Oil pipe lifting control system for underground coal gasification process

Abstract

The invention relates to the technical field of coal underground gasification processes, in particular to an oil pipe lifting control system for a coal underground gasification process, which comprises a coal seam, an underground gasification furnace, an injection well mouth, an oil pipe main body, a well completion sleeve, a sleeve assembly, a well mouth injection device, a hydraulic telescopic rod and a lifting assembly, an injection well mouth is arranged on the ground above a coal seam, a well completion sleeve is arranged on the inner side of the injection well mouth, a sleeve assembly is arranged on the outer side of the well completion sleeve, a well mouth injection device is arranged above the injection well mouth, an oil pipe body is arranged on the inner side of the well completion sleeve, and a hydraulic telescopic rod is arranged on one side of the injection well mouth. A lifting assembly is arranged on one side of the hydraulic telescopic rod. The underground gasification furnace reaction zone is flexibly controlled in a lifting control mode, production water can be injected according to the production requirement of the underground gasification furnace, the yield and quality of produced synthesis gas are effectively guaranteed, and therefore the practical value of the gasification furnace is effectively increased.

Description

Technical Field

[0001] The invention relates to the technical field of underground coal gasification, and in particular to an oil pipe lifting and lowering control system used in an underground coal gasification process. Background Art

[0002] Underground coal gasification (ISC) is a process that converts coal directly into a product gas, commonly called syngas, by combustion and gasification reactions in underground coal seams in the presence of an oxidant. The syngas can then be used as a feedstock for a variety of applications, including fuel production, chemical production, and power generation.

[0003] The current underground gasifier injection well uses a casing channel to directly inject the oxidant, and the oxidant injection position cannot be controlled, so that the underground gasifier reaction zone cannot be effectively controlled, and the output and quality of the synthesis gas produced by the underground gasifier cannot be guaranteed.

[0004] Therefore, in view of the fact that it is difficult to flexibly adjust the oxidant injection position in existing underground coal gasification furnaces, an oil pipe lifting and controlling system for underground coal gasification process can be designed. By means of lifting and lowering control, the reaction zone of the underground gasifier can be flexibly controlled, and production water can be injected according to the production needs of the underground gasifier, effectively ensuring the output and quality of the produced synthesis gas, thereby effectively enhancing the practical value of the gasifier. Summary of the invention

[0005] The present invention is proposed to overcome the problem that most underground gasifiers often cannot control the oxidant injection position, so that the reaction zone of the underground gasifier cannot be effectively controlled, thereby failing to ensure the output and quality of the synthesis gas generated by the underground gasifier.

[0006] The technical solution of the present invention is: a tubing lifting and lowering control system for underground coal gasification process, comprising a coal seam, a gasifier body, an injection wellhead, an tubing body, a completion casing, a casing assembly, a wellhead injection device, an injection assembly, an tubing assembly, a hydraulic telescopic rod and a lifting assembly, wherein the gasifier body is arranged on the inner side of the coal seam, the injection wellhead is arranged on the ground above the coal seam, the completion casing is arranged on the inner side of the injection wellhead, one end of the completion casing is interconnected with the gasifier body, the casing assembly is arranged on the outer side of the completion casing, the wellhead injection device is arranged above the injection wellhead, the injection assembly is arranged on one side of the wellhead injection device, the tubing body is arranged on the inner side of the completion casing, the tubing body is arranged in multiple sections, the tubing assembly is arranged on one side of the tubing body, the hydraulic telescopic rod is arranged on one side of the injection wellhead, and the lifting assembly is arranged on one side of the hydraulic telescopic rod.

[0007] Preferably, the coal seam reaction position is clearly defined by setting the gasifier body, the completion casing is fixed by the casing assembly, the placement path of the oil pipe body is defined by the completion casing, and it is ensured that the oil pipe body can extend to the gasification reaction position of the gasifier body, the wellhead injection device position is fixed by the injection wellhead, the injection assembly is connected through the wellhead injection device, the oxidant and other raw materials required for gasification are injected into the wellhead injection device by the injection assembly, and the gasification raw materials are transported to the oil pipe body by the wellhead injection device, so that the raw materials are injected from the oil pipe body into the gasifier body for gasification reaction. After a period of reaction, the oxidant injection position needs to be adjusted. At this time, the telescopic hydraulic telescopic rod controls the lifting and lowering of the lifting assembly, and the lifting and lowering of the oil pipe body are driven by the lifting assembly to flexibly adjust the oxidant injection position, thereby realizing flexible control of the underground gasifier reaction zone, effectively ensuring the output and quality of the produced synthetic gas, and enhancing the practical value of the gasifier.

[0008] Preferably, the casing assembly includes a technical casing and a cement ring. The technical casing is arranged outside the completion casing, and the cement ring is arranged outside the technical casing. The cement ring is arranged on the bottom surface of the injection wellhead.

[0009] Preferably, the injection assembly includes a four-gate blowout preventer, a working window, a main valve and a blowout preventer box. The top of the injection wellhead is provided with a four-gate blowout preventer, the top of the four-gate blowout preventer is provided with a working window, the wellhead injection device is provided above the working window, the main valve is provided on one side of the wellhead injection device, and the blowout preventer box is provided on one side of the main valve.

[0010] Preferably, the injection assembly also includes a gas detector, a connecting pipe, a flow regulating valve, an oxidant storage tank, an oxygen injection pump, a water storage tank, a water pump, a nitrogen tank and a nitrogen injection pump. A gas detector is arranged above the wellhead injection device, a connecting pipe is arranged on one side of the wellhead injection device, a flow regulating valve is arranged on the outside of the connecting pipe, an oxidant storage tank is arranged at one end of the connecting pipe, an oxygen injection pump is arranged above the oxidant storage tank, a water storage tank is arranged at one end of the connecting pipe, a water pump is arranged above the water storage tank, a nitrogen tank is arranged at one end of the connecting pipe, and a nitrogen injection pump is arranged above the nitrogen tank.

[0011] Preferably, one end of the connecting pipe is interconnected with the wellhead injection device, the other end of the connecting pipe is interconnected with the oxidant storage tank, the water storage tank and the nitrogen tank, and the oxygen injection pump, the water pump and the nitrogen injection pump are electrically connected to the connecting pipe.

[0012] Preferably, the oil pipe assembly includes an oil pipe hanger, an oil pipe check valve and an oil pipe slip. The oil pipe hanger is arranged above the working window, the oil pipe check valve is arranged on the inner side of the oil pipe body, multiple groups of oil pipe check valves are arranged, and an oil pipe slip is arranged on one side of the oil pipe hanger. The oil pipe slip is arranged at one end of the oil pipe body.

[0013] Preferably, the lifting assembly includes a support plate, a lower cava, a telescopic plate and an upper cava. A support plate is arranged on one side of the injection wellhead, a lower cava is arranged on one side of the support plate, a telescopic plate is arranged on the inner side of the support plate, the telescopic plate and the support plate are slidably connected to each other, the telescopic plate is arranged at one end of the hydraulic telescopic rod, and an upper cava is arranged on one side of the telescopic plate.

[0014] Beneficial effects of the present invention:

[0015] During the gasification reaction, the coal seam reaction position is determined through the gasifier body, and the completion casing is used to determine the placement path of the oil pipe body to ensure that the oil pipe body can be extended to the gasification reaction position of the gasifier body. The injection wellhead is used to fix the position of the wellhead injection device, and the oxidant and other raw materials required for gasification are injected into the wellhead injection device. The gasification raw materials are transported to the oil pipe body through the wellhead injection device, so that the raw materials are injected from the oil pipe body into the gasifier body for gasification reaction. After a period of reaction, the oxidant injection position needs to be adjusted. At this time, the telescopic hydraulic telescopic rod controls the lifting and lowering of the oil pipe body, and the oxidant injection position is flexibly adjusted to solve the problem that most underground gasifier injection wells use casing channels to directly inject oxidants, the oxidant injection position cannot be controlled, and the output and quality of the synthetic gas produced by the underground gasifier cannot be guaranteed, thereby enhancing the practical value of the gasifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 What is shown is a cross-sectional three-dimensional structural schematic diagram of an oil pipe lifting control system for underground coal gasification process of the present invention;

[0017] Figure 2 What is shown is a three-dimensional structural schematic diagram of an oil pipe lifting control system for underground coal gasification process of the present invention;

[0018] Figure 3 Shown is a three-dimensional structural schematic diagram of an injection assembly of an oil pipe lifting control system for underground coal gasification process of the present invention;

[0019] Figure 4 Shown is a schematic diagram of the three-dimensional structure of the cross-section of the injection wellhead of an oil pipe lifting control system for underground coal gasification technology of the present invention.

[0020] Explanation of the reference numerals: 1. Coal seam; 2. Gasifier body; 3. Injection wellhead; 4. Completion casing; 401. Technical casing; 402. Cement ring; 5. Wellhead injection device; 501. Four-gate blowout preventer; 502. Working window; 503. Main valve; 504. Blowout preventer box; 505. Gas detector; 506. Connecting pipe; 507. Flow regulating valve; 508. Oxidant storage tank; 509. Oxygen injection pump; 510. Water storage tank; 511. Water pump; 512. Nitrogen tank; 513. Nitrogen injection pump; 6. Oil pipe body; 601. Oil pipe hanger; 602. Oil pipe check valve; 603. Oil pipe slip; 7. Hydraulic telescopic rod; 701. Support plate; 702. Lower slip; 703. Telescopic plate; 704. Upper slip. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] See also Figure 1 and Figure 2 The present invention provides an embodiment: a tubing lifting control system for underground coal gasification process, comprising a coal seam 1, a gasifier body 2, an injection wellhead 3, an tubing body 6, a completion casing 4, a casing assembly, a wellhead injection device 5, an injection assembly, an tubing assembly, a hydraulic telescopic rod 7 and a lifting assembly, wherein the gasifier body 2 is arranged on the inner side of the coal seam 1, the injection wellhead 3 is arranged on the ground above the coal seam 1, the completion casing 4 is arranged on the inner side of the injection wellhead 3, one end of the completion casing 4 is interconnected with the gasifier body 2, the casing assembly is arranged on the outer side of the completion casing 4, the wellhead injection device 5 is arranged above the injection wellhead 3, the injection assembly is arranged on one side of the wellhead injection device 5, the tubing body 6 is arranged on the inner side of the completion casing 4, the tubing body 6 is arranged in multiple sections, the tubing assembly is arranged on one side of the tubing body 6, the hydraulic telescopic rod 7 is arranged on one side of the injection wellhead 3, and the lifting assembly is arranged on one side of the hydraulic telescopic rod 7.

[0023] See also Figure 1 In this embodiment, the casing assembly includes a technical casing 401 and a cement ring 402. The technical casing 401 is arranged on the outside of the completion casing 4, and the cement ring 402 is arranged on the outside of the technical casing 401. The cement ring 402 is arranged on the bottom surface of the injection wellhead 3. The cement ring 402 is used to isolate shallow groundwater, thereby reinforcing the technical casing 401, meeting environmental protection requirements, and using the technical casing 401 to reinforce the completion casing 4.

[0024] See also Figure 3 and Figure 4In this embodiment, the injection assembly includes a four-gate blowout preventer 501, a working window 502, a main valve 503, a blowout preventer box 504, a gas detector 505, a connecting pipe 506, a flow regulating valve 507, an oxidant storage tank 508, an oxygen injection pump 509, a water storage tank 510, a water pump 511, a nitrogen tank 512 and a nitrogen injection pump 513. The top of the injection wellhead 3 is provided with a four-gate blowout preventer 501, the top of the four-gate blowout preventer 501 is provided with a working window 502, the wellhead injection device 5 is provided above the working window 502, the main valve 503 is provided on one side of the wellhead injection device 5, the blowout preventer box 504 is provided on one side of the main valve 503, and the gas detection device 5 is provided above the wellhead injection device 5. The wellhead injection device 505 is provided with a connecting pipe 506 on one side, one end of the connecting pipe 506 is interconnected with the wellhead injection device 5, a flow regulating valve 507 is provided on the outside of the connecting pipe 506, an oxidant storage tank 508 is provided on one end of the connecting pipe 506, an oxygen injection pump 509 is provided above the oxidant storage tank 508, a water storage tank 510 is provided on one end of the connecting pipe 506, a water pump 511 is provided above the water storage tank 510, a nitrogen tank 512 is provided on one end of the connecting pipe 506, the other end of the connecting pipe 506 is interconnected with the oxidant storage tank 508, the water storage tank 510 and the nitrogen tank 512, a nitrogen injection pump 513 is provided above the nitrogen tank 512, and the nitrogen injection pump 514 is provided above the nitrogen tank 514. The oxygen pump 509, the water pump 511 and the nitrogen injection pump 513 are electrically connected to the connecting pipe 506. Before the gasifier body 2 is ignited, the oil pipe body 6 is transported to the working window 502. The working window 502 provides an operating space for the installation and connection of downhole tools. During the production process of the gasifier body 2, the oxidant in the oxidant storage tank 508 needs to be pumped into the connecting pipe 506 by the oxygen injection pump 509, and the water in the water storage tank 510 needs to be pumped into the connecting pipe 506 by the water pump 511. At the same time, the injection amount of the oxidant or water is controlled by the flow regulating valve 507. The wellhead injection device 5 is connected through the connecting pipe 506, and the various raw materials are injected from the channel in the oil pipe body 6 by the wellhead injection device 5. The gasification reaction takes place in the gasifier body 2 to realize the controlled combustion of the coal seam 1 and generate synthesis gas. The nitrogen in the nitrogen tank 512 is extracted by the nitrogen injection pump 513 to purge the internal channel to avoid leakage of high-pressure oxygen or synthesis gas during the lifting process of the tubing body 6 and to prevent poisoning of operators. During the lifting process of the tubing body 6, the concentration of toxic and harmful gases around the wellhead injection device 5 is monitored in real time by the gas detector 505 to ensure the safety of the operators. The tubing body 6 is sealed by the four-gate blowout preventer 501 and the tubing body 6 is cut off under emergency conditions. The blowout preventer box 504 is used to provide sufficient space for the storage of downhole tools. The wellhead injection device 5 is switched on and off by the main valve 503.

[0025] See also Figure 1 and Figure 4In this embodiment, the tubing assembly includes a tubing hanger 601, a tubing check valve 602 and a tubing slip 603. The tubing hanger 601 is arranged above the working window 502, and the tubing check valve 602 is arranged on the inner side of the tubing body 6. There are multiple groups of tubing check valves 602, and the distance between the tubing check valves 602 is 20 to 100 meters. A tubing slip 603 is arranged on one side of the tubing hanger 601, and the tubing slip 603 is arranged at one end of the tubing body 6. The tubing hanger 601 is used to fix the hanging position of the tubing body 6, and the tubing slip 603 is used to statically clamp the tubing body 6, so that the tubing body 6 is stably suspended on the tubing hanger 601, and the tubing check valve 602 is used to prevent the fluid in the tubing body 6 from flowing back, so as to ensure the unidirectional flow of the oxidant and the synthesis gas.

[0026] See also Figure 2 and Figure 4 In this embodiment, the lifting assembly includes a support plate 701, a lower slip 702, a telescopic plate 703 and an upper slip 704. A support plate 701 is provided on one side of the injection wellhead 3, a lower slip 702 is provided on one side of the support plate 701, a telescopic plate 703 is provided on the inner side of the support plate 701, the telescopic plate 703 and the support plate 701 are slidably connected with each other, the telescopic plate 703 is provided at one end of the hydraulic telescopic rod 7, an upper slip 704 is provided on one side of the telescopic plate 703, the lower slip 702 is supported and fixed by the support plate 701, the telescopic hydraulic telescopic rod 7 drives the telescopic plate 703 to rise and fall in the support plate 701, the height of the upper slip 704 is adjusted, and the telescopic hydraulic telescopic rod 7 synchronously transports and lifts the oil pipe body 6. When the oil pipe body 6 is transported downward, the upper slip 704 is used to grab the oil pipe body 6. At the same time, the lower slip 702 is released, and the upper slip 704 transports the oil pipe body 6 downward to the bottom through the hydraulic telescopic rod 7. At this time, the lower slip 702 clamps the oil pipe body 6. The upper slip 704 is released and moved upward to the top through the hydraulic telescopic rod 7 to re-grab the new oil pipe body 6. The above process is repeated until the oil pipe body 6 is transported to the designed position. When the oil pipe body 6 is lifted upward, the upper slip 704 clamps the oil pipe body 6. The lower slip 702 is released. When the upper slip 704 moves to the connecting buckle of the oil pipe body 6, the lower slip 702 clamps the next oil pipe body 6. The above process is repeated until the oil pipe is lifted to the designed position.

[0027] Before ignition, the position of the technical casing 401 is fixed by the cement ring 402, the completion casing 4 is fixed by the technical casing 401, the oil pipe body 6 is transported to the working window 502, and the installation and connection of the downhole tools are completed in the working window 502;

[0028] Subsequently, the tubing body 6 is grasped by the upper slips 704, and at the same time, the lower slips 702 are released, and the tubing body 6 is transported downward to the bottom by the upper slips 704 through the hydraulic telescopic rod 7. At this time, the lower slips 702 clamp the tubing body 6, and the upper slips 704 are released and moved upward to the top through the hydraulic telescopic rod 7 to re-grab the new tubing body 6, and the above process is repeated until the tubing body 6 is transported to the designed position;

[0029] During ignition production, the oxidant in the oxidant storage tank 508 is extracted by the oxygen injection pump 509, and the oxidant is injected into the wellhead injection device 5 through the connecting pipe 506. The oxidant is transported by the oil pipe body 6, and the reaction raw materials are transported to the gasifier body 2 to implement the ignition of the underground coal seam 1. Subsequently, the underground coal gasification production is carried out. At the same time, the production water in the water storage tank 510 is extracted by the water pump 511, and the production water is injected into the gasifier body 2 to adjust the gasification reaction conditions. At the same time, the oil pipe check valve 602 is used to prevent the fluid in the oil pipe body 6 from flowing back. When the quality and output of the synthetic gas product reach the design range, the retreat operation is implemented to continue the underground coal gasification production;

[0030] When the tubing body 6 is raised or lowered, nitrogen in the nitrogen tank 512 is extracted by the nitrogen injection pump 513, and nitrogen is injected into the annulus inside the tubing body 6 to replace the oxygen in the annulus inside the tubing body 6. After the replacement is completed, the flow regulating valve 507 is closed, and at the same time, the gas detector 505 is turned on to monitor the toxic and harmful gases in the operation area in real time;

[0031] Then, according to the production requirements of the gasifier body 2, the lifting quantity of the tubing body 6 is calculated, the main valve 503 is opened, and at the same time, the half-closed gate of the four-gate blowout preventer 501 is closed. After connecting the tubing body 6, the blowout preventer box 504 is closed and the half-closed gate of the four-gate blowout preventer 501 is opened;

[0032] When lifting the tubing body 6, the tubing slip 603 is released, and the length of the first tubing body 6 at the injection wellhead 3 is adjusted so that the length of the tubing body 6 string meets the front position of the tubing body 6;

[0033] When the tubing body 6 is transported downward, the tubing body 6 is grasped by the upper slip 704, and at the same time, the lower slip 702 is released, and the tubing body 6 is transported downward to the bottom by the upper slip 704 through the hydraulic telescopic rod 7. At this time, the lower slip 702 clamps the tubing body 6, and the upper slip 704 is released and moved upward to the top through the hydraulic telescopic rod 7 to re-grab the new tubing body 6. The above process is repeated until the tubing body 6 is transported to the designed position, the tubing slip 603 clamps the tubing body 6, the semi-closed gate of the four-gate blowout preventer 501 is closed, the tubing lifting short section is unhooked and taken out, the semi-closed gate of the four-gate blowout preventer 501 is opened, the main valve 503 is closed, and the production of the gasifier body 2 is resumed;

[0034] When the gasifier body 2 fails, it is necessary to adjust or replace the tool at the front end of the oil pipe body 6, and then the entire oil pipe body 6 must be strung out;

[0035] When the tubing body 6 is pulled out, nitrogen is injected into the annulus inside the tubing body 6 to replace the oxygen in the annulus inside the tubing body 6. After the replacement is completed, the flow regulating valve 507 is closed, the gas detector 505 is turned on to monitor the toxic and harmful gases in the operation area in real time, the half-closed gate of the four-gate blowout preventer 501 is closed, and the main valve 503 is opened;

[0036] Subsequently, the upper slip valve 704 clamps the oil pipe body 6, and the lower slip valve 702 is released. When the upper slip valve 704 moves to the connecting buckle of the oil pipe body 6, the lower slip valve 702 clamps the next oil pipe body 6, and the above process is repeated until the oil pipe is lifted to the designed position, the main valve 503 is closed, and the production of the gasifier body 2 is resumed.

[0037] Through the above steps, the reaction position of the coal seam 1 is clarified by setting the gasifier body 2, the completion casing 4 is fixed by the casing assembly, the placement path of the oil pipe body 6 is clarified by the completion casing 4, and it is ensured that the oil pipe body 6 can extend to the gasification reaction position of the gasifier body 2, the wellhead injection device 5 is fixed by the injection wellhead 3, the injection assembly is connected through the wellhead injection device 5, and the oxidant and other raw materials required for gasification are injected into the wellhead injection device 5 by the injection assembly, and the gasification raw materials are transported to the oil pipe body 6 by the wellhead injection device 5, so that the raw materials are injected from the oil pipe body 6 into the gasifier body 2 for gasification reaction. After a period of reaction, the oxidant injection position needs to be adjusted. At this time, the telescopic hydraulic telescopic rod 7 controls the lifting and lowering of the lifting assembly, and the lifting and lowering of the oil pipe body 6 are driven by the lifting assembly to flexibly adjust the oxidant injection position, thereby flexibly controlling the underground gasifier reaction zone, and effectively ensuring the output and quality of the synthetic gas produced.

[0038] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the spirit of the present invention.

Claims

1. A tubing lifting control system for underground coal gasification process, comprising a coal seam (1), a gasification furnace body (2), an injection wellhead (3), and an tubing body (6), characterized in that: The invention also comprises a completion casing (4), a casing assembly, a wellhead injection device (5), an injection assembly, an oil pipe assembly, a hydraulic telescopic rod (7) and a lifting assembly. A gasification furnace body (2) is arranged on the inner side of the coal seam (1), an injection wellhead (3) is arranged on the ground above the coal seam (1), a completion casing (4) is arranged on the inner side of the injection wellhead (3), one end of the completion casing (4) is connected to the gasification furnace body (2), a casing assembly is arranged on the outer side of the completion casing (4), a wellhead injection device (5) is arranged above the injection wellhead (3), an injection assembly is arranged on one side of the wellhead injection device (5), an oil pipe body (6) is arranged on the inner side of the completion casing (4), the oil pipe body (6) is arranged in multiple sections, an oil pipe assembly is arranged on one side of the oil pipe body (6), a hydraulic telescopic rod (7) is arranged on one side of the injection wellhead (3), and a lifting assembly is arranged on one side of the hydraulic telescopic rod (7).

2. The oil pipe lifting control system for underground coal gasification process according to claim 1, characterized in that: The casing assembly comprises a technical casing (401) and a cement ring (402). The technical casing (401) is arranged on the outside of the completion casing (4), and the cement ring (402) is arranged on the outside of the technical casing (401). The cement ring (402) is arranged on the bottom surface of the injection wellhead (3).

3. The oil pipe lifting control system for underground coal gasification process according to claim 1, characterized in that: The injection assembly comprises a four-gate blowout preventer (501), a working window (502), a main valve (503) and a blowout preventer box (504); the top of the injection wellhead (3) is provided with the four-gate blowout preventer (501); the top of the four-gate blowout preventer (501) is provided with a working window (502); a wellhead injection device (5) is provided above the working window (502); a main valve (503) is provided on one side of the wellhead injection device (5); and a blowout preventer box (504) is provided on one side of the main valve (503).

4. The oil pipe lifting control system for underground coal gasification process according to claim 3 is characterized in that: The injection assembly also includes a gas detector (505), a connecting pipe (506), a flow regulating valve (507), an oxidant storage tank (508), an oxygen injection pump (509), a water storage tank (510), a water pump (511), a nitrogen tank (512) and a nitrogen injection pump (513). The gas detector (505) is arranged above the wellhead injection device (5), and a connecting pipe (506) is arranged on one side of the wellhead injection device (5). The outer side of the connecting pipe (506) A flow regulating valve (507) is provided, an oxidant storage tank (508) is provided at one end of the connecting pipe (506), an oxygen injection pump (509) is provided above the oxidant storage tank (508), a water storage tank (510) is provided at one end of the connecting pipe (506), a water pump (511) is provided above the water storage tank (510), a nitrogen tank (512) is provided at one end of the connecting pipe (506), and a nitrogen injection pump (513) is provided above the nitrogen tank (512).

5. The oil pipe lifting control system for underground coal gasification process according to claim 3, characterized in that: One end of the connecting pipe (506) is interconnected with the wellhead injection device (5), and the other end of the connecting pipe (506) is interconnected with the oxidant storage tank (508), the water storage tank (510) and the nitrogen tank (512). The oxygen injection pump (509), the water pump (511) and the nitrogen injection pump (513) are electrically connected to the connecting pipe (506).

6. The oil pipe lifting control system for underground coal gasification process according to claim 3, characterized in that: The oil pipe assembly comprises an oil pipe seater (601), an oil pipe check valve (602) and an oil pipe slip (603). The oil pipe seater (601) is arranged above the working window (502), the oil pipe check valve (602) is arranged on the inner side of the oil pipe body (6), and the oil pipe check valve (602) is arranged in multiple groups. An oil pipe slip (603) is arranged on one side of the oil pipe seater (601), and the oil pipe slip (603) is arranged at one end of the oil pipe body (6).

7. The oil pipe lifting control system for underground coal gasification process according to claim 3, characterized in that: The lifting assembly comprises a support plate (701), a lower slip (702), a telescopic plate (703) and an upper slip (704); a support plate (701) is arranged on one side of an injection wellhead (3); a lower slip (702) is arranged on one side of the support plate (701); a telescopic plate (703) is arranged on the inner side of the support plate (701); the telescopic plate (703) and the support plate (701) are slidably connected to each other; the telescopic plate (703) is arranged at one end of a hydraulic telescopic rod (7); and an upper slip (704) is arranged on one side of the telescopic plate (703).

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