drilling variable capacity, buffer pressure relief and zero over-limit blowout prevention method, comprising the following steps:

[0006] Step 1: Install a volume buffer at the borehole mouth, and obtain the gas extraction parameters corresponding to each extraction period in real time through various monitoring instruments, wherein the gas extraction parameters corresponding to each extraction period include gas pressure, gas concentration, gas flow, ambient temperature and water level data corresponding to each extraction period;

[0007] Step 2: Obtain the gas pressure safety threshold value corresponding to each extraction period of gas extraction from the database, and at the same time obtain the allowable fluctuation range of each extraction period of gas extraction from the database, standardize the gas pressure of each extraction period of gas extraction, and calculate the gas pressure change value of each extraction period of gas extraction;

[0008] Step 3: Obtain the maximum gas extraction flow rate and the maximum gas concentration of each extraction period corresponding to gas extraction from the database, and obtain the gas extraction flow rate effect value and the gas extraction concentration effect value of each extraction period corresponding to gas extraction by calculation;

[0009] Step 4: Obtain the ambient temperature reference value and the water level reference value corresponding to each extraction period of gas extraction from the database, and obtain the temperature impact value and water level impact value corresponding to each extraction period of gas extraction by calculation;

[0010] Step 5: Sum the gas extraction flow rate effect value and the gas extraction concentration effect value of each extraction period corresponding to gas extraction, and then respectively subtract the temperature influence value and the water level influence value of each extraction period corresponding to gas extraction, and finally multiply the calculated result by the gas pressure change value of each extraction period corresponding to gas extraction to obtain the gas pressure abnormality assessment coefficient of each extraction period corresponding to gas extraction;

[0011] Step 6. Obtain the gas pressure anomaly assessment threshold value corresponding to each extraction period of gas extraction from the database, compare the gas pressure anomaly assessment coefficient corresponding to each extraction period of gas extraction with the gas pressure anomaly assessment threshold value corresponding to each extraction period of gas extraction. If the gas pressure anomaly assessment coefficient corresponding to each extraction period of gas extraction is greater than the gas pressure anomaly assessment threshold value, it means that the gas pressure corresponding to each extraction period of gas extraction is abnormal, generate a gas pressure anomaly signal corresponding to each extraction period of gas extraction, control the volume buffer to adjust the volume, re-analyze and calculate the gas pressure anomaly assessment coefficient corresponding to each extraction period of gas extraction, otherwise, it means that the gas pressure corresponding to each extraction period of gas extraction is normal;

[0012] Step 7, record the gas pressure abnormality assessment coefficient corresponding to each extraction period of gas extraction. If the gas pressure abnormality assessment coefficient corresponding to each extraction period of gas extraction shows an upward trend, it means that the gas pressure corresponding to each extraction period of gas extraction has an upward trend, generate a gas pressure rising change signal, arrange maintenance personnel to inspect and maintain the gas pressure rising state corresponding to each extraction period of gas extraction, and dynamically adjust the volume of the volume buffer until the gas pressure corresponding to each extraction period of gas extraction is in a stable trend;

[0013] Step 8: Using an ultrasonic sensor disposed outside the gas extraction pipeline to measure the sealing value and slag accumulation value of the extraction pipeline at each extraction period corresponding to gas extraction, the sealing value and slag accumulation value of the extraction pipeline at each extraction period corresponding to gas extraction are obtained, and the gas extraction risk coefficient of the gas extraction at each extraction period corresponding to gas extraction is obtained by calculation;

[0014] Step nine, obtain the gas extraction risk coefficient threshold value corresponding to each extraction period of gas extraction from the database, and compare the gas extraction risk coefficient corresponding to each extraction period of gas extraction with the gas extraction risk coefficient threshold value. If the gas extraction risk coefficient corresponding to each extraction period of gas extraction is greater than the gas extraction risk coefficient threshold value, it means that the gas outburst per unit area is large, and a gas over-limit warning signal is generated. Otherwise, it means that the gas outburst state of gas extraction corresponding to each extraction period is normal, and a gas extraction normal signal is generated.

[0015] Furthermore, in step 1, the specific method for obtaining the gas extraction parameters corresponding to each extraction period of gas extraction is as follows:

[0016] The gas pressure of each extraction period corresponding to gas extraction is obtained through a pressure sensor installed in the borehole, the gas concentration of each extraction period corresponding to gas extraction is obtained through a concentration sensor installed in the borehole, the gas flow rate of each extraction period corresponding to gas extraction is obtained through a flow meter installed at the inlet and outlet of the volume buffer, the ambient temperature of each extraction period corresponding to gas extraction is obtained through a temperature sensor installed inside the borehole, and the water level data of each extraction period corresponding to gas extraction is obtained through a liquid level sensor installed in the groundwater level.

[0017] Furthermore, in step 2, the calculation method of the gas pressure change value corresponding to each extraction period of gas extraction is as follows:

[0018] The gas pressure of each extraction period corresponding to the gas extraction period is standardized. The gas pressure change value of each extraction period corresponding to the gas extraction period is obtained by calculating the difference between the gas pressure of each extraction period corresponding to the gas extraction period and the gas pressure safety threshold of each extraction period corresponding to the gas extraction period and dividing it by the allowable fluctuation range of each extraction period corresponding to the gas extraction period.

[0019] Furthermore, in step 3, the gas extraction flow rate effect value and the gas extraction concentration effect value corresponding to each extraction period of gas extraction are calculated as follows:

[0020] The gas flow rate corresponding to each extraction period of gas extraction and the maximum gas extraction flow rate are compared and calculated, and then multiplied by the corresponding weight factor to obtain the gas extraction flow rate effect value corresponding to each extraction period of gas extraction. The gas concentration corresponding to each extraction period of gas extraction and the maximum gas extraction concentration are compared and calculated, and then multiplied by the corresponding weight factor to obtain the gas extraction concentration effect value corresponding to each extraction period of gas extraction.

[0021] Furthermore, in step 4, the temperature impact value and water level impact value of gas extraction corresponding to each extraction period are calculated as follows:

[0022] Calculate the difference between the ambient temperature and the ambient temperature reference value for each extraction period corresponding to gas extraction, as well as the difference between the water level data and the water level data reference value for each extraction period corresponding to gas extraction. Compare the ambient temperature difference for each extraction period corresponding to gas extraction with the ambient temperature for each extraction period corresponding to gas extraction, and then multiply by the corresponding weight factor to obtain the temperature impact value for each extraction period corresponding to gas extraction. Compare the water level data difference for each extraction period corresponding to gas extraction with the water level data for each extraction period corresponding to gas extraction, and then multiply by the corresponding weight factor to obtain the water level impact value for each extraction period corresponding to gas extraction.

[0023] Furthermore, in step eight, the calculation method of the gas extraction risk coefficient corresponding to each extraction period of gas extraction is as follows:

[0024] Compare the gas pressure safety threshold corresponding to each extraction period of gas extraction and the gas pressure corresponding to each extraction period of gas extraction to obtain the calculation result of 1 divided by the ambient temperature difference corresponding to each extraction period of gas extraction, and obtain the calculation result of 1 divided by the sum of the sealing value and the slag accumulation value of the extraction pipeline corresponding to each extraction period of gas extraction. Finally, multiply the above three calculation results by the corresponding weight factors and then perform product calculation to obtain the gas extraction risk coefficient corresponding to each extraction period of gas extraction.

[0025] Beneficial effects of the present invention:

[0026] 1. In the present invention, the gas pressure, gas concentration, gas flow rate, ambient temperature and water level data of each extraction period corresponding to gas extraction are processed, and then the gas pressure of each extraction period corresponding to the gas extraction period is standardized to obtain the gas pressure change value of each extraction period corresponding to the gas extraction. At the same time, the gas extraction flow effect value of each extraction period corresponding to the gas extraction period, the gas extraction concentration effect value of each extraction period corresponding to the gas extraction period, the temperature influence value of each extraction period corresponding to the gas extraction period and the water level influence value of each extraction period corresponding to the gas extraction period are calculated according to the data obtained in real time. Finally, the gas pressure abnormality assessment coefficient of each extraction period corresponding to the gas extraction period is obtained after comprehensive analysis of the above calculation results, which is used for the gas pressure extraction state of each extraction period corresponding to the gas extraction period, so as to provide early warning of the abnormal state of gas pressure in the gas extraction process and ensure the gas pressure safety in the gas extraction process.

[0027] 2. In the present invention, the sealing value and slag accumulation value of the extraction pipeline corresponding to each extraction period of gas extraction are monitored in real time, and the three parameters are comprehensively calculated and analyzed in combination with the gas pressure in each extraction period of gas extraction to obtain the gas extraction risk coefficient for each extraction period of gas extraction. The gas extraction risk coefficient for each extraction period of gas extraction is obtained by comprehensively calculating and analyzing the sealing state and slag accumulation state of the extraction pipeline corresponding to each extraction period of gas extraction in combination with the gas pressure in each extraction period of gas extraction to obtain the gas extraction risk coefficient for each extraction period of gas extraction. Thus, early warning analysis of the gas outburst state in each extraction period of gas extraction is performed to improve the safety of variable capacity, buffer pressure relief and zero overlimit blowout prevention of gas extraction drilling in each extraction period of gas extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Figure 1 The present invention is a flow chart of a method for preventing gas extraction drilling holes from variable capacity, buffering and pressure relief and zero over-limit blowout in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present invention.

[0031] As shown in the present invention and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular, but also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list, and the method or device may also include other steps or elements.

[0032] Although the present invention has made various references to certain modules in the system according to an embodiment of the present invention, any number of different modules can be used and run on a user terminal and / or server. The modules are only illustrative, and different aspects of the system and method can use different modules.

[0033] The present invention uses a flow chart to illustrate the operations performed by the system according to an embodiment of the present invention. It should be understood that the preceding or following operations are not necessarily performed precisely in order. On the contrary, various steps may be processed in reverse order or simultaneously as required. At the same time, other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0034] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described here.

[0035] Embodiment 1:

[0036] See also Figure 1 As shown, the gas extraction drilling variable volume, buffer pressure relief and zero over-limit blowout prevention method includes the following steps:

[0037] Step 1: Install a volume buffer at the borehole mouth, obtain the gas pressure of each extraction period corresponding to gas extraction through a pressure sensor installed in the borehole, obtain the gas concentration of each extraction period corresponding to gas extraction through a concentration sensor installed in the borehole, obtain the gas flow of each extraction period corresponding to gas extraction through a flow meter installed at the inlet and outlet of the volume buffer, obtain the ambient temperature of each extraction period corresponding to gas extraction through a temperature sensor installed inside the borehole, and obtain the water level data of each extraction period corresponding to gas extraction through a liquid level sensor installed at the groundwater level;

[0038] It should be noted that the gas extraction parameters corresponding to each extraction period of gas extraction are jointly constituted by the gas pressure, gas concentration, gas flow, ambient temperature and water level data corresponding to each extraction period of gas extraction.

[0039] Step 2: Obtain the gas pressure safety threshold value corresponding to each extraction period of gas extraction from the database, and at the same time obtain the allowable fluctuation range of each extraction period of gas extraction from the database, standardize the gas pressure of each extraction period of gas extraction, and obtain the gas pressure change value of each extraction period of gas extraction by calculating the difference between the gas pressure of each extraction period of gas extraction and the gas pressure safety threshold value of each extraction period of gas extraction and dividing it by the allowable fluctuation range of each extraction period of gas extraction;

[0040] Step 3: Obtain from the database the maximum gas extraction flow rate and the maximum gas concentration of each extraction period corresponding to gas extraction, compare the gas flow rate of each extraction period corresponding to gas extraction with the maximum gas extraction flow rate, and then multiply them by the corresponding weight factor to obtain the gas extraction flow rate effect value of each extraction period corresponding to gas extraction, compare the gas concentration of each extraction period corresponding to gas extraction with the maximum gas extraction concentration, and then multiply them by the corresponding weight factor to obtain the gas extraction concentration effect value of each extraction period corresponding to gas extraction;

[0041] Step 4. Obtain from the database the ambient temperature reference value for each extraction period corresponding to gas extraction and the water level reference value for each extraction period corresponding to gas extraction, respectively calculate the difference between the ambient temperature for each extraction period corresponding to gas extraction and the ambient temperature reference value, and the difference between the water level data for each extraction period corresponding to gas extraction and the water level data reference value, compare the ambient temperature difference for each extraction period corresponding to gas extraction with the ambient temperature for each extraction period corresponding to gas extraction, and then multiply by the corresponding weight factor to obtain the temperature impact value for each extraction period corresponding to gas extraction, compare the water level data difference for each extraction period corresponding to gas extraction with the water level data for each extraction period corresponding to gas extraction, and then multiply by the corresponding weight factor to obtain the water level impact value for each extraction period corresponding to gas extraction;

[0042] Step 5: Sum the gas extraction flow rate effect value and the gas extraction concentration effect value of each extraction period corresponding to gas extraction, and then respectively subtract the temperature influence value and the water level influence value of each extraction period corresponding to gas extraction, and finally multiply the calculated result by the gas pressure change value of each extraction period corresponding to gas extraction to obtain the gas pressure abnormality assessment coefficient of each extraction period corresponding to gas extraction;

[0043] Specifically, it is assumed that the gas pressure of each extraction period is 1.5MPa, the gas pressure safety threshold of each extraction period is 1.0MPa, the allowable fluctuation range of each extraction period is 0.2MPa, and the gas flow rate of each extraction period is 100m 3 / h, the maximum gas extraction flow rate for each extraction period is 150m 3 / h, the gas concentration of gas extraction corresponding to each extraction period is 40%, the maximum gas extraction concentration of gas extraction corresponding to each extraction period is 50%, the ambient temperature of gas extraction corresponding to each extraction period is 25℃, the ambient temperature reference value of gas extraction corresponding to each extraction period is 20℃, the water level impact value of gas extraction corresponding to each extraction period is 0, the preset corresponding weight factor of the gas extraction flow effect value of gas extraction corresponding to each extraction period is 0.5, the preset corresponding weight factor of the gas extraction concentration effect value of gas extraction corresponding to each extraction period is 0.3, the preset corresponding weight factor of the temperature impact value of gas extraction corresponding to each extraction period is 0.2, and the gas pressure abnormality assessment coefficient of gas extraction corresponding to each extraction period is 1.3 after comprehensive calculation of the above values.

[0044] Step 6. Obtain the gas pressure anomaly assessment threshold value corresponding to each extraction period of gas extraction from the database, compare the gas pressure anomaly assessment coefficient corresponding to each extraction period of gas extraction with the gas pressure anomaly assessment threshold value corresponding to each extraction period of gas extraction. If the gas pressure anomaly assessment coefficient corresponding to each extraction period of gas extraction is greater than the gas pressure anomaly assessment threshold value, it means that the gas pressure corresponding to each extraction period of gas extraction is abnormal, generate a gas pressure anomaly signal corresponding to each extraction period of gas extraction, control the volume buffer to adjust the volume, re-analyze and calculate the gas pressure anomaly assessment coefficient corresponding to each extraction period of gas extraction, otherwise, it means that the gas pressure corresponding to each extraction period of gas extraction is normal;

[0045] Step 7, record the gas pressure abnormality assessment coefficient corresponding to each extraction period of gas extraction. If the gas pressure abnormality assessment coefficient corresponding to each extraction period of gas extraction shows an upward trend, it means that the gas pressure corresponding to each extraction period of gas extraction has an upward trend, generate a gas pressure rising change signal, arrange maintenance personnel to inspect and maintain the gas pressure rising state corresponding to each extraction period of gas extraction, and dynamically adjust the volume of the volume buffer until the gas pressure corresponding to each extraction period of gas extraction is in a stable trend;

[0046] In a specific embodiment, the present invention obtains the gas pressure change value of each extraction period corresponding to gas extraction by processing the gas pressure, gas concentration, gas flow rate, ambient temperature and water level data of each extraction period corresponding to gas extraction, and then standardizes the gas pressure of each extraction period corresponding to gas extraction, and at the same time, obtains the gas extraction flow rate effect value of each extraction period corresponding to gas extraction, the gas extraction concentration effect value of each extraction period corresponding to gas extraction, the temperature influence value of each extraction period corresponding to gas extraction, and the water level influence value of each extraction period corresponding to gas extraction according to the data acquired in real time. Finally, the gas pressure abnormality assessment coefficient of each extraction period corresponding to gas extraction is obtained after comprehensive analysis of the above calculation results, which is used for the gas pressure extraction status of each extraction period corresponding to gas extraction, so as to provide early warning of the abnormal gas pressure status during the gas extraction process and ensure the gas pressure safety during the gas extraction process.

[0047] Step 8. The sealing value and slag accumulation value of the extraction pipeline corresponding to each extraction period of gas extraction are measured by an ultrasonic sensor arranged on the outside of the gas extraction pipeline, and the sealing value and slag accumulation value of the extraction pipeline corresponding to each extraction period of gas extraction are obtained. The gas pressure safety threshold value of the gas extraction corresponding to each extraction period and the gas pressure of the gas extraction corresponding to each extraction period are compared and calculated to obtain 1 divided by the calculation result of the difference in ambient temperature of the gas extraction corresponding to each extraction period, and obtain 1 divided by the sum of the sealing value and slag accumulation value of the extraction pipeline corresponding to each extraction period of gas extraction. Finally, the above three calculation results are multiplied by the corresponding weight factors and then multiplied to obtain the gas extraction risk coefficient of the gas extraction corresponding to each extraction period of gas extraction.

[0048] Step nine, obtain the gas extraction risk coefficient threshold value corresponding to each extraction period of gas extraction from the database, and compare the gas extraction risk coefficient corresponding to each extraction period of gas extraction with the gas extraction risk coefficient threshold value. If the gas extraction risk coefficient corresponding to each extraction period of gas extraction is greater than the gas extraction risk coefficient threshold value, it means that the gas outburst per unit area is large, and a gas over-limit warning signal is generated. Otherwise, it means that the gas outburst state of gas extraction corresponding to each extraction period is normal, and a gas extraction normal signal is generated.

[0049] In a specific embodiment, the present invention obtains the gas extraction risk coefficient for each extraction period corresponding to gas extraction by real-time monitoring of the sealing value and slag accumulation value of the extraction pipeline in each extraction period corresponding to gas extraction, and performs comprehensive calculation and analysis of the three parameters in combination with the gas pressure in each extraction period corresponding to gas extraction, and obtains the gas extraction risk coefficient for each extraction period corresponding to gas extraction by performing comprehensive calculation and analysis from the sealing state and slag accumulation state of the extraction pipeline in each extraction period corresponding to gas extraction, in combination with the gas pressure in each extraction period corresponding to gas extraction, thereby performing early warning analysis on the gas outburst state in each extraction period corresponding to gas extraction, and improving the safety of variable capacity, buffer pressure relief and zero overlimit blowout prevention of gas extraction drilling in each extraction period corresponding to gas extraction.

[0050] In addition, those skilled in the art will appreciate that various aspects of the present invention may be illustrated and described by a number of patentable categories or situations, including any new and useful process, machine, product or combination of substances, or any new and useful improvements thereto. Accordingly, various aspects of the present invention may be performed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software may all be referred to as "data blocks", "modules", "engines", "units", "components" or "systems". In addition, various aspects of the present invention may be represented as a computer product located in one or more computer-readable media, which includes computer-readable program code.

[0051] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. It should also be understood that terms such as those defined in common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such herein.

[0052] The above is an explanation of the present invention and should not be considered as a limitation thereof. Although several exemplary embodiments of the present invention have been described, it will be readily appreciated by those skilled in the art that many modifications may be made to the exemplary embodiments without departing from the novel teachings and advantages of the present invention. Therefore, all such modifications are intended to be included within the scope of the present invention as defined in the claims. It should be understood that the above is an explanation of the present invention and should not be considered as being limited to the specific embodiments disclosed, and modifications to the disclosed embodiments and other embodiments are intended to be included within the scope of the appended claims. The present invention is defined by the claims and their equivalents.

Claims

1. A gas extraction borehole variable capacity, buffer pressure relief and zero over-limit blowout prevention method, characterized in that: The following steps are involved: Step 1: Install a volume buffer at the borehole mouth, and obtain the gas extraction parameters corresponding to each extraction period in real time through various monitoring instruments, wherein the gas extraction parameters corresponding to each extraction period include gas pressure, gas concentration, gas flow, ambient temperature and water level data corresponding to each extraction period; Step 2: Obtain the gas pressure safety threshold value corresponding to each extraction period of gas extraction from the database, and at the same time obtain the allowable fluctuation range of each extraction period of gas extraction from the database, standardize the gas pressure of each extraction period of gas extraction, and calculate the gas pressure change value of each extraction period of gas extraction; Step 3: Obtain the maximum gas extraction flow rate and the maximum gas concentration of each extraction period corresponding to gas extraction from the database, and obtain the gas extraction flow rate effect value and the gas extraction concentration effect value of each extraction period corresponding to gas extraction by calculation; Step 4: Obtain the ambient temperature reference value and the water level reference value corresponding to each extraction period of gas extraction from the database, and obtain the temperature impact value and water level impact value corresponding to each extraction period of gas extraction by calculation; Step 5: Sum the gas extraction flow rate effect value and the gas extraction concentration effect value of each extraction period corresponding to gas extraction, and then respectively subtract the temperature influence value and the water level influence value of each extraction period corresponding to gas extraction, and finally multiply the calculated result by the gas pressure change value of each extraction period corresponding to gas extraction to obtain the gas pressure abnormality assessment coefficient of each extraction period corresponding to gas extraction; Step 6. Obtain the gas pressure anomaly assessment threshold value corresponding to each extraction period of gas extraction from the database, compare the gas pressure anomaly assessment coefficient corresponding to each extraction period of gas extraction with the gas pressure anomaly assessment threshold value corresponding to each extraction period of gas extraction. If the gas pressure anomaly assessment coefficient corresponding to each extraction period of gas extraction is greater than the gas pressure anomaly assessment threshold value, it means that the gas pressure corresponding to each extraction period of gas extraction is abnormal, generate a gas pressure anomaly signal corresponding to each extraction period of gas extraction, control the volume buffer to adjust the volume, re-analyze and calculate the gas pressure anomaly assessment coefficient corresponding to each extraction period of gas extraction, otherwise, it means that the gas pressure corresponding to each extraction period of gas extraction is normal; Step 7, record the gas pressure abnormality assessment coefficient corresponding to each extraction period of gas extraction. If the gas pressure abnormality assessment coefficient corresponding to each extraction period of gas extraction shows an upward trend, it means that the gas pressure corresponding to each extraction period of gas extraction has an upward trend, generate a gas pressure rising change signal, arrange maintenance personnel to inspect and maintain the gas pressure rising state corresponding to each extraction period of gas extraction, and dynamically adjust the volume of the volume buffer until the gas pressure corresponding to each extraction period of gas extraction is in a stable trend; Step 8: Using an ultrasonic sensor disposed outside the gas extraction pipeline to measure the sealing value and slag accumulation value of the extraction pipeline at each extraction period corresponding to gas extraction, the sealing value and slag accumulation value of the extraction pipeline at each extraction period corresponding to gas extraction are obtained, and the gas extraction risk coefficient of the gas extraction at each extraction period corresponding to gas extraction is obtained by calculation; Step nine, obtain the gas extraction risk coefficient threshold value corresponding to each extraction period of gas extraction from the database, and compare the gas extraction risk coefficient corresponding to each extraction period of gas extraction with the gas extraction risk coefficient threshold value. If the gas extraction risk coefficient corresponding to each extraction period of gas extraction is greater than the gas extraction risk coefficient threshold value, it means that the gas outburst per unit area is large, and a gas over-limit warning signal is generated. Otherwise, it means that the gas outburst state of gas extraction corresponding to each extraction period is normal, and a gas extraction normal signal is generated.

2. The gas extraction drilling variable volume, buffer pressure relief and zero over-limit blowout prevention method according to claim 1 is characterized by: In step 1, the specific method for obtaining the gas extraction parameters corresponding to each extraction period is as follows: The gas pressure of each extraction period corresponding to gas extraction is obtained through a pressure sensor installed in the borehole, the gas concentration of each extraction period corresponding to gas extraction is obtained through a concentration sensor installed in the borehole, the gas flow rate of each extraction period corresponding to gas extraction is obtained through a flow meter installed at the inlet and outlet of the volume buffer, the ambient temperature of each extraction period corresponding to gas extraction is obtained through a temperature sensor installed inside the borehole, and the water level data of each extraction period corresponding to gas extraction is obtained through a liquid level sensor installed in the groundwater level.

3. The gas extraction drilling variable volume, buffer pressure relief and zero over-limit blowout prevention method according to claim 1 is characterized by: In step 2, the calculation method of the change value of gas pressure corresponding to each extraction period of gas extraction is as follows: The gas pressure of each extraction period corresponding to the gas extraction period is standardized. The gas pressure change value of each extraction period corresponding to the gas extraction period is obtained by calculating the difference between the gas pressure of each extraction period corresponding to the gas extraction period and the gas pressure safety threshold of each extraction period corresponding to the gas extraction period and dividing it by the allowable fluctuation range of each extraction period corresponding to the gas extraction period.

4. The gas extraction drilling variable volume, buffer pressure relief and zero over-limit blowout prevention method according to claim 1 is characterized by: In step 3, the gas extraction flow rate effect value and gas extraction concentration effect value corresponding to each extraction period are calculated as follows: The gas flow rate corresponding to each extraction period of gas extraction and the maximum gas extraction flow rate are compared and calculated, and then multiplied by the corresponding weight factor to obtain the gas extraction flow rate effect value corresponding to each extraction period of gas extraction. The gas concentration corresponding to each extraction period of gas extraction and the maximum gas extraction concentration are compared and calculated, and then multiplied by the corresponding weight factor to obtain the gas extraction concentration effect value corresponding to each extraction period of gas extraction.

5. The gas extraction drilling variable volume, buffer pressure relief and zero over-limit blowout prevention method according to claim 1 is characterized in that: In step 4, the temperature impact value and water level impact value of gas extraction corresponding to each extraction period are calculated as follows: Calculate the difference between the ambient temperature and the ambient temperature reference value for each extraction period corresponding to gas extraction, as well as the difference between the water level data and the water level data reference value for each extraction period corresponding to gas extraction. Compare the ambient temperature difference for each extraction period corresponding to gas extraction with the ambient temperature for each extraction period corresponding to gas extraction, and then multiply by the corresponding weight factor to obtain the temperature impact value for each extraction period corresponding to gas extraction. Compare the water level data difference for each extraction period corresponding to gas extraction with the water level data for each extraction period corresponding to gas extraction, and then multiply by the corresponding weight factor to obtain the water level impact value for each extraction period corresponding to gas extraction.

6. The gas extraction drilling variable volume, buffer pressure relief and zero over-limit blowout prevention method according to claim 1 is characterized in that: In step 8, the calculation method of the gas extraction risk coefficient corresponding to each extraction period is as follows: Compare the gas pressure safety threshold corresponding to each extraction period of gas extraction and the gas pressure corresponding to each extraction period of gas extraction to obtain the calculation result of 1 divided by the ambient temperature difference corresponding to each extraction period of gas extraction, and obtain the calculation result of 1 divided by the sum of the sealing value and the slag accumulation value of the extraction pipeline corresponding to each extraction period of gas extraction. Finally, multiply the above three calculation results by the corresponding weight factors and then perform product calculation to obtain the gas extraction risk coefficient corresponding to each extraction period of gas extraction.

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