A method and device for coal seam combustion high-temperature high-pressure gas driving coalbed methane extraction and coal seam outburst elimination

Abstract

The present application provides a kind of coal seam combustion high temperature high pressure gas drive coalbed methane extraction and coal seam outburst elimination method and device, in the middle position of multiple ground coalbed methane extraction well, the combustion straight wellbore that passes through coal seam is set, the coal seam section of combustion straight wellbore is cut and forms combustion chamber, ignite the coal seam in combustion chamber, the compressed air nozzle and atomized water injection port on sealing device continuously pass into combustion-supporting gas and water in combustion chamber, so that high temperature and high pressure medium gas is continuously generated in combustion chamber, after the combustion of exposed coal seam in combustion chamber, the gas generated and water atomized heated water vapor form high temperature and high pressure medium gas, to the surrounding coal seam far away penetration and migration, this process is accompanied by heating coal seam and medium gas displacement gas, during gas displacement process, high temperature and high pressure combustion chamber surrounding coal seam is continuously heated to increase its permeability and pyrolysis coalbed methane of coal seam, the coalbed methane formed is continuously pressure driven by high pressure medium gas to penetrate and migrate to low pressure area, finally reaches adjacent gas extraction well and produces from here, so as to complete coalbed methane extraction in coal seam and the purpose of coal mine gas regional management.

Description

Technical Field

[0001] This invention relates to the field of energy extraction and gas control, and more specifically, to a method and apparatus for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven coalbed combustion. Background Technology

[0002] Currently, surface coalbed methane wells or surface wells for gas control in coal mines with low permeability are experiencing low gas production. This is especially true in the later stages of mining, where both water and gas production are low or nonexistent, yet coalbed methane (gas) remains unextracted. This results in energy waste and an imbalance between input and output in coalbed methane development, severely hindering the development of the coalbed methane industry and constantly threatening safe coal mining operations.

[0003] To address the aforementioned problems, it is of great significance to design a highly adaptable, reliable, simple, and safe technology and device for coalbed methane extraction and coalbed outburst suppression using high-temperature and high-pressure gas-driven coalbed combustion. Summary of the Invention

[0004] Based on at least one of the above-mentioned technical problems, this invention proposes a method and apparatus for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven coalbed combustion.

[0005] A method for coalbed methane extraction and coalbed methane outburst mitigation via high-temperature, high-pressure gas-driven coalbed combustion includes the following steps: Step 1: In the middle of multiple surface coalbed methane extraction wells, a combustion well straight cylinder that penetrates the coal seam is set up. The coal seam section of the combustion well straight cylinder is cut to expose the coal seam and expand outwards to form a combustion chamber. Step two: Ignite the coal seam in the combustion chamber using underground coal gasification ignition method; Step 3: Install a sealing device inside the combustion chamber cylinder to seal the combustion chamber at the bottom of the combustion chamber cylinder; Step 4: Continuously introduce combustion-supporting gas and water into the combustion chamber using the compressed air nozzle and atomizing water nozzle on the sealing device. The atomized water is heated into water vapor, causing the combustion chamber to continuously generate high-temperature and high-pressure medium gas. Step 5: The temperature and pressure inside the combustion chamber are monitored by the temperature and pressure sensors on the sealing device. The control system adjusts the injection speed of the compressed air nozzle and the atomizing water nozzle according to the feedback of temperature and pressure changes, so as to maintain a stable temperature and pressure in the combustion chamber.

[0006] In one possible implementation, in step one, the combustion well cylinder is a surface coalbed methane extraction well.

[0007] In one possible implementation, in step three, the sealing device is installed inside a sleeve at the junction of the coal seam and the roof rock above the coal seam.

[0008] A device for high-temperature, high-pressure gas-driven coalbed methane extraction and coalbed methane suppression in coal seam combustion includes a well casing and a sealing device. The well casing is disposed inside the combustion well cylinder, and the sealing device is installed inside the well casing and located above the combustion chamber. The sealing device includes an installation pipe, an outer sleeve, an inner sleeve, a sealing ring, a compressed air nozzle, a high-pressure water nozzle, a temperature sensor, and a pressure sensor. The inner sleeve is a conical hollow pipe, and the outer sleeve is pressed tightly against the outside of the inner sleeve. The outer wall of the outer sleeve is sealed to the well casing. The compressed air nozzle, the high-pressure water nozzle, the temperature sensor, and the pressure sensor are all disposed in the inner sleeve. The installation pipe is installed above the inner sleeve. The air pipe connected to the compressed air nozzle, the water pipe connected to the high-pressure water nozzle, and the wiring of the temperature sensor and the pressure sensor are all disposed inside the installation pipe and connected to equipment on the ground.

[0009] In one possible implementation, the outer casing is a cylinder with a conical cavity in the middle. The top of the outer casing has uniformly distributed cooling water holes and a lifting hole. The lower end of the outer casing's pull rope is fixed in the lifting hole. Multiple sealing ring grooves are formed on the outer side wall of the outer casing, and metal sealing rings are provided in the sealing ring grooves. A flange is provided on the outer side of the bottom of the outer casing, and the flange is engaged with the bottom end of the well casing.

[0010] In one possible implementation, the inner sleeve includes a threaded connecting pipe and a conical pipe, the outer surface of which is a conical surface that matches the conical cavity inside the outer sleeve; the threaded connecting pipe has multiple mounting holes, the threaded connecting pipe is fixed to the top of the conical pipe, the threaded connecting pipe has external threads, and the threaded connecting pipe is threadedly connected and fixed to the mounting pipe.

[0011] In one possible implementation, one end of the mounting tube is provided with an internal thread and the other end is provided with an external thread, the internal thread and the external thread are matched with each other, and a limiting plate is provided on the outer side of the lower part of the mounting tube.

[0012] In one possible implementation, coolant is filled between the well casing and the mounting pipe above the sealing device.

[0013] In one possible implementation, a control system is also included, which receives temperature and pressure signals from the temperature sensor and the pressure sensor, and sends control signals to the air compressor system and the atomizing system, causing them to spray combustion-supporting gas and water through the compressed air nozzle and the atomizing water nozzle according to the data in the control signals.

[0014] In one possible implementation, the lower sidewall of the outer jacket is provided with circumferentially distributed vertical grooves, which divide the lower part of the outer jacket and the flange into evenly spaced and elastic segments.

[0015] Beneficial effects: This invention utilizes coal seam combustion heating to inject combustion-supporting gas and water, thereby generating a high-temperature and high-pressure medium gas. The high-temperature and high-pressure medium gas heats the surrounding coal seam and pyrolyzes the coal seam gas (methane) adsorbed by the coal seam to improve the coal seam permeability. At the same time, a gas that is more easily adsorbed by the coal seam is used to pressurize and displace the coal seam gas (methane) in the coal seam. Attached Figure Description

[0016] Figure 1 A schematic diagram of a high-temperature, high-pressure gas-driven coalbed methane extraction and coalbed methane suppression device for coalbed combustion. Figure 2 This is a cross-sectional view of the sealing device of this application; Figure 3 This is a top view of the sealing device of this application; Figure 4 This is a schematic diagram of the sealing device outer casing of this application; Figure 5 This is a cross-sectional view of the outer casing of the sealing device in this application; Figure 6 This is a cross-sectional view of the inner sleeve of the sealing device of this application; Figure 7 This is a schematic diagram of the inner sleeve of the sealing device of this application; In the attached diagram, 1-coalbed methane extraction well; 2-combustion well cylinder; 3-well casing; 4-coal seam roof rock; 5-sealing device; 6-coal seam; 7-combustion chamber; 8-outer jacket rope; 9-limiting disc; 51-installation pipe; 52-outer jacket; 53-inner jacket; 54-sealing ring; 55-compressed air nozzle; 56-high pressure water nozzle; 57-temperature sensor; 58-pressure sensor; 521-cooling water hole; 522-lifting hole; 523-sealing ring groove; 524-vertical groove; 525-flange; 526-conical cavity; 531-threaded connecting pipe; 532-conical pipe; 533-compressed air nozzle mounting hole; 534-high pressure water nozzle mounting hole; 535-temperature sensor mounting hole; 536-pressure sensor mounting hole. Detailed Implementation

[0017] To better understand the above-described objects, features, and advantages of the present invention, the following description is in conjunction with the accompanying drawings. Figures 1-7 The present invention will be further described in detail below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

[0018] A method for coalbed methane extraction and coalbed methane outburst mitigation via high-temperature, high-pressure gas-driven coalbed combustion includes the following steps: Step 1: Set up a combustion well straight cylinder 2 that runs through the coal seam in the middle of multiple surface coalbed methane extraction wells 1. The combustion well straight cylinder 2 can be newly built in the middle of the coalbed methane extraction well 1, or a coalbed methane extraction straight well 1 can be directly selected and modified. During the modification, the coal seam section of the combustion well straight cylinder 2 is cut to expose the coal seam and expand to the surrounding area to form a combustion chamber 7. Step 2: Ignite the coal seam 6 in the combustion chamber 7 using an underground coal gasification ignition method; Step 3: Install sealing device 5 inside combustion well cylinder 2. Sealing device 5 is installed at the junction of coal seam 6 and roof rock 4 above coal seam 6. Sealing device 5 seals the combustion chamber 7 at the bottom of combustion well cylinder 2. Step 4: Using the compressed air nozzle 55 and atomizing water nozzle on the sealing device 5, combustion gas and water are continuously introduced into the combustion chamber 7 to generate a high-temperature and high-pressure medium gas in the combustion chamber 7; air is preferred as the combustion gas is cheaper. Step 5: The temperature and pressure inside the combustion chamber 7 are monitored by the temperature sensor 57 and pressure sensor 58 on the sealing device 5. The control system adjusts the injection speed of the pressure nozzle and the atomizing water nozzle according to the feedback of temperature and pressure changes, so that the combustion chamber 7 maintains a stable and ideal temperature and pressure.

[0019] A device for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven coalbed combustion includes a well casing 3 and a sealing device 5. The well casing 3 is installed inside the combustion well cylinder 2 and is tightly attached to the combustion well cylinder 2 and fixedly sealed. The sealing device 5 is installed inside the well casing 3 and is located above the combustion chamber 7. The sealing device 5 seals the combustion chamber 7, isolating it from the upper space.

[0020] The sealing device 5 includes an installation pipe 51, an outer sleeve 52, an inner sleeve 53, a sealing ring 54, a compressed air nozzle 55, a high-pressure water nozzle 56, a temperature sensor 57, and a pressure sensor 58. The inner sleeve 53 is a conical hollow pipe. The outer sleeve 52 is pressed tightly against the outside of the inner sleeve 53. The outer wall of the outer sleeve 52 is sealed to the well casing 3. The compressed air nozzle 55, the high-pressure water nozzle 56, the temperature sensor 57, and the pressure sensor 58 are all installed in the inner sleeve 53. The compressed air nozzle 55 is connected to an external compressed air system through an air duct. The high-pressure nozzle is connected to an external atomization system through a water pipe. The temperature sensor 57 and the pressure sensor 58 are electrically connected to the control system of this device through the wires of the temperature sensor 57 and the pressure sensor 58. The installation pipe 51 is installed above the inner sleeve 53. The air duct, the water pipe, the temperature sensor wire, and the pressure sensor wire all pass through the installation pipe 51.

[0021] The outer sleeve 52 is cylindrical and made of heat-resistant stainless steel. A conical cavity 526 is provided in the middle of the outer sleeve 52. The top of the outer sleeve 52 has annularly distributed cooling water holes 521 and a lifting hole 522. The cooling water holes 521 communicate with the well casing 3. The lower end of the outer sleeve pull rope 8 is fixed inside the lifting hole 522. Multiple sealing ring grooves 523 are formed on the outer side wall of the outer sleeve 52. Metal sealing rings 54 are installed in the sealing ring grooves 523, sealing the outer sleeve 52 to the well casing 3. The bottom of the outer sleeve 52... The outer sleeve 52 has a flange 525 on its side, which is snapped into the bottom end of the well casing 3. The lower side wall of the outer sleeve 52 has vertical grooves 524 that are evenly distributed in a circle. The vertical grooves 524 divide the lower part of the outer sleeve 52 and the flange 525 into evenly spaced and elastic partitions. Under normal conditions, the outer sleeve 52 can enter the well casing 3. When the flange 525 extends out from the bottom end of the well casing 3, pulling up the installation pipe 51 can expand the flange 525 on the partition. Therefore, the flange 525 will be snapped into the bottom of the well casing 3, so that the lower end of the well casing 3 is sealed.

[0022] The inner sleeve 53 is made of heat-resistant stainless steel and includes a threaded connecting tube 531 and a conical tube 532. The outer surface of the conical tube 532 is a conical surface that matches the conical cavity 526 inside the outer sleeve 52. The threaded connecting tube 531 has multiple mounting holes 533. The threaded connecting tube 531 is fixed to the top of the conical tube 532. The threaded connecting tube 531 has external threads and is threadedly connected and fixed to the mounting tube 51. One end of the mounting tube 51 has an internal thread and the other end has an external thread. The internal and external threads match each other. Multiple mounting tubes 51 can be extended by connecting them end to end.

[0023] A limiting disc 9 is also provided on the outer side of the lower part of the installation pipe 51. When installing the sealing device 5, the limiting disc 9 on the outer sleeve 52 can be pushed to allow it to enter the well casing 3.

[0024] The continuous combustion of coal seam 6 causes the well casing 3 and sealing device 5 to be continuously heated. In order to protect the structural and functional stability of the well casing 3 and sealing device 5 and to ensure the sealing performance of the combustion chamber 7, water or coolant is injected into the annular space between the well casing 3 and the sealing device connecting pipe. The water or coolant will also enter the cooling water hole 521 in the outer jacket 52 to cool the well casing 3 and sealing device 5.

[0025] In this invention, the control system receives temperature and pressure signals from temperature and pressure sensors 58 and sends control signals to the air compressor system and atomization system, causing them to inject combustion-supporting gas and water through the compressed air nozzle 55 and atomization water nozzle according to the data in the control signals.

[0026] The specific implementation of this invention is as follows: For combustion wells, either new ones can be built or existing surface coalbed methane extraction wells 1 can be modified. First, the extraction equipment in coalbed methane extraction well 1 or surface area gas control extraction wells is removed, leaving only the well casing. At the junction of coal seam 6 and the roof and bottom rock, the well casing 3 of the target coal seam section is cut off, exposing coal seam 6, and a coal seam cavern is constructed to become combustion chamber 7. On the surface, the outer sleeve 52 of the sealing device 5 is installed on the inner sleeve 53, and the compressed air nozzle 55, high-pressure water nozzle 56, temperature sensor 57, and pressure sensor 58 are respectively installed on the inner sleeve 53. The corresponding lines and pipelines pass through the sealing device. After the installation pipe 51 on the 5, the entire sealing device 5 is placed into the well casing 3 of the combustion well straight cylinder 2. When the sealing device 5 reaches the designated position of the well casing 3, that is, the junction of the coal seam 6 and the roof rock 4, above the milled well casing 3, the flange 525 of the lower part of the outer sleeve 52 passes through the well casing 3 and returns to its original position under the action of elasticity, and is stuck on the lower end face of the well casing 3. Pull the installation pipe 51 and the inner sleeve 53 of the sealing device 5 upward. The outer conical surface of the inner sleeve 53 is combined with the inner conical surface of the outer sleeve 52, so that the space below the sealing device 5 forms a relatively sealed combustion chamber 7.

[0027] First, coal seam 6 is ignited using underground coal gasification. Then, a sealing device 5 is installed. The compressed air nozzle 55 on the sealing device 5 continuously injects air or other combustion aids into the combustion chamber 7, causing the coal seam 6 inside the combustion chamber 7 to burn continuously. The temperature sensor 57 and pressure sensor 58 on the sealing device 5 continuously monitor the combustion status of the coal seam 6 inside the combustion chamber 7. The control system located on the ground adjusts the compressed air nozzle 55 and atomizing water nozzle on the sealing device 5 to inject appropriate amounts of air and water into the enclosed space, respectively, to control the combustion status of the coal seam 6, thereby ensuring that the combustion chamber 7 maintains a certain temperature and pressure. The gas produced by combustion and the water vapor heated by water atomization form a high-temperature and high-pressure medium gas. When the inner sleeve 53 moves towards the wellhead, the conical surface increases the diameter of the outer sleeve 52, allowing for a tighter fit with the inner wall of the well casing 3, achieving the purpose of fixation and sealing.

[0028] When the extraction work is completed and it is necessary to disassemble the sealing device 5 in the combustion well casing 2, push the sealing device 5 installation pipe 51 downward and pull the outer sleeve rope 8 upward to separate the mating conical surfaces of the inner sleeve 53 and the outer sleeve 52. The outer diameter of the outer sleeve 52 will then decrease and separate from the inner wall of the well casing 3. Then pull the outer sleeve rope 8 upward to pull the sealing device 5 out of the wellhead along the well casing 3. Finally, add water to the wellhead and let the water flow through the coal seam in the combustion chamber to cool the coal seam and isolate it from the air, so that the coal seam no longer has the possibility of combustion.

[0029] After the exposed coal seam 6 in combustion chamber 7 is burned, the generated gas and the water vapor heated by water atomization form a high-temperature, high-pressure mixed gas, which permeates and migrates to the surrounding coal seams 6. This process is accompanied by heating of coal seam 6 (heating coal seam 6 increases its permeability, forcing coal seam 6 to pyrolyze the gas) and the displacement of gas by the medium gas. During the gas displacement process, the coalbed methane (gas) in the surrounding coal seam 6, which is continuously heated and desorbed, is driven by continuous pressure to permeate and migrate, eventually reaching the nearby gas extraction well and being produced from there, thus completing the extraction of coalbed methane (gas) from coal seam 6 and the purpose of coal mine gas area control.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven combustion in coal seams, characterized in that, The system includes a well casing and a sealing device. The well casing is installed inside the combustion well cylinder, and the sealing device is installed inside the well casing, located above the combustion chamber. The sealing device includes an installation pipe, an outer sleeve, an inner sleeve, a sealing ring, a compressed air nozzle, a high-pressure water nozzle, a temperature sensor, and a pressure sensor. The inner sleeve is a conical hollow pipe, and the outer sleeve is pressed tightly against the outside of the inner sleeve. The outer wall of the outer sleeve seals against the well casing. The compressed air nozzle, the high-pressure water nozzle, the temperature sensor, and the pressure sensor are all located within the inner sleeve. The installation pipe is installed above the inner sleeve. The air pipe connected to the compressed air nozzle, the water pipe connected to the high-pressure water nozzle, and the wiring of the temperature sensor and the pressure sensor are all located within the installation pipe and connected to equipment on the ground.

2. The apparatus for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven combustion according to claim 1, characterized in that, The outer casing is cylindrical with a conical cavity in the middle. The top of the outer casing has evenly distributed cooling water holes and a lifting hole. The lower end of the outer casing's pull rope is fixed in the lifting hole. Multiple sealing ring grooves are formed on the outer side wall of the outer casing, and metal sealing rings are provided in the sealing ring grooves. A flange is provided on the outer side of the bottom of the outer casing, and the flange is engaged with the bottom end of the well casing.

3. The apparatus for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven combustion according to claim 2, characterized in that, The inner sleeve includes a threaded connecting pipe and a conical pipe. The outer surface of the conical pipe is a conical surface that matches the conical cavity inside the outer sleeve. The threaded connecting pipe has multiple mounting holes and is fixed to the top of the conical pipe. The threaded connecting pipe has external threads and is threadedly connected and fixed to the mounting pipe.

4. The apparatus for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven combustion according to claim 1, characterized in that, One end of the mounting tube is provided with an internal thread, and the other end is provided with an external thread. The internal thread and the external thread are matched with each other. A limiting plate is provided on the outer side of the lower part of the mounting tube.

5. The apparatus for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven combustion according to claim 1, characterized in that, Coolant is filled between the well casing above the sealing device and the installation pipe.

6. The apparatus for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven combustion according to claim 1, characterized in that, It also includes a control system, which receives temperature and pressure signals from the temperature sensor and the pressure sensor, and sends control signals to the air compressor system and the atomization system, so that they spray combustion gas and water into the compressed air nozzle and the atomizing water nozzle according to the data of the control signal.

7. The apparatus for coalbed methane extraction and coalbed methane suppression using high-temperature and high-pressure gas-driven combustion according to claim 2, characterized in that, The lower sidewall of the outer jacket is provided with circumferentially distributed vertical grooves, which divide the lower part of the outer jacket and the flange into evenly spaced and elastic segments.

Images