Surrounding rock fracture development horizon identification device and method

Abstract

The invention discloses a surrounding rock fracture development horizon identification device and method.A vacuum pump of the identification device is arranged at the lower end of a test pipeline, the upper end of the test pipeline is closed, a valve is arranged on the test pipeline, the test pipeline is sleeved with a first air bag and a second air bag, and the first air bag is located above the second air bag; the air pump is arranged at the left end of the air injection main pipe, the right end of the air injection main pipe is connected with the bottom end of the first air injection branch pipe and the bottom end of the second air injection branch pipe through a three-way connector, and the upper end of the first air injection branch pipe is connected with an inflation inlet of the first air bag. The two upper ends of the second air injection branch pipe are connected with an inflation inlet of the second air bag, and a pressure sensor is arranged on the testing pipeline and located below the second air bag. According to the method, the surrounding rock fracture development layer position is judged, hole sealing is conducted in time, efficient gas extraction is achieved, and the resource utilization rate is increased on the premise that safety is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mine gas control and engineering geological exploration. Specifically, it relates to a device and method for identifying the layer where surrounding rock fissures develop. Background Art

[0002] During coal mine underground mining operations, when conducting gas drainage through cross - layer boreholes, a series of intractable problems are often encountered. Among them, the low gas drainage concentration is extremely prominent. Ideally, cross - layer boreholes should be able to effectively extract high - concentration gas to ensure safe production and energy utilization. However, in actual operation, the gas concentration extracted by the boreholes is relatively low, and the drainage effect is poor. The main reason for this phenomenon is the poor sealing effect, which fails to form a relatively closed environment, allowing other gases to enter the borehole through fissures, resulting in a decrease in gas concentration.

[0003] In actual sealing, the sealing depth exceeds the area where fissures develop, isolating the entry of external gases. During gas drainage, the concentration can be guaranteed, thus reducing the impact on gas drainage and ensuring the drainage effect. However, the existing identification devices and methods cannot accurately determine the layer where fissures develop, resulting in a great impact on gas drainage. Therefore, a device and method for identifying the layer where surrounding rock fissures develop that can accurately determine the fissure - developed layer are needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for identifying the layer where surrounding rock fissures develop. By accurately determining the layer where fissures develop, blind construction of boreholes and construction of drainage facilities can be avoided, reducing ineffective projects and lowering the cost of gas drainage; and by determining the layer where surrounding rock fissures develop, sealing can be carried out in a timely manner to achieve efficient gas drainage, which helps to improve resource utilization rate on the premise of ensuring safety.

[0005] To achieve the above - mentioned purpose, the present invention adopts the following technical solutions: A device for identifying the layer where surrounding rock fissures develop, comprising a vacuum pump, a test pipeline, a first airbag, a second airbag, an air injection main pipe, a first air injection branch pipe, a second air injection branch pipe, an air pump, and valves. The vacuum pump is arranged at the lower end of the test pipeline, the upper end of the test pipeline is closed, the valves are arranged on the test pipeline, the first airbag and the second airbag are sleeved on the test pipeline, and the first airbag is located above the second airbag. A plurality of air extraction holes are evenly arranged on the test pipeline between the first airbag and the second airbag. The air pump is arranged at the left end of the air injection main pipe. The right end of the air injection main pipe is connected to the bottom ends of the first air injection branch pipe and the second air injection branch pipe respectively through a three - way joint. The upper end of the first air injection branch pipe is connected to the inflation port of the first airbag, the upper end of the second air injection branch pipe is connected to the inflation port of the second airbag, and a pressure sensor is arranged on the test pipeline, and the pressure sensor is located below the second airbag.

[0006] A method for identifying the layer position with developed surrounding rock fissures is implemented based on the above-mentioned device for identifying the layer position with developed surrounding rock fissures, and includes the following steps: (1) Construct several cross-layer boreholes to the target rock formation, and then select a suitable borehole for testing the layer position with developed surrounding rock fissures; (2) Install the identification device in the selected borehole, then start the air pump to inject air into the first airbag and the second airbag through the main air injection pipe, the first air injection branch pipe and the second air injection branch pipe. The first airbag and the second airbag expand and tightly fit the borehole wall, so that the borehole section between the first airbag and the second airbag forms a sealed section; (3) Open the vacuum pump and the corresponding valve, and extract the gas in the sealed section and the test pipeline through the vacuum pump. The gas in the sealed section is extracted through the air extraction holes on the test pipeline, causing the air pressure in the sealed section to drop and forming a negative pressure environment; (4) Observe the data change of the pressure sensor to complete the identification of the developed surrounding rock fissures.

[0007] In step (3), the air pressure in the sealed section to form a negative pressure environment is -20 KPa, and the vacuum pump is timely closed after the air pressure reaches -20 KPa.

[0008] The specific identification process of step (4) is as follows: If the data of the pressure sensor does not fluctuate after a period of time, it means that the surrounding rock of this section is relatively complete and the fissure development is less; If the data of the pressure sensor shows that the pressure in the sealed section gradually increases or remains unchanged after increasing to a certain extent after a period of time, it means that there are fissure developments in the surrounding rock of this section.

[0009] The further specific process of step (4) is as follows: If the data of the pressure sensor does not change within 24 hours, it means that the surrounding rock of this section is relatively complete and the fissures are basically undeveloped; If the data change of the pressure sensor is within 30% within 24 hours, it means that the degree of fissure development of the surrounding rock of this section is low, the fissure development is less, and the small fissures are the main ones; If the data change of the pressure sensor is between 30% and 60% within 24 hours, it means that the degree of fissure development of the surrounding rock of this section is moderate, and the medium and small fissures are the main ones; If the data change of the pressure sensor is more than 60% within 24 hours, it means that the degree of fissure development of the surrounding rock of this section is high, and the connectivity between the fissures and the outside is good.

[0010] After identifying a certain target layer, use the air pump to extract the gas in the first airbag and the second airbag, so that the first airbag and the second airbag are released from the blocked state, and move the identification device to the next test layer, and repeat steps (2) to (4).

[0011] The "two plugs and one injection" hole - sealing method adopted in this application can make the airbag fit well with the borehole wall, effectively seal the target layer, avoid air leakage, improve the sealing performance, and can also achieve sealing and movement by controlling the gas content in the airbag, so as to realize the testing of different layers. The operation is simple and convenient, greatly improving the accuracy of the test results.

[0012] Furthermore, this application uses an air pump to inject and extract gas to increase or decrease the gas in the airbag. This method realizes the sealing and unsealing of the target layer by controlling the gas volume in the airbag, and the operation is convenient; the airbag made of flexible material can closely fit the hole wall to achieve excellent sealing effect.

[0013] After the borehole is sealed in this application, a closed space is formed between the two airbags. A vacuum pump is used to extract gas to create a negative - pressure environment in this section. Since the inside of the test pipeline is under negative pressure and the air - extraction holes on the pipeline allow gas to enter, if there are fissures developed in the layer, it provides a channel for gas migration to the target layer. Under the action of pressure, the gas in this sealed section enters the test pipeline through the air - extraction holes on the test pipeline. By using the pressure sensor connected to the tail of the test pipeline to analyze whether there are fissures developed in the surrounding rock of this section, the accuracy of the identification result is greatly improved. Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of the identification device of the present invention.

[0015] Figure 2 It is a schematic structural diagram of the identification device of the present invention when performing identification work in a borehole.

[0016] Figure 3 It is a schematic structural diagram of the cross - layer borehole in the identification method of the present invention. Detailed Embodiments

[0017] The following further illustrates the embodiments of the present invention with reference to the drawings.

[0018] Embodiment 1 As Figures 1-3As shown in the figure, the device for identifying the strata with developed surrounding rock fissures includes a vacuum pump 1, a test pipeline 2, a first airbag 3, a second airbag 4, an air injection main pipe 5, a first air injection branch pipe 6, a second air injection branch pipe 7, an air pump 8 and a valve 9. The vacuum pump 1 is arranged at the lower end of the test pipeline 2, the upper end of the test pipeline 2 is closed, the valve 9 is arranged on the test pipeline 2, and the valve 9 can control the on-off of the test pipeline 2. The first airbag 3 and the second airbag 4 are sleeved on the test pipeline 2. After the first airbag 3 and the second airbag 4 are inflated, they are in close contact with the test pipeline 2. In addition, to ensure the sealing between the first airbag 3 and the second airbag 4 and the test pipeline 2, sealant can be applied to the contact parts of the first airbag 3 and the second airbag 4 and the test pipeline 2. The first airbag 3 is located above the second airbag 4, and a number of air extraction holes 15 are evenly arranged on the test pipeline 2 between the first airbag 3 and the second airbag 4. The air pump 8 is arranged at the left end of the air injection main pipe 5. The right end of the air injection main pipe 5 is respectively connected to the bottom ends of the first air injection branch pipe 6 and the second air injection branch pipe 7 through a tee joint 12. The upper end of the first air injection branch pipe 6 is connected to the inflation port of the first airbag 3, and the upper end of the second air injection branch pipe 7 is connected to the inflation port of the second airbag 4. A pressure sensor 11 is arranged on the test pipeline 2, and the pressure sensor 11 is located below the second airbag 4. To facilitate reading the pressure data of the pressure sensor 11, a corresponding display screen can be connected through a controller to display the change of the pressure data of the pressure sensor 11 in real time.

[0019] Embodiment 2 The method for identifying the strata with developed surrounding rock fissures is implemented based on the above-mentioned device for identifying the strata with developed surrounding rock fissures, and includes the following steps: (1) Construct several cross-layer boreholes 13 to the target rock stratum, and then select a suitable borehole for testing the strata with developed surrounding rock fissures; (2) Install the identification device in the selected borehole, and then start the air pump 8 to inject air into the first airbag 3 and the second airbag 4 through the air injection main pipe 5, the first air injection branch pipe 6 and the second air injection branch pipe 7. The first airbag 3 and the second airbag 4 expand and are in close contact with the borehole wall 14, so that a sealed section 10 is formed in the borehole section between the first airbag 3 and the second airbag 4; (3) Open the vacuum pump 1 and the corresponding valve 9, and extract the gas in the sealed section 10 and the test pipeline 2 through the vacuum pump 1. The gas in the sealed section 10 is extracted through the air extraction holes 15 on the test pipeline 2, so that the air pressure in the sealed section 10 drops, forming a negative pressure environment; (4) Observe the change of the data of the pressure sensor 11 to complete the identification of the development of the surrounding rock fissures.

[0020] In step (3), the air pressure in the sealed section 10 forms a negative pressure environment of -20 KPa, and the vacuum pump 1 is timely closed after the air pressure reaches -20 KPa.

[0021] The specific identification process of step (4) is as follows: If the data of the pressure sensor 11 does not fluctuate after a period of time, it indicates that the surrounding rock in this section is relatively intact and the fissure development is less; if the data of the pressure sensor 11 shows that the pressure in the sealing section 10 gradually increases or remains unchanged after increasing to a certain extent after a period of time, it indicates that there is fissure development in the surrounding rock in this section.

[0022] A further specific process of step (4) is as follows: If the data of the pressure sensor 11 does not change within 24 hours, it indicates that the surrounding rock in this section is relatively intact and the fissures are basically not developed; if the data change of the pressure sensor 11 is within 30% within 24 hours, it indicates that the degree of fissure development in the surrounding rock in this section is low, the fissure development is less, and the small fissures are the main ones; if the data change of the pressure sensor 11 is between 30% and 60% within 24 hours, it indicates that the degree of fissure development in the surrounding rock in this section is moderate, and the medium and small fissures are the main ones; if the data change of the pressure sensor 11 is more than 60% within 24 hours, it indicates that the degree of fissure development in the surrounding rock in this section is high, and the connectivity between the fissures and the outside is good.

[0023] After identifying a certain target horizon, use the air pump 8 to extract the gas in the first airbag 3 and the second airbag 4, so that the first airbag 3 and the second airbag 4 are released from the sealing state, and move the identification device to the next test horizon, and repeat steps (2) to (4).

[0024] The "two-block-one-injection" hole sealing method adopted in this application can make the airbag fit well with the borehole wall 14, effectively seal the target horizon, avoid air leakage, improve the sealing performance, and can also realize sealing and movement by controlling the gas content in the airbag, so as to realize the testing of different horizons. The operation is simple and convenient, and the accuracy of the test results is greatly improved.

[0025] Furthermore, this application uses the air pump 8 to inject and extract gas to increase or decrease the gas in the airbag. This method realizes the sealing and unsealing of the target horizon by controlling the gas volume in the airbag, and the operation is convenient; the airbag made of flexible material can closely fit the hole wall to achieve excellent sealing effect. In addition, from the actual application effect, this sealing method greatly avoids the common air leakage phenomenon in the traditional hole sealing means. Once the air leakage problem occurs, it will not only lead to serious deviation of the test data, but also affect the overall planning and implementation of gas drainage. The application of the airbag, with its excellent sealing performance, significantly improves the quality of sealing, ensures that the target horizon is in a relatively independent and stable environment during the whole test process, and avoids the gas interference of adjacent horizons.

[0026] After the drilling of this application is plugged, a sealed space is formed between the two airbags. The vacuum pump 1 is used to extract air to create a negative pressure environment in this section. Since the inside of the test pipeline 2 is under negative pressure and the air extraction holes 15 on the pipeline allow gas to enter, if there are fissures developed in the formation, it provides a channel for gas migration to this target formation. Under the action of pressure, the gas in the sealing section 10 enters the test pipeline 2 through the air extraction holes 15 on the test pipeline 2. By using the pressure sensor 11 connected to the tail of the test pipeline 2 to analyze whether there are fissures developed in the surrounding rock of this section, the accuracy of the recognition result is greatly improved.

[0027] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that; still modifications or equivalent replacements can be made to the present invention, and any modification or partial replacement without departing from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims

1. Surrounding rock fracture development horizon identification device, characterized in that: It includes a vacuum pump, a test pipeline, a first airbag, a second airbag, an air injection main pipe, a first air injection branch pipe, a second air injection branch pipe, an air pump and a valve. The vacuum pump is arranged at the lower end of the test pipeline, the upper end of the test pipeline is closed, the valve is arranged on the test pipeline, the first airbag and the second airbag are sleeved on the test pipeline, and the first airbag is located above the second airbag. A number of air extraction holes are evenly arranged on the test pipeline between the first airbag and the second airbag. The air pump is arranged at the left end of the air injection main pipe. The right end of the air injection main pipe is respectively connected to the bottom ends of the first air injection branch pipe and the second air injection branch pipe through a tee joint. The upper end of the first air injection branch pipe is connected to the inflation port of the first airbag, and the upper end of the second air injection branch pipe is connected to the inflation port of the second airbag. A pressure sensor is arranged on the test pipeline, and the pressure sensor is located below the second airbag.

2. A method for identifying the strata with developed surrounding rock fissures, which is implemented based on the device for identifying the strata with developed surrounding rock fissures according to claim 1, and is characterized in that: It includes the following steps: (1) Construct a number of cross - layer boreholes to the target rock stratum, and then select a suitable borehole for testing the stratum where the surrounding rock fissures develop; (2) Install the identification device in the selected borehole, then start the air pump to inject air into the first airbag and the second airbag through the air injection main pipe, the first air injection branch pipe and the second air injection branch pipe. The first airbag and the second airbag expand and tightly fit the borehole wall, so that a sealed section is formed in the borehole section between the first airbag and the second airbag; (3) Open the vacuum pump and the corresponding valve, and extract the gas in the sealed section and the test pipeline through the vacuum pump. The gas in the sealed section is extracted through the air extraction holes on the test pipeline, causing the air pressure in the sealed section to drop and forming a negative pressure environment; (4) Observe the data change of the pressure sensor to complete the identification of the development of surrounding rock fissures.

3. The method for identifying the strata with developed surrounding rock fissures according to claim 2, wherein: In step (3), the air pressure in the sealed section to form a negative pressure environment is - 20KPa, and the vacuum pump is promptly closed after the air pressure reaches - 20KPa.

4. The method for identifying the strata with developed surrounding rock fissures according to claim 3, characterized in that: The specific identification process of step (4) is as follows: If the data of the pressure sensor does not fluctuate after a period of time, it indicates that the surrounding rock of this section is relatively intact and the fissure development is less; If the data of the pressure sensor shows that the pressure in the sealed section gradually increases or remains unchanged after increasing to a certain extent after a period of time, it indicates that there are fissure developments in the surrounding rock of this section.

5. The method for identifying the strata with developed surrounding rock fissures according to claim 4, characterized in that: The further specific process of step (4) is as follows: If the data of the pressure sensor does not change within 24 hours, it indicates that the surrounding rock of this section is relatively intact and the fissures basically do not develop; If the data change of the pressure sensor is within 30% within 24 hours, it indicates that the degree of fissure development in the surrounding rock of this section is low, the fissure development is less, and mainly small fissures; If the data change of the pressure sensor is between 30% and 60% within 24 hours, it indicates that the degree of fissure development in the surrounding rock of this section is moderate, mainly medium - small fissures; If the data change of the pressure sensor is more than 60% within 24 hours, it indicates that the degree of fissure development in the surrounding rock of this section is high, and the connectivity between the fissures and the outside is good.

6. The method for identifying the strata with developed surrounding rock fissures according to claim 5, characterized in that: After identifying a certain target layer, use the air pump to extract the gas in the first airbag and the second airbag, so that the first airbag and the second airbag are released from the sealing state, and move the identification device to the next test layer, and repeat steps (2) - (4).

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