Portable testing device for hole sealing quality of gas extraction drill hole and evaluation method

Abstract

The invention discloses a portable testing device for the hole sealing quality of a gas extraction drill hole and an evaluation method. The portable testing device comprises a gas collecting system and an oxygen concentration measuring system. The gas collection system comprises a gas sampler and an exhaust pipe; the oxygen concentration measuring system comprises an oxygen concentration measuring instrument and an air inlet pipe. The evaluation method comprises the steps of equipment connection, gas collection, gas injection into the oxygen concentration measuring instrument, measurement of the oxygen concentration in a drill hole, measurement of the oxygen concentration in a roadway and evaluation of the quality of drill hole sealing. The gas collecting system and the oxygen concentration measuring system are matched to measure the oxygen concentration value in the drill hole and the oxygen concentration value in the roadway where the drill hole is located, and the drill hole sealing quality is judged through the drill hole sealing quality calculating system; the testing device is light in structure, easy to operate and convenient to carry and use, the evaluation method quantifies the drilling quality grade area, and the hole sealing quality of the gas extraction drilling hole can be effectively judged.

Description

Technical Field

[0001] The present invention belongs to the technical field of coalbed methane and gas extraction, and in particular relates to a portable testing device and evaluation method for gas extraction drilling hole sealing quality. Background Art

[0002] Gas is one of the main threats to mine safety. Drilling to extract coal seam gas has become the primary method for managing this problem in coal mining. The effectiveness of gas extraction through drilling depends on the quality of the borehole sealing. Improving and monitoring the sealing quality of gas extraction boreholes is crucial for coal mine gas extraction and prevention.

[0003] In recent years, the sealing technology for gas extraction boreholes has rapidly advanced. Sealing methods have evolved from a single plugging method to a two-plugging, one-injection method. Sealing materials have evolved from yellow mud and wood plugs to polymer foams, high-water-density materials, cement-based expansive materials, and others. The goal of sealing is to improve borehole sealing quality. However, many factors, beyond the sealing method and grouting materials, influence sealing quality. These include borehole quality, sealing depth, grouting length, mining stress interference, and whether the sealing worker performs the job properly. Therefore, a clear set of sealing quality evaluation standards is necessary to regularly monitor and evaluate each gas extraction borehole to ensure that each one effectively extracts coal seam gas within its extraction area. Sealing operations are closed, concealed engineering operations. Currently, due to limitations in detection methods, no publicly available information exists on equipment and methods that can visualize borehole sealing. Existing common equipment for testing sealing quality is expensive, complex to operate, and bulky and heavy, making it difficult to carry. In addition, there is still no clear indicator to evaluate the sealing quality. Summary of the Invention

[0004] The purpose of the present invention is to provide a portable testing device and evaluation method for the sealing quality of gas extraction boreholes. The testing device has a lightweight structure, simple operation, and is easy to carry and use. The evaluation method quantifies the drilling quality grade area and can effectively determine the sealing quality of gas extraction boreholes.

[0005] To achieve the above-mentioned object, the present invention provides a portable testing device for the quality of gas extraction drilling and sealing, comprising a gas collection system and an oxygen concentration measurement system;

[0006] The gas collection system includes a gas sampler and an exhaust pipe. A sampling chamber is provided inside the gas sampler. An opening communicating with the sampling chamber is provided at one end of the gas sampler. A sampling rod is provided in the opening. A sampling piston is provided at one end of the sampling rod located in the sampling chamber. A sampling inlet and a sampling outlet communicating with the sampling chamber are provided at the other end of the gas sampler. The exhaust pipe is connected to the sampling inlet. An inlet valve is provided on the gas sampler near the sampling inlet, and an outlet valve is provided near the sampling outlet.

[0007] The oxygen concentration measurement system includes an oxygen concentration measuring instrument and an air inlet pipe. The oxygen concentration measuring instrument is provided with a measuring chamber and an oxygen concentration sensor. The oxygen concentration measuring instrument is provided with a gas inlet and a gas outlet. The gas outlet is provided with an outlet valve. One end of the air inlet pipe is connected to the gas inlet, and the other end is connected to the sampling outlet.

[0008] To achieve the above-mentioned object of the invention, the present invention further provides a method for evaluating the sealing quality of a gas extraction borehole, based on a portable testing device for the sealing quality of a gas extraction borehole, comprising the following steps:

[0009] S1. Equipment connection: After assembling the portable test device for gas extraction borehole sealing quality, connect the end of the extraction pipe to the measuring port on the gas extraction pipeline;

[0010] S2. Collect gas: Open the ball valve on the gas extraction pipeline to provide negative pressure for the borehole, then open the air inlet valve and pull the sampling piston outward. After the sampling chamber is filled with gas, close the air inlet valve.

[0011] S3. Inject gas into the oxygen concentration measuring instrument: Open the gas outlet valve and the outlet valve, then push the sampling piston to inject all the gas collected in the sampling chamber into the measurement chamber through the air inlet pipe. Then close the gas outlet valve and the outlet valve, monitor the feedback through the oxygen concentration sensor, and observe the oxygen concentration displayed on the gas concentration measuring instrument;

[0012] S4. Measure the oxygen concentration in the borehole: Repeat steps S2-S3 several times. When the oxygen concentration variation range is less than 0.1%, record the last measured oxygen concentration value C1, which is the oxygen concentration value in the borehole under negative pressure extraction conditions.

[0013] S5. Measuring oxygen concentration in the roadway: Disconnect the exhaust pipe from the measuring port and place the end of the exhaust pipe in the roadway, with the height of the end of the exhaust pipe from the floor consistent with the height of the gas extraction pipeline from the floor. Repeat S2-S3 several times. When the oxygen concentration variation range is less than 0.1%, record the last measured oxygen concentration value, C0, which is the oxygen concentration value in the roadway where the extraction borehole is located.

[0014] S6. Evaluation of drilling hole sealing quality: The drilling hole sealing quality is evaluated based on the oxygen concentration value in the drilling hole obtained in S4 and the oxygen concentration value in the tunnel where the drilling hole is located obtained in S5.

[0015] As a further solution of the present invention: before performing S2, the gas collection step, the sampling chamber is kept free of gas.

[0016] As a further solution of the present invention: let the drilling and sealing quality coefficient η be a parameter for evaluating the drilling and sealing quality, and η satisfies:

[0017]

[0018] Where C1 is the measured oxygen concentration in the borehole; C0 is the measured oxygen concentration in the air in the tunnel; and η is the borehole sealing quality coefficient, which ranges from 0% to 100%.

[0019] As a further solution of the present invention: the criteria for judging the sealing quality of the drilled hole are as follows:

[0020] η of 100% means: the sealing quality of the drilled hole is perfect and there is no air leakage in the drilled hole;

[0021] 100%>η≥90% means: the sealing quality of the drilled hole is excellent;

[0022] 90%>η≥75% means: the sealing quality of the drilled hole is good, and there is slight air leakage in the drilled hole;

[0023] 75%>η≥60% means: the sealing quality of the drilled hole is average, and the drilling leakage phenomenon is more obvious;

[0024] 60%>η≥30% means: the sealing quality of the drilled hole is poor and the drilling leakage phenomenon is serious;

[0025] 60%>η≥30% means: the sealing quality of the drilled hole is extremely poor and the drilled hole has serious air leakage.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention samples and analyzes the gas in the borehole to obtain the oxygen concentration value in the borehole, defines the borehole sealing quality coefficient, quantifies the borehole sealing quality grade area, and then determines the sealing quality of the gas extraction borehole, effectively solving the problem that the sealing quality of the gas extraction borehole cannot be quantitatively evaluated and measured.

[0028] The present invention can be applied to the measurement and evaluation of the sealing quality of roof drilling holes, floor drilling holes and coal seam drilling holes for coal mine gas extraction, and can also be applied to the measurement and evaluation of the sealing quality of goaf areas.

[0029] The testing device of the present invention has a simple pipeline and is easy to operate. The evaluation method is scientific, reasonable, simple and easy to understand, and is worthy of promotion and application in the field of coal mine gas extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of a portable testing device for gas extraction drilling and sealing quality of the present invention.

[0031] Figure 2 The present invention is a flow chart of a method for evaluating the quality of gas extraction drilling and sealing.

[0032] In the figure: 1. Ball valve switch, 2. Gas extraction pipeline, 3. Gas in the borehole, 4. Borehole, 5. Coal seam, 6. Gas, 7. Leakage and plugging gas, 8. Air in the tunnel, 9. Blocking section;

[0033] 11. Gas sampler, 12. Gas extraction pipe;

[0034] 111. Sampling rod, 112. Sampling piston, 113. Sampling chamber, 114. Air inlet valve, 115. Sampling air outlet, 116. Air outlet valve, 117. Sampling air inlet;

[0035] 21. Oxygen concentration measuring instrument, 22. Intake pipe;

[0036] 211. Gas inlet, 212. Measurement chamber, 213. Oxygen concentration sensor, 214. Outlet valve, 215. Gas outlet;

[0037] 41. Measuring port. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings.

[0039] like Figure 1 As shown, a portable testing device for gas extraction borehole sealing quality includes a gas collection system and an oxygen concentration measurement system;

[0040] The gas collection system includes a gas sampler 11 and an exhaust pipe 12. A sampling chamber 113 is provided inside the gas sampler 11. An opening communicating with the sampling chamber 113 is provided at one end of the gas sampler 11. A sampling rod 111 is provided in the opening. A sampling piston 112 is provided at one end of the sampling rod 111 located in the sampling chamber 113. A sampling air inlet 117 and a sampling air outlet 115 communicating with the sampling chamber 113 are provided at the other end of the gas sampler 11. The exhaust pipe 12 is connected to the sampling air inlet 117. An air inlet valve 114 is provided on the gas sampler 11 near the sampling air inlet 117, and an air outlet valve 116 is provided near the sampling air outlet 115.

[0041] Close the air outlet valve 116, open the air inlet valve 114, and pull the sampling rod 111 of the gas sampler 11 to suck the gas into the sampling chamber 113; then switch the valve state, open the air outlet valve 116, close the air inlet valve 114, push the sampling rod 111, and use the sampling piston 112 to compress the sampling chamber 113, so that the gas in the sampling chamber 113 can be discharged from the sampling outlet 115.

[0042] The oxygen concentration measurement system includes an oxygen concentration measuring instrument 21 and an air inlet pipe 22. A measuring chamber 212 and an oxygen concentration sensor 213 are provided inside the oxygen concentration measuring instrument 21. A gas inlet 211 and a gas outlet 215 are provided on the oxygen concentration measuring instrument 21. An outlet valve 214 is provided at the gas outlet 215. One end of the air inlet pipe 22 is connected to the gas inlet 211, and the other end is connected to the sampling outlet 115.

[0043] like Figure 1 and Figure 2 As shown, a method for evaluating the sealing quality of a gas extraction borehole is provided, based on a portable testing device for the sealing quality of a gas extraction borehole, and includes the following steps:

[0044] S1. Equipment connection: After assembling the portable test device for gas extraction borehole sealing quality, connect the end of the extraction pipe 12 to the measuring port 41 on the gas extraction pipeline 2; close the inlet valve 114, outlet valve 116, and outlet valve 214 of the gas sampler 11;

[0045] In order to ensure measurement efficiency, further, before performing S2, gas collection step, the sampling chamber 113 is kept free of gas;

[0046] S2. Collecting Gas: Open the ball valve switch 1 on the gas extraction pipeline 2 to provide negative extraction pressure for the borehole 4. Driven by the negative extraction pressure, the gas 3 in the borehole enters the gas extraction pipeline 2. The extracted gas consists of gas 6 in the borehole 4 and leaked gas 7. The gas 6 in the borehole 4 is the free and adsorbed gas in the coal seam 5 that migrates into the borehole 4. The leaked gas 7 is the air 8 in the tunnel that enters the borehole 4 through the plugging section 9. Then, open the air inlet valve 114 and pull the sampling piston 112 outward. After the sampling chamber 113 is filled with gas, close the air inlet valve 114.

[0047] S3. Inject gas into the oxygen concentration measuring instrument 21: Open the gas outlet valve 116 and the outlet valve 214, then advance the sampling piston 112 to inject all the gas collected in the sampling chamber 113 into the measuring chamber 212 through the inlet pipe 22. Then close the gas outlet valve 116 and the outlet valve 214, monitor the feedback through the oxygen concentration sensor 213, and observe the oxygen concentration displayed on the gas concentration measuring instrument;

[0048] S4. Measure the oxygen concentration in borehole 4: Repeat steps S2-S3 several times. When the oxygen concentration variation range is less than 0.1%, record the last measured oxygen concentration value C1, which is the oxygen concentration value in borehole 4 under negative pressure extraction conditions.

[0049] S5. Measuring the oxygen concentration in the roadway: Disconnect the exhaust pipe 12 from the measuring port 41, and place the end of the exhaust pipe 12 in the roadway, with the height of the end of the exhaust pipe 12 from the floor being the same as the height of the gas extraction pipeline 2 from the floor. Repeat S2-S3 several times. When the oxygen concentration variation range is less than 0.1%, record the last measured oxygen concentration value C0, which is the oxygen concentration value in the roadway where the extraction borehole 4 is located.

[0050] S6. Evaluation of the sealing quality of borehole 4: the sealing quality of borehole 4 is evaluated by calculating based on the oxygen concentration value in borehole 4 obtained in S4 and the oxygen concentration value in the tunnel where borehole 4 is located obtained in S5.

[0051] Furthermore, let the sealing quality coefficient η of borehole 4 be a parameter for evaluating the sealing quality of borehole 4, and η satisfies:

[0052]

[0053] Where C1 is the measured oxygen concentration in borehole 4; C0 is the measured oxygen concentration in the air in the tunnel; η is the sealing quality coefficient of borehole 4, ranging from 0% to 100%;

[0054] Specifically, the quality criteria for sealing borehole 4 are as follows:

[0055] η is 100% means: the sealing quality of drilling hole 4 is perfect and there is no air leakage in drilling hole 4;

[0056] 100%>η≥90% indicates that the sealing quality of borehole 4 is excellent;

[0057] 90%>η≥75% means: the sealing quality of borehole 4 is good, and there is slight air leakage in borehole 4;

[0058] 75%>η≥60% means: the sealing quality of borehole 4 is average, and the air leakage of borehole 4 is more obvious;

[0059] 60%>η≥30% means: the sealing quality of borehole 4 is poor and the air leakage of borehole 4 is serious;

[0060] 60%>η≥30% indicates that the sealing quality of borehole 4 is extremely poor and borehole 4 has serious air leakage.

[0061] The larger η is, the better the sealing quality is; the smaller η is, the worse the sealing quality is.

Claims

1. A portable testing device for gas extraction drilling and sealing quality, characterized in that: Including gas collection system and oxygen concentration measurement system; The gas collection system comprises a gas sampler (11) and an exhaust pipe (12); a sampling chamber (113) is provided inside the gas sampler (11); an opening communicating with the sampling chamber (113) is provided at one end of the gas sampler (11); a sampling rod (111) is provided in the opening; an end of the sampling rod (111) located in the sampling chamber (113) is provided with a sampling piston (112); a sampling air inlet (117) and a sampling air outlet (115) communicating with the sampling chamber (113) are provided at the other end of the gas sampler (11); the exhaust pipe (12) is connected to the sampling air inlet (117); an air inlet valve (114) is provided on the gas sampler (11) near the sampling air inlet (117); and an air outlet valve (116) is provided near the sampling air outlet (115); The oxygen concentration measuring system comprises an oxygen concentration measuring instrument (21) and an air inlet pipe (22). A measuring chamber (212) and an oxygen concentration sensor (213) are provided inside the oxygen concentration measuring instrument (21). A gas inlet (211) and a gas outlet (215) are provided on the oxygen concentration measuring instrument (21). An outlet valve (214) is provided at the gas outlet (215). One end of the air inlet pipe (22) is connected to the gas inlet (211), and the other end is connected to the sampling outlet (115).

2. A method for evaluating the sealing quality of a gas extraction borehole, based on the portable testing device for the sealing quality of a gas extraction borehole as described in claim 1, characterized in that: The following steps are involved: S1. Equipment connection: After assembling the portable test device for gas extraction drilling and sealing quality, connect the end of the extraction pipe (12) to the measuring port (41) on the gas extraction pipeline (2); S2. Collecting gas: Open the ball valve switch (1) on the gas extraction pipeline (2) to provide extraction negative pressure for the borehole (4), then open the air inlet valve (114) and pull the sampling piston (112) outward. After the sampling chamber (113) is filled with gas, close the air inlet valve (114); S3. Inject gas into the oxygen concentration measuring instrument (21): open the gas outlet valve (116) and the outlet valve (214), then push the sampling piston (112), and inject all the gas collected in the sampling chamber (113) into the measuring chamber (212) through the air inlet pipe (22), then close the gas outlet valve (116) and the outlet valve (214), monitor the feedback through the oxygen concentration sensor (213), and observe the oxygen concentration displayed on the gas concentration measuring instrument; S4. Measuring the oxygen concentration in the borehole (4): Repeat steps S2-S3 several times. When the oxygen concentration variation range is less than 0.1%, record the oxygen concentration value C1 of the last measurement, which is the oxygen concentration value in the borehole (4) under negative pressure extraction conditions; S5. Measurement of oxygen concentration in the tunnel: Separate the connection between the exhaust pipe (12) and the measuring port (41), place the end of the exhaust pipe (12) in the tunnel, and make sure that the height of the end of the exhaust pipe (12) from the bottom plate is consistent with the height of the gas extraction pipeline (2) from the bottom plate. Repeat S2-S3 several times. When the oxygen concentration variation range is less than 0.1%, record the oxygen concentration value C0 of the last measurement, which is the oxygen concentration value in the tunnel where the extraction borehole (4) is located. S6. Evaluation of the sealing quality of the borehole (4): the sealing quality of the borehole (4) is evaluated by calculating based on the oxygen concentration value in the borehole (4) obtained in S4 and the oxygen concentration value in the tunnel where the borehole (4) is located obtained in S5.

3. A gas extraction drilling and sealing quality evaluation method according to claim 2, characterized in that: Before performing S2, the gas collection step, the sampling chamber (113) is kept free of gas.

4. A gas extraction drilling and sealing quality evaluation method according to claim 2, characterized in that: Assume that the sealing quality coefficient η of the drilling hole (4) is a parameter for evaluating the sealing quality of the drilling hole (4), and η satisfies: Wherein, C1 is the oxygen concentration value in the borehole (4) obtained by measurement; C0 is the oxygen concentration value of the air in the tunnel obtained by measurement; η is the sealing quality coefficient of the borehole (4), and its value range is 0% to 100%.

5. A gas extraction drilling and sealing quality evaluation method according to claim 4, characterized in that: The quality criteria for sealing the drilled hole (4) are as follows: η is 100% means: the sealing quality of the drill hole (4) is perfect, and there is no air leakage in the drill hole (4); 100%>η≥90% means: the sealing quality of the drill hole (4) is excellent; 90%>η≥75% means: the sealing quality of the drilling hole (4) is good, and the drilling hole (4) has a slight air leakage phenomenon; 75%>η≥60% means: the sealing quality of the drilling hole (4) is average, and the air leakage phenomenon of the drilling hole (4) is relatively obvious; 60%>η≥30% means: the sealing quality of the drilling hole (4) is poor, and the air leakage phenomenon of the drilling hole (4) is serious; 60%>η≥30% indicates that the sealing quality of the drill hole (4) is extremely poor and the drill hole (4) has serious air leakage.

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