Double casing protection device for drilling holes in layers and its application technology

Abstract

The present invention discloses a double-casing hole protection device for in-layer drilling and an application process. The device includes a guide tube, which includes an outer guide tube and an inner guide tube, and the outer guide tube is provided with an eyelet; an outer hole protection screen and an inner hole protection tube, the outer hole protection screen being connected to the outer guide tube, and the inner hole protection tube being connected to the inner guide tube; and an orifice sealing tube provided at the orifice of the in-layer drilling via an orifice sealing device, wherein one end of the inner hole protection tube located at the orifice of the in-layer drilling leads to the outside of the orifice sealing tube. The method includes installing a double-casing hole protection device for in-layer drilling, detecting gas concentration at the orifice and the end of the drilling hole, and negative extraction pressure during extraction, treating blockages in the drilling hole, and then extracting coal seam gas from the end of the in-layer drilling hole using the inner hole protection tube. The advantages of the present invention are that it avoids the defects of being unable to detect the extraction effect at the end of the drilling hole, and preventing the drilling hole from being blocked by water or coal slag and becoming ineffective and unable to be treated, which affects the application of in-layer drilling in coal mine gas control.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine gas control, and in particular to a double-casing hole protection device for layer drilling and an application process thereof. Background Art

[0002] Along-beam drilling is constructed in coal seams, with a high coal penetration rate and long effective borehole length. It is an important drilling arrangement method for coal mine gas control. Along-beam drilling is widely used in high-gas mines and outburst mines to pre-extract coal seam gas. The methods of using along-beam drilling to pre-extract coal seam gas in regional outburst prevention measures include: along-beam drilling to pre-extract coal seam gas in sections, along-beam drilling to pre-extract coal seam gas in mining areas, along-beam drilling to pre-extract coal seam gas in coal lanes and strips, and directional long-hole drilling to pre-extract coal seam gas in coal lanes and strips. Among them, directional long-hole drilling to pre-extract coal seam gas in coal lanes and strips uses a directional drill to construct along-beam drilling holes. The drilling trajectory is controllable and the length can exceed 300m.

[0003] When drilling holes through soft coal seams to extract coal seam gas, the boreholes are prone to collapse and failure. Typically, screens are installed throughout the borehole to support the borehole wall, allowing for extraction of coal seam gas through the screens. This improves the effectiveness of drilling through the boreholes. However, drilling through the boreholes over long distances still poses challenges, such as the distance between the borehole end and the hole mouth, making it difficult to monitor extraction results, and the borehole becoming clogged by water or coal slag, rendering it inoperable and unmanageable. These issues hinder the application of drilling through the boreholes in coal mine gas control. Summary of the Invention

[0004] The technical problems to be solved by the present invention are:

[0005] In the existing technology, when long-distance in-seam drilling is used to extract coal seam gas, there are technical problems such as the distance between the end of the drill hole and the hole mouth, the extraction effect cannot be detected, and the drill hole is blocked by water and coal slag, making it ineffective and unable to be treated, which affects the application of in-seam drilling in coal mine gas control.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A double-casing hole protection device for in-bed drilling, comprising a guide tube placed at the bottom of the in-bed drilling hole, the guide tube comprising an outer guide tube and an inner guide tube arranged inside the outer guide tube, wherein the outer guide tube is provided with eyelets;

[0008] The invention also includes an outer hole screen located in the bedding borehole, wherein an inner hole pipe is provided in the outer hole screen, the outer hole screen is connected to the outer pipe of the guide pipe, and the inner hole pipe is connected to the inner pipe of the guide pipe;

[0009] The invention also includes a hole sealing pipe arranged at the hole of the in-layer drill hole through the hole sealing device, and the outer hole protection screen is located in the hole sealing pipe;

[0010] The hole-sealing pipe extends from the hole of the in-layer drilling hole, and one end of the inner hole-protecting pipe located at the hole of the in-layer drilling hole leads to the outside of the hole-sealing pipe.

[0011] The double-casing hole protection device for in-layer drilling in the present invention is applied to in-layer extraction drilling in soft coal seams with a hole depth greater than 30m. The device can be used to check whether there is airflow passing through the end of the in-layer drilling hole and whether the coal seam gas at the end of the drilling hole is effectively extracted; the gas concentration at the end of the in-layer drilling hole can be detected and compared with the gas concentration at the hole mouth to evaluate the tightness of the hole mouth sealing; the drilling blockages such as water and coal slag in the in-layer drilling hole can be cleaned; and the coal seam gas can be extracted from the end of the drilling hole using the inner hole protection pipe. The application of the device can improve the gas extraction effect at the end of the in-layer drilling hole, eliminate or reduce the blind spots of coal seam gas extraction, and have significant safety, economic and social benefits. It avoids the defects such as the inability to detect the extraction effect, the failure of the borehole due to water and coal slag and the inability to treat it, which affects the application of in-layer drilling in coal mine gas control.

[0012] Optimally, the front end of the guide tube is provided with a pointed cone.

[0013] If manual casing running is used, the sharp cone at the front end of the guide tube is helpful in guiding the casing into the end of the borehole.

[0014] Optimally, the pointed cone is mounted on the outer tube end of the guide tube by welding or threaded connection.

[0015] Optimally, the outer pipe of the guide pipe and the outer hole protection screen pipe are connected by threads.

[0016] Optimally, a plurality of eyelets are provided, and all eyelets are evenly distributed along the circumference of the outer tube of the guide tube.

[0017] Optimally, the eyelet is a long hole, the length direction of which is parallel to the axial direction of the outer tube of the guide tube.

[0018] The eyelets are arranged to facilitate the flow of air and water.

[0019] Optimally, the inner tube of the guide tube and the outer tube of the guide tube are coaxially arranged.

[0020] Optimally, a fixing piece is provided between the inner tube of the guide tube and the outer tube of the guide tube, and the inner tube of the guide tube is fixed inside the outer tube of the guide tube through the fixing piece.

[0021] Optimally, the inner tube of the guide tube and the inner hole protection tube are connected via a joint.

[0022] The present invention further discloses an application process of any of the above-mentioned in-bed drilling double-casing hole protection devices, comprising the following steps:

[0023] S1. Lowering a double-casing hole protection device for in-bed drilling, including a guide pipe, an inner hole protection pipe, and an outer hole protection screen, to the end of the in-bed drilling hole;

[0024] S2, connecting the hole sealing pipe to the extraction system for extraction;

[0025] During the drilling and extraction process, the outer screen is used to protect the hole and the coal seam gas is extracted normally. The hole sealing pipe and the gas detection device are used to measure the gas concentration at the hole mouth of the drilling hole and detect the drilling condition.

[0026] Use the inner hole protection tube to measure the gas concentration at the end of the bedding borehole and the negative pressure at the end of the borehole to check whether there is airflow at the end of the bedding borehole;

[0027] If it is found that the drilling hole along the layer is not smooth or there is a blockage in the hole, connect the inner hole protection pipe to high-pressure compressed air to clean the hole;

[0028] S3. After using the inner hole protection pipe to detect the end of the borehole and deal with the borehole blockage, the inner hole protection pipe is connected to the extraction system and the coal seam gas is extracted from the end of the borehole.

[0029] The application process of the above-mentioned double-casing hole protection device for in-layer drilling in the present invention is applied to in-layer extraction drilling in soft coal seams with a hole depth greater than 30m. The application of this process can check whether there is airflow passing through the end of the in-layer drilling hole and whether the coal seam gas at the end of the drilling hole is effectively extracted; detect the gas concentration at the end of the in-layer drilling hole and compare it with the gas concentration at the hole mouth to evaluate the tightness of the hole mouth sealing; clean the drilling hole blockages such as water and coal slag in the in-layer drilling hole; and use the inner hole protection pipe to extract coal seam gas from the end of the drilling hole. The application of this process can improve the gas extraction effect at the end of the in-layer drilling hole, eliminate or reduce the blind spots of coal seam gas extraction, and have significant safety, economic and social benefits. It avoids the defects such as the inability to detect the extraction effect, the failure of the borehole due to water and coal slag and inability to treat, which affects the application of in-layer drilling in coal mine gas control.

[0030] The advantages of the present invention are:

[0031] The double-casing hole protection device and application process of the in-layer drilling in the present invention are applied to in-layer extraction drilling in soft coal seams with a hole depth greater than 30m. The application of this device and application process can check whether there is airflow passing through the end of the in-layer drilling hole and whether the coal seam gas at the end of the drilling hole is effectively extracted; detect the gas concentration at the end of the in-layer drilling hole and compare it with the gas concentration at the hole mouth to evaluate the tightness of the hole mouth sealing; clean the drilling hole blockages such as water and coal slag in the in-layer drilling hole; and use the inner hole protection pipe to extract coal seam gas from the end of the drilling hole. The application of this device and application process can improve the gas extraction effect at the end of the in-layer drilling hole, eliminate or reduce the blind spots of coal seam gas extraction, and have significant safety, economic and social benefits. It avoids the defects such as the inability to detect the extraction effect, the inability to treat the failure of the drilling hole due to water and coal slag at the end of the drilling hole, and the impact on the application of in-layer drilling in coal mine gas control.

[0032] If manual casing is used, the pointed cone at the front of the guide tube helps guide the casing into the end of the borehole. The eyelet is set to facilitate the flow of gas and water. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of a double-casing hole protection device for in-layer drilling in Example 1 of the present invention;

[0034] Figure 2 Schematic diagram of the guide tube in Example 1 of the present invention;

[0035] Figure 3 This is a diagram of the arrangement of coal seam gas drilling holes in the pre-extraction section of the seam drilling in the second embodiment of the present invention;

[0036] in,

[0037] Bedding drill hole-1;

[0038] Guide tube-2; guide tube outer tube-21; guide tube inner tube-22; pointed cone-23; eyelet-211; fixing piece-221;

[0039] External sieve tube-3;

[0040] Inner protection hole pipe-4; first connecting pipe-41;

[0041] Hole sealing device-5;

[0042] Hole sealing pipe-6; second connecting pipe-61. DETAILED DESCRIPTION

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0044] Example 1:

[0045] like Figure 1 As shown, a double-casing hole protection device for layer drilling includes a guide pipe 2, an outer hole protection screen pipe 3, an inner hole protection pipe 4, a hole opening sealing device 5, and a hole opening sealing pipe 6.

[0046] like Figure 1 、 2As shown, the guide tube 2 is placed at the bottom of the in-bedding borehole 1. The guide tube 2 is made of steel and includes an outer guide tube 21 and an inner guide tube 22 disposed inside the outer guide tube 21. A fixing member 221 is provided between the inner guide tube 22 and the outer guide tube 21. The inner guide tube 22 is fixed to the inner guide tube 21 by the fixing member 221. The fixing member 221 is not limited to a specific shape and can connect the inner guide tube 22 to the outer guide tube 21. For example, a cylindrical, sheet-like structure, or angle steel can be used. The fixing member 221 can be connected to the inner guide tube 22 and the outer guide tube 21 by welding. The inner guide tube 22 and the outer guide tube 21 are coaxially arranged.

[0047] In this embodiment, the outer guide tube 21 has a diameter of 1 inch, and the inner guide tube 22 has an inner diameter of 12 mm.

[0048] like Figure 2 As shown, the guide tube outer tube 21 is provided with eyelets 211. A plurality of eyelets 211 are provided, and all eyelets 211 are evenly distributed along the circumference of the guide tube outer tube 21. The eyelets 211 are long holes, and their length direction is parallel to the axial direction of the guide tube outer tube 21.

[0049] like Figure 2 As shown, the front end of the guide tube 2 is provided with a sharp cone 23. The sharp cone 23 is mounted on the end of the guide tube outer tube 21 by welding or threading. The sharp cone is conical, which is conducive to the guide casing being sent into the end of the drill hole.

[0050] like Figure 1 As shown, it also includes an outer hole screen pipe 3 located in the layer drilled hole 1. The outer hole screen pipe 3 is a PVC pipe with a diameter of 1 inch, generally each length is 1.5 to 2 meters, and is connected by a pipe clamp or plug-in. The outer hole screen pipe 3 should have a certain supporting strength, and the pipeline hole wall is provided with uniform eyelets.

[0051] like Figure 1 As shown, an inner hole protection pipe 4 is provided in the outer hole protection screen pipe 3. The inner hole protection pipe 4 is a PVC pipe with an inner diameter of 12 mm. The pipe wall must be tight and airtight, the joints should be reduced, and the joints should be tight and airtight; the joints must be firmly connected to prevent the joints from being blown off by high-pressure compressed air.

[0052] The outer hole screen 3 is connected to the guide pipe outer tube 21, and the diameters of the two are matched. The guide pipe outer tube 21 is connected to the outer hole screen 3 by threads. Further, the guide pipe outer tube 21 is connected to the outer hole screen 3 by threads and couplings.

[0053] The inner hole protection tube 4 is connected to the guide tube inner tube 22, and the diameters of the two tubes match; the guide tube inner tube 22 and the inner hole protection tube 4 are connected by a joint, and the joint is a quick joint.

[0054] like Figure 1 As shown, it also includes a hole sealing pipe 6 set at the hole mouth of the in-bedding borehole 1 through the hole sealing device 5, and the outer hole protection screen 3 is located in the hole sealing pipe 6; that is, in actual application, the hole sealing pipe 6 passes through the outer hole protection screen 3 and goes down to the position required for drilling sealing, and the hole sealing pipe 6 extends 0.1-0.3m from the hole mouth of the in-bedding borehole 1.

[0055] The functions of the hole sealing pipe 6 are: supporting the hole wall of the layered borehole and the hole sealing grouting pressure; draining the channel of coal seam gas in the layered borehole, connecting the drainage system, and draining the coal seam gas in the layered borehole; detecting the drainage effect of the layered borehole; and leading the inner hole protection pipe out of the borehole.

[0056] like Figure 1 As shown, one end of the inner hole protection pipe 4 located at the orifice of the in-bed drill hole 1 is connected to the exterior of the hole sealing pipe 6. Specifically, a first connecting pipe 41 can be provided at the exterior end of the hole sealing pipe 6. The inner end of the first connecting pipe 41 is connected to the inner hole protection pipe 4, and the front end is connected to the exterior of the hole sealing pipe 6. This first connecting pipe 41 is used to connect high-pressure compressed air, detect gas concentration, and check whether there is airflow passing through the end of the in-bed drill hole 1.

[0057] like Figure 1 As shown, a second connecting pipe 61 is further provided at the outer end of the hole sealing pipe 6. The second connecting pipe 61 connects the inside and outside of the hole sealing pipe 6 and is used to connect a gas detection device to measure the hole gas concentration of the layer-bearing borehole 1 and detect the borehole negative pressure.

[0058] Example 2:

[0059] The present invention also discloses an application process of the above-mentioned double-casing hole protection device for in-bed drilling, comprising the following steps:

[0060] In this embodiment, the arrangement of the drill holes along the layer at the implementation site is as follows: Figure 3 As shown in the figure, a borehole was drilled along the coal seam from the first roadway to a distance outside the outline of the second roadway to pre-extract coal seam gas from the second roadway and the area between the first and second roadways. The borehole diameter was 113 mm, the depth was 140 m, and the coal seam f-value was 0.5, making the borehole prone to water accumulation and collapse. To improve the effectiveness of pre-extraction of coal seam gas in the borehole, especially in the second roadway, a double-casing hole protection device was used.

[0061] S1. Lower the in-bed drilling double-casing protection device including the guide pipe 2, the inner protection pipe 4 and the outer protection screen 3 to the end of the in-bed drilling hole 1;

[0062] Specifically, after the in-bed borehole 1 is completed and casing is ready, a double-casing hole protection device is installed using either manual or pipe-following drilling. If manual casing is used, a sharp cone is installed at the front end of the guide pipe; if pipe-following drilling is used, the sharp cone is not installed at the front end of the guide pipe.

[0063] First, lower a guide pipe into the in-layer borehole. The guide pipe is connected to the inner protection hole pipe through the inner pipe joint of the guide pipe. The outer protection hole screen pipe passes through the inner protection hole pipe and is firmly connected to the outer pipe joint of the guide pipe. According to this method, the double-casing hole protection device including the inner protection hole pipe and the outer protection hole screen pipe is lowered to the end of the in-layer borehole through the guide pipe. The outer protection hole screen pipe is extended to the vicinity of the borehole mouth, and the inner protection hole pipe is led out of the borehole mouth.

[0064] The hole sealing pipe passes through the outer hole screen and goes down to the position required for drilling sealing. The hole sealing pipe is extended to 0.1-0.3m outward from the drilling hole. The hole sealing device is used to seal the in-beam drilling hole.

[0065] S2. Connect the borehole sealing pipe 6 to the drainage system for extraction. During implementation, a "two-blocking, one-injection" process was used to tightly seal the outer section of the in-bed borehole. This ensured that the in-bed borehole was connected to the drainage system for extraction. The borehole was protected by an external screen, and normal coal seam gas extraction continued. The borehole sealing depth at the implementation site was greater than 15 meters.

[0066] During the in-layer drilling and extraction, the outer hole protection screen 3 is used to protect the hole and the coal seam gas is extracted normally. The hole sealing pipe 6 is connected to the gas detection device through the second connecting pipe 61 to measure the gas concentration at the hole mouth of the in-layer drilling hole 1 and detect the extraction negative pressure at the hole mouth of the drilling hole 1. In this embodiment, the gas detection device and the device for measuring the extraction negative pressure at the hole mouth are existing technologies.

[0067] The inner hole protection tube 4 is used to measure the gas concentration at the end of the in-layer borehole 1 and check the conditions such as the extraction negative pressure at the end of the in-layer borehole 1; specifically, the gas concentration is measured by connecting the first connecting tube 41 to the gas detection device, and the extraction negative pressure is measured by connecting the first connecting tube 41 to the extraction negative pressure device.

[0068] If it is found that there is no negative pressure at the end of the layer-parallel borehole 1 or the negative pressure is smaller than the normal value, it indicates that the borehole is not smooth and there is a blockage in the borehole. Connect the inner hole protection pipe 4 to high-pressure compressed air to clean the borehole. Specifically, it can be connected to the high-pressure compressed air through the first connecting pipe 41.

[0069] S3. After the inner hole protection pipe 4 detects whether the end of the layer drill hole 1 is unobstructed and handles the borehole blockage, the inner hole protection pipe 4 is connected to the extraction system, specifically, it can be connected to the first connecting pipe 41 of the inner hole protection pipe 4, and the inner hole protection pipe 4 is used to extract coal seam gas from the end of the layer drill hole 1.

[0070] The double-casing hole protection device and application process of the in-layer drilling in the present invention are applied to in-layer extraction drilling in soft coal seams with a hole depth greater than 30m. The application of this device and application process can check whether there is airflow passing through the end of the in-layer drilling hole and whether the coal seam gas at the end of the drilling hole is effectively extracted; detect the gas concentration at the end of the in-layer drilling hole and compare it with the gas concentration at the hole mouth to evaluate the tightness of the hole mouth sealing; clean the drilling hole blockages such as water and coal slag in the in-layer drilling hole; and use the inner hole protection pipe to extract coal seam gas from the end of the drilling hole. The application of this device and application process can improve the gas extraction effect at the end of the in-layer drilling hole, eliminate or reduce the blind spots of coal seam gas extraction, and have significant safety, economic and social benefits. It avoids the defects such as the inability to detect the extraction effect, the inability to treat the failure of the drilling hole due to water and coal slag at the end of the drilling hole, and the impact on the application of in-layer drilling in coal mine gas control.

[0071] If manual casing is used, the pointed cone 23 at the front end of the guide pipe 2 is helpful for guiding the casing into the end of the borehole. The setting of the eyelet 211 is convenient for gas and water to flow.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An application process using a double casing hole protection device for drilling holes in the layer, characterized by: The double-casing hole protection device for a layer-beamed drilling hole comprises a guide tube (2) arranged at the bottom of a layer-beamed drilling hole (1), a pointed cone (23) being provided at the front end of the guide tube (2), the guide tube (2) comprising a guide tube outer tube (21) and a guide tube inner tube (22) arranged inside the guide tube outer tube (21), the guide tube outer tube (21) being provided with eyelets (211), and further comprising an outer hole protection screen tube (3) located in the layer-beamed drilling hole (1), an inner hole protection tube (4) being provided in the outer hole protection screen tube (3), the outer hole protection screen tube (21) being provided with an inner hole protection tube (4 ... The hole screen pipe (3) is connected to the outer pipe (21) of the guide pipe, and the inner hole protection pipe (4) is connected to the inner pipe (22) of the guide pipe; the hole protection pipe (6) is also included, which is arranged at the hole mouth of the layer drill hole (1) through the hole mouth sealing device (5), and the outer hole protection pipe (3) is located in the hole mouth sealing pipe (6); the hole mouth sealing pipe (6) extends from the hole mouth of the layer drill hole (1), and one end of the inner hole protection pipe (4) located at the hole mouth of the layer drill hole (1) leads to the outside of the hole mouth sealing pipe (6); the steps include: S1. Lowering a double-casing hole protection device for a layered borehole, which includes a guide pipe (2), an inner hole protection pipe (4), and an outer hole protection screen pipe (3), to the end of the layered borehole (1); S2, connecting the hole sealing pipe (6) to the extraction system for extraction; During the extraction process of the seam drilling, the outer hole screen (3) is used to protect the hole and the coal seam gas in the drilling hole is extracted normally. The hole sealing pipe (6) is connected to the gas detection device to measure the gas concentration at the hole of the seam drilling hole (1) and detect the extraction negative pressure at the hole of the drilling hole; Using the inner hole protection tube (4) to measure the gas concentration at the end of the in-bed drill hole (1), and to measure the negative pressure at the end of the drill hole to check whether there is air flow passing through the end of the in-bed drill hole (1); If it is found that the bedding borehole (1) is blocked or there is a blockage in the borehole, connect the inner hole protection pipe (4) to high-pressure compressed air to clean the borehole; S3. After the inner hole protection pipe (4) detects the end of the bed drill hole (1) and processes the blockage in the drill hole, the inner hole protection pipe (4) is connected to the extraction system, and the inner hole protection pipe (4) is used to extract coal seam gas from the end of the bed drill hole (1).

2. The application process of the double-casing hole protection device for in-bed drilling according to claim 1 is characterized in that: The pointed cone (23) is mounted on the end of the guide tube outer tube (21) by welding or threaded connection.

3. The application process of the double-casing hole protection device for drilling in-bed according to claim 1 is characterized in that: The guide tube outer tube (21) and the outer hole protection screen tube (3) are connected via threads.

4. The application process of the double-casing hole protection device for drilling in-bed according to claim 1 is characterized in that: A plurality of eyelets (211) are provided, and all eyelets (211) are evenly distributed along the circumferential direction of the guide tube outer tube (21).

5. The application process of the double-casing hole protection device for in-bed drilling according to claim 1 is characterized in that: The eyelet (211) is a long hole, the length direction of which is parallel to the axial direction of the guide tube outer tube (21).

6. The application process of the double-casing hole protection device for in-bed drilling according to claim 1 is characterized in that: The guide tube inner tube (22) and the guide tube outer tube (21) are coaxially arranged.

7. The application process of the double-casing hole protection device for in-bed drilling according to claim 1 is characterized in that: A fixing piece (221) is provided between the guide tube inner tube (22) and the guide tube outer tube (21), and the guide tube inner tube (22) is fixed inside the guide tube outer tube (21) via the fixing piece (221).

8. The application process of the double-casing hole protection device for in-bed drilling according to claim 1 is characterized in that: The guide tube inner tube (22) and the inner hole protection tube (4) are connected via a joint.

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