Coal seam gas injection displacement device and method

Abstract

The invention discloses a coal seam gas injection displacement device, and relates to the technical field of coal mine gas extraction, the coal seam gas injection displacement device comprises a plurality of gas injection pipes, a plurality of gas injection screen pipes and a plugging capsule, the plurality of gas injection pipes are connected in sequence and limit a gas transmission channel, and the gas injection pipes are connected with a gas injection pump and are used for extending into a gas injection drill hole; the gas injection screen pipes are sequentially arranged at the end of the gas injection pipe, the gas injection screen pipes are provided with a plurality of gas holes used for gas injection, and the blocking capsule comprises a connecting pipe and a capsule body. The connecting pipes are arranged between every two adjacent gas injection pipes and / or between every two adjacent gas injection screen pipes and / or between the adjacent gas injection pipes and the adjacent gas injection screen pipes and / or the ends, away from the gas injection pipes, of the gas injection screen pipes, and the connecting pipes communicate with the gas conveying channel. The bag body can be filled with fluid and is used for expanding at the position of a coal seam fault so as to block and support a gas injection drill hole. According to the coal seam gas injection displacement device, the fault area is effectively blocked, and the reliability of drilling gas injection and the gas extraction efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of coal mine gas extraction technology, specifically to a coal seam gas injection displacement device and method. Background Technology

[0002] With the continuous development towards intelligent, efficient, and intensive mining, the problem of "low gas content and high gas emission" caused by high-intensity mining is becoming increasingly serious, severely hindering the safe and efficient mining of coal. Targeted gas pre-drainage technology has been proposed, which can not only reduce gas emission from the working face during mining but also improve the utilization rate of coal gas. However, in actual mining, the low gas content in some coal seams leads to low gas migration driving force and rapid flow decay during gas drainage. This results in the inadequacy of traditional negative pressure pre-drainage and permeability enhancement measures in the mining area, leading to problems such as low drainage efficiency, low drainage concentration (usually less than 5%), low utilization value, long drainage time to meet standards, and high residual desorbable gas content in the coal seam after prolonged drainage.

[0003] Among related technologies, coal seam gas injection for gas displacement and extraction has been proposed. This technology involves injecting high-pressure gas (CO2, N2, etc.) into the coal seam. On one hand, this creates a gas pressure differential within the coal seam, promoting gas migration. On the other hand, the competitive adsorption effect between the injected gas and methane on the coal surface displaces the methane gas originally adsorbed in the micropores of the coal matrix, thereby improving gas extraction efficiency. However, in actual mining, some coal seams are constrained by geological conditions, with prominent fault development. When gas injection drilling encounters a fault, the injected gas is prone to leakage along the fault channel, making it difficult to maintain stable pressure in the borehole and build an effective fracturing gradient within the coal seam, ultimately causing the gas injection operation to fail. Furthermore, due to tectonic movements, the coal body surrounding fault-developed areas is usually soft. Under the continuous action of in-situ stress, the borehole is prone to creep and collapse, which not only damages the integrity of the gas injection channel and hinders the smooth injection of high-pressure gas but also adversely affects the normal operation of subsequent gas extraction, severely restricting the overall gas extraction efficiency. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, this invention proposes a coal seam gas injection displacement device, which improves the reliability of borehole gas injection and the efficiency of gas extraction by effectively sealing the fault area.

[0006] This invention also proposes a coal seam gas injection displacement method.

[0007] The coal seam gas injection displacement device of this invention includes: Multiple air injection pipes are connected in sequence and communicate with each other in the inner cavity of the air injection pipes to restrict the air delivery channel. The air injection pipes are connected to the air injection pump and are used to extend into the air injection borehole. Multiple gas injection screens are arranged sequentially at one end of the gas injection pipe and connected to the gas delivery channel. Each gas injection screen has multiple air holes connected to the gas delivery channel. The gas injection screens are used to inject gas into the gas injection borehole and coal seam. A sealing capsule, comprising a connecting tube and a capsule body, wherein the connecting tube is disposed between two adjacent gas injection pipes and / or between two adjacent gas injection screens and / or between adjacent gas injection pipes and gas injection screens and / or at the end of the gas injection screens away from the gas injection pipes, the inner cavity of the connecting tube is in communication with the gas delivery channel, and the capsule body is capable of being filled with fluid to expand, the capsule body being used to expand at the location of a coal seam fault to seal and support the gas injection borehole.

[0008] The coal seam gas injection displacement device of this invention sets sealing capsules on the gas injection pipe and the gas injection screen pipe. Under the condition of satisfying the gas delivery effect of the gas injection pipe and the gas injection effect of the gas injection screen pipe, the capsule body expands to seal the fault corresponding to the coal seam fault location, thereby preventing gas leakage from the gas injection screen pipe through the coal seam fault. This facilitates maintaining the gas injection pressure in the gas injection borehole, constructing an effective fracturing gradient inside the coal seam, and preventing the gas injection borehole from collapsing at the coal seam fault location. It also facilitates maintaining the integrity and stability of the gas injection borehole, providing a stable and reliable borehole channel for gas drainage operations, and improving the efficiency of coal seam gas drainage.

[0009] In some embodiments, the sealing capsule includes a solidification capsule, the solidification capsule including a first connecting tube and a first bladder disposed on the first connecting tube, the first bladder being connected to a grouting pipe for conveying slurry, one end of the grouting pipe extending out of the air injection borehole and connected to a grouting pump.

[0010] In some embodiments, the sealing capsules are provided in multiple ways, and the grouting tube passes through the multiple sealing capsules in sequence. The section of the grouting tube located inside the first capsule is provided with an grouting hole that communicates with the inner cavity of the first capsule.

[0011] In some embodiments, the occlusion capsule includes a movable tube sleeved on the first connecting tube, the first capsule body fixedly disposed on the movable tube, and a support pin provided on the first connecting tube for pushing the movable tube to move along with the first connecting tube.

[0012] In some embodiments, the sealing capsule includes a gas-sealing capsule, the gas-sealing capsule including a second connecting tube and a second bladder fixedly disposed on the second connecting tube, the second bladder being connected to a gas delivery pipe for delivering gas, and the other end of the gas delivery pipe extending out of the gas injection hole and connected to a gas injection pump.

[0013] In some embodiments, multiple air-sealed capsules are provided, and two adjacent air-sealed capsules are connected by an air supply branch pipe.

[0014] In some embodiments, the occlusion capsules are provided in multiple groups, each group of the occlusion capsules including two solid-sealing capsules and one air-sealing capsule, wherein in each group of the occlusion capsules, the air-sealing capsule is disposed between the two solid-sealing capsules.

[0015] The coal seam gas injection displacement method of this invention includes the coal seam gas injection displacement device of any of the above embodiments, and the gas injection displacement method includes the following steps: S1. Conduct gas injection drilling in the coal seam and determine the fault location based on the slag return during the drilling process; S2. Lower the gas injection screen pipe and gas injection pipe into the gas injection borehole, and according to the fault location, insert the sealing capsule during the process of lowering the gas injection screen pipe and gas injection pipe. S3. Inject filling fluid into the bladder, and the bladder expands to seal and support the coal seam fault segment. S4. Perform sealing operations near the inlet of the gas injection borehole, and inject gas into the gas injection borehole and coal seam through the gas transmission channel; S5. After the gas injection is completed, gas extraction operations are carried out on the coal seam.

[0016] In some embodiments, the sealing capsule includes a solid sealing capsule and a gas sealing capsule. In step S2, when the sealing capsule is placed at the location of the coal seam fault, two solid sealing capsules and one gas sealing capsule are placed in each group of sealing capsules, and the gas sealing capsule is placed between the two solid sealing capsules.

[0017] In some embodiments, the solidified capsule includes a first connecting tube, a movable tube, and a first bladder body fixedly disposed on the movable tube; the air-sealed capsule includes a second connecting tube and a second bladder body fixedly disposed on the second connecting tube; the first connecting tube and the second connecting tube are respectively connected to an injection tube or an injection screen tube; the movable tube is slidably sleeved on the first connecting tube; in step S5, after the injection is completed, the pressure of the second bladder body is released, the injection tube is pulled, and the injection tube, the injection screen tube, the first connecting tube, and the air-sealed capsule in the injection borehole are recovered. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the coal seam gas injection displacement device according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the installation of the coal seam gas injection displacement device in a coal seam according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the coal seam gas injection displacement device initially inserted into the gas injection borehole according to an embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the coal seam gas injection displacement device of this invention sealing and supporting the gas injection borehole during gas injection.

[0022] Figure 5 This is a schematic diagram of the solidified capsule sealing and supporting the gas injection borehole after recovery by the coal seam gas injection displacement device according to an embodiment of the present invention.

[0023] Figure 6 This is a schematic diagram of the gas injection pipe in the coal seam gas injection displacement device according to an embodiment of the present invention.

[0024] Figure 7 This is a schematic diagram of the structure of the gas injection screen pipe in the coal seam gas injection displacement device according to an embodiment of the present invention.

[0025] Figure 8 This is a schematic diagram of the solidified capsule in the coal seam gas injection displacement device according to an embodiment of the present invention.

[0026] Figure 9 This is a schematic diagram of the gas-sealed capsule in the coal seam gas injection displacement device according to an embodiment of the present invention.

[0027] Figure label: 100 coal seam gas injection displacement device; Inflation tube 1; 2 air injection screen tubes; Blocking capsule 3; sealing capsule 31; first connecting tube 311; first capsule body 312; movable tube 313; support pin 314; air-sealing capsule 32; second connecting tube 321; second capsule body 322; 4. Inject air and drill holes. Coal seam fault 5; Grouting pipe 6; Gas delivery main pipe 7. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] like Figures 1 to 9 As shown, the coal seam gas injection displacement device 100 of this embodiment includes a plurality of gas injection pipes 1, a plurality of gas injection screen pipes 2, and a sealing capsule 3.

[0030] Multiple gas injection pipes 1 are connected in sequence and communicate with each other in the inner cavity of the gas injection pipe 1 to restrict the gas delivery channel. The gas injection pipe 1 is connected to the gas injection pump and is used to extend into the gas injection borehole 4. Multiple gas injection screen pipes 2 are arranged in sequence at one end of the gas injection pipe 1 and communicate with the gas delivery channel. The gas injection screen pipe 2 is provided with multiple air holes that communicate with the gas delivery channel. The gas injection screen pipe 2 is used to inject gas into the gas injection borehole 4 and the coal seam.

[0031] The sealing capsule 3 includes a connecting tube and a capsule body. The connecting tube is located between two adjacent gas injection pipes 1 and / or between two adjacent gas injection screen pipes 2 and / or between adjacent gas injection pipes 1 and gas injection screen pipes 2 and / or at the end of the gas injection screen pipe 2 away from the gas injection pipe 1. The inner cavity of the connecting tube is connected to the gas delivery channel. The capsule body can be filled with fluid to expand. The capsule body is used to expand at the location of the coal seam fault 5 to seal and support the gas injection borehole 4.

[0032] It is understood that when the sealing capsule 3 is installed, at least one of the following connection methods exists: the connecting pipe is connected between two adjacent gas injection pipes 1; the connecting pipe is connected between two adjacent gas injection screen pipes 2; the connecting pipe is connected between adjacent gas injection pipes 1 and gas injection screen pipes 2; the connecting pipe is connected to the end of the gas injection screen pipe 2 away from the gas injection pipe 1. When the sealing capsule 3 is installed, the position of the sealing capsule 3 relative to the gas injection pipes 1 and gas injection screen pipes 2 is set according to the position of the coal seam fault 5 in the gas injection borehole 4, so that when the gas injection pipes 1 and gas injection screen pipes 2 are lowered to the target position in the gas injection borehole 4, the sealing capsule 3 and the position of the coal seam fault 5 expand to seal and support the gas injection borehole 4.

[0033] The working principle of the coal seam gas injection displacement device in this embodiment of the invention is as follows: Based on the length of the gas injection borehole 4 and the position of the coal seam fault 5 relative to the gas injection borehole 4, a set number of gas injection pipes 1, gas injection screen pipes 2, and sealing capsules 3 are selected. The ends of the gas injection screen pipes 2 or connecting pipes located in the gas injection borehole 4 are sealed. The gas injection screen pipes 2, connecting pipes, and gas injection pipes 1 are sequentially lowered into the gas injection borehole 4. The gas injection screen pipes 2, connecting pipes, and gas injection pipes 1 are assembled to form a gas transmission pipeline, and a gas transmission channel is formed inside the gas transmission pipeline. Fluid is filled into the capsule through the pipeline. The capsule expands to seal and support the gas injection borehole 4 at the position of the coal seam fault 5. The expanded capsule blocks the connection between the gas injection borehole 4 and the coal seam fault 5, sealing the inlet end of the gas injection borehole 4. Gas is transported through the gas injection pipes 1. The gas enters the gas injection borehole 4 and the coal seam through the gas holes at the position of the gas injection screen pipes 2 via the transmission channel.

[0034] The coal seam gas injection displacement device 100 of this invention sets sealing capsules 3 on the gas injection pipe 1 and the gas injection screen pipe 2. Under the condition of satisfying the gas delivery effect of the gas injection pipe 1 and the gas injection effect of the gas injection screen pipe 2, the capsule body of the sealing capsule 3 expands at the location of the coal seam fault 5 to seal the fault, thereby preventing the gas in the gas injection screen pipe 2 from leaking through the coal seam fault 5. This facilitates the maintenance of the gas injection pressure in the gas injection borehole 4, constructs an effective fracturing gradient inside the coal seam, and prevents the gas injection borehole 4 from collapsing at the location of the coal seam fault 5. This facilitates the maintenance of the integrity and stability of the gas injection borehole 4, provides a stable and reliable borehole channel for gas drainage operations, and improves the efficiency of coal seam gas drainage.

[0035] Optionally, the gas injection pipe 1, the gas injection screen pipe 2, and the connecting pipe are all made of PVC material with a compressive strength greater than 6MPa.

[0036] Optionally, the gas injection pipe 1, the gas injection screen pipe 2, and the connecting pipe can be connected by threads.

[0037] In some embodiments, such as Figure 1 , Figure 3 , Figure 4 and Figure 8 As shown, the sealing capsule 3 includes a solidification capsule 31, which includes a first connecting pipe 311 and a first bladder 312 disposed on the first connecting pipe 311. The first bladder 312 is connected to a grouting pipe 6 for conveying slurry. One end of the grouting pipe 6 extends out of the air injection hole 4 and is connected to the grouting pump.

[0038] Specifically, when the sealing capsule 3 is lowered, the first connecting pipe 311 is connected to the gas injection screen pipe 2 or the gas injection pipe 1. The first capsule 312 moves with the first connecting pipe 311, and the grouting pipe 6 is connected to the first capsule 312. The grouting pipe 6 moves together with the first connecting pipe 311. When the sealing capsule 3 moves to the position of the coal seam fault 5, grout is pumped into the first capsule 312 through the grouting pump. The first capsule 312 expands. After the grout solidifies, the expansion state of the first capsule 312 is fixed. The first capsule 312 seals and supports the gas injection borehole 4 at the position of the coal seam fault 5. The gas in the gas injection pipe 1 reaches the gas injection screen pipe 2 along the gas transmission channel or through the first connecting pipe 311.

[0039] By filling the first capsule 312 of the solidified capsule 31 with slurry, the slurry has a good supporting effect after solidification, which facilitates the support of the gas injection borehole 4 and prevents the gas injection borehole 4 from collapsing at the coal seam fault 5. This helps maintain the integrity and stability of the gas injection borehole 4, providing a stable and reliable drilling channel for gas drainage operations. At the same time, it enhances the blocking effect between the gas injection borehole 4 and the coal seam fault 5, improving gas injection efficiency and coal seam gas drainage efficiency.

[0040] Optionally, the first capsule 312 is made of coated cloth with an expansion rate greater than 30%.

[0041] In some embodiments, such as Figure 1 , Figure 3 , Figure 4 , Figure 5 and Figure 8 As shown, there are multiple sealing capsules 31, and the grouting pipe 6 passes through multiple sealing capsules 31 in sequence. The section of the grouting pipe 6 located inside the first capsule 312 is provided with a grouting hole that communicates with the inner cavity of the first capsule 312.

[0042] Specifically, at least two solidification capsules 31 are provided for each coal seam fault 5. Preferably, at the location of the coal seam fault 5, the two solidification capsules 31 are respectively set on both sides of the coal seam fault 5. Each first capsule 312 is provided with a grouting pipe 6. The two ends of the grouting pipe 6 extend out of the first capsule 312 along the extension direction of the first connecting pipe 311. Two adjacent first capsules 312 are connected by the grouting pipe 6. The section of the grouting pipe 6 located inside the first capsule 312 is provided with grouting holes. The grout in the grouting pipe 6 enters the inner cavity of the first capsule 312 through the grouting holes.

[0043] By setting multiple sealing capsules 31, the sealing and support effect on the borehole end of the coal seam fault 5 in the gas injection borehole 4 is improved, which facilitates the maintenance of the stability and reliability of the gas injection borehole 4, provides a stable and reliable borehole channel for gas drainage operations, and improves the efficiency of coal seam gas drainage.

[0044] Optionally, a tubular burst valve is provided at the grouting hole location. The tubular burst valve is used to open under a set pressure to connect the grouting pipe 6 and the inner cavity of the first bladder 312. The tubular burst valve increases the initial pressure when the grout enters the first bladder 312, thereby improving the filling effect of the grout on the first bladder 312. It should be noted that the tubular burst valve is prior art, and its specific structure and working principle will not be described in detail here.

[0045] Optionally, an elastic sealing sleeve is fitted on the grouting pipe 6 corresponding to the grouting hole. The sealing sleeve is used to expand when the grout conveying pressure reaches the set pressure, thereby allowing the grout to be discharged from the grouting hole and improving the filling effect of the grout on the first bladder 312.

[0046] In some embodiments, such as Figure 8 As shown, the sealing capsule 3 includes a movable tube 313, which is sleeved on the first connecting tube 311. The first capsule body 312 is fixedly mounted on the movable tube 313. The first connecting tube 311 is provided with a support pin 314, which is used to push the movable tube 313 to move with the first connecting tube 311.

[0047] Specifically, before installing and lowering the first connecting pipe 311, the movable pipe 313 is fitted onto the first connecting pipe 311 and abuts against the support pin 314. The first connecting pipe 311 is then lowered, and the support pin 314 pushes the movable pipe 313 to move. The first bladder 312 follows the movable pipe 313 and connects. After the gas injection operation is completed in the gas injection borehole 4, the first connecting pipe 311 and the gas injection screen pipe 2 can be extracted through the gas injection pipe 1, realizing the reuse of the gas injection pipe 1, the first connecting pipe 311 and the gas injection screen pipe 2, reducing construction costs. At the same time, after the gas injection is completed, gas extraction is still carried out through the gas injection borehole 4, improving the utilization rate of the gas injection borehole 4.

[0048] Optionally, the support pin 314 is rotatably mounted on the first connecting pipe 311 via a pivot, and at least two support pins 314 are spaced apart circumferentially on the first connecting pipe 311. The support pins 314 have a first position and a second position relative to the first connecting pipe 311. In the first position, the extension line of the support pin 314 forms an angle with the axis of the first connecting pipe 311, preferably 90°, and the support pin 314 abuts against the movable pipe 313 so that the movable pipe 313 moves with the first connecting pipe 311. In the second position, the extension line of the support pin 314 is parallel to the axis of the first connecting pipe 311, and the support pin 314 is located at the pivot... On the side of the shaft away from the air injection pipe 1, the distance from the side of the support pin 314 to the axis of the first connecting pipe 311 is not greater than the radius of the movable pipe 313. If the inner radius of the movable pipe 313 is 2-3 cm greater than the inner radius of the first connecting pipe 311, the thickness of the support pin 314 is not greater than 1 cm. When multiple sealing capsules 3 are provided, when the air injection pipe 1 is pulled out, the first connecting pipe 311 located on the rear side, that is, the side away from the air injection pipe 1, passes through the movable pipe 313 located on the front side, that is, the side close to the air injection pipe 1. The support pin 314 can be rotated to be pulled out, which makes it easy to remove the air injection screen pipe 2 and the first connecting pipe 311. The operation is convenient.

[0049] Optionally, the length of the movable tube 313 is 30-50cm shorter than the length of the first connecting tube 311.

[0050] In some embodiments, such as Figure 1 , Figure 3 , Figure 4 and Figure 9 As shown, the sealing capsule 3 includes an air-sealing capsule 32, which includes a second connecting pipe 321 and a second bladder 322 fixedly disposed on the second connecting pipe 321. The second bladder 322 is connected to a gas delivery pipe for delivering gas, and the other end of the gas delivery pipe extends out of the gas injection hole 4 and is connected to the gas injection pump.

[0051] Specifically, when the sealing capsule 3 is lowered, the second connecting pipe 321 is connected to the gas injection screen pipe 2, the gas injection pipe 1, or the first connecting pipe 311. The second capsule 322 moves with the second connecting pipe 321, and the gas delivery pipe is connected to the second capsule 322. The gas delivery pipe moves with the second connecting pipe 321. When the sealing capsule 3 moves to the position of the coal seam fault 5, gas is delivered into the second capsule 322 through the gas injection pump. The second capsule 322 expands. The second capsule 322 seals and supports the gas injection borehole 4 at the position of the coal seam fault 5. The gas in the gas injection pipe 1 reaches the gas injection screen pipe 2 along the gas delivery channel or reaches the gas injection screen pipe 2 through the first connecting pipe 311 and the second connecting pipe 321.

[0052] By filling the second capsule 322 of the gas-sealing capsule 32 with gas, when gas is injected into the gas injection borehole 4, the second capsule 322 seals the coal seam cross section within the gas injection borehole 4, preventing gas from entering the coal seam fault 5 and thus causing leakage. When gas extraction is carried out after gas injection, the second capsule 322 is depressurized, and the coal seam fault 5 is connected to the gas injection borehole 4, further improving the gas extraction efficiency and the utilization rate of the gas injection borehole 4.

[0053] Optionally, the second capsule 322 is made of flexible rubber with an expansion rate greater than 40%.

[0054] In some embodiments, multiple gas-sealing capsules 32 are provided, and two adjacent gas-sealing capsules 32 are connected by a gas supply branch pipe. Specifically, gas reaches the first second capsule 322 through the gas supply main pipe, and then reaches other second capsules 322 in sequence through the gas supply branch pipe. The multiple second capsules 322 gradually expand to seal the coal seam fault 5 in the gas injection borehole 4.

[0055] Multiple gas-sealing bags are set up to enhance the sealing effect of the gas-sealing capsule 32 on the coal seam fault 5, prevent the gas in the gas injection screen pipe 2 from leaking through the coal seam fault 5, facilitate the maintenance of the gas injection pressure in the gas injection borehole 4, build an effective fracturing gradient inside the coal seam, and improve the gas injection effect.

[0056] Optionally, both the main gas supply pipe and the branch gas supply pipe are located within the gas delivery channel.

[0057] In some embodiments, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the sealing capsule 3 is provided in multiple groups. Each group of sealing capsules 3 includes two solid sealing capsules 31 and one air sealing capsule 32. In each group of sealing capsules 3, the air sealing capsule 32 is located between the two solid sealing capsules 31.

[0058] Specifically, within the gas injection borehole 4, at the location of the coal seam fault 5, two sealing capsules 31 are respectively placed on both sides of the coal seam fault 5 surface, and gas sealing capsules 32 are placed corresponding to the coal seam fault 5 surface. This improves the sealing and support effect on the borehole end at the location of the coal seam fault 5 within the gas injection borehole 4, making it easier to maintain the stability and reliability of the gas injection borehole 4. At the same time, it provides a stable and reliable borehole channel for gas drainage operations, thereby improving the efficiency of coal seam gas drainage.

[0059] The following describes a coal seam gas injection displacement method according to an embodiment of the present invention.

[0060] The coal seam gas injection displacement method of this invention includes the coal seam gas injection displacement device of any of the above embodiments, and the gas injection displacement method includes the following steps: S1. Conduct gas injection drilling in the coal seam and determine the fault location based on the slag return during the drilling process; Specifically, the drilling rig is driven to the predetermined position to construct an air injection borehole in the coal seam. During the construction of the air injection borehole, the backflow of slag is recorded in real time, and the location of the fault is recorded. After the air injection borehole is completed, high-pressure water is used to preliminarily clean the drill cuttings inside the air injection borehole. S2. Lower the gas injection screen pipe and gas injection pipe into the gas injection borehole, and according to the fault location, insert the sealing capsule during the process of lowering the gas injection screen pipe and gas injection pipe. S3. Inject filling fluid into the bladder, and the bladder expands to seal and support the coal seam fault segment. S4. Perform sealing operations near the inlet of the gas injection borehole, and inject gas into the gas injection borehole and coal seam through the gas transmission channel; Optionally, a biodegradable sealing material is injected into the orifice of the air-injection drill to seal the orifice; S5. After the gas injection is completed, gas extraction operations are carried out on the coal seam.

[0061] Optionally, after the gas injection is completed, a degrading liquid for the sealing material is injected into the orifice to release the seal on the orifice.

[0062] The coal seam gas injection displacement method of this invention locates the fault position in the coal seam and sets sealing capsules on the gas injection pipe and the gas injection screen. While ensuring the gas delivery effect of the gas injection pipe and the gas injection effect of the gas injection screen, the capsule expands to seal the fault position, preventing gas in the gas injection screen from leaking through the coal seam fault. This facilitates maintaining the gas injection pressure in the gas injection borehole, constructs an effective fracturing gradient inside the coal seam, and improves gas injection efficiency.

[0063] In some embodiments, the sealing capsule includes a solid sealing capsule and a gas sealing capsule. In step S2, when the sealing capsule is placed at the location of the coal seam fault, two solid sealing capsules and one gas sealing capsule are placed in each group of sealing capsules, and the gas sealing capsule is placed between the two solid sealing capsules.

[0064] When placing sealing capsules in the gas injection borehole, two solid sealing capsules are placed on both sides of the coal seam fault plane at the coal seam fault location, and the gas sealing capsule is placed on the corresponding coal seam fault plane. This improves the sealing and support effect on the borehole end at the coal seam fault location in the gas injection borehole, making it easier to maintain the stability and reliability of the gas injection borehole. At the same time, it provides a stable and reliable borehole channel for gas drainage operations, improving the efficiency of coal seam gas drainage.

[0065] Specifically, cement grout is injected into the second capsule through the grouting pipe at a pressure of not less than 1.5 MPa, so that the flexible grout-coated capsule expands and adheres tightly to the borehole wall. After grouting, the grouting pipe is closed and the expanded cement is allowed to solidify (generally 24 hours). High-pressure air is injected into the gas-sealing capsule through the gas supply pipe at a pressure of not less than 2.5 MPa, so that the flexible rubber capsule adheres tightly to the borehole wall. A pressure gauge is installed at the inlet of the gas supply pipe. When the pressure is less than 2 MPa, gas replenishment is required. When performing coal seam gas injection, high-pressure gas is continuously injected into the gas injection pipe, and the gas injection pressure in the gas injection pipe shall not exceed 80% of the gas injection pressure of the gas supply pipe.

[0066] In some embodiments, the solid-sealed capsule includes a first connecting tube, a movable tube, and a first bladder body fixedly disposed on the movable tube; the air-sealed capsule includes a second connecting tube and a second bladder body fixedly disposed on the second connecting tube. The first connecting tube and the second connecting tube are respectively connected to the air injection tube or the air injection screen tube. The movable tube is slidably sleeved on the first connecting tube. In step S5, after the air injection is completed, the pressure of the second bladder body is released, the air injection tube is pulled, and the air injection tube, the air injection screen tube, the first connecting tube, and the air-sealed capsule in the air injection borehole are recovered.

[0067] The support pin is rotatably mounted on the first connecting pipe via a rotating shaft, and at least two support pins are spaced apart circumferentially on the first connecting pipe. The support pin has a first position and a second position relative to the first connecting pipe. In the first position, the extension line of the support pin is set at an angle to the axis of the first connecting pipe, preferably 90°. The support pin is used to abut against the movable pipe so that the movable pipe moves with the first connecting pipe. In the second position, the extension line of the support pin is parallel to the axis of the first connecting pipe, and the support pin is located on the side of the rotating shaft away from the air injection pipe. At this time, the distance from the side of the support pin to the axis of the first connecting pipe is not greater than the radius of the movable pipe.

[0068] Multiple sealing capsules are provided. Before installing and lowering the first connecting pipe, the movable pipe is sleeved on the first connecting pipe and abuts against the support pin. As the first connecting pipe continues to be lowered, the support pin pushes the movable pipe to move, and the first capsule follows the movable pipe and connects. After the gas injection operation is completed in the gas injection borehole, when the gas injection pipe is pulled out, the first connecting pipe, which is located on the rear side (i.e., the side away from the gas injection pipe), passes through the movable pipe, which is located on the front side (i.e., the side close to the gas injection pipe). The support pin can be rotated to be pulled out, which facilitates the removal of the gas injection screen pipe, the first connecting pipe, and the gas sealing capsule. The operation is convenient and allows for the reuse of the gas injection pipe, the first connecting pipe, the gas injection screen pipe, and the gas sealing capsule, reducing construction costs. At the same time, after the gas injection is completed, gas extraction can still be carried out through the gas injection borehole, improving the utilization rate of the gas injection borehole.

[0069] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0071] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0072] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0073] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0074] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A coal seam gas injection displacement device, characterized in that, include: Multiple air injection pipes are connected in sequence and communicate with each other in the inner cavity of the air injection pipes to restrict the air delivery channel. The air injection pipes are connected to the air injection pump and are used to extend into the air injection borehole. Multiple gas injection screens are arranged sequentially at one end of the gas injection pipe and connected to the gas delivery channel. Each gas injection screen has multiple air holes connected to the gas delivery channel. The gas injection screens are used to inject gas into the gas injection borehole and coal seam. A sealing capsule, comprising a connecting tube and a capsule body, wherein the connecting tube is disposed between two adjacent gas injection pipes and / or between two adjacent gas injection screens and / or between adjacent gas injection pipes and gas injection screens and / or at the end of the gas injection screens away from the gas injection pipes, the inner cavity of the connecting tube is in communication with the gas delivery channel, and the capsule body is capable of being filled with fluid to expand, the capsule body being used to expand at the location of a coal seam fault to seal and support the gas injection borehole.

2. The coal seam gas injection displacement device according to claim 1, characterized in that, The sealing capsule includes a solidification capsule, which includes a first connecting tube and a first bladder body disposed on the first connecting tube. The first bladder body is connected to a grouting pipe for conveying slurry, and one end of the grouting pipe extends out of the air injection hole and is connected to a grouting pump.

3. The coal seam gas injection displacement device according to claim 2, characterized in that, The solidification capsule is provided in multiple ways, and the grouting tube passes through multiple solidification capsules in sequence. The section of the grouting tube located in the first capsule is provided with an grouting hole that communicates with the inner cavity of the first capsule.

4. The coal seam gas injection displacement device according to claim 2, characterized in that, The occlusion capsule includes a movable tube, which is sleeved on the first connecting tube. The first capsule body is fixedly mounted on the movable tube. A support pin is provided on the first connecting tube, which is used to push the movable tube to move with the first connecting tube.

5. The coal seam gas injection displacement device according to any one of claims 2-4, characterized in that, The sealing capsule includes an air-sealing capsule, which includes a second connecting tube and a second bladder fixedly disposed on the second connecting tube. The second bladder is connected to a gas delivery pipe for delivering gas, and the other end of the gas delivery pipe extends out of the gas injection hole and is connected to a gas injection pump.

6. The coal seam gas injection displacement device according to claim 5, characterized in that, The gas-sealed capsules are provided in multiple ways, and two adjacent gas-sealed capsules are connected by an air supply branch pipe.

7. The coal seam gas injection displacement device according to claim 5, characterized in that, The sealing capsule is provided in multiple groups, and each group of sealing capsules includes two solid sealing capsules and one air sealing capsule. In each group of sealing capsules, the air sealing capsule is located between the two solid sealing capsules.

8. A coal seam gas injection displacement method, based on the coal seam gas injection displacement device according to any one of claims 1-7, characterized in that, The gas injection displacement method includes the following steps: S1. Conduct gas injection drilling in the coal seam and determine the fault location based on the slag return during the drilling process; S2. Lower the gas injection screen pipe and gas injection pipe into the gas injection borehole, and according to the fault location, insert the sealing capsule during the process of lowering the gas injection screen pipe and gas injection pipe. S3. Inject filling fluid into the bladder, and the bladder expands to seal and support the coal seam fault segment. S4. Perform sealing operations near the entrance of the gas injection borehole, and inject gas into the gas injection borehole and coal seam through the gas transmission channel; S5. After the gas injection is completed, gas extraction operations are carried out on the coal seam.

9. The coal seam gas injection displacement method according to claim 8, characterized in that, The sealing capsule includes a solid sealing capsule and a gas sealing capsule. In step S2, when the sealing capsule is placed at the location of the coal seam fault, two solid sealing capsules and one gas sealing capsule are placed in each group of sealing capsules, and the gas sealing capsule is placed between the two solid sealing capsules.

10. The coal seam gas injection displacement method according to claim 9, characterized in that, The solid-sealing capsule includes a first connecting tube, a movable tube, and a first capsule fixedly disposed on the movable tube. The air-sealing capsule includes a second connecting tube and a second capsule fixedly disposed on the second connecting tube. The first connecting tube and the second connecting tube are respectively connected to the air injection tube or the air injection screen tube. The movable tube is slidably sleeved on the first connecting tube. In step S5, after the air injection is completed, the pressure of the second capsule is released, the air injection tube is pulled, and the air injection tube, the air injection screen tube, the first connecting tube, and the air-sealing capsule in the air injection borehole are recovered.

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