A gas-liquid combined fracturing device and method

Abstract

The present invention discloses a gas-liquid combined fracturing device, including an end sealer, a front fracturing pipe, an extended connecting pipe, a rear fracturing pipe and a rear sealer, wherein the front fracturing pipe, the extended connecting pipe, the rear fracturing pipe and the rear sealer are connected to each other by threads, and the end sealer and the rear sealer are both covered with expandable high-pressure capsules, and the front fracturing pipe and the rear fracturing pipe are both provided with gas perforations for spraying gas fracturing media and liquid perforations for spraying liquid fracturing media, and the front fracturing pipe is provided with a front liquid outlet for liquid fracturing; S3: hydraulic fracturing of the measure hole is completed by a hydraulic fracturing device, and a gas-liquid combined fracturing method is also disclosed. Gas fracturing and liquid fracturing can be realized simultaneously by using one device, so that during fracturing, the advantages of gas fracturing and liquid fracturing can be effectively combined, so that the fractured coal seam has a good permeability enhancement effect and a large range.

Description

Technical Field

[0001] The invention belongs to the technical field of coal seam permeability enhancement in underground coal mines, and in particular relates to a gas-liquid combined fracturing device and method. Background Art

[0002] The occurrence conditions of coal seams in my country are complex, and many coal mines are simultaneously facing disasters such as gas, water, fire, and dust. Among them, the gas problem is one of the most common and difficult to solve problems in coal mine safety production. At present, the most important technical measure for coal mine gas problems is gas extraction, including coal seam gas pre-extraction, goaf decompression gas extraction, etc. Since most coal seams in my country have low permeability, resulting in low gas extraction efficiency, in order to improve the efficiency of coal seam gas extraction, many experts and scholars have studied and developed many coal seam permeability enhancement methods and technical equipment, including hydraulic permeability enhancement technology (hydraulic cutting, hydraulic punching, hydraulic fracturing, etc.) and related equipment, blasting permeability enhancement technology (deep hole pre-splitting blasting, CO2 phase change fracturing, loosening blasting, etc.) and related equipment, and chemical modification permeability enhancement technology (coal seam acidification, coal seam permeability enhancement fluid, etc.) and related equipment. However, each unidirectional permeability enhancement measure has certain defects. For example, hydraulic fracturing technology can achieve large-scale coal seam permeability enhancement, but the cracks produced by fracturing are uncontrollable; CO2 phase change fracturing can achieve coal seam fracturing and displace coal seam gas, but its fracturing range is limited. Summary of the invention

[0003] The present invention proposes a gas-liquid combined fracturing device, which can not only realize the hydraulic permeability enhancement technology, but also realize the blasting permeability enhancement technology, and combines the two to achieve a good permeability enhancement effect and a large range for the coal seam.

[0004] To this end, the technical solution adopted by the present invention is: a gas-liquid combined fracturing device, including an end sealer, a front end fracturing tube, an extended connecting tube, a rear end fracturing tube and a rear end sealer, wherein the front end fracturing tube, the extended connecting tube, the rear end fracturing tube and the rear end sealer are connected to each other through threads, and the end sealer and the rear end sealer are both sleeved with expandable high-pressure capsules, and the front end fracturing tube and the rear end fracturing tube are both provided with gas perforations for spraying gas fracturing media and liquid perforations for spraying liquid fracturing media, and the front end fracturing tube is provided with a front end liquid outlet for liquid fracturing;

[0005] The liquid perforations and the front liquid outlets are both equipped with corresponding plugs. When the gas fracturing medium is ejected from the gas perforations, it is a gas fracturing state; when the front liquid outlet is blocked with the plug, the liquid fracturing medium is ejected from the liquid perforations, it is a liquid fracturing state; when the liquid perforations are blocked with the plug, the liquid fracturing medium flows out from the front liquid outlet, it is a liquid fracturing state.

[0006] As a preferred embodiment of the above scheme, the end sealer includes a conical head, an end seal section and an end connection section arranged in sequence from front to back, the outer side of the end seal section is fixedly sleeved with an end high pressure capsule, the rear end of the end high pressure capsule is provided with an end high pressure tube for expanding the end high pressure capsule, and the rear end of the end connection section is provided with an end threaded hole for connecting with the front end of the front fracturing tube;

[0007] The front end of the front end fracturing tube is provided with a front end fracturing connector with external threads for connecting with the rear end of the end sealer, the front end fracturing tube is provided with a front end fracturing hole for liquid fracturing medium to pass through, the middle part of the front end fracturing tube is provided with a front end liquid outlet connected with the front end of the front end fracturing hole in the diameter direction, the middle part of the front end fracturing tube is provided with a row of front end liquid perforations connected with the front end fracturing hole in the axial direction, the rear end of the front end fracturing tube is provided with a front end fracturing threaded hole for connecting with the front end of the extended connecting tube, and the front end fracturing hole is connected with the front end fracturing threaded hole, the middle part of the front end fracturing tube is also provided with a front end fracturing groove for the front end fracturing gas tube to be loaded, the middle part of the front end fracturing tube is also provided with a row of front end gas perforations for fracturing gas ejection in the axial direction, and the front end gas perforations are connected with the front end fracturing gas tube, the front end gas perforations and the front end liquid perforations are circumferentially staggered, and the front end fracturing gas tube is provided with a front end high pressure tube capable of filling the fracturing gas into the front end fracturing gas tube;

[0008] The front end of the extended connecting pipe is provided with an extended connector with external threads for connecting with the rear end of the front fracturing pipe, the rear end of the extended connecting pipe is provided with an extended threaded hole for connecting with the front end of the rear fracturing pipe, and the extended connecting pipe is provided with an extended through hole for liquid fracturing medium to pass through;

[0009] The front end of the rear fracturing tube is provided with a rear fracturing connector with external threads for connecting with the rear end of the extended connecting tube, the rear fracturing tube is provided with a rear fracturing through hole for liquid fracturing medium to pass through, the middle part of the rear fracturing tube is provided with a row of rear liquid perforations connected with the rear fracturing holes along the axial direction, the rear end of the rear fracturing tube is provided with a rear fracturing threaded hole for connecting with the front end of the rear hole sealer, the middle part of the rear fracturing tube is also provided with a rear fracturing groove for the rear fracturing gas tube to be loaded, the middle part of the rear fracturing tube is also provided with a row of rear gas perforations for fracturing gas ejection along the axial direction, and the rear gas perforations are connected with the rear fracturing gas tube, the rear gas perforations and the rear liquid perforations are circumferentially staggered, and the rear fracturing gas tube is provided with a rear high-pressure tube capable of filling the fracturing gas into the rear fracturing gas tube;

[0010] The rear hole sealer is provided with a rear through hole extending forward and backward for the liquid fracturing medium to pass through. The rear hole sealer comprises a hole sealing connector, a rear hole sealing section and a rear connecting section which are arranged in sequence from front to back. A rear high-pressure capsule is fixedly sleeved on the outer side of the rear hole sealing section. A rear high-pressure pipe for expanding the rear high-pressure capsule is provided at the rear end of the rear high-pressure capsule. A rear threaded hole for connecting to the front end of the extended connecting pipe is provided at the rear end of the rear connecting section.

[0011] Further preferably, the front-end fracturing gas tube and the rear-end fracturing gas tube have the same structure, both comprising a gas collecting chamber for accommodating gaseous gas and a storage chamber for storing liquid gas arranged in front and back, the gas perforations are connected to the gas collecting chamber, the gas collecting chamber and the storage chamber are arranged in front and back and separated by an energy discharge plate, the storage chamber is spirally wound with a heating ring, and the heating ring is equipped with a heating wire; when the heating ring is heated, the gas in the liquid is heated to vaporize it into gas, thereby increasing the pressure in the storage chamber, and when the pressure reaches a certain value, it will break through the energy discharge plate to connect the gas collecting chamber and the storage chamber.

[0012] Further preferably, the depths of the front end fracturing groove and the rear end fracturing groove are both greater than the radius of the corresponding fracturing tube, the gas collecting chamber and the storage chamber are both mounted on the intermediate support tube, a fracturing through hole for liquid fracturing medium to pass through is provided in the intermediate support tube, and the front and rear ends of the intermediate support tube are connected to the front and rear ends of the corresponding fracturing tube by threads.

[0013] Further preferably, the front end fracturing tube, the extended connecting tube, the rear end fracturing tube and the rear hole sealer are provided with pipe notches for passing the end high-pressure pipe, each pipe notch is equipped with a corresponding sealing cover, sealing grooves are provided on both sides of each pipe notch, and sealing protrusions are provided at positions corresponding to the sealing protrusions on the sealing cover, and when the sealing protrusions are inserted into the sealing grooves, the sealing cover can be buckled on the notch of the pipe notch, thereby fixing the wires or pipes in the pipe notch.

[0014] Further preferably, the end sealing section and the subsequent sealing section are provided with annular grooves for conveniently corresponding to the capsule set.

[0015] More preferably, a reducer is provided for communicating with a liquid fracturing medium pipeline.

[0016] Further preferably, the portion of the plug extending into the corresponding hole is provided with an annular protrusion, and the liquid perforation and the front end liquid outlet are provided with annular grooves corresponding to the annular protrusions. When the annular protrusion is stuck in the annular groove, the plug is clamped in the corresponding hole.

[0017] Also disclosed is a gas-liquid combined fracturing method. Based on the above-mentioned fracturing device, gas-liquid combined fracturing can be performed. The gas-liquid combined fracturing includes gas fracturing and liquid fracturing, and includes the following steps:

[0018] S1: Drilling in the coal seam, constructing a borehole in the coal seam and flushing it;

[0019] S2: Assembling the fracturing device, connecting the end sealer, front end fracturing tube, extended connecting tube, rear end sealer, rear end fracturing tube, rear end sealer and extended connecting tube, and ensuring that there are sealers on the front and rear sides of the front end fracturing tube, and sealers on the front and rear sides of each rear end fracturing tube, and then installing plugs on the front end liquid perforation and the rear end liquid perforation, and at the same time, according to the depth of the borehole, increase or decrease the number of extended connecting tubes, so that the front end fracturing tube and the rear end fracturing tube are at the designed position in the borehole, and respectively connect the end high pressure tube and the rear end high pressure tube to the corresponding manual pressure pump, connect the front end high pressure tube and the rear end high pressure tube to the fracturing gas cylinder containing fracturing gas, and connect the rear end extended connecting tube to the liquid fracturing box with a high pressure pump through a reducer;

[0020] S3: Complete gas fracturing. First, use a manual pressure pump to fill the expansion medium into the end high-pressure capsule and the rear high-pressure capsule to expand them to complete the sealing, and then make the fracturing gas be ejected along the gas perforations to complete the fracturing;

[0021] S4: completing liquid fracturing, using staged fracturing during liquid fracturing, including the following steps:

[0022] S41: The first stage of fracturing, in which the fracturing liquid is delivered to the extended connecting pipe at the rear end by a pressure pump, so that the fracturing liquid reaches the front fracturing hole along the liquid fracturing medium pipeline, and finally is discharged along the front liquid outlet, and the gap caused by the fracturing gas discharged from the front fracturing pipe in S3 is fractured;

[0023] S42: Second stage fracturing: after the first stage fracturing is completed, the end high pressure capsule and the rear high pressure capsule are depressurized to release the sealing state, and then the rear end of the fracturing device is moved outward, and after removing part of the extended connecting pipe or the rear sealing device or the rear end fracturing pipe, the front end fracturing pipe is positioned at the position of the second stage fracturing in step S3, and the connection of each pipeline remains unchanged, and then the steps in step S41 are performed to complete the second stage fracturing;

[0024] S43: After fracturing is completed, step S42 is repeated to change the position of the front fracturing tube until the fracturing of all the fracturing sections is completed. After completion, the entire fracturing device is retracted.

[0025] Further preferably, the fracturing device is inserted into the borehole or taken out using a drilling rig or a pushing device.

[0026] The beneficial effects of the present invention are as follows: one device can realize gas fracturing and liquid fracturing at the same time, so that during fracturing, the advantages of gas fracturing and liquid fracturing can be effectively combined, so that the permeability enhancement effect of the fractured coal seam is good and the range is large; the device has a simple structure, convenient operation, low labor intensity, and a high degree of mechanization, and the device can be reused to achieve the purpose of less investment and good effect; by increasing or decreasing the number of lengthened connecting pipes, the device can be applicable to boreholes of various lengths. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the end hole sealer in the present invention.

[0028] Figure 2 It is a schematic diagram of the front end fracture tube in the present invention.

[0029] Figure 3 It is a schematic diagram of the lengthened connecting pipe in the present invention.

[0030] Figure 4 It is a schematic diagram of the rear end fracturing tube in the present invention.

[0031] Figure 5 It is a schematic diagram of the hole sealer in the present invention.

[0032] Figure 6 It is a schematic diagram of the plug in the present invention.

[0033] Figure 7 It is a schematic diagram of the sealing cover in the present invention.

[0034] Figure 8 It is a schematic diagram of the effect of the present invention during fracturing.

[0035] Fig. 9 It is a schematic diagram of the effect of the present invention at the front end of fracturing.

[0036] Fig.10 This is a schematic diagram of the installation of the present invention during mid-section fracturing.

[0037] Description of the accompanying drawings: 1-end sealer, 101-conical head, 102-end sealing section, 103-end connecting section, 104-end high-pressure capsule, 105-end high-pressure pipe, 106-end threaded hole, 2-front end fracturing pipe, 201-front end fracturing connector, 202-front end fracturing hole, 203-front end liquid outlet, 204-front end liquid perforation, 205-front end fracturing threaded hole, 206-front end fracturing gas pipe, 2 07-front fracturing groove, 208-front gas perforation, 209-front high-pressure pipe, 210-front gas collecting chamber, 211-front storage chamber, 212-front energy release plate, 213-front heating ring, 214-front heating wire, 215-front pipeline slot, 3-extended connecting pipe, 301-extended connector, 302-extended threaded hole, 303-extended through hole, 304-extended pipeline slot, 4-rear fracturing pipe, 401 -rear end fracturing connector, 402-rear end fracturing through hole, 403-rear end liquid perforation, 404-rear end fracturing threaded hole, 405-rear end fracturing gas pipe, 406-rear end fracturing groove, 407-rear end gas perforation, 408-rear end high pressure pipe, 409-rear end gas collecting chamber, 410-rear end storage chamber, 411-rear end energy release plate, 412-rear end heating ring, 413-rear end heating line, 414-rear end pipeline missing groove, 5-rear end Connect the hole sealer, 501-rear through hole, 502-hole sealing connector, 503-rear sealing section, 504-rear connecting section, 505-rear high-pressure capsule, 506-rear high-pressure pipe, 507-rear threaded hole, 508-pipeline through hole, 6-plug, 7-middle support cylinder, 8-reducing joint, 9-drilling, 10-manual pressure pump, 11-high-pressure pump, 12-liquid fracturing box, 13-pushing device, 14-heating controller. DETAILED DESCRIPTION

[0038] The present invention will be further described below by way of embodiments and in conjunction with the accompanying drawings:

[0039] like Figure 1-10 As shown, a gas-liquid combined fracturing device is mainly composed of an end sealer 1, a front end fracturing tube 2, an extended connecting tube 3, a rear end fracturing tube 4 and a rear end sealer 5, and the number of the end sealer 1 and the front end fracturing tube 2 is set to 1, but the extended connecting tube 3, the rear end fracturing tube 4 and the rear end sealer 5 are each provided with a plurality of tubes, wherein the front end fracturing tube 2, the extended connecting tube 3, the rear end fracturing tube 4 and the rear end sealer 5 are connected to each other by threads. To achieve sealing, an expandable high-pressure capsule is sleeved on the end sealer 1 and the rear end sealer 5. To achieve gas or liquid fracturing, a gas perforation for spraying gas fracturing medium and a liquid perforation for spraying liquid fracturing medium are provided on the front end fracturing tube 2 and the rear end fracturing tube 4. To achieve liquid fracturing, a front end liquid outlet 203 for liquid fracturing is provided on the front end fracturing tube 2.

[0040] The front liquid outlet 203 and all liquid perforations are equipped with corresponding plugs 6. When the gas fracturing medium is ejected from the gas perforations, it is a gas fracturing state. When the front liquid outlet 203 is blocked with the plug 6, the liquid fracturing medium is ejected from the liquid perforations, it is a liquid fracturing state. When the liquid perforations are blocked with the plug 6, the liquid fracturing medium flows out from the front liquid outlet 203, it is a liquid fracturing state.

[0041] The specific structure of the end sealer 1 includes a conical head 101, an end sealer section 102 and an end connection section 103 arranged in sequence from front to back, a end high pressure capsule 104 is fixedly sleeved on the outside of the end sealer section 102, a end high pressure tube 105 for expanding the end high pressure capsule 104 is arranged at the rear end of the end high pressure capsule 104, and an end threaded hole 106 for connecting with the front end of the front fracturing tube is arranged at the rear end of the end connection section 103. In order to reduce weight, the end sealer 1 can be set as a hollow structure.

[0042] A front end fracturing connector 201 with external threads for connecting to the rear end of the end plugging device 1 is provided at the front end of the front end fracturing tube 2, a front end fracturing hole 202 for liquid fracturing medium to pass through is provided on the front end fracturing tube 2, and a front end liquid outlet 203 communicating with the front end of the front end fracturing hole 202 is provided in the diameter direction at a position near the front end of the middle part of the front end fracturing tube 2. A row of front end liquid perforations 204 communicating with the front end fracturing hole 202 is provided in the middle part of the front end fracturing tube 2 along the axial direction, and a front end fracturing threaded hole 205 for connecting to the front end of the extended connecting tube 3 is provided at the rear end of the front end fracturing tube 2, and the front end fracturing hole 202 is communicated with the front end fracturing threaded hole 205. In order to realize the supply and injection of gas fracturing medium, a front fracturing groove 207 for inserting the front fracturing gas pipe 206 is also provided in the middle of the front fracturing pipe 2. Alternatively, the front fracturing pipe 2 may be composed of front and rear ends, and the front fracturing gas pipe 206 is directly provided between the front end and the rear end of the front fracturing pipe 2. A row of front gas perforations 208 for injecting fracturing gas is also provided in the middle of the front fracturing pipe along the axial direction, and the front gas perforations 208 are connected to the front fracturing gas pipe 206. Preferably, the front gas perforations 208 and the front liquid perforations 204 are circumferentially staggered, and the staggered angle is 90 degrees. At the same time, the front fracturing gas pipe 206 is provided with a front high pressure pipe 209 capable of filling the fracturing gas into the front fracturing gas pipe 206.

[0043] An extended connector 301 with external threads for connecting to the rear end of the front fracturing tube 2 is provided at the front end of the extended connecting tube 3, and an extended threaded hole 302 for connecting to the front end of the rear fracturing tube 4 is provided at the rear end of the extended connecting tube 3. At the same time, an extended through hole 303 for liquid fracturing medium to pass through is provided in the extended connecting tube 3.

[0044] A rear fracturing connector 401 with external threads for connecting to the rear end of the extended connecting pipe 3 is provided at the front end of the rear fracturing tube 4, a rear fracturing through hole 402 for liquid fracturing medium to pass through is provided on the rear fracturing tube 4, a row of rear liquid perforations 403 connected to the rear fracturing holes are provided in the middle of the rear fracturing tube 4 along the axial direction, and a rear fracturing threaded hole 404 for connecting to the front end of the rear plugging device 5 is provided at the rear end of the rear fracturing tube 4. In order to realize the supply and injection of fracturing gas, a rear fracturing groove 406 for the rear fracturing gas pipe 405 to be installed is also provided in the middle of the rear fracturing tube 4, and the rear fracturing tube 4 can also be composed of front and rear ends, and the front fracturing gas pipe 206 is directly provided between the front and rear ends of the rear fracturing tube 4. A row of rear gas perforations 407 for the emission of fracturing gas is arranged in the middle of the rear fracturing tube 4 along the axial direction, and the rear gas perforations 407 are connected to the rear fracturing gas tube 405. Preferably, the rear gas perforations 407 and the rear liquid perforations 403 are circumferentially staggered, and the staggered angle is 90 degrees. The rear fracturing gas tube 405 is equipped with a rear high pressure tube 408 capable of filling the rear fracturing gas into the rear fracturing gas tube 405.

[0045] A rear through hole 501 extending forward and backward for the liquid fracturing medium to pass through is arranged in the rear sealer 5. The specific structure of the rear sealer 5 includes a sealing connector 502, a rear sealing section 503 and a rear connecting section 504 which are arranged in sequence from front to back. A rear high-pressure capsule 505 is fixedly sleeved on the outer side of the rear sealing section 503. A rear high-pressure pipe 506 for expanding the rear high-pressure capsule 505 is provided at the rear end of the rear high-pressure capsule 505. A rear threaded hole 507 for connecting with the front end of the extended connecting pipe 3 is provided at the rear end of the rear connecting section 504.

[0046] The front-end fracturing gas pipe 206 and the rear-end fracturing gas pipe 405 have the same structure, both of which include a gas collecting chamber for accommodating gaseous gas and a storage chamber for storing liquid gas, and the gas perforation is connected to the gas collecting chamber. The gas collecting chamber and the storage chamber are arranged front and back and separated by an energy dissipation plate. A heating ring is spirally wound outside the storage chamber, and the heating ring is equipped with a heating wire. In specific use, liquid gas can be provided and stored in the storage chamber in advance. When the heating ring is heated, the gas in the liquid is heated to vaporize it into gas, thereby increasing the pressure in the storage chamber. When the pressure reaches a certain value, it will break through the energy dissipation plate and reach the gas collecting chamber, and then be ejected to the outside of the fracturing pipe along the gas perforation. The gas collecting chamber, storage chamber, energy dissipation plate, heating ring and heating wire on the front-end fracturing gas pipe 206 correspond to the front-end gas collecting chamber 210, the front-end storage chamber 211, the front-end energy dissipation plate 212, the front-end heating ring 213 and the front-end heating wire 214. The gas collecting chamber, storage chamber, energy dissipation plate, heating ring and heating wire on the rear fracturing gas pipe 405 correspond to the rear gas collecting chamber 409 , the rear storage chamber 410 , the rear energy dissipation plate 411 , the rear heating ring 412 and the rear heating wire 413 .

[0047] To facilitate installation, the depths of the front fracturing groove 207 and the rear fracturing groove 406 are both greater than the radius of the corresponding fracturing tube. At the same time, the gas collecting chamber and the storage chamber are both mounted on the middle support tube 7, and a fracturing through hole is provided in the middle support tube 7 for the liquid fracturing medium to pass through.

[0048] In order to facilitate the fixing of pipelines and wires, pipeline notches are provided on the front-end fracturing tube 2, the extended connecting tube 3 and the rear-end fracturing tube 4, and each pipeline notch is equipped with a corresponding sealing cover. In order to facilitate the fixing of the sealing cover on the pipeline notch, sealing grooves are provided on both sides of each pipeline notch, and sealing protrusions are provided at the corresponding positions on the sealing cover. When the sealing protrusions are inserted into the sealing grooves, the sealing cover can be buckled on the notch of the pipeline notch, thereby fixing the wire or pipeline in the pipeline notch. Grooves can also be provided on the sealing cover and the pipeline notch, and a sealing ring is provided between the two grooves. A pipeline through hole 508 for the front high-pressure pipe to pass through is provided on the rear-end sealing device 5. The pipeline notch on the front-end fracturing tube 2 corresponds to the front-end pipeline notch 215, the pipeline notch on the extended connecting tube 3 corresponds to the extended pipeline notch 304, and the pipeline notch on the rear-end fracturing tube 4 corresponds to the rear-end pipeline notch 414.

[0049] In order to facilitate the fixing of the capsule on the sealer, an annular groove is provided on the end sealing section 102 and the subsequent sealing section 503 for conveniently corresponding to the capsule set, and the capsule is just stuck in the annular groove.

[0050] In order to facilitate the connection of the device with a box containing liquid fracturing medium, a reducer 8 for communicating with a pipeline of the liquid fracturing medium is also provided.

[0051] In order to ensure the firmness of the installation of the plug and the sealing after the plug is installed, an annular protrusion 601 is provided on the part of the plug 6 extending into the corresponding hole, and an annular groove is provided corresponding to the annular protrusion 601 at the liquid perforation and the front liquid outlet. When the annular protrusion 601 is stuck in the annular groove, the plug 6 is clamped in the corresponding hole.

[0052] Based on the above-mentioned gas-liquid combined fracturing device, a gas-liquid combined fracturing method is also included, which specifically includes the following steps:

[0053] The first step is to drill a hole 9 in the coal seam, specifically to construct a hole 9 in the coal seam and flush it;

[0054] Step 2: assembling the fracturing device, connecting the end sealer 1, the front end fracturing tube 2, the extended connecting tube 3, the rear end fracturing tube 4 and the rear end sealer 5, and ensuring that there are sealers on the front and rear sides of the front end fracturing tube 2, and each rear end fracturing tube 4 has a sealer on the front and rear sides, and then installing plugs 6 on the front end liquid perforations 204 and the rear end liquid perforations 403. At the same time, according to the depth of the borehole 9, the number of extended connecting tubes 3 is increased or decreased, so that the front end fracturing tube 2 and the rear end fracturing tube 4 are at the designed positions in the borehole 9, and the end high-pressure pipe 105 and the rear end high-pressure pipe 506 are respectively connected to the corresponding manual pressure pump 10, the front end high-pressure pipe 209 and the rear end high-pressure pipe 408 are connected to the fracturing gas cylinder containing fracturing gas, and the rear end extended connecting pipe 3 is connected to the liquid fracturing box 12 with a high-pressure pump 11 through a reducer, and the heating line is electrically connected to the heating controller 14. In this embodiment, a three-stage fracturing is adopted, and the specific connection of the whole device is that the end sealer 1, the front end fracturing tube 2, the extended connecting tube 3, the rear sealer 5, the rear end fracturing tube 4, the extended connecting tube 3, the rear sealer 5, the extended connecting tube 3, the rear end fracturing tube 4, the rear end fracturing tube 4, the rear sealer 5 and the extended connecting tube 3 are connected in sequence, and the number of extended connecting tubes 3 is rotated according to the actual length.

[0055] Step 3: Complete gas fracturing. First, use the manual pressure pump 10 to fill the expansion medium into the end high-pressure capsule 104 and the rear high-pressure capsule 505 to make them expand and complete the sealing. Start the heating controller to heat and vaporize the liquid gas in the storage chamber to reach the gas collecting chamber, or use the pressure pump to transport the fracturing gas to the front fracturing tube 2 and the rear fracturing tube 4 respectively, so that the fracturing gas is ejected along the gas perforations to complete the fracturing.

[0056] Step 4: Complete liquid fracturing. Staged fracturing is used during liquid fracturing, which specifically includes the following steps:

[0057] 1. In the first stage of fracturing, the high-pressure pump 11 is used to deliver fracturing liquid to the rear-end extended connecting pipe 3, so that the fracturing liquid reaches the front fracturing hole 202 along the liquid fracturing medium pipeline, and is finally discharged along the front liquid outlet 203, thereby fracturing the gap caused by the fracturing gas discharged from the front fracturing pipe 2 in S3.

[0058] 2. Second stage fracturing: After the first stage fracturing is completed, the end high pressure capsule 104 and the rear high pressure capsule 505 are depressurized to release the sealing state, and then the rear end of the fracturing device is moved outward, and after removing part of the extended connecting pipe 3 or the rear sealer 5 or the rear end fracturing tube 4, the front end fracturing tube 2 is positioned at the position where the rear end fracturing tube 4 of the first stage is fractured in step S3, and then the steps in step S41 are performed to complete the second stage fracturing.

[0059] 3. After fracturing is completed, the above steps are repeated by changing the position of the front end fracturing tube 2 so that it is located in different sections until the fracturing of all the fracturing sections is completed. After completion, the entire fracturing device is retracted.

[0060] In this embodiment, the fracturing device is put in and taken out by a drill 27. Both the fracturing sealing capsule and the pressure fracturing sealing capsule 17 are equipped with a pressure sensor, and the pressure value in the pressure sensor is used to determine whether the sealing should be stopped.

Claims

1. A gas-liquid combined fracturing device, characterized in that: The invention comprises an end hole sealer (1), a front end fracturing tube (2), an extended connecting tube (3), a rear end fracturing tube (4) and a rear end hole sealer (5), wherein the front end fracturing tube (2), the extended connecting tube (3), the rear end fracturing tube (4) and the rear end hole sealer (5) are connected to each other via threads, the end hole sealer (1) and the rear end hole sealer (5) are both provided with an expandable high-pressure capsule, the front end fracturing tube (2) and the rear end fracturing tube (4) are both provided with gas perforations for spraying gas fracturing medium and liquid perforations for spraying liquid fracturing medium, and the front end fracturing tube (2) is provided with a front end liquid outlet (203) for liquid fracturing; The liquid perforation and the front liquid outlet (203) are both equipped with corresponding plugs (6). When the gas fracturing medium is ejected from the gas perforation, it is a gas fracturing state. When the front liquid outlet (203) is blocked by the plug (6), the liquid fracturing medium is ejected from the liquid perforation. It is a liquid fracturing state. When the liquid perforation is blocked by the plug (6), the liquid fracturing medium flows out from the front liquid outlet (203). It is a liquid fracturing state. The end hole sealer (1) comprises a conical head (101), an end hole sealing section (102) and an end connecting section (103) which are arranged in sequence from front to back; a high-pressure capsule (104) is fixedly sleeved on the outside of the end hole sealing section (102); a high-pressure tube (105) for expanding the high-pressure capsule (104) is provided at the rear end of the end hole sealing section (102); and a threaded hole (106) for connecting to the front end of the front fracturing tube is provided at the rear end of the end hole sealing section (103); The front end of the front fracturing tube (2) is provided with a front fracturing connector (201) with external threads for connecting to the rear end of the end sealer (1); the front fracturing tube (2) is provided with a front fracturing hole (202) for liquid fracturing medium to pass through; a front liquid outlet (203) communicating with the front end of the front fracturing hole (202) is provided in the diameter direction at a position close to the front end of the middle part of the front fracturing tube (2); a row of front liquid perforations (204) communicating with the front fracturing hole (202) is provided in the middle part of the front fracturing tube (2) along the axial direction; and a front fracturing threaded hole for connecting to the front end of the extended connecting tube (3) is provided at the rear end of the front fracturing tube (2). (205), and the front-end fracturing hole (202) is connected to the front-end fracturing threaded hole (205), the middle part of the front-end fracturing tube (2) is also provided with a front-end fracturing groove (207) for the front-end fracturing gas tube (206) to be installed, the middle part of the front-end fracturing tube is also provided with a row of front-end gas perforations (208) for the fracturing gas to be ejected along the axial direction, and the front-end gas perforations (208) are connected to the front-end fracturing gas tube (206), the front-end gas perforations (208) and the front-end liquid perforations (204) are circumferentially staggered, and the front-end fracturing gas tube (206) is equipped with a front-end high-pressure tube (209) capable of filling the fracturing gas into the front-end fracturing gas tube (206); The front end of the extended connecting pipe (3) is provided with an extended connecting head (301) with external threads for connecting to the rear end of the front fracturing pipe (2); the rear end of the extended connecting pipe (3) is provided with an extended threaded hole (302) for connecting to the front end of the rear fracturing pipe (4); and the extended connecting pipe (3) is provided with an extended through hole (303) for the liquid fracturing medium to pass through. The front end of the rear fracturing tube (4) is provided with a rear fracturing connector (401) with external threads for connecting to the rear end of the extended connecting tube (3); the rear fracturing tube (4) is provided with a rear fracturing through hole (402) for the liquid fracturing medium to pass through; a row of rear liquid perforations (403) communicating with the rear fracturing holes are provided in the middle of the rear fracturing tube (4) along the axial direction; the rear end of the rear fracturing tube (4) is provided with a rear fracturing threaded hole (404) for connecting to the front end of the rear hole sealer (5); the middle of the rear fracturing tube (4) is provided with a rear fracturing through hole (402) for the liquid fracturing medium to pass through; The rear end of the fracturing tube (405) is provided with a rear end fracturing groove (406) for the rear end fracturing gas pipe (405) to be installed, and the middle part of the rear end fracturing tube (4) is provided with a row of rear end gas perforations (407) for the fracturing gas to be ejected along the axial direction, and the rear end gas perforations (407) are connected to the rear end fracturing gas tube (405), and the rear end gas perforations (407) and the rear end liquid perforations (403) are arranged in an annular staggered manner, and the rear end fracturing gas tube (405) is equipped with a rear end high pressure tube (408) capable of filling the fracturing gas into the rear end fracturing gas tube (405); The rear hole sealer (5) is provided with a rear hole (501) extending forward and backward and allowing a liquid fracturing medium to pass therethrough. The rear hole sealer (5) comprises a hole sealing connector (502), a rear hole sealing section (503) and a rear connecting section (504) which are arranged in sequence from front to back. A rear high-pressure capsule (505) is fixedly sleeved on the outside of the rear hole sealing section (503). A rear high-pressure tube (506) for expanding the rear high-pressure capsule (505) is provided at the rear end of the rear high-pressure capsule (505). A rear threaded hole (507) for connecting to the front end of the extended connecting tube (3) is provided at the rear end of the rear connecting section (504).

2. The gas-liquid combined fracturing device according to claim 1, characterized in that: The front-end fracturing gas tube (206) and the rear-end fracturing gas tube (405) have the same structure, both comprising a gas collecting chamber for accommodating gaseous gas and a storage chamber for storing liquid gas, arranged in front and back, the gas perforations communicating with the gas collecting chamber, the gas collecting chamber and the storage chamber arranged in front and back and separated by an energy dissipation plate, the storage chamber being spirally wound with a heating ring, the heating ring being provided with a heating wire; when the heating ring is heated, the gas in the liquid is heated to vaporize it into gas, thereby increasing the pressure in the storage chamber, and when the pressure reaches a certain value, it breaks through the energy dissipation plate and reaches the gas collecting chamber, and then is ejected out of the fracturing tube along the gas perforations.

3. The gas-liquid combined fracturing device according to claim 2, characterized in that: The depths of the front fracturing groove (207) and the rear fracturing groove (406) are both greater than the radius of the corresponding fracturing tube; the gas collecting chamber and the storage chamber are both mounted on the middle support tube (7); and a fracturing through hole for liquid fracturing medium to pass through is provided in the middle support tube (7).

4. The gas-liquid combined fracturing device according to claim 1 or 2, characterized in that: The front end fracture tube (2), the extended connection tube (3) and the rear end fracture tube (4) are provided with a pipeline notch for the front side high pressure tube to pass through, each pipeline notch is equipped with a corresponding sealing cover, and sealing grooves are provided on both sides of each pipeline notch, and a sealing protrusion is provided at a position corresponding to the sealing protrusion. When the sealing protrusion is inserted into the sealing groove, the sealing cover can be buckled on the notch of the pipeline notch, thereby fixing the wire or pipeline in the pipeline notch, and the rear end sealing device (5) is provided with a pipeline through hole (508) for the front side high pressure tube to pass through.

5. The gas-liquid combined fracturing device according to claim 1 or 2, characterized in that: The end sealing section (102) and the rear sealing section (503) are both provided with an annular groove for conveniently corresponding to the capsule set.

6. The gas-liquid combined fracturing device according to claim 1 or 2, characterized in that: It is also equipped with a reducer (8) for communicating with a liquid fracturing medium pipeline.

7. The gas-liquid combined fracturing device according to claim 1 or 2, characterized in that: The portion of the plug (6) extending into the corresponding hole is provided with an annular protrusion (601), and the liquid perforation and the front end liquid outlet are provided with an annular groove corresponding to the annular protrusion (601); when the annular protrusion (601) is stuck in the annular groove, the plug (6) is clamped in the corresponding hole.

8. A gas-liquid combined fracturing method, characterized in that: The fracturing device according to any one of claims 1 to 7 can perform gas-liquid combined fracturing, wherein the gas-liquid combined fracturing includes gas fracturing and liquid fracturing, and includes the following steps: S1: drilling a hole (9) in the coal seam, constructing a hole (9) in the coal seam, and flushing the hole; S2: Assembling the fracturing device, connecting the end hole sealer (1), the front end fracturing tube (2), the extended connecting tube (3), the rear end fracturing tube (4) and the rear end hole sealer (5), and ensuring that the front and rear sides of the front end fracturing tube (2) have hole sealers, and the front and rear sides of each rear end fracturing tube (4) have hole sealers, and then installing plugs (6) on the front end liquid perforation (204) and the rear end liquid perforation (403), and at the same time, increasing or decreasing the length of the extended connecting tube (403) according to the depth of the drilling hole (9). 3), so that the front end fracturing tube (2) and the rear end fracturing tube (4) are at the designed positions in the borehole (9), and the end high pressure tube (105) and the rear end high pressure tube (506) are respectively connected to the corresponding manual pressure pump (10), the front end high pressure tube (209) and the rear end high pressure tube (408) are connected to the fracturing gas cylinder containing the fracturing gas, and the rear end extended connecting tube (3) is connected to the liquid fracturing box (12) with the high pressure pump (11) through a reducer; S3: gas fracturing is completed by first using a manual pressure pump (10) to fill an expansion medium into the end high pressure capsule (104) and the rear high pressure capsule (505) to expand them to complete the hole sealing, and then the fracturing gas is ejected along the gas perforations to complete the fracturing; S4: completing liquid fracturing, using staged fracturing during liquid fracturing, including the following steps: S41: the first stage of fracturing, in which a fracturing liquid is delivered to the rear extended connecting pipe (3) through a high-pressure pump (11), so that the fracturing liquid reaches the front fracturing hole (202) along the liquid fracturing medium pipeline, and finally is discharged along the front liquid outlet (203), thereby fracturing the gap caused by the fracturing gas discharged from the front fracturing pipe (2) in S3; S42: second stage fracturing. After the first stage fracturing is completed, the end high pressure capsule (104) and the rear high pressure capsule (505) are depressurized to release the sealing state. Then, the rear end of the fracturing device is moved outward, and after removing part of the extended connecting pipe (3) or the rear sealing device (5) or the rear fracturing pipe (4), the front end fracturing pipe (2) is positioned at the position of the second stage fracturing in step S3. Then, the steps in step S41 are performed to complete the second stage fracturing. S43: After the fracturing is completed, step S42 is repeated to change the position of the front fracturing tube (2) until the fracturing of all the fracturing sections is completed. After completion, the entire fracturing device is retracted.

9. The gas-liquid combined fracturing method according to claim 8, characterized in that: The fracturing device is inserted into a borehole or removed using a drilling machine or a pushing device (13).

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