In-situ pyrolysis system and method for heating oil-rich coal through slow oxidation of semicoke

Abstract

The invention discloses an in-situ pyrolysis system and method for heating oil-rich coal through slow oxidation of semicoke, the in-situ pyrolysis system comprises a pyrolysis semicoke block and an oil-rich coal block which are adjacent to each other, a pyrolysis injection well and a pyrolysis output well are excavated in the oil-rich coal block, and the semicoke block is formed after the oil-rich coal block is pyrolyzed; converting the pyrolysis injection well and the pyrolysis output well into a slow oxidation injection well and a slow oxidation output well; waste heat of a pyrolytic semi-coke stratum and slow oxidation heat release are used for a pyrolytic reaction of a subsequent coal seam, through combined operation of adjacent plots, heat and material resources of a semi-coke layer are fully utilized, effective development of pyrolytic semi-coke is achieved, meanwhile, a new feasible in-situ heating way is provided, oil-rich coal resources are comprehensively utilized, and the economic benefit is improved. External heat energy does not need to be additionally injected, and remarkable economic advantages are achieved; cO2 generated by slow oxidation of the semicoke and combustion power generation of oil-rich coal pyrolysis product gas is sealed and stored in a pyrolysis semicoke block, carbon emission reduction is effectively achieved, and the method has remarkable environmental advantages.

Description

Technical Field

[0001] The invention belongs to the technical field of boilers, relates to the technical field of gas heating and flue gas waste heat recovery, and in particular to an in-situ pyrolysis system and method for slowly oxidizing and heating oil-rich coal with semi-coke. Background Art

[0002] Oil-rich coal is a type of coal with a tar content of 7 to 12%. The research on using coal-to-oil technology to increase oil and gas production has been widely and deeply discussed. However, the traditional coal mining and utilization process will cause serious environmental pollution, resource waste, casualties and other problems. Based on this, in recent years, a new concept of in-situ pyrolysis of oil-rich coal has been proposed, that is, directly heating the oil-rich coal in situ underground, pyrolyzing it to generate oil and gas products and extracting them to the ground. The development and application of in-situ pyrolysis technology of oil-rich coal provides a way to supply oil and gas with broad application prospects.

[0003] Common in-situ heating methods include conduction heating, convection heating and radiation heating. Regardless of the heating method used, a large amount of external energy injection is required, resulting in huge economic costs. Semi-coke is one of the final products formed by the in-situ pyrolysis of oil-rich coal. After the oil-rich coal is pyrolyzed to remove oil and gas products, the remaining solid semi-coke remains underground to form a huge carbon matrix. The abandonment of the semi-coke will cause a waste of resources. By using the waste heat of the semi-coke layer and the heat released by its slow oxidation reaction for the subsequent heating and pyrolysis of the coal seam, the economic investment can be significantly reduced, the joint operation of adjacent plots and the full utilization of the semi-coke layer resources can be achieved. Therefore, it is of great practical significance to develop an in-situ pyrolysis system and method for slow oxidation heating of oil-rich coal by semi-coke. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an in-situ pyrolysis system and method for slow oxidation heating of oil-rich coal by semi-coke, so as to achieve full and comprehensive utilization of land resources and joint operation of adjacent land plots, and effectively reduce economic investment.

[0005] The present invention is achieved through the following technical solutions:

[0006] An in-situ pyrolysis system for heating oil-rich coal by slow oxidation of semi-coke comprises a plurality of adjacent oil-rich coal plots, wherein pyrolysis injection wells and pyrolysis output wells are excavated in the oil-rich coal plots; after pyrolysis of the oil-rich coal plots is completed, semi-coke plots are formed, and the pyrolysis injection wells and pyrolysis output wells are converted into slow oxidation injection wells and slow oxidation output wells;

[0007] A fan for injecting air into the pyrolysis semi-coke layer is provided at the inlet of the slow oxidation injection well of the pyrolysis semi-coke block; the outlet of the slow oxidation output well of the first pyrolysis semi-coke block is connected to the inlet of the pyrolysis injection well of the adjacent first oil-rich coal block through a pipeline, so as to inject the oxidation product of the slow oxidation reaction of the first pyrolysis semi-coke block into the first oil-rich coal block; the outlet of the pyrolysis output well of the first pyrolysis semi-coke block is connected to a gas-liquid separation device, the liquid phase outlet of the gas-liquid separation device is connected to an oil storage device, the gas phase outlet is connected to a combustion power generation device, and the flue gas outlet of the combustion power generation device is connected to a CO 2 Separation device;

[0008] The fan pumps air into the pyrolysis semi-coke plot, and the high-temperature oxidation products of the slow oxidation reaction in the pyrolysis semi-coke plot flow out along the slow oxidation output well and enter the adjacent oil-rich coal plot for pyrolysis reaction. The pyrolysis products and the gas that does not participate in the reaction flow out along the pyrolysis output well and enter the heat exchanger. After heat exchange and cooling with the air pumped in by the fan, they enter the gas-liquid separation device to separate the tar and collect it in the oil storage device. The remaining mixed gas is sent to the combustion power generation device for combustion reaction with the preheated air, and the combustion flue gas enters the CO 2 Separation device, separated CO 2 The flue gas sealed in the semi-coke block after the slow oxidation reaction and the remaining flue gas carrying the heat of the combustion reaction are continuously injected into the adjacent pyrolysis semi-coke block that has not undergone the slow oxidation reaction to participate in the next reaction.

[0009] Preferably, a pyrolysis injection well and a pyrolysis output well are excavated from the ground downwards in the oil-rich coal block, and a pyrolysis horizontal well connecting the pyrolysis injection well and the pyrolysis output well is excavated at the same time. After the pyrolysis of the oil-rich coal block is completed, a semi-coke block is formed, the pyrolysis injection well and the pyrolysis output well are converted into a slow oxidation injection well and a slow oxidation output well, and the pyrolysis horizontal well is converted into a slow oxidation horizontal well.

[0010] Preferably, the slow oxidation injection well and the slow oxidation output well are vertical wells extending vertically from the ground to the pyrolysis semi-coke layer of the pyrolysis semi-coke block; the pyrolysis injection well and the pyrolysis output well are vertical wells extending vertically from the ground to the oil-rich coal layer of the oil-rich coal block.

[0011] Preferably, the slow oxidation injection wells and the slow oxidation output wells in the pyrolysis semi-coke block are arranged in a triangular pattern, with the slow oxidation injection wells located at the vertices of the triangle and the slow oxidation output wells located at the circumcenter of the triangle; the pyrolysis injection wells and the pyrolysis output wells in the oil-rich coal block are arranged in a triangular pattern, with the pyrolysis injection wells located at the vertices of the triangle and the pyrolysis output wells located at the circumcenter of the triangle.

[0012] The in-situ pyrolysis method of semi-coke slow oxidation heating of oil-rich coal comprises the following steps:

[0013] 1) injecting fracturing fluid into the oil-rich coal seam along the pyrolysis injection well of the first oil-rich coal block to form a large number of irregular fracturing cracks;

[0014] 2) air is pumped into the first pyrolysis semi-coke plot along the slow oxidation injection well by a fan, the semi-coke layer of the first pyrolysis semi-coke plot retains residual heat of pyrolysis, a slow oxidation reaction occurs in the air atmosphere, and the oxidation product flows out along the slow oxidation output well and then continues to flow into the first oil-rich coal plot along the pyrolysis injection well, and the pyrolysis reaction is started in the oil-rich coal layer of the first oil-rich coal plot under convection heating of the high-temperature mixed gas;

[0015] 3) The pyrolysis products and the mixed gas that did not participate in the reaction flow out along the pyrolysis output well and enter the heat exchanger. After heat exchange and cooling with the air pumped in by the fan, they enter the gas-liquid separation device to obtain tar through condensation separation. The separated pyrolysis gas, CO 2 and N 2 The mixed gas is sent to the combustion power generation device to participate in the combustion reaction with the preheated air, and the generated flue gas enters the CO 2 The separation device separates CO 2 It is sealed in the first pyrolysis semi-coke block after the slow oxidation reaction, and the remaining flue gas carrying the heat of the combustion reaction continues to be injected into the second pyrolysis semi-coke block 2 to participate in the slow oxidation reaction.

[0016] Preferably, the atmosphere for the slow oxidation reaction of the first pyrolysis semi-coke block is air, and the atmosphere for the slow oxidation reaction of the remaining pyrolysis semi-coke blocks is air and separated CO 2 After the combustion of flue gas, the atmosphere participating in the pyrolysis reaction of the first oil-rich coal block is N 2 and CO 2 The atmosphere involved in the pyrolysis reaction of the remaining oil-rich coal blocks is N 2 , CO 2 and smoke mixture.

[0017] Preferably, the CO generated by the slow oxidation reaction of the first semi-coke block 2 , the first oil-rich coal block pyrolysis gas combustion power generation generated CO 2 They are all sealed in the first pyrolysis semi-coke block after the slow oxidation reaction.

[0018] Preferably, the pyrolysis products and the heat they carry are sent to a combustion power generation device for combustion reaction, and the combustion power generation device is used to power the fan.

[0019] Preferably, the heat release intensity of the slow oxidation reaction is changed by controlling the air injection rate into the semi-coke layer, thereby regulating the oil / gas production rate of the in-situ pyrolysis of the oil-rich coal.

[0020] The present invention opens injection wells and output wells in the oil-rich coal formation, and uses the residual heat of the pyrolysis semi-coke formation and the heat released by slow oxidation for the pyrolysis reaction of the subsequent coal seam. Through the joint operation of adjacent plots, the heat and material resources of the semi-coke layer are fully utilized, and the effective development of pyrolysis semi-coke is realized. In addition, the entire system operation process fully utilizes the oil-rich coal resources, and no additional external heat energy is required, which has significant economic advantages; the CO generated by the slow oxidation of semi-coke and the combustion of the pyrolysis product gas of the oil-rich coal for power generation 2 They are all sealed in pyrolysis semi-coke plots, effectively achieving carbon emission reduction and having significant environmental advantages.

[0021] The present invention sequentially carries out pyrolysis reaction of oil-rich coal and slow oxidation reaction of semi-coke on the plots of land. After the joint exploitation of the current semi-coke plot and the oil-rich coal plot is completed, the oil-rich coal plot is converted into a semi-coke plot, and the residual heat from pyrolysis of the semi-coke and the heat released from the slow oxidation reaction are both used for subsequent heating and pyrolysis of the oil-rich coal layer. The operation process does not require additional input of external energy, and effectively realizes the full utilization of heat and material in the semi-coke layer, while enriching the mining mode of in-situ pyrolysis and oil extraction of oil-rich coal.

[0022] The present invention has at least the following beneficial technical effects:

[0023] (1) The pyrolysis waste heat of the semi-coke layer and the slow oxidation heat release of the semi-coke layer are simultaneously used for the subsequent in-situ pyrolysis of the oil-rich coal seam, which fully utilizes the pyrolysis waste heat and material resources of the semi-coke layer and realizes the effective development of the pyrolysis semi-coke layer.

[0024] (2) After the complete pyrolysis of the oil-rich coal block, it is transformed into a pyrolysis semi-coke block, and continues to participate in the in-situ pyrolysis of the next oil-rich coal block, thus achieving full utilization of the block resources and joint operation of adjacent blocks.

[0025] (3) The operation of the system relies on geological resources and does not require the injection of additional external heat energy, effectively reducing economic investment.

[0026] (4) Slowly oxidize the semi-coke to generate CO 2 and CO generated by combustion of pyrolysis gas from oil-rich coal fields 2 At the same time, it is sealed in the pyrolysis semi-coke after the slow oxidation reaction, realizing the CO 2 Emission reduction will effectively contribute to my country's "dual carbon" goals.

[0027] (5) During the operation of the system, the pyrolysis products are burned to generate electricity, and the combustion power generation device is used to power the fan, which effectively utilizes the pyrolysis product gas resources and saves costs. The injection wells are arranged at the vertices of the equilateral triangle. The injected fluid can be pushed inward more evenly from three directions. The output well is arranged at the circumcenter of the triangle to maximize the displacement effect of the injection well. The distance from the circumcenter to the three vertices of the triangle is equal. The reaction products are output along the shortest path or the most reasonable pressure gradient path. The circumcenter position can ensure that the fluid resistance in each direction is relatively balanced, so that during the convergence process of the fluid, the fluid in one direction will not arrive first while the fluid in other directions will lag behind, which is conducive to improving mining efficiency and recovery.

[0028] (6) The formation adopts an equilateral triangle well layout method, with the injection wells at the vertices of the triangle and the output wells at the circumcenter of the triangle, which rationally utilizes space resources and improves the utilization rate of coal mining.

[0029] (7) Fracturing fluid is injected into the oil-rich coal formation along the pyrolysis injection well to form artificial fracturing cracks, which increases the permeability of the coal seam and is beneficial to the subsequent heat and mass transfer process, thereby further improving the in-situ mining rate of the oil-rich coal.

[0030] (8) The coupling of slow oxidation of semi-coke and in-situ pyrolysis of coal enriches the in-situ pyrolysis mining mode of oil-rich coal and provides new ideas for the oil extraction and clean utilization of oil-rich coal resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 2. It is a schematic structural diagram of an in-situ pyrolysis system for slowly oxidizing and heating oil-rich coal with semi-coke according to the present invention;

[0032] Figure 2 It is a top view of the well arrangement structure in the in-situ pyrolysis system of the present invention;

[0033] Explanation of the reference numerals: 1 is a rock layer, 2 is a pyrolysis semi-coke layer, 3 is an oil-rich coal seam, 4 is a fracturing fracture, 5 is a slow oxidation injection well, 6 is a slow oxidation output well, 7 is a slow oxidation horizontal well, 8 is a pyrolysis injection well, 9 is a pyrolysis output well, 10 is a pyrolysis horizontal well, 11 is air, 12 is a fan, 13 is a heat exchanger, 14 is a gas-liquid separation device, 15 is an oil storage device, 16 is a combustion power generation device, 17 is a CO 2 Separation device, 18 is CO 2 , 19 is the first pyrolysis semi-coke plot, 20 is the first oil-rich coal plot, and 21 is the second pyrolysis semi-coke plot. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0035] See also Figure 1 As shown, the in-situ pyrolysis system for slow oxidation heating of oil-rich coal by semi-coke of the present invention comprises a plurality of adjacent pyrolysis semi-coke plots and oil-rich coal plots operating in conjunction with each other, and a fan 12, a heat exchanger 13, a gas-liquid separation device 14, an oil storage device 15, a combustion power generation device 16 and a CO 2 Separation device 17.

[0036] The pyrolysis semi-coke plot includes a rock layer 1 and a pyrolysis semi-coke layer 2, and the oil-rich coal plot includes a rock layer 1 and an oil-rich coal layer 3. In the oil-rich coal plot, a pyrolysis injection well 8 and a pyrolysis output well 9 are excavated vertically from the ground downward, and a pyrolysis horizontal well 10 is excavated to connect the pyrolysis injection well 8 and the pyrolysis output well 9. After the pyrolysis of the oil-rich coal plot 19 is completed, a semi-coke plot 20 is formed, and the pyrolysis injection well 8 and the pyrolysis output well 9 are converted into a slow oxidation injection well 5 and a slow oxidation output well 6, and the pyrolysis horizontal well 10 is converted into a slow oxidation horizontal well 7; a fan 12 is set in the slow oxidation injection well 5 of the pyrolysis semi-coke plot to inject air 11 into the pyrolysis semi-coke layer 2.

[0037] The outlet of the slow oxidation output well 6 of the first pyrolysis semi-coke block 19 is connected to the inlet of the pyrolysis injection well 8 of the adjacent first oil-rich coal block 20 through a pipeline, so as to inject the oxidation product of the slow oxidation reaction of the first pyrolysis semi-coke block 19 in the air atmosphere into the first oil-rich coal block 20. The pyrolysis output well 9 of the first pyrolysis semi-coke block 19 is connected to the gas-liquid separation device 14, the combustion power generation device 16, the CO 2 The gas-liquid separation device 17 is connected to the oil storage device 15, and the pyrolysis products of the first pyrolysis semi-coke block 19 and the N 2 The tar enters the heat exchanger 13, exchanges heat with the air pumped in by the fan, and is then sent to the gas-liquid separation device 14 after cooling. The tar obtained by condensation separation is collected in the oil storage device 15, and the remaining pyrolysis gas, CO 2 and N 2 The mixed gas is sent to the combustion power generation device 16 to combine with the preheated air for combustion reaction, and the generated flue gas enters the CO 2 Separation device 17, separates CO 2 The char is sealed in the first pyrolysis coke block 19 after the slow oxidation reaction, and the remaining flue gas carrying the heat of the combustion reaction is continuously injected into the adjacent second pyrolysis coke block 21 to participate in the slow oxidation reaction.

[0038] In the present invention, the atmosphere for the slow oxidation reaction of the first pyrolysis semi-coke block 19 is air, and the atmosphere for the slow oxidation reaction of the remaining pyrolysis semi-coke blocks is air and separated CO 2 After the combustion of flue gas, the atmosphere participating in the pyrolysis reaction of the first oil-rich coal block 20 is N 2 and CO2 The atmosphere involved in the pyrolysis reaction of the remaining oil-rich coal blocks is N 2 , CO 2 and smoke mixture.

[0039] The fan 12 pumps air 11 into the first pyrolysis semi-coke plot 19. The pyrolysis semi-coke layer 2 retains the residual heat of pyrolysis and undergoes a slow oxidation reaction in the air atmosphere. The oxidation products flow out along the slow oxidation output well 6 and then continue along the pyrolysis injection well 8 to enter the first oil-rich coal plot 20. The oxidation products mainly include CO carrying a large amount of heat energy. 2 and N 2 The first oil-rich coal layer 3 of the oil-rich coal block 20 starts the pyrolysis reaction, and the pyrolysis products and the N 2 The pyrolysis gas flows out along the pyrolysis output well 9, enters the heat exchanger 13, exchanges heat with air, and then enters the gas-liquid separation device 14, where the tar is separated and collected in the oil storage device 15. The remaining pyrolysis gas, CO 2 and N 2 The mixed gas is sequentially fed into the combustion power generation device 16 and the CO 2 Separation device 17, the separated CO 2 The char is sealed in the first pyrolysis coke block 19 after the slow oxidation reaction, and the remaining flue gas carrying the heat of the combustion reaction continues to be injected into the second pyrolysis coke block 21.

[0040] The first semi-coke block 19 is slowly oxidized to generate CO 2 The first oil-rich coal block 20 pyrolysis gas combustion power generation also generates CO 2 , CO from different sources 2 They are all sealed in the first pyrolysis semi-coke plot 20 after the slow oxidation reaction, and the same applies to subsequent plots.

[0041] See also Figure 2 As shown, the slow oxidation injection well 5 and the slow oxidation output well 6 in the pyrolysis semi-coke plot are arranged in a triangular pattern, the slow oxidation injection well 5 is located at the vertex of the triangle, and the slow oxidation output well 6 is located at the circumcenter of the triangle. Similarly, the pyrolysis injection well 8 and the pyrolysis output well 9 in the oil-rich coal plot are arranged in a triangular pattern, the pyrolysis injection well 8 is located at the vertex of the triangle, and the pyrolysis output well 9 is located at the circumcenter of the triangle.

[0042] The present invention comprehensively considers the slow oxidation part of pyrolysis semi-coke, the pyrolysis part of oil-rich coal, the coupled operation of semi-coke plots and oil-rich coal plots, the utilization of system waste heat and CO 2 The sealing method, combined with a unique well layout method, uses the waste heat from pyrolysis of the semi-coke layer and the heat released by slow oxidation for pyrolysis of the next oil-rich coal layer, thus achieving full utilization of the heat and material of the semi-coke, enriching the thermal energy supply method for in-situ heating, and providing a new idea for the in-situ pyrolysis and oil extraction model of oil-rich coal.

[0043] The in-situ pyrolysis method of the present invention for slowly oxidizing and heating oil-rich coal with semi-coke comprises the following steps:

[0044] 1) injecting fracturing fluid into the coal seam 3 along the pyrolysis injection well 8 of the first oil-rich coal block 20 to form a large number of irregular fracturing cracks 4;

[0045] 2) Air 11 is pumped into the first pyrolysis semi-coke plot 19 through the slow oxidation injection well 5 by the fan 12. The semi-coke layer 2 retains the residual heat of pyrolysis and undergoes a slow oxidation reaction in the air atmosphere. The oxidation products flow out through the slow oxidation output well 6 and continue to flow through the pyrolysis injection well 8 into the first oil-rich coal plot 20, mainly including CO carrying a large amount of heat energy. 2 and N 2 , at high temperature CO 2 and N 2 The pyrolysis reaction of the oil-rich coal layer 3 is initiated under the convection heating of the mixed gas;

[0046] 3) Pyrolysis products and N that did not participate in the reaction 2 The pyrolysis gas flows out along the pyrolysis output well 9, enters the heat exchanger 13, exchanges heat with air, and is then sent to the gas-liquid separation device 14. The tar obtained by condensation and separation is collected in the oil storage device 15. The remaining pyrolysis gas, CO 2 and N 2 The mixed gas is sent to the combustion power generation device 16 to participate in the combustion reaction with the preheated air, and the generated flue gas enters the CO 2 Separation device 17, separates CO 2 The char is sealed in the first pyrolysis coke block 19 after the slow oxidation reaction, and the remaining flue gas carrying the heat of the combustion reaction is continuously injected into the second pyrolysis coke block 21 to participate in the slow oxidation reaction.

[0047] In the present invention, air 11 is pumped into the first pyrolysis semi-coke plot 19 through a fan 12, and the air 11 is injected into the first pyrolysis semi-coke plot 19 along a slow oxidation injection well 5. Since the pyrolysis semi-coke layer 2 retains the residual heat of pyrolysis, the semi-coke undergoes a relatively controllable slow oxidation reaction in the air atmosphere, and the oxidation products react with the N 2 The slow oxidation output well 6 flows out and enters the first oil-rich coal block 20 along the pyrolysis injection well 8, mainly including CO carrying a large amount of heat energy. 2 and N 2 , at high temperature CO 2 and N 2 Under the convection heating of the mixed gas, the pyrolysis reaction of the oil-rich coal layer 3 is initiated;

[0048] As the in-situ pyrolysis reaction proceeds, the pyrolysis products, CO 2 and N 2It flows out along the pyrolysis output well 9, enters the heat exchanger 13, exchanges heat with the air pumped in by the fan 12, and then enters the gas-liquid separation device 14. The tar obtained by condensation and separation is collected in the oil storage device 15, and the remaining pyrolysis gas, CO 2 and N 2 The mixed gas enters the combustion power generation device 16 and combines with the preheated air to participate in the combustion reaction. The combustion power generation device 16 supplies energy to the fan 13, and the combustion flue gas enters the CO 2 Separation device 17, separates CO 2 It is then sealed in the first pyrolysis semi-coke block 19 where the slow oxidation reaction is completed, and the remaining flue gas carrying the heat of the combustion reaction is continuously injected into the second pyrolysis semi-coke block 21 to participate in the slow oxidation reaction.

Claims

1. An in-situ pyrolysis system for heating oil-rich coal by slow oxidation of semi-coke, characterized in that: It comprises a plurality of adjacent oil-rich coal plots, in which pyrolysis injection wells (8) and pyrolysis output wells (9) are excavated; after pyrolysis of the oil-rich coal plots is completed, semi-coke plots are formed, and the pyrolysis injection wells (8) and pyrolysis output wells (9) are converted into slow oxidation injection wells (5) and slow oxidation output wells (6); A fan (12) for injecting air (11) into the pyrolysis semi-coke layer (2) is provided at the inlet of the slow oxidation injection well (5) of the pyrolysis semi-coke block; the outlet of the slow oxidation output well (6) of the first pyrolysis semi-coke block (19) is connected to the inlet of the pyrolysis injection well (8) of the adjacent first oil-rich coal block (20) through a pipeline, so as to inject the oxidation product of the slow oxidation reaction of the first pyrolysis semi-coke block (19) into the first oil-rich coal block (20); the outlet of the pyrolysis output well (9) of the first pyrolysis semi-coke block (19) is connected to a gas-liquid separation device (14); the liquid phase outlet of the gas-liquid separation device (14) is connected to an oil storage device (15); the gas phase outlet is connected to a combustion power generation device (16); and the flue gas outlet of the combustion power generation device (16) is connected to a CO2 separation device (17); The fan (12) pumps air (11) into the pyrolysis semi-coke block, and the high-temperature oxidation products of the slow oxidation reaction in the pyrolysis semi-coke block flow out along the slow oxidation output well (6) and enter the adjacent oil-rich coal block for pyrolysis reaction. The pyrolysis products and the gas that does not participate in the reaction flow out along the pyrolysis output well (9) and enter the heat exchanger (13). After heat exchange and cooling with the air pumped in by the fan (12), they enter the gas-liquid separation device (14), separate the tar and collect it in the oil storage device (15), and the remaining mixed gas is sent to the combustion power generation device (16) to react with the preheated air for combustion. The combustion flue gas enters the CO2 separation device (17), and the separated CO2 is sealed in the semi-coke block after the slow oxidation reaction. The remaining flue gas carrying the combustion reaction heat continues to be injected into the adjacent pyrolysis semi-coke block that has not undergone the slow oxidation reaction to participate in the next reaction.

2. The in-situ pyrolysis system for slow oxidation heating of oil-rich coal by semi-coke according to claim 1 is characterized in that: In the oil-rich coal block, a pyrolysis injection well (8) and a pyrolysis output well (9) are excavated from the ground downwards, and a pyrolysis horizontal well (10) is excavated to connect the pyrolysis injection well (8) and the pyrolysis output well (9). After the pyrolysis of the oil-rich coal block is completed, a semi-coke block is formed, the pyrolysis injection well (8) and the pyrolysis output well (9) are converted into a slow oxidation injection well (5) and a slow oxidation output well (6), and the pyrolysis horizontal well (10) is converted into a slow oxidation horizontal well (7).

3. The in-situ pyrolysis system for slowly oxidizing and heating oil-rich coal with semi-coke according to claim 2, characterized in that: The slow oxidation injection well (5) and the slow oxidation output well (6) are vertical wells extending vertically from the ground to the pyrolysis semi-coke layer (2) of the pyrolysis semi-coke block; the pyrolysis injection well (8) and the pyrolysis output well (9) are vertical wells extending vertically from the ground to the oil-rich coal layer (3) of the oil-rich coal block.

4. The in-situ pyrolysis system for slowly oxidizing and heating oil-rich coal with semi-coke according to any one of claims 1 to 3, characterized in that: The slow oxidation injection well (5) and the slow oxidation output well (6) in the pyrolysis semi-coke plot are arranged in a triangular pattern, the slow oxidation injection well (5) is located at the vertex of the triangle, and the slow oxidation output well (6) is located at the circumcenter of the triangle; the pyrolysis injection well (8) and the pyrolysis output well (9) in the oil-rich coal plot are arranged in a triangular pattern, the pyrolysis injection well (8) is located at the vertex of the triangle, and the pyrolysis output well (9) is located at the circumcenter of the triangle.

5. The in-situ pyrolysis method of slowly oxidizing and heating oil-rich coal with semi-coke based on the pyrolysis system of claim 4 is characterized in that The following steps are involved: 1) injecting fracturing fluid into the oil-rich coal seam (3) along a pyrolysis injection well (8) of a first oil-rich coal block (20) to form a large number of irregular fracturing cracks (4); 2) air (11) is pumped into the first pyrolysis semi-coke block (19) along the slow oxidation injection well (5) through the fan (12), the semi-coke layer (2) of the first pyrolysis semi-coke block (19) retains the residual heat of pyrolysis, and a slow oxidation reaction occurs in the air atmosphere, and the oxidation product flows out along the slow oxidation output well (6) and then continues to flow along the pyrolysis injection well (8) into the first oil-rich coal block (20), and the pyrolysis reaction is started in the oil-rich coal layer (3) of the first oil-rich coal block (20) under the convection heating of the high-temperature mixed gas; 3) The pyrolysis products and the mixed gas that has not participated in the reaction flow out along the pyrolysis output well (9) and enter the heat exchanger. After heat exchange with the air pumped in by the fan and cooling, they enter the gas-liquid separation device (14) to obtain tar through condensation separation. The separated pyrolysis gas, CO2 and N2 mixed gas are sent to the combustion power generation device (16) to participate in the combustion reaction together with the preheated air. The generated flue gas enters the CO2 separation device (17) to separate the CO2 and seal it in the first pyrolysis semi-coke block (19) after the slow oxidation reaction. The remaining flue gas carrying the combustion reaction heat continues to be injected into the second pyrolysis semi-coke block (21) to participate in the slow oxidation reaction.

6. The in-situ pyrolysis method of slowly oxidizing and heating oil-rich coal with semi-coke based on the pyrolysis system of claim 5, characterized in that: The atmosphere for the slow oxidation reaction of the first pyrolysis semi-coke block (19) is air, and the atmosphere for the slow oxidation reaction of the remaining pyrolysis semi-coke blocks is air and combustion flue gas after CO2 separation. The atmosphere for the pyrolysis reaction of the first oil-rich coal block (20) is N2 and CO2, and the atmosphere for the pyrolysis reaction of the remaining oil-rich coal blocks is a mixture of N2, CO2 and flue gas.

7. The in-situ pyrolysis method of slowly oxidizing and heating oil-rich coal with semi-coke based on the pyrolysis system of claim 5, characterized in that: The CO2 generated by the slow oxidation reaction of the first semi-coke block (19) and the CO2 generated by the combustion of pyrolysis gas to generate electricity in the first oil-rich coal block (20) are both sealed in the first pyrolysis semi-coke block (19) after the slow oxidation reaction.

8. The in-situ pyrolysis method of slowly oxidizing and heating oil-rich coal with semi-coke based on the pyrolysis system of claim 7, characterized in that: The pyrolysis products and the heat they carry are sent to a combustion power generation device (16) for combustion reaction, and the combustion power generation device is used to supply energy to the fan.

9. The in-situ pyrolysis method of slowly oxidizing and heating oil-rich coal with semi-coke based on the pyrolysis system of claim 7, characterized in that: By controlling the air injection rate in the semi-coke layer, the exothermic intensity of the slow oxidation reaction can be changed, thereby regulating the oil / gas production rate of the in-situ pyrolysis of oil-rich coal.

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