Multi-well cooperative oxygen injection control oil-rich coal in-situ pyrolysis system and method

Abstract

The invention discloses a multi-well cooperative oxygen injection control oil-rich coal in-situ pyrolysis system and method.The system comprises a multi-layer horizontal well network, an upper first combustion horizontal well, a middle pyrolysis / gasification horizontal well and a lower second combustion horizontal well which are arranged in an initial land parcel and communicate with the ground through vertical wells correspondingly; the pyrolysis method comprises three stages: in the first stage, low-oxygen-concentration mixed gas is injected into a pyrolysis / gasification injection well, and an electric heater is combined to start a coal seam pyrolysis reaction, and in the second stage, high-oxygen-concentration gas is injected into an upper combustion injection well and a lower combustion injection well, upper and lower coal seams are ignited, and heat is supplied to pyrolysis of a middle coal seam; in the third stage, medium-oxygen-concentration gas is injected into a pyrolysis / gasification injection well, residual semicoke is gasified, and a gasified product provides a starting heat source for a subsequent plot; and ordered conversion of pyrolysis-combustion-gasification in the plot and cross-plot energy circulation are achieved through multi-well cooperation and accurate oxygen control, external energy dependence and operation cost are reduced, and the utilization rate of oil-rich coal resources is increased.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of energy, and relates to a pyrolysis system and method for oil-rich coal, in particular to an oil-rich coal in-situ pyrolysis system and method with multi-well coordinated oxygen injection. BACKGROUND

[0002] As a new technology proposed in recent years, oil-rich coal in-situ pyrolysis directly heats the coal seam underground to convert it into target oil and gas resources and extract them to the ground for use. The core challenge of current oil-rich coal in-situ conversion technology is how to achieve efficient and comprehensive utilization of coal seam resources. Traditional in-situ heating methods cannot form a uniform heat field in thick coal seams, resulting in excessive reaction near the wellbore area and insufficient heat in the distal region, causing a large amount of coal resources to be wasted. In addition, the single in-situ pyrolysis process mainly extracts volatile matter from coal, leaving a large amount of semi-coke products wasted, resulting in low overall resource utilization of oil-rich coal.

[0003] In-situ combustion and in-situ gasification are common methods for mining strata. When heating or reacting with oxygen-containing media, process control is particularly critical. Too low oxygen concentration may cause the reaction to stop, while too high oxygen concentration may easily cause uncontrollable intense combustion, not only posing a safety hazard, but also damaging the quality and yield of target products. By injecting oxygen, oil-rich coal in-situ mining can be achieved while regulating oxygen concentration to control different reaction types (slow oxidation, combustion, gasification), thereby achieving directional conversion of oil-rich coal and semi-coke resources (thermal energy, oil and gas products, etc.), which can maximize the utilization of oil-rich coal resources. Therefore, it is of great practical significance to develop an oil-rich coal in-situ pyrolysis system and method with multi-well coordinated oxygen injection. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide an in-situ pyrolysis system and method for heating inclined oil-rich coal seams in sections, which enriches the heat source for oil-rich coal in-situ mining and significantly improves the utilization rate of oil-rich coal resources.

[0005] The present application is achieved by the following technical solutions: An oil-rich coal in-situ pyrolysis system with multi-well coordinated oxygen injection, a first combustion injection well, a second combustion injection well, a pyrolysis / gasification injection well, a first combustion output well, a second combustion output well and a pyrolysis / gasification production well are vertically excavated into the interior of the oil-rich coal seam from the ground, a first combustion horizontal well is excavated to connect the first combustion injection well and the first combustion output well, a second combustion horizontal well is excavated to connect the second combustion injection well and the second combustion output well, a pyrolysis / gasification horizontal well is excavated to connect the pyrolysis / gasification injection well and the pyrolysis / gasification production well, and the first combustion horizontal well, the pyrolysis / gasification horizontal well and the second combustion horizontal well are sequentially arranged in the vertical direction from top to bottom. A No. 1 mixing unit and an air compressor are arranged at the wellhead of the pyrolysis / gasification injection well, a gas-liquid separation device is arranged at the pyrolysis / gasification production well, a No. 2 mixing unit is arranged at the wellhead of the first combustion injection well and the second combustion injection well, and a No. 3 mixing unit is arranged at the wellhead of the first combustion output well and the second combustion output well; an electric heater is arranged in the pyrolysis / gasification horizontal well, and an igniter is arranged in the first combustion horizontal well and the second combustion horizontal well; In the first stage, the low-oxygen-concentration mixed gas is injected into the pyrolysis / gasification injection well through the No. 1 mixing unit and the air compressor, and the coal bed pyrolysis reaction is started by the electric heater; in the second stage, the high-temperature gas generated in the first stage and oxygen are injected into the first combustion injection well and the second combustion injection well through the No. 2 mixing unit, the upper and lower coal beds are ignited by the igniter, and the middle coal bed is heated for pyrolysis; in the third stage, the high-temperature combustion flue gas generated in the second stage is injected into the pyrolysis / gasification injection well through the No. 3 mixing unit and the air compressor, the residual semi-coke is gasified, the gasification products are used to start the pyrolysis reaction of the second land, and the orderly conversion of pyrolysis-combustion-gasification and the cross-land energy circulation are realized by multi-well cooperation and oxygen control.

[0006] Preferably, an insulation layer is arranged at the top and bottom of the oil-rich coal bed.

[0007] Preferably, a temperature and gas component sensor is arranged at the bottom end of the first combustion output well, the second combustion output well and the pyrolysis / gasification production well.

[0008] Preferably, a plurality of pyrolysis / gasification horizontal wells are arranged in the thick coal bed to connect the same group of pyrolysis / gasification injection wells and pyrolysis / gasification production wells at different depths, and the first combustion horizontal well and the second combustion horizontal well are laid on the upper and lower layers of each pyrolysis / gasification horizontal well.

[0009] The multi-well cooperation oxygen control injection oil-rich coal in-situ pyrolysis method comprises the following steps: 1) The low-oxygen-concentration flue gas and the compressed air prepared by the air compressor are introduced into the No. 1 mixing unit to generate low-oxygen-concentration mixed gas, which is injected into the oil-rich coal bed along the pyrolysis / gasification injection well, the electric heater in the pyrolysis / gasification fluid passage is turned on, the product flows out of the pyrolysis / gasification production well, and then is introduced into the gas-liquid separation device, the pyrolysis tar obtained by separation is collected, and the remaining high-temperature gas enters the No. 2 mixing unit to mix with high-purity oxygen from a liquid oxygen tank; 2) On the basis of maintaining the reaction of step 1), the high-oxygen-concentration mixed gas output by the No. 2 mixing unit is injected into the first combustion injection well and the second combustion injection well, the igniter at the bottom of the injection well is turned on, a combustion reaction occurs, and the high-temperature combustion flue gas flows out of the first combustion output well and the second combustion output well, and then is mixed with the compressed air prepared by the air compressor in the No. 3 mixing unit; 3) When the oil-rich coal resources near the top and bottom of the oil-rich coal seam are exhausted, the main coal seam area is pyrolyzed, and a large amount of semi-coke products remain, the first and second stage reactions are terminated. The medium-oxygen concentration mixed gas output from the No. 3 mixing unit is injected into the pyrolysis / gasification injection well. The igniter at the bottom of the injection well is turned on, and a gasification reaction occurs. The gasification products flow out along the pyrolysis / gasification production well and enter the gas-fired heating furnace, where they are burned and heated by the compressed air from the air compressor. The resulting high-temperature air and the combustion flue gas from the heating furnace are then introduced into the No. 1 mixing unit of the second block to generate a low-oxygen concentration mixed gas, which is then injected into the second block. The above process is repeated.

[0010] Preferably, the initial plot adopts a composite heating method that couples electric heating and convection heating, while the second plot and subsequent plots adopt a single convection heating method.

[0011] Preferably, in the first stage, the initial plot utilizes the flue gas from the gas turbine, and an electric heater is arranged inside the pyrolysis / gasification fluid channel. The heat required for the reaction start-up comes from the waste heat of the flue gas and the electric heater. In the first stage, the second plot utilizes the combustion flue gas from the heating furnace of the gasification products of the initial plot. No electric heater is required inside the pyrolysis / gasification fluid channel. The heat required for the reaction start-up comes from the heat released by the combustion of the gasification products of the initial plot in the gas heating furnace.

[0012] Preferably, the oxygen content of the low-oxygen-concentration mixed gas is 1-8%, the oxygen content of the medium-oxygen-concentration mixed gas is 8-18% (>18%), and the oxygen content of the high-oxygen-concentration mixed gas is >18%.

[0013] This invention's system deploys a multi-layered horizontal well network in the initial coal seam: an upper first combustion horizontal well, a middle pyrolysis / gasification horizontal well, and a lower second combustion horizontal well, all connected to the surface via vertical wells. Through the coordinated operation of horizontal wells at different depths and precise control of oxygen concentration, different reaction zones are formed in different parts of the coal seam, with oxygen concentrations from low to high corresponding to pyrolysis and slow oxidation reactions, gasification reactions, and combustion reactions, respectively. In the first stage, a low-oxygen-concentration mixed gas is injected into the pyrolysis / gasification injection well, combined with an electric heater to initiate the coal seam pyrolysis reaction. In the second stage, a high-oxygen-concentration gas is injected into the upper and lower combustion injection wells, igniting the upper and lower coal seams and providing heat for the pyrolysis of the middle coal seam. In the third stage, a medium-oxygen-concentration gas is injected into the pyrolysis / gasification injection well to gasify the residual semi-coke. The gasification products provide a start-up heat source for subsequent coal seams. Through multi-well coordination and precise oxygen control, the system achieves an orderly conversion between pyrolysis, combustion, and gasification within the coal seam and cross-landscape energy circulation, reducing external energy dependence and operating costs, and significantly improving the utilization rate of oil-rich coal resources. By operating different plots together, the oil-rich coal resources are utilized to the maximum extent, and the final product is pyrolysis tar.

[0014] The present invention has at least the following beneficial technical effects: (1) The coal seam is divided into three functional layers in the vertical direction—the upper and lower combustion and heating layers and the middle core pyrolysis layer, which realizes the layered development of a single coal seam, and can orderly extract energy and materials from different areas, thereby improving the overall coal seam resource extraction rate.

[0015] (2) The heat of combustion of the gasification products of the initial plot is used to start the pyrolysis reaction of the second plot, which significantly reduces the external energy input for the development of subsequent plots and realizes the self-sustaining of energy between different plots.

[0016] (3) The hydrocarbon gas generated in the first stage of pyrolysis is used as the reactant in the second stage of combustion reaction. This simplifies the ground gas treatment process and reduces operating costs while making full use of intermediate products.

[0017] (4) In the first stage, by strictly controlling the oxygen concentration (1-8%), the oxidation reaction is limited to a relatively mild range, making it an auxiliary heat source to maintain the pyrolysis temperature and reducing external economic input.

[0018] (5) The flue gas discharged from the gas turbine is injected into the initial plot, which realizes the effective utilization of waste heat. At the same time, its inert gas components help to create a controllable low-oxygen environment.

[0019] (6) Adding insulation layers to the top and bottom of the coal seam concentrates heat into the target coal seam, reduces heat loss, and effectively improves heating efficiency.

[0020] (7) The initial plots rely on high-grade electrical energy for startup, while subsequent plots rely entirely on low-grade process waste heat. This energy input method can significantly reduce operating costs and reduce dependence on high-quality energy, which is of great strategic significance.

[0021] (8) First, the thermal energy and oil and gas resources of the coal seam are extracted through combustion and pyrolysis reactions respectively. Then, the remaining semi-coke is converted into thermal energy and syngas through gasification reaction. Finally, the ash remains underground, thus maximizing the utilization of oil-rich coal resources. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the multi-well coordinated oxygen-controlled injection in-situ pyrolysis system for oil-rich coal according to the present invention; Figure 2 This is a top view of the well layout structure of the multi-well coordinated oxygen-controlled injection in-situ pyrolysis system for oil-rich coal according to the present invention. Explanation of reference numerals in the attached diagram: 1 represents an oil-rich coal seam; 2 represents surrounding rock strata; 3 represents a pyrolysis / gasification injection well; 4 represents the first combustion injection well; 5 represents the second combustion injection well; 6 represents a pyrolysis / gasification production well; 7 represents the first combustion output well; 8 represents the second combustion output well; 9 represents a pyrolysis / gasification horizontal well; 10 represents the first combustion horizontal well; 11 represents the second combustion horizontal well; 12 represents an insulation layer; 13 represents an electric heater; 14 represents a temperature and gas composition sensor; 15 represents an igniter; 16 represents a semi-coke layer; and 17 represents a pyrolysis-slow-release layer. Slow oxidation zone, 18 is combustion zone, 19 is gasification zone, 20 is combustion cavity, 21 is mixing unit 1, 22 is mixing unit 2, 23 is mixing unit 3, 24 is gas-liquid separator, 25 is oil storage tank, 26 is gas-fired heater, 27 is gas turbine, 28 is liquid oxygen tank, 29 is air compressor, 30 is high-temperature gas, 31 is high-temperature combustion flue gas, 32 is gasification product, 33 is high-temperature air, 34 is heater combustion flue gas, 35 is initial plot, 36 is second plot. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0024] See Figure 1 As shown, the multi-well coordinated oxygen-controlled injection in-situ pyrolysis system for oil-rich coal of the present invention includes an initial block 35 containing an oil-rich coal seam 1 and surrounding rock strata 2. A first combustion injection well 4, a second combustion injection well 5, a pyrolysis / gasification injection well 3, a first combustion output well 7, a second combustion output well 8, and a pyrolysis / gasification production well 6 are excavated vertically downwards from the ground. A first combustion horizontal well 10 is excavated within the oil-rich coal seam 1 to connect the first combustion injection well 4 and the first combustion output well 7. A second combustion horizontal well 11 is excavated to connect the second combustion injection well 5 and the second combustion output well 8. A pyrolysis / gasification horizontal well 9 is excavated to connect the pyrolysis / gasification injection well 3 and the pyrolysis / gasification production well 6. Vertically, from top to bottom, the components are the first combustion horizontal well 10, the pyrolysis / gasification horizontal well 9, and the second combustion horizontal well 11. Thermal insulation layers 12 are added at the top and bottom of the coal seam. In the first stage, the flue gas discharged from the gas turbine 27 and the compressed air prepared by the air compressor 29 are introduced into the No. 1 mixing unit 21 to generate a low-oxygen concentration mixed gas, which is then injected into the oil-rich coal seam 1 along the pyrolysis / gasification injection well 3. The electric heater 13 inside the pyrolysis / gasification fluid channel is turned on, and the oil-rich coal seam 1 undergoes a chemical reaction mainly based on in-situ pyrolysis and supplemented by slow oxidation. At this time, the pyrolysis / gasification injection well 3, the pyrolysis / gasification horizontal well 9, and the pyrolysis / gasification production well 6 function as a pyrolysis injection well, a pyrolysis horizontal well, and a pyrolysis production well, respectively. The main coal seam area near the pyrolysis / gasification horizontal well 9 is the pyrolysis-slow oxidation zone 17. After the products flow out along the pyrolysis / gasification production well 6, they are introduced into the gas-liquid separation device 24, and the separated pyrolysis tar is collected in the oil storage tank 25. In the middle stage, the remaining high-temperature gas (mainly pyrolysis hydrocarbon gas) 30 enters the No. 2 mixing unit 22 and mixes with the high-purity oxygen from the liquid oxygen tank 28. In the second stage, while maintaining the reaction in the first stage, the high-oxygen-concentration mixed gas output from the No. 2 mixing unit 22 is injected into the first combustion injection well 4 and the second combustion injection well 5. The igniter 15 at the bottom of the injection well is turned on, and a combustion reaction occurs. The heat released by the combustion spreads to the middle oil-rich coal seam 1, which helps the in-situ pyrolysis reaction in the main coal seam area. The coal seam area near the first combustion horizontal well 10 and the second combustion horizontal well 11 is the combustion zone 18. After the high-temperature combustion flue gas 31 flows out from the first combustion output well 7 and the second combustion output well 8, it enters the No. 3 mixing unit 23 and mixes with the compressed air prepared by the air compressor 29. In the third stage, the oil-rich coal resources near the top and bottom of the oil-rich coal seam 1 are exhausted, the main coal seam area is pyrolyzed, and a large amount of semi-coke products remain. At this time, the first and second stage reactions are terminated, and the medium-oxygen concentration mixed gas output from the No. 3 mixing unit 23 is injected into the pyrolysis / gasification injection well 3. The igniter 15 at the bottom of the injection well is turned on, and a gasification reaction occurs. At this time, the functions of the pyrolysis / gasification injection well 3, the pyrolysis / gasification horizontal well 9, and the pyrolysis / gasification production well 6 are respectively gasification injection well, gasification horizontal well, and gasification production well. The main coal seam area near the pyrolysis / gasification horizontal well 9 is the gasification zone 19. The product 32 flows out along the pyrolysis / gasification production well 6 and enters the gas-fired heating furnace 26, where it is burned and heated by the compressed air from the air compressor 29. The generated high-temperature air 33 and the combustion flue gas 34 of the heating furnace are introduced into the No. 1 mixing unit 21 of the second block 36 to generate a low-oxygen concentration mixed gas, which is then injected into the second block 36, and the above process is repeated.

[0025] Different oxygen concentrations of gas were injected sequentially to control the dominant reactions at different stages. The mixed gas with low to high oxygen concentrations corresponded to the pyrolysis and slow oxidation reaction, gasification reaction, and combustion reaction of the oil-rich coal seam 1, respectively. The first stage was dominated by the pyrolysis and slow oxidation reaction, which extracted a large amount of oil and gas resources while reducing energy input. Oxygen served as a heat supplement source. The second stage was dominated by the combustion reaction, which made full use of the pyrolysis gas and coal resources near the top / bottom plate to facilitate the pyrolysis reaction in the first stage. The third stage was dominated by the gasification reaction, in which the energy of the coal resources was transferred to the gasification products, and the heat from combustion was used to start the pyrolysis reaction in the second block.

[0026] In the first stage, the initial plot 35 utilizes the flue gas from the gas turbine 27. An electric heater 13 is arranged inside the pyrolysis / gasification fluid channel. The heat required for the reaction start-up comes from the waste heat of the flue gas and the electric heater 13. In the first stage, the second plot 36 utilizes the combustion flue gas 34 of the gasification product 32 from the initial plot 35 in the heating furnace. No electric heater 13 is required inside the pyrolysis / gasification fluid channel. The heat required for the reaction start-up comes from the heat released by the combustion of the gasification product 32 from the initial plot 35 in the gas heating furnace 26.

[0027] The initial plot 35 adopts a combined heating method that couples electric heating and convection heating, while the second plot 35 and subsequent plots adopt a single convection heating method.

[0028] Temperature and gas composition sensors 14 are installed at the bottom of the first combustion output well 7, the second combustion output well 8, and the pyrolysis / gasification production well 6 to implement feedback regulation of the inlet gas injection rate and oxygen concentration. The oxygen content of the low-oxygen-concentration, medium-oxygen-concentration, and high-oxygen-concentration mixed gases are 1-8%, 8-18%, and >18%, respectively.

[0029] See Figure 2 As shown, the dashed lines only represent the geometry of the well layout; the viewing result along the line of sight is... Figure 1 The number of horizontal wells is increased in thicker coal seams. Multiple pyrolysis / gasification horizontal wells 9 are connected to the same group of pyrolysis / gasification injection wells 3 and pyrolysis / gasification production wells 6 at different depths. The first combustion horizontal well 10 and the second combustion horizontal well 11 are laid in the same manner.

[0030] The present invention relates to a multi-well coordinated oxygen-controlled injection method for in-situ pyrolysis of oil-rich coal, comprising the following steps: 1) The flue gas discharged from the gas turbine 27 and the compressed air prepared by the air compressor 29 are introduced into the No. 1 mixing unit 21 to generate a low oxygen concentration mixed gas and inject it into the oil-rich coal seam 1 along the pyrolysis / gasification injection well 3. The electric heater 13 inside the pyrolysis / gasification fluid channel is turned on. The product flows out along the pyrolysis / gasification production well 6 and is introduced into the gas-liquid separation device 24. The separated pyrolysis tar is collected into the oil storage tank 25. The remaining high temperature gas 30 enters the No. 2 mixing unit 22 and is mixed with high purity oxygen from the liquid oxygen tank 28. 2) While maintaining the first stage reaction, the high oxygen concentration mixed gas output from the No. 2 mixing unit 22 is injected into the first combustion injection well 4 and the second combustion injection well 5. The igniter 15 at the bottom of the injection well is turned on, and a combustion reaction occurs. The high temperature combustion flue gas 31 flows out from the first combustion output well 7 and the second combustion output well 8 and enters the No. 3 mixing unit 23 to mix with the compressed air prepared by the air compressor 29. 3) When the oil-rich coal resources near the top and bottom of the oil-rich coal seam 1 are exhausted, the main coal seam area is pyrolyzed and a large amount of semi-coke products remain, the first and second stage reactions are terminated. The medium-oxygen concentration mixed gas output from the No. 3 mixing unit 23 is injected into the pyrolysis / gasification injection well 3. The igniter 15 at the bottom of the injection well is turned on, and a gasification reaction occurs. The gasification product 32 flows out along the pyrolysis / gasification production well 6 and enters the gas heating furnace 26, where it is burned and heated by the compressed air from the air compressor 29. The resulting high-temperature air 33 and the combustion flue gas 34 of the heating furnace are introduced into the No. 1 mixing unit 21 of the second block 36 to generate a low-oxygen concentration mixed gas, which is then injected into the second block 36. The above process is repeated.

Claims

1. A multi-well coordinated oxygen-controlled injection of oil-rich coal in-situ pyrolysis system, characterized by: The first combustion injection well (4), the second combustion injection well (5), the pyrolysis / gasification injection well (3), the first combustion output well (7), the second combustion output well (8) and the pyrolysis / gasification production well (6) are vertically downwardly excavated into the deep oil-rich coal seam (1) from the ground, the first combustion horizontal well (10) is excavated to connect the first combustion injection well (4) and the first combustion output well (7) in the oil-rich coal seam (1), the second combustion horizontal well (11) is excavated to connect the second combustion injection well (5) and the second combustion output well (8), the pyrolysis / gasification horizontal well (9) is excavated to connect the pyrolysis / gasification injection well (3) and the pyrolysis / gasification production well (6), and the first combustion horizontal well (10), the pyrolysis / gasification horizontal well (9) and the second combustion horizontal well (11) are sequentially arranged from top to bottom in the vertical direction; The 1st mixing unit (21) and the air compressor (29) are arranged at the well mouth of the pyrolysis / gasification injection well (3), the gas-liquid separation device (24) is arranged at the pyrolysis / gasification production well (6), the 2nd mixing unit (22) is arranged at the well mouth of the first combustion injection well (4) and the second combustion injection well (5), and the 3rd mixing unit (23) is arranged at the well mouth of the first combustion output well (7) and the second combustion output well (8); the electric heater (13) is arranged in the pyrolysis / gasification horizontal well (9), and the igniter (15) is arranged in the first combustion horizontal well (10) and the second combustion horizontal well (11); In the first stage, the low-oxygen-concentration mixed gas is injected into the pyrolysis / gasification injection well (3) through the 1st mixing unit (21) and the air compressor (29), and the coal seam pyrolysis reaction is started through the electric heater (13); in the second stage, the high-temperature gas (30) generated in the first stage and oxygen are injected into the first combustion injection well (4) and the second combustion injection well (5) through the 2nd mixing unit (22), and the upper and lower coal seams are ignited through the igniter (15) and heat is supplied for the middle coal seam pyrolysis; in the third stage, the high-temperature combustion flue gas (31) generated in the second stage is injected into the pyrolysis / gasification injection well through the 3rd mixing unit (23) and the air compressor (29), and the residual semi-coke is gasified, the gasification products are used to start the pyrolysis reaction of the second land block (36), and the orderly conversion of pyrolysis-combustion-gasification and the cross-land block energy circulation are realized through multi-well cooperation and oxygen control.

2. The multi-well coordinated oxygen-controlled injection of oil-rich coal in-situ pyrolysis system of claim 1, wherein: The heat insulation layer (12) is arranged at the top plate and the bottom plate positions of the oil-rich coal seam (1).

3. The multi-well coordinated oxygen-controlled injection of oil-rich coal in-situ pyrolysis system of claim 2, wherein: The temperature and gas component sensors (14) are arranged at the bottom ends of the first combustion output well (7), the second combustion output well (8) and the pyrolysis / gasification production well (6).

4. The multi-well coordinated oxygen-controlled injection of oil-rich coal in-situ pyrolysis system of claim 3, wherein: In the thicker coal seam, a plurality of pyrolysis / gasification horizontal wells (9) are arranged to connect the same group of pyrolysis / gasification injection wells (3) and pyrolysis / gasification production wells (6) at different depth positions, and the first combustion horizontal well (10) and the second combustion horizontal well (11) are laid on the upper and lower layers of each pyrolysis / gasification horizontal well (9).

5. The multi-well coordinated oxygen-controlled injection enriched oil in-situ coal pyrolysis method according to any one of claims 1-4, wherein The method comprises the following steps: 1), the low oxygen concentration flue gas and air compressor (29) preparation of compressed air into the first mixing unit (21), the generation of low oxygen concentration mixed gas and along the pyrolysis / gasification injection well (3) injection oil-rich coal seam (1) inside, open pyrolysis / gasification fluid passage inside the electric heater (13), the product along the pyrolysis / gasification production well (6) flow into the gas-liquid separation device (24), collection and separation of pyrolysis tar, the remaining high temperature gas (30) into the second mixing unit (22), and mixed with high purity oxygen from the liquid oxygen tank (28); 2), on the basis of maintaining step 1) reaction, the high oxygen concentration mixed gas from the second mixing unit (22) is injected into the first combustion injection well (4) and the second combustion injection well (5), the igniter (15) at the bottom of the injection well is opened, and the high temperature combustion flue gas (31) flows out from the first combustion output well (7) and the second combustion output well (8) and enters the third mixing unit (23) and mixes with the compressed air prepared by the air compressor (29); 3), the oil-rich coal resources near the roof and floor of the oil-rich coal seam (1) are consumed, the main coal seam area is pyrolyzed, and a large amount of semi-coke products remain, at this time, the first stage and the second stage reaction are terminated, the medium oxygen concentration mixed gas from the third mixing unit (23) is injected into the pyrolysis / gasification injection well (3), the igniter (15) at the bottom of the injection well is opened, and the gasification reaction occurs, the gasification product (32) flows out along the pyrolysis / gasification production well (6) and enters the gas heating furnace (26), burns and heats the compressed air from the air compressor (29), the obtained high temperature air (33) and the heating furnace combustion flue gas (34) are introduced into the first mixing unit (21) of the second plot (36), a low oxygen concentration mixed gas is generated and injected into the second plot (36), and the above process is repeated.

6. The multi-well coordinated oxygen-controlled injection of oil-rich coal in-situ pyrolysis system of claim 5, wherein: The initial plot (35) adopts a composite heating mode of coupling electric heating and convection heating, and the second plot (35) and subsequent plots adopt a single convection heating mode.

7. The multi-well coordinated oxygen-controlled injection of oil-rich coal in-situ pyrolysis system of claim 5, wherein: The initial plot (35) uses the flue gas of the gas turbine (27) in the first stage, and the electric heater (13) is arranged inside the pyrolysis / gasification fluid passage, and the heat required for reaction start is obtained from the flue gas waste heat and the electric heater (13), the second plot (36) uses the heating furnace combustion flue gas (34) of the gasification product (32) of the initial plot (35) in the first stage, and the electric heater (13) does not need to be arranged inside the pyrolysis / gasification fluid passage, and the heat required for reaction start is obtained from the combustion heat release of the gasification product (32) of the initial plot (35) in the gas heating furnace (26).

8. The multi-well coordinated oxygen-controlled injection of oil-rich coal in-situ pyrolysis system of claim 5, wherein: The oxygen content of the low oxygen concentration mixed gas is 1-8%, the oxygen content of the medium oxygen concentration mixed gas is 8-18%, and the oxygen content of the high oxygen concentration mixed gas is >18%.

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