A quantitative delivery tool and method for a combustion-supporting agent in in-situ combustion explosion fracturing of methane

Abstract

A quantitative delivery tool and method for a combustion-supporting agent for in-situ combustion and explosion fracturing of methane. The delivery tool includes an inner cylinder, a piston B, and an outer cylinder. A gas inlet pipe B is fixedly connected to the center of the upper end of the inner cylinder, and its bottom has an inner cylinder bottom plate. A spray hole is formed in the central area of the inner cylinder bottom plate, and a constant-pressure plug is installed in the spray hole. The piston B is assembled inside the inner cylinder. A plurality of perforations B are formed in the barrel wall of the outer cylinder, and its bottom has an outer cylinder bottom plate. The outer cylinder is coaxially sleeved outside the inner cylinder, and its upper end is fixedly connected to the upper end of the inner cylinder. The method includes installing a bridge plug in the wellbore; lowering the delivery tool to the position of the reservoir through the wellbore by using a coiled tubing; forming a sealed delivery section at the position of the delivery tool by using a packer and a bridge plug; and moving the piston downward until the combustion-supporting agent is completely filled into the sealed delivery section. This tool and method can conveniently perform quantitative delivery operations on the pre-stored combustion-supporting agent at a specific position.

Description

Technical Field

[0001] The present invention belongs to the technical field of unconventional natural gas reservoir transformation and exploitation, and particularly relates to a tool and method for quantitatively injecting a combustion promoter for in-situ methane combustion fracturing. Background Art

[0002] The reserves of unconventional natural gas in China are huge. As a clean energy source, natural gas is expected to become an important energy source to replace coal in the future. However, due to the insufficient permeability of its reservoir, the mining difficulty is very high and the mining efficiency is very low. In order to ensure the mining efficiency, it is usually necessary to carry out fracturing transformation and permeability enhancement operations. At present, the main fracturing method is hydraulic fracturing, but the hydraulic fracturing technology has many problems such as difficult liquid drainage, water resource waste, and large environmental pollution.

[0003] In order to improve the fracturing effect of unconventional natural gas reservoirs and, at the same time, to avoid various problems existing in hydraulic fracturing, some scholars have proposed a technology of in-situ methane combustion fracturing in reservoirs. This technology uses reservoir methane as fuel, forms a methane-combustion promoter mixed gas at the bottom of the well or in the reservoir by artificially injecting the combustion promoter, and then generates an instantaneous combustion explosion high pressure by detonating the methane-combustion promoter mixed gas, fractures the reservoir to form impact fractures, thereby forming a complex three-dimensional fracture network, and finally realizes the production increase and permeability enhancement of unconventional natural gas reservoirs. Compared with the conventional hydraulic fracturing technology, the in-situ methane combustion fracturing technology can generate a greater fracturing pressure, does not have the problem of water resource waste, and can effectively solve problems such as environmental pollution, thus realizing the so-called "local material utilization" in a true sense.

[0004] However, since the diameter of the conventional fracturing wellbore is only about 120 mm and the bottom-hole space is relatively narrow, and for special working conditions, the depth of the methane reservoir can reach several hundred meters or even thousands of meters. Therefore, it is difficult to accurately inject the combustion promoter quantitatively, centrally or evenly in the complex underground space, and realizing the safe injection of the combustion promoter in the deep and narrow space is the key technical problem that this technology needs to solve. At the same time, for the long-distance transportation of the combustion promoter during continuous injection, there are relatively large potential safety hazards. Therefore, there is an urgent need to provide a tool and method for quantitatively injecting a combustion promoter for in-situ methane combustion fracturing to solve problems such as difficult injection, inaccurate and uneven injection of the combustion promoter caused by the narrow and deep underground space. Summary of the Invention

[0005] Aiming at the problems existing in the above-mentioned prior art, the present invention provides a quantitative delivery tool and method for a combustion-supporting agent for in-situ methane combustion explosion fracturing. The tool has a simple structure and high reliability. It can realize the pre-storage of the quantitative combustion-supporting agent and can conveniently carry out the quantitative delivery operation of the pre-stored combustion-supporting agent at a specific position by means of gas injection. The implementation steps of the method are simple. It adopts the pre-charging and delivery method, which can meet the delivery requirements of the combustion-supporting agent in different complex environments, and can deliver the combustion-supporting agent quantitatively, directionally and centrally according to the size of the underground space and the delivery distance.

[0006] To achieve the above-mentioned invention purpose, the present invention provides a quantitative delivery tool for a combustion-supporting agent for in-situ methane combustion explosion fracturing. The delivery tool is a delivery body A, and the delivery body A includes a gas storage cylinder, a piston A, a barrier slide plate, a telescopic sleeve rod and a limit block;

[0007] The upper end of the gas storage cylinder is open, and an air inlet pipeline A is fixedly connected to the central area of the upper end; the lower end of the gas storage cylinder is fixedly connected with a barrier block, and two injection holes A are opened on the upper end of the barrier block on opposite sides; two arc-shaped grooves are opened on the upper part of the barrier block on opposite sides, and the outer edge surfaces of the two arc-shaped grooves are respectively fitted with the inner side walls of the opposite sides of the gas storage cylinder;

[0008] The outer diameter of the piston A is adapted to the inner diameter of the gas storage cylinder. The piston A is slidably and sealingly assembled inside the gas storage cylinder, and a gas storage space A is formed between the piston A and the barrier block;

[0009] Two barrier slide plates are respectively adapted to the two arc-shaped grooves, and a pair of holes are opened opposite to each other; the two barrier slide plates are respectively vertically slidably assembled in the two arc-shaped grooves, and the outer arc surfaces of the two barrier slide plates are slidably and sealingly fitted with the inner side walls of the opposite sides of the gas storage cylinder; when the two barrier slide plates are completely embedded in the two arc-shaped grooves, the upper ends of the two barrier slide plates are located above the two injection holes A, and the two holes on the two barrier slide plates are respectively aligned with the two injection holes A;

[0010] Two telescopic sleeve rods are vertically distributed above the two barrier slide plates. The lower ends of the telescopic sections are respectively fixedly connected to the centers of the upper ends of the two barrier slide plates, and the fixed sections are respectively fixedly inserted into the opposite sides of the lower part of the piston A;

[0011] Two limit blocks are relatively distributed above the two arc-shaped grooves and are respectively fixedly connected to the opposite sides of the inner side wall of the gas storage cylinder; the lower ends of the two limit blocks are respectively in abutting fit with the upper ends of the two barrier slide plates. When the upper ends of the two barrier slide plates are in abutting contact with the lower ends of the two limit blocks, the lower ends of the two barrier slide plates are located below the two injection holes A.

[0012] As a preference, the lower end of the intake air pipeline A is fixedly connected to the upper end of the air storage cylinder through an annular connecting plate A. The annular connecting plate A can also be used to limit the maximum upward stroke of the piston A, so as to avoid the situation that the piston A slips out of the air storage cylinder.

[0013] In the present invention, two arc-shaped grooves are formed on the upper part of the opposite sides of the barrier block at the lower end of the air storage cylinder, and two barrier sliding plates are slidably assembled in the two arc-shaped grooves. At the same time, two injection holes A are formed in the air storage cylinder, and two holes are correspondingly formed in the two barrier sliding plates. In this way, the blocking operation or the opening operation of the two injection holes A can be realized by changing the height of the two barrier sliding plates in the two arc-shaped grooves. When the two injection holes A are in the blocked state, the sealing state of the air storage space A can be ensured, and thus the pre-storage operation of the combustion improver can be realized. When the two injection holes A are in the open state, it is beneficial for the pre-stored combustion improver in the air storage space A to be quickly discharged out through the injection holes A. The piston A slidably sealed in the air storage cylinder is connected to the upper ends of the two barrier sliding plates through two telescopic rods. At the same time, the upward maximum stroke of the two barrier sliding plates is limited by two limiting blocks fixed on the inner side wall of the air storage cylinder, so that the movement process of the piston A can be associated with the blocking action and the opening action of the two barrier sliding plates. In this way, during the process of filling the combustion improver, the piston A far from the barrier block can drive the two telescopic sleeve rods to reach the extended state, and can drive the two barrier sliding plates to reach the state of abutting against the two limiting blocks. In this way, the two holes and the two injection holes A can be in a staggered state, and at the same time, the sealing state of the air storage space A can be ensured by the fitting of the two barrier sliding plates with the inner side wall of the air storage cylinder. At the same time, during the compression process of the piston A, the piston A can be used to compress the two telescopic sleeve rods to reach the contracted state, and at the same time, push the two barrier sliding plates to be completely embedded in the two arc-shaped chutes. In this way, the two holes can be aligned and communicated with the two injection holes A, and further the air storage space A can be communicated with the outside through the injection holes A. This tool has a simple structure and high reliability. It can realize the pre-storage of a quantitative combustion improver, and can conveniently carry out the quantitative feeding operation of the pre-stored combustion improver at a specific position by means of gas injection.

[0014] The present invention also provides a quantitative multi-hole feeding tool for the in-situ combustion explosion fracturing combustion improver of methane. The feeding tool is a feeding body B, and the feeding body B includes an inner cylinder, a piston B and an outer cylinder;

[0015] The upper end of the inner cylinder is open, and an intake air pipeline B is fixedly connected to the center of the upper end. Its bottom has an inner cylinder bottom plate. A spray hole is formed in the central area of the inner cylinder bottom plate, and a constant pressure plug is installed in the spray hole;

[0016] The outer diameter of the piston B is adapted to the inner diameter of the inner cylinder body. The piston B is assembled inside the inner cylinder body in a sliding and sealing fit manner, and an air storage space B is formed between the piston B and the inner cylinder bottom plate.

[0017] The upper end of the outer cylinder body is an open structure, and a plurality of perforations B are provided on its cylinder body, and its bottom has an outer cylinder bottom plate. The outer cylinder body is coaxially sleeved outside the inner cylinder body, and its upper end is fixedly connected to the upper end of the inner cylinder body through an annular connecting plate B. At the same time, an annular cavity is formed between the inner cylinder body and the outer cylinder body.

[0018] As a preference, the cross-section of the outer cylinder bottom plate is in the shape of an inverted truncated cone. In this way, it can play a role in rapid diversion, which is beneficial for the combustion-supporting agent discharged from the injection holes to quickly reach the perforations B, and is beneficial for quickly completing the delivery operation.

[0019] Furthermore, in order to effectively expand the delivery range of the combustion-supporting agent, a plurality of perforations B are evenly divided into four groups from top to bottom, and each group is composed of four perforations B circumferentially and evenly distributed on the same plane.

[0020] In the present invention, the outer cylinder body is coaxially sleeved outside the inner cylinder body. At the same time, the upper end of the outer cylinder body is fixedly connected to the upper end of the inner cylinder body through the annular connecting plate B, so that an annular cavity can be formed between the inner cylinder body and the outer cylinder body. The piston B is assembled in the inner cylinder body in a sliding and sealing manner, so that a sealed air storage space B can be formed between the piston B and the inner cylinder body, which is beneficial for the pre-storage operation of the quantitative combustion-supporting agent. A spray hole is opened on the inner cylinder bottom plate, and a constant-pressure plug is installed in the spray hole, which can facilitate ensuring the airtightness of the air storage space B under normal conditions. At the same time, after the pressure in the air storage space B reaches the opening pressure of the constant-pressure plug, the air storage space B can be quickly communicated with the annular cavity. A plurality of perforations B are provided on the cylinder body of the outer cylinder body, which can effectively communicate the annular cavity with the external space. Furthermore, after the air storage space B is communicated with the annular cavity, the combustion-supporting agent can be quickly ejected through the spray hole, the annular cavity and the perforations B and reach the predetermined delivery position. This tool has a simple structure and high reliability. It can realize the pre-storage of the quantitative combustion-supporting agent and can conveniently perform the quantitative delivery operation of the pre-stored combustion-supporting agent at a specific position by means of gas injection.

[0021] The present invention also provides a method for quantitatively delivering a combustion-supporting agent for in-situ methane combustion explosion fracturing, using a tool for quantitatively delivering a combustion-supporting agent for in-situ methane combustion explosion fracturing or using a tool for quantitatively and multi-porously delivering a combustion-supporting agent for in-situ methane combustion explosion fracturing, including the following steps:

[0022] Step 1: According to the amount of the combustion-supporting agent required by the reservoir, fill the required amount of the combustion-supporting agent into the delivery tool;

[0023] Step 2: Arrange a fracturing truck on one side of the wellbore where the fracturing operation is to be preformed on the ground. At the same time, prepare a coiled tubing, and sleeve a packer outside the lower end of the coiled tubing;

[0024] Step 3: Install a bridge plug in the wellbore and set the bridge plug below the reservoir.

[0025] Step 4: Connect the lower end of the coiled tubing to the feed pipeline on the placement tool, lower the placement tool to the location of the reservoir through the wellbore using the coiled tubing, and then connect the upper end of the coiled tubing to the output pipeline of the fracturing truck.

[0026] Step 5: Pump nitrogen into the coiled tubing through the fracturing truck, use the high-pressure nitrogen to set the packer, and form a sealed placement section at the location of the placement tool using the packer and the bridge plug.

[0027] Step 6: Continuously pump high-pressure nitrogen into the coiled tubing through the fracturing truck, use the nitrogen with increasing pressure to act on the upper end face of the piston in the placement tool, move the piston in the placement tool downward until the combustion promoter in the gas storage space is completely filled into the sealed placement section through the perforations, and the quantitative placement operation of the combustion promoter can be completed.

[0028] As an optimization, in Step 1, when the placement tool is Placement Body A, the combustion promoter is filled into the gas storage space A; when the placement tool is Placement Body B, the combustion promoter is filled into the gas storage space B.

[0029] As an optimization, in Step 6, when the placement tool is Placement Body A, under the action of the nitrogen with increasing pressure, piston A moves downward, and the lengths of the two telescopic sleeve rods contract. At the same time, the two barrier slides are pushed by the two telescopic sleeve rods to slide towards the bottoms of the two arc-shaped grooves. When the two barrier slides are completely embedded in the two arc-shaped grooves, the two holes on the two barrier slides are respectively aligned and communicated with the two perforations A. The combustion promoter in the gas storage space A sprays out at high speed through the communicated holes and the perforations A, and is fully mixed with the in-situ methane in the reservoir space.

[0030] When the placement tool is Placement Body B, under the action of the nitrogen with increasing pressure, piston B moves downward. The compression of the downward-moving piston B causes the pressure in the gas storage space B to continuously increase. When the pressure in the gas storage space B reaches the opening pressure of the pressure-fixed plug, the pressure-fixed plug is pressed out of the spray hole. The combustion promoter in the gas storage space B sprays out at high speed through the spray hole, the annular cavity, and the perforation B in sequence, and is fully mixed with the in-situ methane in the reservoir space.

[0031] In the present invention, pre-storing the required amount of combustion improver in the delivery tool can avoid the process of transporting the combustion improver along the way, and the combustion improver can be delivered after the delivery tool reaches the predetermined position. Connecting the intake pipeline of the delivery tool to the fracturing truck using coiled tubing can facilitate lowering the delivery tool to the target reservoir position using the coiled tubing. Installing a bridge plug at the position below the reservoir in the wellbore. At the same time, a packer is sleeved outside the coiled tubing, so that after the delivery tool is lowered to the predetermined position, a sealed delivery section can be formed at the position where the delivery tool is located using the packer and the bridge plug. Using high-pressure nitrogen pumped in to push the piston B to move downward, the pressurization operation of the combustion improver in the gas storage space B can be realized. During the pressurization process, the constant pressure plug can be automatically pressed out of the spray hole, so that the spray hole and the annular cavity can be quickly connected. Thus, the pre-stored combustion improver can be quickly delivered into the sealed delivery section. In this way, it can ensure that the combustion improver is delivered into the bottom closed space, and the methane in the gas storage can be fully mixed with the combustion improver under closed conditions, ensuring that the methane combustion explosion fracturing is carried out in the closed section of the wellbore.

[0032] The implementation steps of this method are simple. It adopts the pre-charging and delivery method, which helps to realize the efficient combination of conventional staged fracturing technology and pre-charging and quantitative delivery technology. It can meet the requirements of delivering combustion improver under different complex environments. The combustion improver can be delivered directionally, quantitatively and concentratedly according to the size of the underground space and the delivery distance. In addition, it can also meet the requirement of evenly delivering the combustion improver in deep and narrow spaces, enabling the combustion improver to be more fully mixed with the in-situ methane in the underground reservoir space. It can also prevent the impact of the instantaneous high pressure generated by the explosion of the methane-combustion improver mixed gas on the surface equipment, ensuring the safety of delivering the combustion improver for in-situ methane combustion explosion fracturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a three-dimensional structure diagram of the first embodiment of the delivery tool in the present invention;

[0034] Figure 2 is Figure 1 the longitudinal sectional view of

[0035] Figure 3 is a three-dimensional structure diagram of the second embodiment of the delivery tool in the present invention;

[0036] Figure 4 is Figure 3 the longitudinal sectional view of

[0037] Figure 5 is Figure 3 the half-sectional view of

[0038] Figure 6 is a schematic diagram of the state of delivering the combustion improver using the delivery tool in the first embodiment of the present invention;

[0039] Figure 7 It is a schematic diagram of the state of the combustion improver injection using the injection tool in the second embodiment of the present invention.

[0040] In the figure: 1. Piston A, 2. Inner cylinder, 3. Gas storage cylinder, 4. Combustion improver, 5. Inlet gas pipeline A, 6. Coiled tubing, 7. Spray hole, 8. Constant pressure plug, 9. Annular connecting plate A, 10. Blocking block, 11. Annular cavity, 12. Perforation A, 13. Fracturing truck, 14. Nitrogen, 15. Wellbore, 16. Reservoir, 17. Telescopic sleeve rod, 18. Limit block, 19. Hole, 20. Blocking slide plate, 21. Arc-shaped groove, 22. Injection tool, 23. Outer cylinder, 24. Piston B, 25. Inlet gas pipeline B, 26. Inner cylinder bottom plate, 27. Perforation B, 28. Outer cylinder bottom plate, 29. Annular connecting plate B, 30. Bridge plug, 31. Packer. Detailed implementation mode

[0041] The present invention will be further described below with reference to the accompanying drawings.

[0042] As Figure 1 and Figure 2 shown, the present invention provides a quantitative injection tool for the in-situ combustion explosion fracturing combustion improver. The injection tool 22 is injection body A, and the injection body A includes a gas storage cylinder 3, a piston A 1, a blocking slide plate 20, a telescopic sleeve rod 17 and a limit block 18;

[0043] The upper end of the gas storage cylinder 3 is open, and an inlet gas pipeline A 5 is fixedly connected to the central area of the upper end; the lower end of the gas storage cylinder 3 is fixedly connected with a blocking block 10, and two perforations A 12 are opened on the upper end of the blocking block 10 on opposite sides; two arc-shaped grooves 21 are opened on the upper part of the blocking block 10 on opposite sides, and the outer edge surfaces of the two arc-shaped grooves 21 are respectively attached to the inner side walls of the opposite sides of the gas storage cylinder 3;

[0044] The outer diameter of the piston A 1 is adapted to the inner diameter of the gas storage cylinder 3, and the piston A 1 is slidably and sealingly assembled inside the gas storage cylinder 3, and a gas storage space A is formed between the piston A 1 and the blocking block 10; the gas storage space A is used to store the combustion improver 4;

[0045] Two blocking slide plates 20 are respectively adapted to the two arc-shaped grooves 21, and a pair of holes 19 are opened opposite to each other; the two blocking slide plates 20 are respectively vertically slidably assembled in the two arc-shaped grooves 21, and the outer arc surfaces of the two blocking slide plates 20 and the inner side walls of the opposite sides of the gas storage cylinder 3 are in sliding sealing fit; when the two blocking slide plates 20 are completely embedded in the two arc-shaped grooves 21, the upper ends of the two blocking slide plates 20 are located above the two perforations A 12, and the two holes 19 on the two blocking slide plates 20 are respectively aligned with the two perforations A 12;

[0046] Two telescopic rods 17 are vertically distributed above the two barrier slides 20. The lower ends of their telescopic sections are respectively fixedly connected to the centers of the upper ends of the two barrier slides 20, and their fixed sections are respectively fixedly inserted on the opposite sides of the lower part of the piston A1. As a preference, the fixed sections of the telescopic rods 17 are completely inserted into the interior of the piston A1. At the same time, the telescopic sections of the telescopic rods 17 can be completely retracted into the fixed sections. In this way, it can ensure that the displacement of the piston A1 moving downward is the largest. In this way, it can ensure that the combustion improver 4 in the gas storage space A is discharged as completely as possible.

[0047] Two limit blocks 18 are relatively distributed above the two arc-shaped grooves 21 and are respectively fixedly connected to the opposite sides of the inner side wall of the air storage cylinder 3. The lower ends of the two limit blocks 18 are respectively abutted and matched with the upper ends of the two barrier slides 20. When the upper ends of the two barrier slides 20 are abutted against the lower ends of the two limit blocks 18, the lower ends of the two barrier slides 20 are located below the two injection holes A12.

[0048] As a preference, the lower end of the air inlet pipeline A5 is fixedly connected to the upper end of the air storage cylinder 3 through an annular connecting plate A9. The annular connecting plate A can also be used to limit the maximum upward stroke of the piston A, so as to avoid the situation that the piston A slips out of the air storage cylinder. Among them, the annular connecting plate A9 is hermetically connected to both the air inlet pipeline A5 and the upper end of the air storage cylinder 3 to maintain the airtightness at the connection position.

[0049] As a preference, a one-way intake valve communicating with the gas storage space A is connected to the barrier block 10. In this way, the combustion improver 4 can be conveniently filled into the gas storage space A through the one-way intake valve. During the process of filling the combustion improver 4, the piston A1 is pushed to the maximum upward displacement. At this time, the two limit blocks 18 are abutted against the upper ends of the two barrier slides 20 to realize the upward limit of the two barrier slides 20. At the same time, the two telescopic rods 17 reach the maximum extension state. In this state, the two holes 19 on the two barrier slides 20 are misaligned with the two injection holes A12, and the gas storage air A forms a closed space.

[0050] In the present invention, on the upper part of the barrier block at the lower end of the air storage cylinder, two arc-shaped grooves are provided on opposite sides, and two barrier sliding plates are slidably assembled in the two arc-shaped grooves. At the same time, two injection holes A are provided on the air storage cylinder, and two holes are correspondingly provided on the two barrier sliding plates. In this way, the blocking operation or the opening operation of the two injection holes A can be realized by changing the height of the two barrier sliding plates in the two arc-shaped grooves. When the two injection holes A are in the blocked state, the sealing state of the air storage space A can be ensured, and thus the pre-storage operation of the combustion-supporting agent can be realized. When the two injection holes A are in the open state, it is beneficial for the pre-stored combustion-supporting agent in the air storage space A to be quickly discharged through the injection holes A. The piston A slidably and sealingly assembled in the air storage cylinder is connected to the upper ends of the two barrier sliding plates through two telescopic rods. At the same time, the upward maximum stroke of the two barrier sliding plates is limited by two limit blocks fixed on the inner side wall of the air storage cylinder, so that the movement process of the piston A can be associated with the blocking action and the opening action of the two barrier sliding plates. In this way, during the process of filling the combustion-supporting agent, the piston A far from the barrier block can drive the two telescopic sleeve rods to reach the extended state, and can drive the two barrier sliding plates to reach the state of abutting against the two limit blocks. In this way, the two holes and the two injection holes A can be in a staggered state, and at the same time, the sealing state of the air storage space A can be ensured by the fitting of the two barrier sliding plates and the inner side wall of the air storage cylinder. At the same time, during the compression process of the piston A, the piston A can compress the two telescopic sleeve rods to reach the contracted state, and at the same time, push the two barrier sliding plates to be completely embedded in the two arc-shaped chutes. In this way, the two holes can be aligned and communicated with the two injection holes A, and thus the air storage space A can be communicated with the outside through the injection holes A. This tool has a simple structure and high reliability. It can realize the pre-storage of a quantitative combustion-supporting agent, and can conveniently carry out the quantitative feeding operation of the pre-stored combustion-supporting agent at a specific position by means of gas injection.

[0051] As Figures 3 to 5 shown, the present invention also provides a methane in-situ combustion explosion fracturing combustion-supporting agent quantitative multi-hole feeding tool. The feeding tool 22 is a feeding body B. The feeding body B includes an inner cylinder 2, a piston B 24 and an outer cylinder 23;

[0052] The upper end of the inner cylinder 2 is open, and an air inlet pipe B 25 is fixedly connected to the center of the upper end. Its bottom has an inner cylinder bottom plate 26. A spray hole 7 is provided in the central area of the inner cylinder bottom plate 26, and a constant pressure plug 8 is installed in the spray hole 7. The constant pressure plug 8 automatically disengages from the spray hole 7 when the upper acting pressure reaches the set pressure value;

[0053] The outer diameter of the piston B 24 is adapted to the inner diameter of the inner cylinder 2. The piston B 24 is slidably and sealingly assembled inside the inner cylinder 2. An air storage space B is formed between the piston B 24 and the inner cylinder bottom plate 26. The air storage space B is used to store the combustion-supporting agent 4;

[0054] The upper end of the outer cylinder body 23 is an open structure, and a plurality of perforations B27 are formed in its cylinder wall, and its bottom has an outer cylinder bottom plate 28; the outer cylinder body 23 is coaxially sleeved outside the inner cylinder body 2, and its upper end is fixedly connected to the upper end of the inner cylinder body 2 through an annular connecting plate B29. At the same time, an annular cavity 11 is formed between the inner cylinder body 2 and the outer cylinder body 23. The annular connecting plate B29 is hermetically connected between the outer surface of the inner cylinder body 2 and the upper end of the outer cylinder body 23 to ensure the airtightness of the subsequent formed annular cavity;

[0055] As a preference, the cross section of the outer cylinder bottom plate 28 is in the shape of an inverted truncated cone. In this way, it can play a role in rapid diversion, which is beneficial for the combustion-supporting agent discharged from the injection holes to quickly reach the perforations B, and is beneficial for quickly completing the delivery operation.

[0056] In order to effectively expand the delivery range of the combustion-supporting agent, a plurality of perforations B27 are evenly divided into four groups from top to bottom, and each group is composed of four perforations B27 evenly distributed circumferentially on the same plane.

[0057] As a preference, an air filling pipeline communicating with the air storage space B is connected to the inner cylinder bottom plate 26. The air inlet end of the air filling pipeline passes through the outer cylinder bottom plate 28 to reach the lower part outside the outer cylinder body 23. At the same time, a one-way valve is installed at the air inlet end of the air filling pipeline. In this way, the combustion-supporting agent 4 can be conveniently filled into the air storage space B through the one-way valve and the air filling pipeline. During the process of filling the combustion-supporting agent 4, the piston B24 is pushed to the maximum upward displacement. At this time, the annular connecting plate B29 abuts against the piston B24 to realize the upper limit position of the piston B24.

[0058] In the present invention, the outer cylinder body is coaxially sleeved outside the inner cylinder body. At the same time, the upper end of the outer cylinder body is fixedly connected to the upper end of the inner cylinder body through the annular connecting plate B, so that an annular cavity can be formed between the inner cylinder body and the outer cylinder body. The piston B is slidably and hermetically assembled in the inner cylinder body, so that a sealed air storage space B can be formed between the piston B and the inner cylinder body, which is beneficial for the pre-storage operation of the quantitative combustion-supporting agent. A spray hole is formed in the inner cylinder bottom plate, and a constant pressure plug is installed in the spray hole, which can facilitate ensuring the airtightness of the air storage space B under normal conditions. At the same time, after the pressure in the air storage space B reaches the opening pressure of the constant pressure plug, the air storage space B can be quickly communicated with the annular cavity. A plurality of perforations B are formed in the cylinder wall of the outer cylinder body, which can effectively communicate the annular cavity with the outside space. Furthermore, after the air storage space B is communicated with the annular cavity, the combustion-supporting agent can be quickly ejected through the spray hole, the annular cavity and the perforations B and reach the predetermined delivery position. This tool has a simple structure and high reliability. It can realize the pre-storage of the quantitative combustion-supporting agent and can conveniently perform the quantitative delivery operation of the pre-stored combustion-supporting agent at a specific position by means of gas injection.

[0059] The present invention provides two types of tools for injecting combustion aids for in-situ methane combustion fracturing, namely injection body A and injection body B, which can meet the requirements for injecting combustion aids in different complex environments.

[0060] As Figure 6 and Figure 7 shown, the present invention also provides a method for quantitatively injecting a combustion aid for in-situ methane combustion fracturing. Using a tool for quantitatively injecting a combustion aid for in-situ methane combustion fracturing or a tool for quantitatively injecting a combustion aid for in-situ methane combustion fracturing, the method includes the following steps:

[0061] Step 1: According to the amount of combustion aid required for reservoir 16, fill the required amount of combustion aid 4 into the injection tool 22.

[0062] Step 2: On the ground, arrange a fracturing truck 13 on one side of the wellbore 15 where fracturing operation is to be preformed. Meanwhile, prepare a coiled tubing 6 and sleeve a packer 31 outside the lower end of the coiled tubing 6.

[0063] Step 3: Install a bridge plug 30 in the wellbore 15 and set the bridge plug 30 below the reservoir 16.

[0064] Step 4: Connect the lower end of the coiled tubing 6 to the feed pipeline on the injection tool 22, and lower the injection tool 22 to the position where the reservoir 16 is located through the wellbore 15 using the coiled tubing 6. Then, connect the upper end of the coiled tubing 6 to the output pipeline of the fracturing truck 13.

[0065] Step 5: Pump nitrogen 14 into the coiled tubing 6 through the fracturing truck 13. Use the high-pressure nitrogen 14 to set the packer 31, and form a sealed injection section at the position where the injection tool 22 is located using the packer 31 and the bridge plug 30.

[0066] Step 6: Continuously pump high-pressure nitrogen 14 into the coiled tubing 6 through the fracturing truck 13. Use the continuously increasing pressure of the nitrogen 14 to act on the upper end face of the piston in the injection tool 22, so that the piston in the injection tool 22 moves downward until the combustion aid 4 in the gas storage space completely fills the sealed injection section through the perforations, and the quantitative injection operation of the combustion aid 4 can be completed.

[0067] As a preference, in Step 1, when the injection tool 22 is injection body A, the filling operation of the combustion aid 4 is carried out in the gas storage space A; when the injection tool 22 is injection body B, the filling operation of the combustion aid 4 is carried out in the gas storage space B.

[0068] As a preference, in step six, when the delivery tool 22 is the delivery body A, under the action of the continuously increasing pressure of the nitrogen gas 14, the piston A1 moves downward, and the lengths of the two telescopic rods 17 contract. At the same time, the two barrier slides 20 are pushed by the two telescopic rods 17 to slide towards the bottoms of the two arc-shaped grooves 21. When the two barrier slides 20 are completely embedded in the two arc-shaped grooves 21, the two holes 19 on the two barrier slides 20 are respectively aligned and communicated with the two perforations A12. The combustion promoter 4 in the gas storage space A sprays out at high speed through the communicated holes 19 and perforations A12, and is fully mixed with the in-situ methane in the reservoir 16 space. Thus, the quantitative and concentrated delivery operation of the pre-charged combustion promoter 4 in the delivery tool 22 is realized;

[0069] When the delivery tool 22 is the delivery body B, under the action of the continuously increasing pressure of the nitrogen gas 14, the piston B24 moves downward. By using the compression action of the downward-moving piston B24, the pressure in the gas storage space B continuously increases. When the pressure in the gas storage space B reaches the opening pressure of the constant pressure plug 8, the constant pressure plug 8 is pressed out of the spray hole 7. The combustion promoter 4 in the gas storage space B sprays out at high speed through the spray hole 7, the annular cavity 11, and the perforation B27 in sequence, and is fully mixed with the in-situ methane in the reservoir 16 space. Thus, the quantitative and concentrated delivery operation of the pre-charged combustion promoter 4 in the delivery tool 22 is realized.

[0070] In the present invention, pre-storing the required amount of combustion promoter in the delivery tool can avoid the process of transporting the combustion promoter along the way, and the combustion promoter can be delivered after the delivery tool reaches the predetermined position. Connecting the intake pipeline of the delivery tool and the fracturing truck by using the coiled tubing can facilitate lowering the delivery tool to the target reservoir position by using the coiled tubing. Installing a bridge plug at the position below the reservoir in the wellbore first, and at the same time, sleeving a packer outside the coiled tubing can form a sealed delivery section at the position where the delivery tool is located after the delivery tool is lowered to the predetermined position. Using the high-pressure nitrogen gas pumped in to push the piston B to move downward can realize the pressurization operation of the combustion promoter in the gas storage space B. During the pressurization process, the constant pressure plug can be automatically pressed out of the spray hole, so as to quickly connect the spray hole and the annular cavity. Thus, the pre-stored combustion promoter can be quickly delivered into the sealed delivery section. In this way, it can ensure that the combustion promoter is delivered into the bottom closed space of the well, and can make the methane in the gas storage fully mixed with the combustion promoter under the closed condition, ensuring that the methane detonation fracturing is carried out in the closed section of the wellbore.

[0071] The implementation steps of this method are simple. By adopting the pre-charging and dispensing method, it helps to achieve the efficient combination of conventional staged fracturing technology and pre-charging and quantitative dispensing technology, can meet the requirements of fuel promoter dispensing in different complex environments, can dispense the fuel promoter in a directional, quantitative and concentrated manner according to the size of the underground space and the dispensing distance. In addition, it can also meet the requirement of uniform dispensing of fuel promoter in deep and narrow spaces, enable the fuel promoter to be more fully mixed with in-situ methane in the underground reservoir space, and prevent the impact of the instantaneous high pressure generated by the explosion of methane-fuel promoter mixed gas on surface equipment, ensuring the safety of methane in-situ combustion and explosion fracturing fuel promoter dispensing.

Claims

1. A methane in-situ explosive fracturing combustion aid quantitative delivery tool, the delivery tool (22) being a delivery body A, the delivery body A comprising a gas storage cylinder (3), characterized in that: It also includes a piston A (1), a blocking slide (20), a telescopic sleeve rod (17) and a limit block (18); The upper end of the gas storage cylinder (3) is open, and an air intake pipeline A (5) is fixedly connected to the central area of ​​the upper end; the lower end of the gas storage cylinder (3) is fixedly connected to a blocking block (10), and two perforations A (12) are provided on opposite sides of the upper end of the blocking block (10); two arc-shaped grooves (21) are provided on opposite sides of the upper part of the blocking block (10), and the outer edge surfaces of the two arc-shaped grooves (21) are respectively in contact with the inner side walls of the opposite sides of the gas storage cylinder (3); The outer diameter of the piston A (1) is matched to the inner diameter of the air storage cylinder (3), and the piston A (1) is slidably and sealingly mounted inside the air storage cylinder (3), forming an air storage space A between the piston A (1) and the barrier block (10); The two blocking slides (20) are respectively matched with the two arc-shaped grooves (21) and are provided with a pair of holes (19) opposite to each other; the two blocking slides (20) are respectively slidably mounted in the two arc-shaped grooves (21) in the vertical direction, and the outer arc surfaces of the two blocking slides (20) are slidably sealed with the inner side walls of the gas storage cylinder (3) on opposite sides; when the two blocking slides (20) are completely embedded in the two arc-shaped grooves (21), the upper ends of the two blocking slides (20) are located above the two perforations A (12), and the two holes (19) on the two blocking slides (20) are respectively aligned with the two perforations A (12); Two telescopic sleeve rods (17) are vertically distributed above the two blocking slides (20), the lower ends of the telescopic sections are respectively fixedly connected to the centers of the upper ends of the two blocking slides (20), and the fixed sections are respectively fixedly inserted at opposite sides of the lower part of the piston A (1); The two limit blocks (18) are relatively distributed above the two arc-shaped grooves (21) and are respectively fixedly connected to opposite sides of the inner wall of the gas storage cylinder (3); the lower ends of the two limit blocks (18) are respectively abutted against the upper ends of the two blocking slides (20), and when the upper ends of the two blocking slides (20) are abutted against the lower ends of the two limit blocks (18), the lower ends of the two blocking slides (20) are located below the two perforations A (12).

2. A methane in-situ explosion fracturing combustion aid quantitative delivery tool according to claim 1, characterized in that: The lower end of the air intake pipeline A (5) is fixedly connected to the upper end of the air storage cylinder (3) via an annular connecting plate A (9).

3. A quantitative porous delivery tool for methane in-situ explosive fracturing combustion aid, the delivery tool (22) being a delivery body B, the delivery body B comprising an inner cylinder (2), characterized in that: It also includes a piston B (24) and an outer cylinder (23); The upper end of the inner cylinder (2) is open, and an air intake pipeline B (25) is fixedly connected to the center of the upper end, and the bottom thereof is provided with an inner cylinder bottom plate (26); a spray hole (7) is provided in the central area of ​​the inner cylinder bottom plate (26), and a constant pressure plug (8) is installed in the spray hole (7); The outer diameter of the piston B (24) is matched to the inner diameter of the inner cylinder (2), and the piston B (24) is slidably and sealingly mounted inside the inner cylinder (2), forming an air storage space B between the piston B (24) and the inner cylinder bottom plate (26); The upper end of the outer cylinder (23) is an open structure, a plurality of perforations B (27) are formed on the cylinder, and the bottom of the outer cylinder (23) has an outer cylinder bottom plate (28); the outer cylinder (23) is coaxially sleeved on the outside of the inner cylinder (2), and the upper end of the outer cylinder (2) is fixedly connected to the upper end of the inner cylinder (2) via an annular connecting plate B (29), and an annular cavity (11) is formed between the inner cylinder (2) and the outer cylinder (23).

4. A quantitative porous delivery tool for methane in-situ explosion fracturing combustion aid according to claim 3, characterized in that: The cross section of the outer cylinder bottom plate (28) is in the shape of an inverted frustum.

5. A quantitative multi-porous delivery tool for methane in-situ explosion fracturing combustion aid according to claim 3, characterized in that: The plurality of perforations B (27) are evenly divided into four groups from top to bottom, and each group consists of four perforations B (27) evenly distributed circumferentially on the same plane.

6. A method for quantitatively placing a methane in-situ explosion fracturing combustion aid, using a methane in-situ explosion fracturing combustion aid quantitative placement tool as claimed in claim 1 or a methane in-situ explosion fracturing combustion aid quantitative porous placement tool as claimed in claim 3, characterized in that: The following steps are involved: Step 1: according to the combustion-aiding agent dosage required by the reservoir (16), the required amount of combustion-aiding agent (4) is charged into the delivery tool (22); Step 2: Arrange a fracturing vehicle (13) on the ground at one side of the wellbore (15) to be subjected to fracturing operation, prepare a section of coiled tubing (6), and install a packer (31) on the outside of the lower end of the coiled tubing (6); Step 3: installing a bridge plug (30) in the wellbore (15), and setting the bridge plug (30) below the reservoir (16); Step 4: Connect the lower end of the coiled tubing (6) to the feed pipeline on the delivery tool (22), and use the coiled tubing (6) to lower the delivery tool (22) through the wellbore (15) to the location of the reservoir (16), and then connect the upper end of the coiled tubing (6) to the output pipeline of the fracturing vehicle (13); Step 5: nitrogen (14) is pumped into the coiled tubing (6) through the fracturing vehicle (13), the high-pressure nitrogen (14) is used to seal the packer (31), and the packer (31) and the bridge plug (30) are used to form a sealed delivery section at the location of the delivery tool (22); Step 6: Continue to pump high-pressure nitrogen (14) into the coiled tubing (6) through the fracturing vehicle (13), and use the nitrogen (14) with increasing pressure to act on the upper end surface of the piston in the delivery tool (22), so that the piston in the delivery tool (22) moves downward until the combustion aid (4) in the gas storage space is completely filled into the sealed delivery section through the perforations, thereby completing the quantitative delivery operation of the combustion aid (4).

7. A method for quantitatively placing a methane in-situ explosion fracturing combustion aid according to claim 6, characterized in that: In step one, when the delivery tool (22) is a delivery body A, the combustion aid (4) is charged into the gas storage space A; when the delivery tool (22) is a delivery body B, the combustion aid (4) is charged into the gas storage space B.

8. The method for quantitatively placing a methane in-situ explosion fracturing combustion aid according to claim 6, characterized in that: In step six, when the delivery tool (22) is the delivery body A, under the action of the nitrogen (14) with increasing pressure, the piston A (1) moves downward and causes the length of the two telescopic sleeve rods (17) to shrink. At the same time, the two blocking slides (20) are pushed to slide toward the bottom of the two arc-shaped grooves (21) by the two telescopic sleeve rods (17). When the two blocking slides (20) are completely embedded in the two arc-shaped grooves (21), the two holes (19) on the two blocking slides (20) are respectively aligned with and connected to the two perforations A (12), and the combustion aid (4) in the gas storage space A is ejected at a high speed through the connected holes (19) and perforations A (12), and is fully mixed with the in-situ methane in the reservoir (16) space; When the delivery tool (22) is the delivery body B, the piston B (24) moves downward under the action of the nitrogen (14) with increasing pressure, and the pressure in the gas storage space B is continuously increased by the compression effect of the downwardly moving piston B (24). When the pressure in the gas storage space B reaches the opening pressure of the constant pressure plug (8), the constant pressure plug (8) is pressed out of the spray hole (7), and the combustion aid (4) in the gas storage space B is sprayed out at a high speed through the spray hole (7), the annular cavity (11) and the perforation B (27) in sequence, and is fully mixed with the in-situ methane in the reservoir (16) space.

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