System and method for underground in-situ hydro-liquefaction of oil-rich coal

Abstract

The invention discloses a system and a method for oil-rich coal underground in-situ hydro-liquefaction, and belongs to the technical field of oil-rich coal hydro-liquefaction. The oil-rich coal underground in-situ hydro-liquefaction system comprises an injection well, a fracturing well and a production well, fracturing fluid is injected into the oil-rich coal seam through the fracturing well to fracture the oil-rich coal seam, fracturing cracks are formed, a fracturing crack network is formed in the oil-rich coal seam between the injection well and the production well, and an oil-gas channel is generated; firstly, mixed turbid liquid formed by a hydrogen-donating solvent and a catalyst is introduced into the oil-rich coal seam through the fracturing well, and then carbon monoxide is introduced into the oil-rich coal seam through the fracturing well; supercritical water is introduced into an oil-rich coal seam through an injection well, the supercritical water and carbon monoxide are subjected to a supercritical shift reaction, and the oil-rich coal is subjected to a hydro-liquefaction reaction under the action of the supercritical shift reaction, a catalyst and a hydrogen-donating solvent, so that the viscosity and density of product oil are reduced, the fluidity is improved, and the blockage problem of an oil-gas migration channel is relieved; and the in-situ liquefaction efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil-rich coal hydroliquefaction, and in particular relates to a system and method for underground in-situ oil-rich coal hydroliquefaction. Background Art

[0002] Oil-rich coal, a special type of coal resource, has a high oil content and can be converted into liquid oil through technologies such as liquefaction and pyrolysis. Currently, the main methods for converting and utilizing oil-rich coal include post-mining pyrolysis and in-situ pyrolysis.

[0003] Post-surface pyrolysis involves first extracting oil-rich coal from conventional underground mining operations and then converting it into other fuels or chemical feedstocks through pyrolysis and liquefaction. This method is simple in principle, and the surface pyrolysis process is relatively mature. However, underground mining of oil-rich coal is expensive, and surface processing can cause significant environmental pollution.

[0004] In-situ pyrolysis of oil-rich coal involves heating underground oil-rich coal seams to promote their in-situ pyrolysis, producing oil and gas products that are then discharged to the surface. This method allows for direct oil and gas extraction, leaving solid residues in the formation, minimizing environmental pollution and lowering extraction and transportation costs. However, the in-situ conversion process suffers from low heat and mass transfer efficiencies, resulting in high density, high viscosity, and poor fluidity. This pyrolysis oil easily accumulates and adheres to oil and gas channels during production, causing losses and potentially blocking these channels, reducing recovery efficiency.

[0005] Therefore, there is an urgent need to find a clean and efficient in-situ development method for oil-rich coal. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a system and method for underground in-situ hydrogenation liquefaction of oil-rich coal, so as to alleviate the blockage of oil and gas mass transfer channels and improve the efficiency of oil and gas product drainage.

[0007] To solve the above technical problems, according to one aspect of the present invention, a system for underground in-situ hydroliquefaction of oil-rich coal is provided, comprising an injection well, a fracturing well, and a production well; The injection wells, fracturing wells and production wells are all vertical wells drilled from the ground to the oil-rich coal seams; Injection wells are used to introduce supercritical water into oil-rich coal seams; fracturing wells are used to successively inject fracturing fluid, a mixed suspension formed by a hydrogen-supplying solvent and a catalyst, and carbon monoxide into the oil-rich coal seams; and production wells are used to discharge the oil and gas produced by the in-situ hydrogenation liquefaction of oil-rich coal.

[0008] Furthermore, it includes a water tower, a supercritical water preparation device, a high-pressure water fracturing fluid preparation device, a mixed suspension tank, a carbon monoxide storage tank, a gas-liquid separation device, a gas product storage tank, and a liquid product storage tank arranged on the ground; The outlet pipe of the water tower is respectively connected to the supercritical water preparation device and the high-pressure water fracturing fluid preparation device; the outlet pipe of the supercritical water preparation device is connected to the injection well; the outlet pipes of the high-pressure water fracturing fluid preparation device, the carbon monoxide storage tank, and the mixed suspension tank are all connected to the fracturing well; the inlet pipe of the gas-liquid separation device is connected to the production well, the gas phase outlet of the gas-liquid separation device is connected to the gas product storage tank, and the liquid phase outlet of the gas-liquid separation device is connected to the liquid product storage tank.

[0009] According to another aspect of the present invention, a method for underground in-situ hydroliquefaction of oil-rich coal is provided, which uses the above-mentioned system for underground in-situ hydroliquefaction of oil-rich coal, comprising the following steps: Step 1: injecting fracturing fluid into the oil-rich coal seam through a fracturing well to fracture the oil-rich coal seam, forming fracturing cracks, forming a fracturing crack network in the oil-rich coal seam between the injection well and the production well, and generating oil and gas channels; First, a mixed suspension formed by a hydrogen supply solvent and a catalyst is introduced into the oil-rich coal seam through a fracturing well, and then carbon monoxide is introduced into the oil-rich coal seam through the fracturing well; Step 2: Supercritical water is injected into the oil-rich coal seam through an injection well. The supercritical water reacts with carbon monoxide to produce a supercritical shift reaction. The oil-rich coal undergoes a hydrogenation liquefaction reaction under the action of the supercritical shift reaction, a catalyst, and a hydrogen-donating solvent, thereby producing oil and gas products. Step three: the generated oil and gas are discharged to the ground through oil and gas channels and production wells, and then separated and processed.

[0010] Furthermore, in step 1, the fracturing fluid is high-pressure water with a pressure of 20 to 50 MPa.

[0011] Furthermore, in step 1, the catalyst is any two of oxides, chlorides, carbonates and sulfates of K, Na, Ca and Mg.

[0012] Furthermore, the catalyst is a combination of any two of potassium chloride, sodium chloride, calcium oxide, magnesium oxide, potassium carbonate, magnesium carbonate, sodium sulfate, and magnesium sulfate.

[0013] Furthermore, in step 1, the hydrogen-donating solvent is a mixed solution of any two alcohols with a carbon chain length of ≤4.

[0014] Furthermore, the hydrogen-donating solvent is a combination of any two of methanol, ethanol, ethylene glycol, and isopropanol.

[0015] Furthermore, in step 1, the ratio of the catalyst to the hydrogen-donating solvent is 1 kg: (30-60) L.

[0016] Furthermore, in step 2, the supercritical water is water with a temperature of 400° C. to 600° C. and a pressure of 22.15 MPa to 30 MPa.

[0017] In the present invention, supercritical water and carbon monoxide undergo a supercritical shift reaction (H2O + CO → CO2 + H2). Combined with the addition of a hydrogen-donating solvent, this reaction generates more active hydrogen. This high concentration of active hydrogen can bind to free radicals generated during the hydroliquefaction of oil-rich coal, inhibiting their polymerization into coke and generating low-molecular-weight products. This promotes the hydroliquefaction reaction, reduces the density and viscosity of the product oil, and improves its fluidity, thereby increasing the efficiency of product oil discharge. The water-gas shift reaction is exothermic, providing more heat for the hydroliquefaction of oil-rich coal and improving energy efficiency.

[0018] In the present invention, the addition of the catalyst can increase the rate of hydroliquefaction of oil-rich coal, promote the generation of active hydrogen and its transfer to the product oil, improve the efficiency of the supercritical shift reaction, and further reduce the density and viscosity of the product oil, thereby alleviating the blockage of the oil and gas channels. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings herein are used to provide further illustration of the present invention and constitute a part of this application. The illustrative embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] Figure 1 Schematic diagram of the system for underground in-situ hydrogenation liquefaction of oil-rich coal provided by the present invention.

[0021] In the figure, 1-oil-rich coal seam; 2-injection well; 3-fracture well; 4-production well; 5-water tower; 6-supercritical water preparation device; 7-high-pressure water fracturing fluid preparation device; 8-carbon monoxide storage tank; 9-mixed suspension tank; 10-gas-liquid separation device; 11-gas product storage tank; 12-liquid product storage tank; 13-oil and gas channel. DETAILED DESCRIPTION

[0022] Oil-rich coal refers to coal with a tar yield of more than 7%. Oil-rich coal is hydrogenated and liquefied under the action of supercritical shift reaction, catalyst and hydrogen supply solvent to produce oil and gas.

[0023] Supercritical shift reaction and hydrogen-donating solvent can produce active hydrogen at high temperature. Active hydrogen can quickly and stably crack oil free radical fragments, induce further cracking of heavy oil, generate more light oil, inhibit its polymerization into coke, and thus accelerate the hydrogenation liquefaction reaction of oil-rich coal. The addition of catalyst can simultaneously improve the efficiency of supercritical shift reaction and oil-rich coal liquefaction reaction, promote hydrogen-donating solvent and supercritical shift reaction to provide more active hydrogen, and transfer it to product oil, reduce the density and viscosity of product oil, promote the discharge process of product oil and gas, alleviate the blockage problem of oil and gas migration channel, and improve in-situ liquefaction efficiency.

[0024] Based on the above principles, the basic concept of the present invention is to first inject fracturing fluid into the oil-rich coal seam 1 through the fracturing well 3 to fracture the oil-rich coal seam 1, forming fracturing cracks, forming a fracturing crack network in the oil-rich coal seam 1 between the injection well 2 and the production well 4, and generating an oil and gas channel 13; then, a mixed suspension formed by a hydrogen supply solvent and a catalyst is introduced into the underground oil-rich coal seam 1 through the fracturing well 3, and then carbon monoxide is introduced into the underground oil-rich coal seam 1 through the fracturing well 3, so that carbon monoxide, catalyst and hydrogen supply solvent are present in the fracturing crack network; supercritical water is introduced into the oil-rich coal seam 1 through the injection well 2, and supercritical water and carbon monoxide undergo a supercritical shift reaction, and the oil-rich coal undergoes a hydrogenation liquefaction reaction under the action of the supercritical shift reaction, the catalyst and the hydrogen supply solvent, and produces oil and gas.

[0025] During the implementation process, first establish Figure 1 In the system shown, surface facilities and drilling work are carried out simultaneously.

[0026] The outlet pipe of the water tower 5 is connected to the supercritical water preparation device 6 and the high-pressure water fracturing fluid preparation device 7 respectively; the outlet pipe of the supercritical water preparation device 6 is connected to the injection well 2; the outlet pipes of the high-pressure water fracturing fluid preparation device 7, the carbon monoxide storage tank 8, and the mixed suspension tank 9 are all connected to the fracturing well 3; the inlet pipe of the gas-liquid separation device 10 is connected to the production well 4, the gas phase outlet of the gas-liquid separation device 10 is connected to the gas product storage tank 11, and the liquid phase outlet of the gas-liquid separation device 10 is connected to the liquid product storage tank 12.

[0027] The injection well 2 , the fracturing well 3 and the production well 4 are all vertical wells drilled from the ground to the oil-rich coal seam 1 .

[0028] The technical solutions claimed in the present invention are further illustrated below by means of some examples. However, the examples are intended to illustrate the embodiments of the present invention and do not exceed the scope of the subject matter of the present invention. The scope of protection of the present invention is not limited by these examples. Unless otherwise specified, the materials and reagents used in the present invention can be obtained from commercial products in the art.

[0029] Example 1

[0030] The oil-rich coal seam 1 involved in this embodiment is a lignite coal seam with a burial depth of 500 meters, and the lignite tar yield is about 12%.

[0031] After the surface facilities are completed, supercritical water and high-pressure water fracturing fluid are prepared using the supercritical water preparation unit 6 and the high-pressure water fracturing fluid preparation unit 7, respectively. The supercritical water preparation unit 6 is set to a temperature of 400°C and a pressure of 22.15 MPa, while the high-pressure water fracturing fluid preparation unit 7 produces high-pressure water fracturing fluid at a pressure of 20 MPa. Potassium chloride and sodium chloride are selected as catalysts in a mass ratio of 1:1. Methanol and ethanol are selected as hydrogen-donating solvents in a volume ratio of 1:1. The catalyst and hydrogen-donating solvent are placed in a ratio of 1 kg to 30 L. This ratio is then placed in the mixed suspension tank 9.

[0032] After the drilling work is completed, high-pressure water fracturing fluid is injected into the oil-rich coal seam 1 from the fracturing well 3 to fracture the oil-rich coal seam 1, forming fracturing cracks. A fracturing crack network is formed in the oil-rich coal seam 1 between the injection well 2 and the production well 4, generating an oil and gas channel 13. After the fracturing is completed, a mixed suspension formed by a catalyst and a hydrogen-donating solvent is injected, and then carbon monoxide is introduced into the underground oil-rich coal seam 1 through the fracturing well 3, so that carbon monoxide, catalyst and hydrogen-donating solvent are present in the fracturing crack network; supercritical water is introduced into the oil-rich coal seam 1 through the injection well 2, and supercritical water and carbon monoxide undergo a supercritical shift reaction. The oil-rich coal undergoes a hydrogenation liquefaction reaction under the action of the supercritical shift reaction, the catalyst and the hydrogen-donating solvent, and produces oil and gas products; the oil and gas products are discharged to the ground through the oil and gas channel 13 and the production well 4, and pass through the gas-liquid separation device 10. The gas product is discharged into the gas product storage tank 11, and the liquid product is discharged into the liquid product storage tank 12.

[0033] Example 2

[0034] The oil-rich coal seam 1 involved in this embodiment is a fat coal seam with a burial depth of 700 meters, and the tar yield of the fat coal is about 15%.

[0035] After the surface facilities are completed, supercritical water and high-pressure water fracturing fluid are prepared using supercritical water preparation unit 6 and high-pressure water fracturing fluid preparation unit 7, respectively. The supercritical water preparation unit 6 is set to a temperature of 600°C and a pressure of 30 MPa, while the high-pressure water fracturing fluid preparation unit 7 produces high-pressure water fracturing fluid at a pressure of 35 MPa. Magnesium carbonate and magnesium sulfate are used as catalysts, with a mass ratio of 1:1.2. Methanol and ethylene glycol are used as hydrogen-donating solvents, with a volume ratio of 1:1.2. The catalyst and hydrogen-donating solvent are placed in a ratio of 1 kg to 60 L. This ratio is then placed in a mixed suspension tank 9.

[0036] After the drilling work is completed, high-pressure water fracturing fluid is injected into the oil-rich coal seam 1 from the fracturing well 3 to fracture the oil-rich coal seam 1, forming fracturing cracks. A fracturing crack network is formed in the oil-rich coal seam 1 between the injection well 2 and the production well 4, generating an oil and gas channel 13. After the fracturing is completed, a catalyst and a hydrogen-donating solvent suspension is injected, and then carbon monoxide is introduced into the underground oil-rich coal seam 1 through the fracturing well 3, so that carbon monoxide, catalyst, and hydrogen-donating solvent are present in the fracturing crack network; supercritical water is introduced into the oil-rich coal seam 1 through the injection well 2, and a supercritical shift reaction occurs between the supercritical water and carbon monoxide. The oil-rich coal undergoes a hydrogenation liquefaction reaction under the action of the supercritical shift reaction, the catalyst, and the hydrogen-donating solvent, and produces oil and gas products; the oil and gas products are discharged to the ground through the oil and gas channel 13 and the production well 4, and pass through the gas-liquid separation device 10. The gas product is discharged into the gas product storage tank 11, and the liquid product is discharged into the liquid product storage tank 12.

[0037] Example 3

[0038] The oil-rich coal seam 1 involved in this embodiment is a long flame coal seam with a burial depth of 1000 meters, and the tar yield of the long flame coal is about 12%.

[0039] After the surface facilities are completed, supercritical water and high-pressure water fracturing fluid are prepared using the supercritical water preparation unit 6 and the high-pressure water fracturing fluid preparation unit 7, respectively. The supercritical water preparation unit 6 is set to a temperature of 500°C and a pressure of 23 MPa, while the high-pressure water fracturing fluid preparation unit 7 produces a high-pressure water fracturing fluid at a pressure of 40 MPa. Sodium chloride and calcium oxide are selected as catalysts, with a mass ratio of sodium chloride to calcium oxide of 1:1.5. Ethanol and isopropanol are selected as hydrogen-donating solvents, with a volume ratio of 1:1. The catalyst and hydrogen-donating solvent are placed in a ratio of 1 kg to 40 L. This ratio is then placed in the mixed suspension tank 9.

[0040] After the drilling work is completed, high-pressure water fracturing fluid is injected into the oil-rich coal seam 1 from the fracturing well 3 to fracture the oil-rich coal seam 1, forming fracturing cracks. A fracturing crack network is formed in the oil-rich coal seam 1 between the injection well 2 and the production well 4, generating an oil and gas channel 13. After the fracturing is completed, a catalyst and a hydrogen-donating solvent suspension is injected, and then carbon monoxide is introduced into the underground oil-rich coal seam 1 through the fracturing well 3, so that carbon monoxide, catalyst, and hydrogen-donating solvent are present in the fracturing crack network; supercritical water is introduced into the oil-rich coal seam 1 through the injection well 2, and a supercritical shift reaction occurs between the supercritical water and carbon monoxide. The oil-rich coal undergoes a hydrogenation liquefaction reaction under the action of the supercritical shift reaction, the catalyst, and the hydrogen-donating solvent, and produces oil and gas products; the oil and gas products are discharged to the ground through the oil and gas channel 13 and the production well 4, and pass through the gas-liquid separation device 10. The gas product is discharged into the gas product storage tank 11, and the liquid product is discharged into the liquid product storage tank 12.

[0041] Example 4

[0042] The oil-rich coal seam 1 involved in this embodiment is a fat coal seam with a burial depth of 700 meters, and the tar yield of the fat coal is about 15%.

[0043] After the surface facilities are completed, supercritical water and high-pressure water fracturing fluid are prepared using a supercritical water preparation unit 6 and a high-pressure water fracturing fluid preparation unit 7, respectively. The supercritical water preparation unit 6 is set to a temperature of 450°C and a pressure of 27 MPa, while the high-pressure water fracturing fluid preparation unit 7 produces a high-pressure water fracturing fluid at a pressure of 20 MPa. Magnesium carbonate and magnesium sulfate are used as catalysts in a 1:1 mass ratio. Methanol and ethylene glycol are used as hydrogen-donating solvents in a 1:1 volume ratio. The catalyst and hydrogen-donating solvent are placed in a ratio of 1 kg to 50 L. This ratio is then placed in a mixed suspension tank 9.

[0044] After the drilling work is completed, high-pressure water fracturing fluid is injected into the oil-rich coal seam 1 from the fracturing well 3 to fracture the oil-rich coal seam 1, forming fracturing cracks. A fracturing crack network is formed in the oil-rich coal seam 1 between the injection well 2 and the production well 4, generating an oil and gas channel 13. After the fracturing is completed, a catalyst and a hydrogen-donating solvent suspension is injected, and then carbon monoxide is introduced into the underground oil-rich coal seam 1 through the fracturing well 3, so that carbon monoxide, catalyst, and hydrogen-donating solvent are present in the fracturing crack network; supercritical water is introduced into the oil-rich coal seam 1 through the injection well 2, and a supercritical shift reaction occurs between the supercritical water and carbon monoxide. The oil-rich coal undergoes a hydrogenation liquefaction reaction under the action of the supercritical shift reaction, the catalyst, and the hydrogen-donating solvent, and produces oil and gas products; the oil and gas products are discharged to the ground through the oil and gas channel 13 and the production well 4, and pass through the gas-liquid separation device 10. The gas product is discharged into the gas product storage tank 11, and the liquid product is discharged into the liquid product storage tank 12.

[0045] Example 5

[0046] The oil-rich coal seam 1 involved in this embodiment is a fat coal seam with a burial depth of 700 meters, and the tar yield of the fat coal is about 15%.

[0047] After the surface facilities are completed, supercritical water and high-pressure water fracturing fluid are prepared using supercritical water preparation unit 6 and high-pressure water fracturing fluid preparation unit 7, respectively. The supercritical water preparation unit 6 is set to a temperature of 550°C and a pressure of 25 MPa, while the high-pressure water fracturing fluid preparation unit 7 produces high-pressure water fracturing fluid at a pressure of 50 MPa. Magnesium carbonate and magnesium sulfate are used as catalysts, with a mass ratio of magnesium oxide to sodium sulfate of 1:1.5. Methanol and ethylene glycol are used as hydrogen-donating solvents in a volume ratio of 1:2. The catalyst and hydrogen-donating solvent are placed in a ratio of 1 kg to 45 L. This ratio is then placed in a mixed suspension tank 9.

[0048] After the drilling work is completed, high-pressure water fracturing fluid is injected into the oil-rich coal seam 1 from the fracturing well 3 to fracture the oil-rich coal seam 1, forming fracturing cracks. A fracturing crack network is formed in the oil-rich coal seam 1 between the injection well 2 and the production well 4, generating an oil and gas channel 13. After the fracturing is completed, a catalyst and a hydrogen-donating solvent suspension is injected, and then carbon monoxide is introduced into the underground oil-rich coal seam 1 through the fracturing well 3, so that carbon monoxide, catalyst, and hydrogen-donating solvent are present in the fracturing crack network; supercritical water is introduced into the oil-rich coal seam 1 through the injection well 2, and a supercritical shift reaction occurs between the supercritical water and carbon monoxide. The oil-rich coal undergoes a hydrogenation liquefaction reaction under the action of the supercritical shift reaction, the catalyst, and the hydrogen-donating solvent, and produces oil and gas products; the oil and gas products are discharged to the ground through the oil and gas channel 13 and the production well 4, and pass through the gas-liquid separation device 10. The gas product is discharged into the gas product storage tank 11, and the liquid product is discharged into the liquid product storage tank 12.

[0049] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various variations and modifications. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A system for underground in-situ hydroliquefaction of oil-rich coal, characterized by: Including injection well (2), fracturing well (3) and production well (4); The injection well (2), fracturing well (3) and production well (4) are all vertical wells drilled from the ground to the oil-rich coal seam (1); The injection well (2) is used to introduce supercritical water into the oil-rich coal seam (1); the fracturing well (3) is used to inject fracturing fluid, a mixed suspension formed by a hydrogen supply solvent and a catalyst, and carbon monoxide into the oil-rich coal seam (1) in sequence; and the production well (4) is used to discharge oil and gas produced by in-situ hydrogenation and liquefaction of the oil-rich coal.

2. The system for underground in-situ hydroliquefaction of oil-rich coal according to claim 1, characterized in that: It comprises a water tower (5) arranged on the ground, a supercritical water preparation device (6), a high-pressure water fracturing fluid preparation device (7), a mixed suspension tank (9), a carbon monoxide storage tank (8), a gas-liquid separation device (10), a gas product storage tank (11), and a liquid product storage tank (12); The outlet pipe of the water tower (5) is connected to the supercritical water preparation device (6) and the high-pressure water fracturing fluid preparation device (7), respectively; the outlet pipe of the supercritical water preparation device (6) is connected to the injection well (2); the outlet pipes of the high-pressure water fracturing fluid preparation device (7), the carbon monoxide storage tank (8), and the mixed suspension tank (9) are all connected to the fracturing well (3); the inlet pipe of the gas-liquid separation device (10) is connected to the production well (4), the gas phase outlet of the gas-liquid separation device (10) is connected to the gas product storage tank (11), and the liquid phase outlet of the gas-liquid separation device (10) is connected to the liquid product storage tank (12).

3. A method for underground in-situ hydroliquefaction of oil-rich coal, characterized by: The system for underground in-situ hydroliquefaction of oil-rich coal according to any one of claims 1 to 2 comprises the following steps: Step 1: injecting fracturing fluid into the oil-rich coal seam (1) through a fracturing well (3) to fracture the oil-rich coal seam (1) to form fracturing cracks, forming a fracturing crack network in the oil-rich coal seam (1) between the injection well (2) and the production well (4), and generating an oil and gas channel (13); First, a mixed suspension formed by a hydrogen supply solvent and a catalyst is introduced into the oil-rich coal seam (1) through a fracturing well (3), and then carbon monoxide is introduced into the oil-rich coal seam (1) through the fracturing well (3); Step 2: Supercritical water is introduced into the oil-rich coal seam (1) through an injection well (2); supercritical water and carbon monoxide undergo a supercritical shift reaction; the oil-rich coal undergoes a hydrogenation liquefaction reaction under the action of the supercritical shift reaction, the catalyst, and the hydrogen-donating solvent, and produces oil and gas products; Step three: the generated oil and gas is discharged to the ground through the oil and gas channel (13) and the production well (4), and then separated and processed.

4. The method for underground in-situ hydroliquefaction of oil-rich coal according to claim 3, characterized in that: In step 1, the fracturing fluid is high-pressure water with a pressure of 20 to 50 MPa.

5. The method for underground in-situ hydroliquefaction of oil-rich coal according to claim 3 or 4, characterized in that: In step 1, the catalyst is any two of oxides, chlorides, carbonates and sulfates of K, Na, Ca and Mg.

6. The method for underground in-situ hydroliquefaction of oil-rich coal according to claim 5, characterized in that: The catalyst is a combination of any two of potassium chloride, sodium chloride, calcium oxide, magnesium oxide, potassium carbonate, magnesium carbonate, sodium sulfate, and magnesium sulfate.

7. The method for underground in-situ hydroliquefaction of oil-rich coal according to claim 3 or 6, characterized in that: In step 1, the hydrogen-donating solvent is a mixed solution of any two alcohols with a carbon chain length of ≤4.

8. The method for underground in-situ hydroliquefaction of oil-rich coal according to claim 7, characterized in that: The hydrogen-donating solvent is a combination of any two of methanol, ethanol, ethylene glycol and isopropanol.

9. The method for underground in-situ hydroliquefaction of oil-rich coal according to claim 3 or 8, characterized in that: In step 1, the ratio of catalyst to hydrogen-donating solvent is 1 kg: (30-60) L.

10. The method for underground in-situ hydroliquefaction of oil-rich coal according to claim 9, characterized in that: In step 2, the supercritical water is water at a temperature of 400° C. to 600° C. and a pressure of 22.15 MPa to 30 MPa.

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