Device and method for reusable thermoplastic film sealing

Abstract

The present invention discloses a device and method for sealing holes with reusable thermoplastic film, which is suitable for use in the field of gas extraction. It comprises an outer air-filled bag and an inner air-filled bag which are sleeved on the extraction pipe. The extraction pipe is provided with a pipe and a thermoplastic film outside. A groove is provided at the location of the outer bag to ensure that the bag will not move due to extraction. A plurality of heat spray pipes are provided around the extraction pipe, and a circle of thermoplastic film is placed on the area from the inner bag to the outer bag of the heat spray pipe. At the same time, a CO injection device is installed at a position slightly lower than the upper right heat spray pipe and slightly lower than the extraction pipe. 2 The gas injection pipe is used for conventional gas injection displacement. When a large number of cracks appear in the borehole wall, gas is used to blow a circle of thermoplastic film close to the borehole wall, and then high-temperature gas is used to melt the hot melt film and adhere it to the borehole wall to seal the cracks in the borehole wall. It can achieve complete sealing at one time, has strong timeliness, is easy to operate, and can be reused.

Description

Technical Field

[0001] The present invention relates to a device and method for sealing holes with a reusable thermoplastic film, and is particularly suitable for use in the field of gas extraction. Background Art

[0002] At present, common gas extraction sealing methods are roughly divided into three categories according to the sealing method: non-pressure sealing, "two plugging and one injection" pressure sealing and multiple sealing. Non-pressure sealing includes mechanical sealing, cement slurry sealing and polymer foam material sealing. The most common sealing is to inject grout into the bag and use pressure grouting to achieve the function of slurry plugging cracks and actively supporting the borehole. In the prior art, multiple sealing is usually used to solve the development of cracks in the extraction process through powder plugging and delayed sealing. However, the above three sealing methods cannot guarantee that the newly generated cracks are effectively blocked, and the facilities used are all disposable.

[0003] The prior art with the publication number CN204511507U discloses a recyclable gas extraction hole sealing and crack filling device, including: extraction hole, gas extraction pipe, connecting hose, double-sided grouting pipe, grouting baffle, grouting port, grouting connecting pipe, grouting pump, grouting cylinder, hole sealing mud, the gas extraction pipe is arranged in the extraction hole, and the pore between the extraction hole and the gas extraction pipe is blocked by hole sealing mud; the connecting hose is connected to the gas extraction pipe; the double-sided grouting pipe is arranged in the cracks around the extraction hole and connected to the grouting baffle. The device injects slurry into the cracks around the extraction hole through the inner and outer hyperbolic surfaces of the double-sided grouting pipe to fill the cracks, and at the same time solidifies the slurry to seal the part within the hole sealing mud. It can only be said that it will be blocked with slurry, and the extraction pipe will not be able to be taken out of the borehole after plowing. Summary of the invention

[0004] Purpose of the invention: In view of the shortcomings of the prior art, a device and method for sealing holes with reusable thermoplastic films are provided, which can use gas to effectively seal and repair cracks generated in extraction drilling and tapping, effectively improving the extraction effect. It has a simple structure, is easy to use, has a good repair effect, and can be used repeatedly.

[0005] Technical solution: To achieve the above technical purpose, the present invention provides a reusable thermoplastic film sealing device, which is suitable for use with two-stage variable diameter drilling, and the two-stage variable diameter drilling includes a first-stage variable diameter and a second-stage variable diameter, wherein the second-stage variable diameter is provided with a concave limiting groove near the drilling hole mouth; it includes a pumping tube, and the pumping tube is respectively provided with an inner bag and an outer bag for inflation at the front and back, the diameter of the outer bag is larger than that of the inner bag, the inner bag is arranged at the shoulder between the first-stage variable diameter and the second-stage variable diameter of the two-stage variable diameter drilling, and the outer bag is stuck in the limiting groove of the second-stage variable diameter to ensure that the outer bag will not move due to the pressure difference caused by extraction after expansion, and the outer bag and the inner bag share an inflation tube for inflating both at the same time;

[0006] There is a thermoplastic film sealing section between the inner bag and the outer bag. The thermoplastic film sealing section includes four heat spraying pipes arranged between the inner bag and the outer bag and parallel to the extraction pipe, wherein the four heat spraying pipes are arranged at equal intervals around the extraction pipe to form a rectangular distribution, the ends of the four heat spraying pipes are provided with high temperature resistant gaskets and in contact with the end face of the inner bag to prevent the inner bag from being scalded, the tail ends of the four heat spraying pipes are connected to the heat spraying pipes of the heat source, a plurality of jet holes are opened on the side walls of the four heat spraying pipes between the inner bag and the outer bag, and the outer sides of the four heat spraying pipes with a plurality of jet holes are fluffyly provided with a thermoplastic film that can be expanded under the influence of gas and generate viscosity after heating and adhere to the borehole wall to fully seal the cracks, and the thermoplastic film sealing section is located between the four heat spraying pipes and is provided with a CO 2 Gas source connection CO 2 Injection tube.

[0007] Furthermore, the inflation tubes of the outer bag and the inner bag are connected to an inflation gas source, and a bag inflation tube valve is provided at the connection with the inflation gas source.

[0008] Furthermore, the four heat spray pipes are respectively located at the upper left, lower left, upper right and lower right of the extraction tube, the four heat spray pipes are arranged through the outer bag, and the four heat spray pipes are not connected to the outer bag; a valve is provided at the connection between the heat spray pipe and the heat source.

[0009] Furthermore, the jet holes on the bladder inflation tube are evenly spaced at intervals of 2 to 4 cm, and all the jet holes are the same size.

[0010] Furthermore, the thermoplastic film is a thin film of hot-adhesive film, which is not sticky at room temperature and becomes sticky and fluid only when the temperature reaches the melting point; the thermoplastic film is specifically a high-elastic TPU hot-melt adhesive film-high-rebound adhesive film, model GXJU150.

[0011] Furthermore, CO passing through the outer capsule 2 The injection pipe is located at a higher level than the extraction pipe but is surrounded by four hot spray pipes. A CO 2 Gas injection valve.

[0012] A sealing method using a reusable thermoplastic film sealing device, characterized by the following steps:

[0013] a. Preset the sealing depth of the extraction borehole in the coal seam according to the actual geological conditions on site, and set the extraction borehole as a secondary variable diameter borehole. The depth of the step area matches the overall length from the outer bag (3) to the inner bag (2) on the extraction pipe (1), and set a limit groove near the orifice of the extraction borehole. The depth of the limit groove matches the size of the outer bag after inflation. After the extraction borehole is constructed, use airflow to clean the borehole;

[0014] b. First, let the extraction tube pass through the inner bag and the outer bag, and ensure that the part where the extraction tube passes through the bag is kept sealed to prevent air leakage. Similarly, let the four heat spray pipes pass through the outer bag respectively, and the passing positions are located at the upper left, upper right, lower left, and lower right positions of the extraction tube, and ensure that the part passing through the outer bag is kept sealed; set a CO 2 The air injection pipe passes through the outer bag and ensures the sealing of the passing part. First, slightly inflate the inner bag and the outer bag, and stop infusing air when the air is about 1 / 3 of the full air state; place the thermoplastic film in a ring shape on the four hot spray pipes; install the extraction pipe with the inner bag and the outer bag installed into the extraction borehole until the inner bag reaches the shoulder of the variable diameter extraction borehole;

[0015] c. Correct the positions of the inner bag and the outer bag so that the outer bag can be exactly in the limiting groove, and then start to inject gas using the gas injection pipe; until the inner bag and the outer bag fully fill the two ends of the extraction borehole, and the limiting groove where the outer bag is located ensures that there will be no movement caused by pressure difference during the extraction process; when the inner bag and the outer bag are full of gas, close the bag inflation valve, and separate the primary diameter reduction section of the extraction borehole into the gas extraction area through the inner bag, and separate the secondary diameter reduction section between the inner bag and the outer bag into the thermoplastic film sealing section;

[0016] d. Before gas extraction begins, 2 The insufflation tube injects CO between the inner and outer bags 2 Gas, the injected CO 2 The gas escapes from the gaps in the thermoplastic film, thereby CO2-absorbing the secondary borehole wall between the inner and outer bladder bags. 2 Gas injection for gas extraction;

[0017] e. As the gas is extracted, the borehole wall between the inner bag and the outer bag is filled with CO2. 2 Gas gradually develops a group of cracks. As new cracks open, the gas leakage of the extraction borehole becomes more serious, resulting in a decrease in the gas concentration extracted by the extraction pipe. When the gas concentration drops significantly to a preset value, dry air is first injected into the four heat-spraying pipes. The dry air is ejected from the jet holes, so that the thermoplastic film is expanded and adhered to the coal wall of the thermoplastic film sealing section under the action of the gas ejected from the heat-spraying pipes. Then, high-pressure hot air is injected into the four heat-spraying pipes. The thermoplastic film is melted and becomes sticky under the action of the high-pressure hot air ejected from the jet holes. The melted thermoplastic film is tightly adhered to the borehole wall of the thermoplastic film sealing section under the action of the air pressure, thereby blocking the group of cracks generated on the borehole wall. Stop gas injection to complete the blocking of the cracks in the borehole wall of the secondary reducer section of the extraction borehole, and only use the primary reducer section for gas extraction.

[0018] f. When the extraction is completed, the gas in the inner and outer bags is discharged through the bag air injection tube, and then the sealing device is removed and only a new thermoplastic film is installed for reuse.

[0019] Furthermore, the high-pressure hot gas ejected from the jet hole of the heat spray pipe has a pressure of 1 MPa and a temperature exceeding the thermal melting point of the thermoplastic film.

[0020] Furthermore, the pressure of the injected dry air was 1 MPa, and after 30 seconds to 1 minute of the injection of the dry air, it was considered that the thermoplastic film was completely attached to the coal wall. Beneficial Effects

[0021] The cost of plugging cracks is saved. After the device is installed, only the thermoplastic film needs to be replaced each time it is used, so it can be recycled. In addition, the gas injected between the inner and outer bags can play a supporting role, reduce the multiple damage caused by mining, and reduce the re-development of cracks.

[0022] The use of thermoplastic film for sealing is quick and effective. Unlike the previous method of using particles and other gases to produce chemical reactions before sealing, the thermoplastic film can directly seal the cracks generated in the drill hole, which is quick and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of an implementation of a reusable thermoplastic film sealing device according to an embodiment of the present invention;

[0024] Figure 2 is a cross-sectional view of a reusable thermoplastic film sealing device in a drill hole before extraction in an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the thermoplastic film sealing the cracks in the borehole wall after being preheated and melted in an embodiment of the present invention.

[0026] In the figure: 1- extraction tube, 2- inner bag, 3- outer bag, 4- high temperature resistant gasket, 5- hot spray pipe, 6- CO 2 Injection tube, 8-thermoplastic film, 9-jet hole, 10-bladder inflation tube, 11-CO 2 Gas injection valve, 12- extraction pipe valve, 13- bladder inflation pipe valve, 14- heat injection pipe valve. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are further described below in conjunction with the accompanying drawings:

[0028] like Figure 1As shown, the reusable thermoplastic film sealing device of the present invention is sleeved on an inflatable outer bag 3 and an inner bag 2 on an extraction tube 1, wherein the outer bag 3 is arranged on the right and the inner bag 2 is arranged on the left, and air is injected into the two bags simultaneously through an inflatable tube 10 between the inner and outer bags. The outer bag 3 has a larger diameter than the inner bag 2, and has a groove that matches its shape in the area where it is located, to ensure that the bag will not move due to the pressure difference caused by extraction. There are four heat spray pipes 5 passing through the outer bag 3, and there is a thermoplastic film 8 on the periphery of the heat spray pipe 5 between the inner and outer bags, and the heat spray pipe 8 is provided with a nozzle 9 in the area covered by the thermoplastic film. There is CO passing through the outer bag 3 2 Gas injection tube 6.

[0029] Both the inner and outer airbags are inflatable airbags, and are filled with air. They can be inflated by an inflation tube 10, and a valve 13 is provided at the end of the inflation tube. The inflation tube 10 directly connects the two bags and can inflate the two bags at the same time. A device for reusable thermoplastic film sealing, four heat spray pipes 5 are respectively located at the upper left, lower left, upper right, and lower right of the extraction tube 1. A valve 14 is provided at the right end of the heat spray pipe 5, 2 to 4 cm in front of the left inflatable bag 2 from the left end of the heat spray pipe 5. The heat spray pipe 5 is provided with jet holes 9 of the same size, and the jet holes 9 are evenly distributed from the left end to 2 to 4 cm near the left side of the right bag. The thermoplastic film 8 selected for sealing is a hot adhesive film, which has stickiness when heated and can be quickly adsorbed on an object. A CO2 nozzle is provided to pass through the outer bag. 2 The gas injection pipe 6 is slightly higher than the extraction pipe 1 and lower than the heat injection pipe 5 , and a valve 14 is provided at the right end of the gas injection pipe 6 .

[0030] A sealing method for a real-time multiple sealing device, the steps are as follows:

[0031] a. Preset the sealing depth of the borehole in the coal seam according to the actual geological conditions on site, and set a variable diameter borehole at a moderate depth from the bottom of the borehole. Through the diameter difference, a step area is formed at a moderate depth of the borehole. The depth of the step area matches the overall length from the outer bag 3 to the inner bag 2 on the extraction tube 1, and a groove is set near the borehole mouth. The depth of the groove matches the size of the outer bag after inflation. Use airflow to clean the borehole after drilling;

[0032] b. First, let the extraction tube 1 pass through the inner bag 2 and the outer bag 3, and ensure that the part where the extraction tube 1 passes through the bag is kept sealed to prevent air leakage. Similarly, let the four heat spray pipes 5 pass through the outer bag 3 respectively, and the passing positions are respectively located at the upper left, upper right, lower left, and lower right positions of the extraction tube 10, and ensure that the part passing through the outer bag 3 is kept sealed; set a CO 2The gas injection pipe 6 passes through the outer bag 3 and ensures the sealing of the passing part. First, slightly inflate the inner bag 2 and the outer bag 3, and stop infusing gas when the gas is about 1 / 3 of the full gas state; place the thermoplastic film 8 in a ring shape on the four hot spray pipes 5; install the extraction pipe 10 installed with the inner bag 2 and the outer bag 3 into the extraction borehole until the inner bag 2 reaches the shoulder of the variable diameter extraction borehole;

[0033] c. Appropriately adjust the positions of the inner and outer bags so that the outer bag 3 can be exactly in the groove, and then start to inject air. Until the inner and outer bags fully fill the drill holes at both ends, the groove where the outer bag 3 is located ensures that there will be no movement caused by pressure difference during the extraction process. Then close the bag inflation valve 13;

[0034] d. Before gas extraction begins, 2 The gas injection tube 6 injects CO into the space between the inner bag 2 and the outer bag 3. 2 To achieve the effect of gas injection displacement;

[0035] e. As gas is extracted, fractures gradually develop around the borehole. As new fractures open, the borehole leaks more and more. By observing the concentration of extracted gas, when the gas concentration is compared with CO 2 When the concentration drops significantly, it means that new cracks have opened. At this time, dry air is slowly injected into the heat spray pipe 5 to make the thermoplastic film 8 slowly rise from the heat spray pipe to the vicinity of the coal wall, and then high-pressure hot air is injected. The characteristics of the thermoplastic film 8 are used to make it completely and tightly fit the coal wall under the action of high-pressure hot air. The high-pressure hot air flow is continuously injected until the thermoplastic film 8 is completely attached to the coal wall, and the gas injection is stopped to achieve a one-time sealing operation, as shown in 3;

[0036] f. When the extraction is finished, close the extraction tube valve 12, use the bag gas injection tube 10 to suck out the gas in the inner bag 2 and the outer bag 3, and then take out the used device. The next extraction only needs to replace the thermoplastic film 8.

Claims

1. A device for reusable thermoplastic film sealing, characterized in that: Adapted to use in a secondary variable diameter drilling hole, the secondary variable diameter drilling hole includes a first-stage variable diameter and a second-stage variable diameter, wherein the second-stage variable diameter is provided with a concave limiting groove near the borehole mouth; comprising an extraction tube (1), the extraction tube (1) is respectively provided with an inner bag (2) and an outer bag (3) for inflation, the diameter of the outer bag (3) is larger than that of the inner bag (2), the inner bag (2) is arranged at a shoulder between the first-stage variable diameter and the second-stage variable diameter of the secondary variable diameter drilling hole, the outer bag (3) is stuck in the limiting groove of the second-stage variable diameter, to ensure that the outer bag (3) will not move due to the pressure difference caused by extraction after expansion, and the outer bag (3) and the inner bag (2) share a bag inflation tube (10) for inflating both at the same time; A thermoplastic film sealing section is provided between the inner bag (2) and the outer bag (3), and the thermoplastic film sealing section includes four heat spray pipes (5) arranged between the inner bag (2) and the outer bag (3) and arranged parallel to the extraction pipe (1), wherein the four heat spray pipes (5) are arranged at equal intervals around the extraction pipe (1) to form a rectangular distribution, and the ends of the four heat spray pipes (5) are provided with high temperature resistant gaskets (4) and are in contact with the end surface of the inner bag (2) to prevent the inner bag (2) from being scalded. ) is connected to a heat spray pipe of a heat source in the tail end thereof, a plurality of jet holes (9) are provided on the side walls of four heat spray pipes (5) between the inner bag (2) and the outer bag (3), and a thermoplastic film (8) which is fluffy and can be expanded under the influence of gas and become sticky after heating and adhere to the borehole wall to fully seal the cracks is provided on the outer side of the four heat spray pipes (5), and a CO2 gas injection pipe (6) connected to the CO2 gas source is provided in the thermoplastic film sealing section located between the four heat spray pipes (5).

2. The device for reusable thermoplastic film sealing according to claim 1, characterized in that: The bag inflation tubes (10) of the outer bag (3) and the inner bag (2) are connected to an inflation gas source, and a bag inflation tube valve (13) is provided at the connection point with the inflation gas source.

3. The device for reusable thermoplastic film sealing according to claim 2, characterized in that: The four heat spray pipes (5) are respectively located at the upper left, lower left, upper right and lower right of the extraction pipe (1); the four heat spray pipes (5) are arranged through the outer bag (3), and the four heat spray pipes (5) are not connected to the outer bag (3); a valve (14) is provided at the connection between the heat spray pipe (5) and the heat source.

4. The device for reusable thermoplastic film sealing according to claim 1, characterized in that: The air jet holes (9) on the bladder inflation tube (10) are evenly spaced, with a spacing of 2 to 4 centimeters, and all the air jet holes (9) are of the same size.

5. The device for reusable thermoplastic film sealing according to claim 4, characterized in that: The thermoplastic film (8) is a thin film of hot-adhesive film, which is not sticky at room temperature and becomes sticky and fluid only when the temperature reaches the melting point; the thermoplastic film (8) is specifically a high-elastic TPU hot-melt adhesive film-high-rebound adhesive film, model number GXJU150.

6. The device for reusable thermoplastic film sealing according to claim 1, characterized in that: The CO2 injection pipe (6) passing through the outer bag is located at a higher level than the extraction pipe (1) but is surrounded by four heat injection pipes (5). A CO2 injection valve (11) is provided at the tail end of the CO2 injection pipe (6).

7. A sealing method using the reusable thermoplastic film sealing device according to any one of claims 1 to 6, characterized in that Here are the steps: a. Preset the sealing depth of the extraction borehole in the coal seam according to the actual geological conditions on site, and set the extraction borehole as a secondary variable diameter borehole. The depth of the step area matches the overall length from the outer bag (3) on the extraction pipe (1) to the inner bag (2), and set a limit groove near the extraction borehole opening. The depth of the limit groove matches the size of the outer bag (3) after inflation. After the extraction borehole is constructed, use airflow to clean the borehole; b. First, the extraction tube (1) is passed through the inner bag (2) and the outer bag (3), and the portion where the extraction tube (1) passes through the bag is kept sealed to prevent air leakage. Similarly, four heat spray pipes (5) are passed through the outer bag (3) respectively, and the positions where they pass through are located at the upper left, upper right, lower left, and lower right positions of the extraction tube (1), and the portions where they pass through the outer bag (3) are kept sealed. At a horizontal height lower than the upper right heat spray pipe (5) and higher than the extraction tube (1), the outer bag (3) is sealed. A CO2 gas injection pipe (6) is arranged at the position of the pipe (1) to pass through the outer bag (3), and the sealing of the passing part is ensured. The inner bag (2) and the outer bag (3) are first slightly gassed, and the gas injection is stopped when the gas is about 1 / 3 of the full gas state; a thermoplastic film (8) is placed in a ring shape on the four hot spray pipes (5); the extraction pipe (1) with the inner bag (2) and the outer bag (3) installed is installed in the extraction borehole until the inner bag (2) reaches the shoulder of the variable diameter extraction borehole; c. Correcting the positions of the inner bag (2) and the outer bag (3) so that the outer bag (3) can be exactly located in the limiting groove, and then starting to inject gas using the bag inflation pipe (10); until the inner bag (2) and the outer bag (3) fully fill the two ends of the extraction borehole, the limiting groove where the outer bag (3) is located ensures that no movement caused by pressure difference occurs during the extraction process; when the inner bag (2) and the outer bag (3) are filled with gas, the bag inflation pipe valve (13) is closed, and the first-stage variable diameter section of the extraction borehole is separated into a gas extraction area through the inner bag (2), and the second-stage variable diameter section between the inner bag (2) and the outer bag (3) is separated into a thermoplastic film sealing section; d. Before gas extraction begins, CO2 gas is injected into the space between the inner bag (2) and the outer bag (3) through the CO2 gas injection pipe (6). At this time, the injected CO2 gas overflows from the gap of the thermoplastic film (8), thereby performing CO2 gas injection displacement on the secondary borehole wall between the inner bag (2) and the outer bag (3) to extract gas; e. As the gas is extracted, a group of cracks gradually develops around the borehole wall between the inner bag (2) and the outer bag (3) as the CO2 gas is injected. As new cracks open, the gas leakage in the extraction borehole becomes more serious, causing the gas concentration extracted by the extraction pipe (1) to decrease. When the gas concentration drops significantly to a preset value, dry air is first injected into the four hot spray pipes (5), and the dry air is ejected from the air jet holes (9), so that the thermoplastic film (8) is exposed to the gas ejected from the hot spray pipes (5). The thermoplastic film (8) is expanded and adhered to the coal wall of the thermoplastic film sealing section under the action of the body, and then high-pressure hot gas is injected into the four hot injection pipes (5). The thermoplastic film (8) is melted and becomes sticky under the action of the high-pressure hot gas ejected from the gas injection holes (9). The melted thermoplastic film (8) is tightly adhered to the borehole wall of the thermoplastic film sealing section under the action of the gas pressure, thereby sealing the cracks generated on the borehole wall; stopping the gas injection, completing the sealing of the cracks on the borehole wall of the secondary diameter reducing section of the extraction borehole, and only using the primary diameter reducing section for gas extraction; f. When the extraction is completed, the gas in the inner bag (2) and the outer bag (3) is discharged using the bag inflation tube (10), and then the sealing device is removed and only a new thermoplastic film (8) is installed for reuse.

8. The sealing method according to claim 7, characterized in that: The high-pressure hot gas ejected from the jet hole (9) of the hot spray pipe (5) has a pressure of 1 MPa and a temperature exceeding the thermal melting point of the thermoplastic film (8).

Images