Method and device for in-situ remediation and concentration by extraction drilling

Abstract

The application discloses a kind of extraction borehole in-situ repair concentration methods and devices, belong to coal mine gas extraction technical field.The method includes: screening concentration attenuation to initial concentration 1 / 3 below's invalid borehole;Along original envelope hole tube inside insertion pneumatic self-advancing delivery and internal drainage extraction pipeline to borehole bottom, utilize high-pressure airflow to remove blockage and restore gas discharge path;Seal the gap between internal drainage extraction pipeline and original envelope hole tube to form airtight space, move negative pressure extraction position to borehole bottom, make coalbed gas reverse convergence, improve extraction concentration;Connect extraction pipe network balance system pressure.The device includes pneumatic self-advancing delivery and internal drainage extraction pipeline.The application does not need to remove original envelope structure, construction is simple, low in cost, realizes concentration by reconstructing gas flow direction, eliminates extraction blind area safety hazard.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas extraction technology, specifically relating to an in-situ repair and enrichment method and device for extraction boreholes. It is applicable to the in-situ repair and gas enrichment extraction of failed boreholes in coal mines where the extraction concentration has decreased due to channel blockage or gas leakage from the sealing hole. Background Technology

[0002] Gas drainage is one of the core measures for coal mine gas control. Currently, underground coal seam gas drainage commonly adopts the borehole sealing drainage process. This involves installing drainage pipes in the completed drainage borehole and using high-pressure grouting to seal the annular gap between the borehole wall and the drainage pipes, forming a sealing device structure. During drainage, negative pressure is applied to the drainage pipe opening at the sealing device. Under the action of negative pressure, the gas in the coal seam converges from the bottom of the borehole towards the sealing device and is discharged through the drainage pipes to the surface drainage system.

[0003] However, the above-mentioned traditional sampling model has the following drawbacks in actual operation: First, during the extraction process, some boreholes may leak gas due to aging and cracking of the sealing material, or the coal slag and rock cuttings in the borehole may be transported and deposited with the airflow, causing blockage of the channel, resulting in a rapid decrease in the extraction concentration and the formation of a failed borehole.

[0004] Secondly, because traditional processes use high-pressure grouting for sealing, the grout volume is large, the sealing section is long, and the sealer is firmly bonded to the borehole wall, making it difficult to remove and re-construct. Therefore, such failed boreholes are usually abandoned after the grout concentration decreases and cannot be reused.

[0005] Third, the abandonment of a large number of failed boreholes creates extraction blind zones in the coal seam. The gas in these zones cannot be effectively extracted, which not only wastes gas resources but may also become a hidden channel for gas leakage into the mining space, leaving serious safety hazards.

[0006] Fourth, if the failed boreholes are to be re-drilled, they need to be re-drilled and sealed, which is time-consuming and costly. In addition, due to the limitations of downhole space and geological conditions, it is difficult to re-drill in some areas.

[0007] Therefore, there is an urgent need for a method and device that can repair failed boreholes in situ and increase extraction concentration without removing the original sealing structure. Summary of the Invention

[0008] To address the technical problem that failed boreholes are difficult to repair and utilize in existing technologies, resulting in safety hazards due to the formation of extraction blind zones, this invention provides a method and apparatus for in-situ repair and concentration enhancement of extraction boreholes. By using a pneumatic self-propelled delivery device to clear blockages and deliver gas into the internal drainage pipeline to the bottom of the borehole without removing the original sealing structure, and then reconstructing the gas flow direction by moving the negative pressure extraction position forward to the bottom of the borehole, the in-situ repair of failed boreholes and the enhancement of gas extraction concentration are achieved.

[0009] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for in-situ remediation and enrichment of extraction boreholes includes the following steps: S1. Screening of Low-Concentration Extraction Boreholes: The gas concentration parameters of each extraction borehole are detected using an extraction monitoring system. Boreholes with substandard concentrations are screened out, and their locations are determined. The criterion for substandard concentration is: after extraction begins, the extracted concentration decreases to less than 1 / 3 of the initial concentration.

[0010] S2. In-situ borehole repair: At the selected failed borehole location, a pneumatic self-propelled delivery device and an internal drainage pipe are inserted along the interior of the original sealing pipe. The pneumatic self-propelled delivery device is located at the front end of the internal drainage pipe. The pneumatic self-propelled delivery device uses high-pressure airflow to clear blockages within the borehole and drags the internal drainage pipe towards the bottom of the borehole until the pneumatic self-propelled delivery device at the front end of the internal drainage pipe reaches the bottom of the borehole. The internal drainage pipe forms a new gas extraction channel, restoring the gas discharge path.

[0011] S3. Gas Extraction and Enrichment: After the internal drainage pipeline reaches the bottom of the borehole, sealant is used to seal the gap between the internal drainage pipeline and the original sealing pipe, creating a sealed space inside the borehole to prevent air from entering. A negative pressure extraction end is connected to the end of the internal drainage pipeline located at the bottom of the borehole. Negative pressure is applied at the bottom of the borehole to create a negative pressure zone, causing coal seam gas to converge in the reverse direction from the direction of the sealing device towards the bottom of the borehole, thus reversing the gas flow direction and increasing the extracted gas concentration. The internal drainage pipeline is then connected to the extraction pipeline network to balance the pressure of the extraction system, enabling the reuse of failed boreholes.

[0012] An in-situ repair and enrichment device for extraction boreholes includes a pneumatic self-propelled delivery device and an internal drainage pipeline.

[0013] The pneumatic self-propelled delivery device is connected to the front end of the internal drainage pipe. The pneumatic self-propelled delivery device is used to clear blockages in the borehole using high-pressure airflow and to drag the internal drainage pipe toward the bottom of the borehole.

[0014] The internal drainage pipe is installed inside the original sealing pipe and extends to the bottom of the borehole. The internal drainage pipe is used as a new gas extraction channel after reaching the bottom of the borehole to discharge the gas at the bottom of the borehole.

[0015] The gap between the internal drainage pipe and the original sealing pipe is sealed with sealant, forming a sealed space inside the borehole to prevent outside air from entering.

[0016] Using the above technical solution, the functions of each component in this invention are as follows: (1) Pneumatic self-propelled delivery device: As a power and obstacle clearing unit, it uses high-pressure airflow to achieve two functions: first, to impact and clear blockages such as coal slag in the borehole and restore the passage; second, to use the reaction force of the airflow to provide propulsion power and drag the internal drainage pipe to the bottom of the hole to achieve self-propelled delivery.

[0017] (2) Internal drainage pipeline: As a new gas extraction channel, it replaces the original blocked extraction channel and guides the gas at the bottom of the borehole to the extraction pipeline network.

[0018] (3) Sealant: fills the annular gap between the internal drainage pipe and the original sealing pipe to form a sealing barrier, preventing outside air from entering the borehole and ensuring that the gas concentration in the borehole is not diluted by the air.

[0019] (4) Original sealing pipe: It is retained as an existing structure and not removed, providing an entry channel and guidance for the pneumatic self-propelled delivery device and the internal drainage pipeline.

[0020] (5) Sealing device: It is a sealing structure formed by the original high-pressure grouting sealing, located at the borehole opening section. It is retained in this invention as part of the original sealing structure of the borehole.

[0021] In summary, compared with the prior art, the present invention has the following beneficial effects: 1) Achieve in-situ repair and utilization of failed boreholes: There is no need to remove the original sealing structure or re-drill. The repair can be completed by inserting a pneumatic self-advancing delivery device and an internal drainage pipe into the original sealing pipe. The construction is simple and low-cost, which greatly saves the construction cost and time of re-drilling.

[0022] 2) Reconstructing the gas flow direction to achieve concentration: By moving the negative pressure extraction position from the sealing device to the bottom of the borehole, the convergence direction of gas in the borehole is changed, causing the gas to flow in the forward direction to converge in the reverse direction. The gas is enriched at the bottom of the borehole, effectively increasing the concentration of extracted gas.

[0023] 3) Eliminate safety hazards in drainage blind spots: reintegrate failed boreholes that may become gas leakage channels into the drainage system, clear and reduce gas pressure in coal seams or goaf areas, shift from passive response to proactive management, and eliminate potential safety hazards.

[0024] 4) Improve the overall efficiency of the gas extraction system: Reconnect failed boreholes to the extraction pipeline network to balance the pressure of the extraction system, make up for the lack of existing extraction capacity, and make the entire gas extraction system operate more stably and efficiently. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of a gas extraction borehole under the traditional extraction process. Figure 2 This is a schematic diagram of the overall structure of the in-situ repair and enrichment device for extraction boreholes according to the present invention.

[0026] In the diagram: 1—Pneumatic self-propelled delivery device; 2—Internal drainage pipe; 3—Original sealing pipe; 4—Sealing device.

[0027] Figure 1 In the process, the original sealing pipe 3 is installed inside the borehole, and the sealing device 4 is located at the borehole opening. Negative pressure is applied at the sealing device 4, and coal seam gas converges from the bottom of the borehole towards the sealing device 4 and is then discharged through the extraction pipeline.

[0028] Figure 2 In the process, the pneumatic self-propelled delivery device 1 is located at the front end of the internal drainage pipe 2, and the two advance towards the bottom of the borehole along the internal channel of the original sealing pipe 3. After the internal drainage pipe 2 reaches the bottom of the borehole, the negative pressure extraction position is transferred to the bottom of the borehole, and the coal seam gas converges in the opposite direction from the sealing device 4 towards the bottom of the borehole and is discharged through the internal drainage pipe 2. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Example 1

[0030] like Figure 1 and Figure 2 As shown in the figure, this embodiment provides an in-situ repair and enrichment method for drainage boreholes, which is applied to the repair of failed coal seam gas drainage boreholes in underground coal mines. The method specifically includes the following steps: S1: Screening of low-concentration extraction boreholes The gas concentration parameters of each drainage borehole are monitored using a mine gas drainage monitoring system. When the gas concentration in a borehole decreases to less than one-third of its initial concentration, the borehole is determined to be a failed borehole. The borehole number, location, and original construction parameters are recorded.

[0031] like Figure 1As shown, in the traditional extraction mode, the original sealing pipe 3 is installed inside the borehole, and the sealing device 4 is sealed at the borehole opening section through a high-pressure grouting process. Negative pressure is applied to the extraction pipe opening at the sealing device 4, and coal seam gas converges from the bottom of the borehole towards the sealing device 4 and is then discharged. When the sealing device 4 ages and leaks gas or the borehole channel becomes blocked, the extraction concentration decreases, resulting in a failed borehole.

[0032] S2: In-situ drilling repair like Figure 2 As shown, at the selected failed borehole, a pneumatic self-propelled delivery device 1 and an internal drainage pipe 2 are inserted along the inside of the original sealing pipe 3, with the pneumatic self-propelled delivery device 1 located at the front end of the internal drainage pipe 2.

[0033] When the high-pressure air source is turned on, the nozzle at the front end of the pneumatic self-propelled delivery device 1 sprays high-pressure airflow, which impacts and breaks up the coal slag and blockages deposited in the borehole. At the same time, the reaction force of the airflow drives the pneumatic self-propelled delivery device 1 to advance along the borehole axis, dragging the internal drainage pipe 2 to advance towards the bottom of the borehole.

[0034] As the pneumatic self-propelled delivery device 1 advances, the blockage is gradually cleared, and the internal drainage pipe 2 continues to extend towards the bottom of the borehole. When the pneumatic self-propelled delivery device 1 reaches the bottom of the borehole, the high-pressure air source is shut off, completing the channel clearing and pipe delivery. At this point, the front end of the internal drainage pipe 2 is located at the bottom of the borehole, forming a complete gas extraction channel from the bottom of the borehole to the borehole opening, restoring the gas discharge path.

[0035] S3: Gas extraction The annular gap between the internal drainage pipe 2 and the original sealing pipe 3 is sealed with sealant. After the sealant cures, a completely sealed space is formed inside the borehole, preventing outside air from entering and diluting the gas concentration.

[0036] The orifice end of the internal drainage pipeline 2 is connected to the extraction pipeline network through an access pipeline, and a negative pressure zone is formed at the bottom of the borehole by applying negative pressure. Since the negative pressure point is located at the bottom of the borehole, the gas in the coal seam, driven by the pressure difference, converges in the opposite direction to the bottom of the borehole from the direction of the sealing device 4. The gas flow direction is completely opposite to the traditional forward convergence mode, thus achieving the reversal of the gas flow direction.

[0037] Due to reverse convergence, gas accumulates at the bottom of the borehole, and the enclosed space prevents air from mixing in, resulting in a significant increase in the concentration of extracted gas. After connecting the internal drainage pipeline 2 to the extraction network, the pressure of the extraction system is balanced, the insufficiency of the existing extraction capacity is compensated, and the failed borehole is reused.

[0038] The working mechanism of this invention is as follows: Traditional sampling methods (such as) Figure 1Negative pressure is applied at the sealing device 4, causing gas to converge from the bottom of the hole towards the opening. When the sealing device 4 ages and leaks, outside air enters the borehole through the leak point, diluting the gas concentration and causing a decrease in the extraction concentration.

[0039] This invention (e.g.) Figure 2 The negative pressure extraction position is moved forward to the bottom of the borehole, and the gap between the internal drainage pipe 2 and the original sealing pipe 3 is completely sealed with sealant to form a new sealed space. At this time, even if the original sealing device 4 has air leakage, because the sealing position is located inside the original sealing pipe 3, the leakage point is isolated outside the sealing section, and air cannot enter the new sealed space. At the same time, the negative pressure is located at the bottom of the borehole, and the gas converges in the opposite direction from the sealing device 4 to the bottom of the borehole, avoiding the influence of the original leakage channel, thereby achieving an increase in extraction concentration.

[0040] The above description is merely a preferred embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for in-situ remediation and enrichment of extraction boreholes, characterized in that: Includes the following steps: S1. Screening low-concentration extraction boreholes: The gas concentration parameters of each extraction borehole are detected by the extraction monitoring system, and the failure boreholes with substandard concentrations are screened out and the location of the failure boreholes is determined. S2. In-situ repair of borehole: At the selected failed borehole, a pneumatic self-propelled delivery device (1) and an internal drainage pipe (2) are inserted along the inside of the original sealing pipe (3). The pneumatic self-propelled delivery device (1) is located at the front end of the internal drainage pipe (2). The pneumatic self-propelled delivery device (1) uses high-pressure airflow to clear the blockage in the borehole and drags the internal drainage pipe (2) towards the bottom of the borehole until the pneumatic self-propelled delivery device (1) at the front end of the internal drainage pipe (2) reaches the bottom of the borehole. The internal drainage pipe (2) forms a new gas extraction channel and restores the gas discharge path. S3. Gas extraction and concentration: After the internal drainage pipe (2) reaches the bottom of the borehole, sealant is used to seal the gap between the internal drainage pipe (2) and the original sealing pipe (3) to form a closed space inside the borehole and prevent air from entering; the negative pressure extraction end is connected to the end of the internal drainage pipe (2) located at the bottom of the borehole, and negative pressure is applied at the bottom of the borehole to form a negative pressure zone, so that the coal seam gas converges in the opposite direction from the direction of the sealing device (4) to the bottom of the borehole, thereby reversing the gas flow direction and increasing the gas extraction concentration; the internal drainage pipe (2) is connected to the extraction pipeline network to balance the pressure of the extraction system and realize the reuse of the failed borehole.

2. The in-situ repair and enrichment method for extraction boreholes according to claim 1, characterized in that: In step S1, the criterion for determining that the concentration does not meet the standard is: after the sampling is started, the sampling concentration decreases to less than 1 / 3 of the initial concentration.

3. The in-situ repair and enrichment method for extraction boreholes according to claim 1, characterized in that: In step S2, the pneumatic self-propelled delivery device (1) uses high-pressure airflow to impact the blockage in the borehole, breaking and removing the blockage, and uses the airflow reaction force to drive itself and the internal drainage pipe (2) to move forward along the borehole axis toward the bottom of the hole.

4. The in-situ repair and enrichment method for extraction boreholes according to claim 1, characterized in that: In step S3, the sealant seals the annular gap between the internal drainage pipe (2) and the original sealing pipe (3). After sealing, the inside of the borehole is isolated from the outside atmosphere to prevent air from mixing in and diluting the gas concentration.

5. A device for in-situ repair and enrichment of extraction boreholes, characterized in that: Includes a pneumatic self-propelled delivery device (1) and an internal drainage pipe (2); The pneumatic self-advancing delivery device (1) is connected to the front end of the internal drainage pipe (2). The pneumatic self-advancing delivery device (1) is used to remove the blockage in the borehole by using high-pressure airflow and to drag the internal drainage pipe (2) to the bottom of the borehole. The internal drainage pipe (2) is installed inside the original sealing pipe (3) and extends to the bottom of the borehole. The internal drainage pipe (2) is used as a new gas extraction channel after reaching the bottom of the borehole. The gap between the internal drainage pipe (2) and the original sealing pipe (3) is sealed with sealant to form a closed space inside the borehole.

6. The in-situ repair and enrichment device for extraction boreholes according to claim 5, characterized in that: The pneumatic self-propelled delivery device (1) includes a body and a nozzle disposed at the front end of the body. The nozzle is used to spray high-pressure airflow to impact and clear blockages in the borehole. The body is self-propelled along the borehole axis under the drive of the airflow reaction force.

7. The in-situ repair and enrichment device for extraction boreholes according to claim 5, characterized in that: The outer diameter of the inner drainage pipe (2) is smaller than the inner diameter of the original sealing pipe (3), and the inner drainage pipe (2) can advance along the internal channel of the original sealing pipe (3) towards the bottom of the borehole.

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