System and method for underground hydro-liquefaction of oil shale

Abstract

The invention discloses an oil shale underground hydro-liquefaction system and method, and belongs to the technical field of oil shale in-situ exploitation. According to the oil shale underground hydro-liquefaction system, an injection well, a fracturing well and a production well are arranged in an oil shale exploitation area. A fracturing medium is injected into the oil shale layer through the fracturing well for fracturing, and an oil-gas channel is generated; a hydrogen-donating solvent and catalyst mixed suspension is injected into an oil shale stratum through a fractured well, then CO is injected into the fractured well and is introduced into the underground oil shale stratum through microwave heating, and a wellhead of the fractured well is sealed; and finally, supercritical water is injected into the oil shale stratum through the injection well. In a fracture network and pores of an oil shale stratum, supercritical water and CO are subjected to a supercritical water-gas shift reaction, and oil shale is subjected to in-situ hydro-liquefaction under the action of the supercritical shift reaction, a hydrogen-donating solvent and a catalyst to generate an oil-gas product. Oil-gas products are discharged to the ground through the production well and are separated through the gas-liquid separator and the oil-water separator, and underground hydro-liquefaction exploitation of the oil shale is completed.

Description

Technical Field

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

[0002] Currently, in-situ mining has become the only path forward for the development and utilization of oil shale. Oil shale's low thermal conductivity, low permeability, and low grade lead to common challenges during in-situ mining, including low heating efficiency, low recovery rates, and poor oil quality. Therefore, there is an urgent need to find a clean and efficient method for oil shale extraction to promote its large-scale development and utilization.

[0003] Supercritical water has a low dielectric constant, weak hydrogen bonds, and a high ionization constant, resulting in a strong solvation and extraction effect on organic matter in oil shale. In situ oil shale extraction using supercritical water has been a promising development approach in recent years, significantly improving oil and gas recovery rates. However, supercritical water has difficulty hydrogenating organic matter, and the pyrolysis reaction is insufficient, resulting in the presence of large amounts of high-viscosity and high-density colloids and asphaltenes in the oil, which severely block oil and gas mass transfer pathways and reduce in-situ extraction efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a system and method for underground hydrogenation liquefaction of oil shale, so as to alleviate the blockage of oil and gas mass transfer channels and improve the discharge efficiency of liquefied oil and gas.

[0005] To solve the above technical problems, according to one aspect of the present invention, a system for underground hydroliquefaction of oil shale is provided. In the oil shale mining area, injection wells, fracturing wells, and production wells are arranged. The injection wells, fracturing wells, and production wells are all drilled from the surface into the oil shale layer. The fracturing wells are located between the injection wells and the production wells and are located close to the injection wells. The injection well is used to inject supercritical water into the oil shale formation; the fracturing well is used to inject fracturing medium, a mixed suspension of hydrogen-supplying solvent and catalyst, and CO into the oil shale formation in sequence; and the production well is used to discharge the oil and gas products of the in-situ hydrogenation liquefaction of the oil shale.

[0006] Furthermore, a double-layer casing structure is arranged in the fracturing well, and the double-layer casing includes an outer tube, an inner tube, a support assembly, a temperature sensor and an exhaust valve; The inner tube is fixed to the outer tube through a support assembly. A microwave heating device is installed inside the inner tube. The cavity formed between the outer wall of the inner tube and the inner wall of the outer tube is used to inject CO. An exhaust port is arranged at the bottom of the outer tube, an exhaust valve is arranged at the exhaust port, and a temperature sensor is arranged on the inner wall of the bottom of the outer tube.

[0007] Furthermore, the microwave heating device includes a magnetron and a waveguide. The magnetron is arranged at the inlet of the inner tube. The inner tube is made of ceramic material. A plurality of waveguides are arranged on the inner wall of the inner tube.

[0008] Furthermore, it includes a water tower arranged on the ground, a supercritical water generator, a microwave control room, a pressure pump, a CO storage tank, a hydrogen supply solvent and catalyst suspension storage tank, an oil-water separator, a gas-liquid separator, and an exhaust pump; The water outlet pipe of the water tower is respectively connected to the inlet end of the supercritical water generator and the inlet end of the pressure pump; the outlet end of the supercritical water generator is connected to the injection well; the microwave control room is used to control the microwave emission frequency in the fracturing well; the CO storage tank and the hydrogen supply solvent and catalyst suspension storage tank are all connected to the fracturing well; the inlet end and outlet end of the exhaust pump are respectively connected to the production well and the gas-liquid separator; and the outlet end of the gas-liquid separator is connected to the oil-water separator.

[0009] According to another aspect of the present invention, a method for underground hydroliquefaction of oil shale is provided, which uses the above-mentioned system for underground hydroliquefaction of oil shale, comprising: In step 1, the fracturing medium is pressurized by a pressure pump and then injected into the oil shale layer through a fracturing well for fracturing, thereby forming a fracturing crack network and generating oil and gas channels; the fracturing medium is preferably high-pressure water.

[0010] Step 2: injecting a mixed suspension of hydrogen-donating solvent and catalyst from a hydrogen-donating solvent and catalyst suspension storage tank into the oil shale formation through a fracturing well, then heating CO2 through microwaves in the fracturing well and passing it into the underground oil shale formation, sealing the wellhead of the fracturing well; and finally, injecting supercritical water into the oil shale formation through an injection well. In the fracture network and pores of the oil shale formation, supercritical water and CO undergo a supercritical water-gas shift reaction. Under the action of the supercritical shift reaction, hydrogen-donating solvent, and catalyst, the oil shale is in situ hydrogenated and liquefied to produce oil and gas products.

[0011] During the in-situ mining process of oil shale, the supercritical shift reaction and hydrogen-donating solvent both release active hydrogen under heating conditions, which directly combines with the oil and gas free radical fragments generated by the pyrolysis of oil shale, inhibiting the repolymerization of large molecular free radicals into coke and generating more light oil. The hydrogen-donating solvent and the shift system work synergistically to prolong and improve the efficiency and effect of hydrogen supply, significantly improving the quality and yield of the product oil.

[0012] Step three: The oil and gas products are discharged to the ground through the production well and separated by the gas-liquid separator and the oil-water separator.

[0013] Furthermore, in step 2, the temperature of the CO after microwave heating is 200-300° C., the temperature of the supercritical water is 450-550° C., and the pressure of the supercritical water is above 22.1 MPa.

[0014] Furthermore, in step 2, the catalyst is a combination of any two of the oxides, sulfates, chlorides, or nitrates of iron, nickel, copper, or zinc. The mass ratio of the two metal catalysts is preferably 1:(1.3-1.7).

[0015] Furthermore, in step 2, the hydrogen-donating solvent is anthracene or phenanthrene and their derivatives, preferably a combination of any two of anthracene or phenanthrene and their derivatives. The volume ratio of the two hydrogen-donating solvents is preferably 1:(1.2-1.5).

[0016] Furthermore, in step 2, the mass of the catalyst corresponding to 1L of hydrogen donor solvent is 50-120g, ensuring that the active centers in the catalyst are in full contact with the hydrogen donor solvent to enhance the hydrogen transfer efficiency.

[0017] Furthermore, in step 2, the volume ratio of supercritical water to CO is (1.5-2.5):1, and the mass ratio of hydrogen-donating solvent to supercritical water is (0.02-0.06):1. This ensures a high-quality hydrogen source environment, improves product quality, and reduces the density and viscosity of the product oil.

[0018] The present invention injects a mixed suspension of supercritical water, carbon monoxide, a catalyst and a hydrogen-donating solvent into the oil shale layer, and preheats the CO by microwave heating. Under this state, the supercritical water and carbon monoxide undergo a supercritical water-gas shift reaction under the combined action of the hydrogen-donating solvent and the catalyst, thereby promoting the oil shale hydrogenation liquefaction process and generating more light oil.

[0019] In this method, microwaves in a double-layer casing are used to preheat CO. Compared to surface heating, this method heats the oil shale layer faster and avoids heat loss in the wellbore, resulting in lower heat loss. The high-temperature CO enters the oil shale layer and heats the mixed suspension of catalyst and hydrogen-donating solvent, bringing it to a boiling state, thereby more evenly distributing the catalyst and hydrogen-donating solvent within the oil shale formation.

[0020] In this method, supercritical water and carbon monoxide undergo a water-gas shift reaction (H₂O + CO → CO₂ + H₂), producing active hydrogen intermediates. Simultaneously, the hydrogen-donating solvent, at high temperatures, also provides active hydrogen, stabilizing free radicals in the reaction, promoting the cracking of macromolecular organic matter in the oil shale, inhibiting polymerization, and improving the quality of the oil product. The hydrogen-donating solvent and catalyst work synergistically, promoting the shift reaction and oil shale liquefaction, reducing the density and viscosity of the product oil, and improving the recovery efficiency of oil and gas products. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of underground oil shale hydroliquefaction provided by the present invention; Figure 2 This is a schematic structural diagram of the double-layer casing of the present invention; Figure 3This is a schematic diagram of the connection between the outer tube and the inner tube in the double-layer casing of the present invention.

[0022] In the figure, 1-oil shale layer; 2-other rock layers; 3-injection well; 4-fracture well; 5-double-layer casing; 501-outer pipe; 502-inner pipe; 503-support assembly; 504-temperature sensor; 505-exhaust valve; 506-magnetron; 507-waveguide; 6-production well; 7-water tower; 8-supercritical water generator; 9-microwave control room; 10-pressure pump; 11-carbon monoxide storage tank; 12-hydrogen supply solvent and catalyst suspension storage tank; 13-oil-water separator; 14-gas-liquid separator; 15-exhaust pump; 16-flow meter; 17-valve; 18-oil and gas channel. DETAILED DESCRIPTION

[0023] Microwave heating offers rapid heating speeds and high energy efficiency. It can directly penetrate the gas, shortening heating time and improving efficiency. After preheating CO, it is introduced into the oil shale formation, where it reacts with supercritical water in a water-gas shift reaction (H₂O + CO → CO₂ + H₂) to produce active hydrogen. Furthermore, the hydrogen-donating solvent, at high temperatures, also provides active hydrogen, which reacts with the liquefied oil from the oil shale. The shift reaction and the hydrogen-donating solvent synergistically promote oil shale cracking, reducing the density and viscosity of the product oil and improving its fluidity. Simultaneously, the catalyst catalyzes both the supercritical shift reaction and the oil shale liquefaction reaction, promoting the transfer of active hydrogen into the oil.

[0024] Based on the above principles, the basic concept of the present invention is to inject supercritical water and microwave-heated CO into the oil shale formation to carry out a water-gas shift reaction. Under the synergistic action of the hydrogen-donating solvent and catalyst, the organic matter in the oil shale undergoes in situ hydrogenation and liquefaction, effectively alleviating the problem of heavy oil blocking the oil and gas migration channels. Example 1

[0025] This embodiment relates to a system for underground hydroliquefaction of oil shale, such as Figure 1 As shown, in the oil shale mining area, there are injection wells 3, fracturing wells 4 and production wells 6. The injection wells 3, fracturing wells 4 and production wells 6 are all drilled from the surface into the oil shale layer 1. The fracturing well 4 is between the injection well 3 and the production well 6 and is set close to the injection well 3.

[0026] The fracturing well 4 is a double-casing structure. Figure 2 As shown, the double-layer casing 5 includes an outer tube 501 , an inner tube 502 , a support assembly 503 , a temperature sensor 504 , and an exhaust valve 505 .

[0027] The inner cavity of the inner tube 502 of the double-layer casing 5 is a microwave heating device system, including a magnetron 506 arranged at the inlet of the inner tube 502, and multiple waveguides 507 arranged on the inner tube 502. The inner tube 502 is a ceramic medium. The cavity formed between the outer wall of the inner tube 502 and the inner wall of the outer tube 501 is used for injecting CO. The inner tube (502) is fixed to the inside of the outer tube (501) by a support assembly (503) ( Figure 3 ).

[0028] like Figure 2 As shown, the lower part of the double-layer casing is an inverted truncated cone structure, and a temperature sensor 504 is arranged on the inner wall of the outer tube 501 near the exhaust valve 505. The exhaust valve 505 is automatically opened when the CO temperature reaches the required temperature.

[0029] like Figure 1 As shown, the mining area also includes a water tower 7, a supercritical water generator 8, a microwave control room 9, a pressure pump 10, a CO storage tank 11, a hydrogen supply solvent and catalyst suspension storage tank 12, an oil-water separator 13, a gas-liquid separator 14, and an exhaust pump 15 arranged on the ground.

[0030] The water outlet pipe of the water tower 7 is respectively connected to the supercritical water generator 8 and the pressure pump 10, the supercritical water generator 8 is connected to the injection well 3, the microwave control terminal 9 is connected to the microwave heating device for controlling the microwave emission frequency, the CO storage tank 11 and the hydrogen supply solvent and catalyst suspension storage tank 12 are all connected to the fracturing well 4, the inlet and outlet ends of the exhaust pump 15 are respectively connected to the production well 6 and the gas-liquid separator 14, and the gas-liquid separator 14 is connected to the oil-water separator 13.

[0031] The mixed suspension of hydrogen supply solvent and catalyst is transported from the hydrogen supply solvent and catalyst suspension storage tank 12 to the fracturing well 4 and directly injected into the oil shale formation 1. CO is heated by microwaves from the CO storage tank 11 through the fracturing well 4 and then injected into the oil shale formation 1. The water in the water tower 7 is converted into a supercritical state by the supercritical water generator 8 and is injected into the oil shale formation 1 through the injection well 3.

[0032] After the well is completed, a fracturing medium is injected into the oil shale layer 1 through the fracturing well 4 to fracture the oil shale layer 1, thereby fracturing the fracture network and generating oil and gas channels 18.

[0033] After the fracturing is completed, a double-layer casing 5 is arranged in the fracturing well 4 to the bottom of the well, and cement slurry is injected into the annulus between the double-layer casing 5 and the well wall for cementing.

[0034] After cementing is completed, the wellheads of the injection well 3 and the fracturing well 4 are sealed. The hydrogen supply solvent and catalyst suspension mixture in the hydrogen supply solvent and catalyst suspension storage tank 12 is first injected into the oil shale formation 1 through the fracturing well 4. Then, CO is introduced into the underground oil shale formation 1 through the fracturing well 4. The microwave control chamber 9 controls the magnetron 506 to generate microwaves to heat the CO. After the temperature reaches the set temperature, the exhaust valve 505 is opened. Finally, supercritical water is injected into the oil shale formation 1 through the injection well 3.

[0035] In the fracture network and pores of the oil shale formation 1, supercritical water and CO undergo a supercritical water-gas shift reaction under the action of a hydrogen-donating solvent and a catalyst. The oil shale is in situ hydrogenated and liquefied under the action of the supercritical shift reaction, the hydrogen-donating solvent, and the catalyst to generate oil and gas products. The oil and gas products are discharged to the surface through a production well 6.

[0036] The oil and gas products enter the gas-liquid separator 14 through the exhaust pump 15, and the separated liquid enters the oil-water separator 13 for further separation.

[0037] The buried depth of the oil shale layer 1 involved in Examples 2 to 6 is 1000 m, the average grade of the oil shale is 12.00% to 20.00%, and the thickness of the oil shale ore layer is 11 m to 20 m. Example 2

[0038] Based on the principles and structural design described in Example 1, a system for underground hydrogenation and liquefaction of oil shale was established.

[0039] High-pressure water was introduced into fracturing well 4 to perform drilling and fracturing on oil shale layer 1. A mixture of 9-anthracene methanol and 9-phenanthrene methanol was selected as a hydrogen donor solvent in a volume ratio of 1:1.2. Copper oxide and ferric chloride were selected as metal catalysts in a mass ratio of 1:1.3. The mass of the catalyst corresponding to 1 L of hydrogen donor solvent was 50 g. CO was heated to 200°C by microwave and then introduced into the oil shale layer. Finally, 450°C supercritical water was injected. The mass ratio of the injected hydrogen donor solvent to supercritical water was 0.02:1, and the volume ratio of supercritical water to CO was 1.5:1. Example 3

[0040] Based on the principles and structural design described in Example 1, a system for underground hydrogenation and liquefaction of oil shale was established.

[0041] High-pressure water was introduced into fracturing well 4 to perform drilling and fracturing on oil shale layer 1. A mixture of 9-anthracenecarboxylic acid and 9-phenanthracenecarboxylic acid was selected as a hydrogen donor solvent in a volume ratio of 1:1.3. Ferric sulfate and zinc nitrate were selected as metal catalysts in a mass ratio of 1:1.4. The mass of the catalyst corresponding to 1 L of hydrogen donor solvent was 80 g. CO was introduced into the oil shale layer after being heated to 270°C by microwaves. Finally, supercritical water at 480°C was injected. The mass ratio of the injected hydrogen donor solvent to supercritical water was 0.04:1, and the volume ratio of supercritical water to CO was 1.6:1. Example 4

[0042] Based on the principles and structural design described in Example 1, a system for underground hydrogenation and liquefaction of oil shale was established.

[0043] High-pressure water was introduced into fracturing well 4 to perform drilling and fracturing on oil shale layer 1. A mixture of 9,10-dihydroanthracene and 9,10-dihydrophenanthrene was selected as a hydrogen-donating solvent in a volume ratio of 1:1.5. Ferric nitrate and copper chloride were selected as metal catalysts in a mass ratio of 1:1.6. The mass of the catalyst corresponding to 1 L of hydrogen-donating solvent was 80 g. CO was heated by microwaves to a temperature of 280° C. and then introduced into the oil shale layer. Finally, supercritical water at 500° C. was injected. The mass ratio of the injected hydrogen-donating solvent to supercritical water was 0.03:1, and the volume ratio of supercritical water to CO was 2:1. Example 5

[0044] Based on the principles and structural design described in Example 1, a system for underground hydrogenation and liquefaction of oil shale was established.

[0045] High-pressure water was introduced into fracturing well 4 to perform drilling and fracturing on oil shale layer 1. A mixture of 9,10-dibromoanthracene and 9,10-dibromophenanthrene was selected as a hydrogen donor solvent in a volume ratio of 1:1.3. Copper nitrate and zinc chloride were selected as metal catalysts in a mass ratio of 1:1.5. The mass of the catalyst corresponding to 1 L of hydrogen donor solvent was 110 g. CO was introduced into the oil shale layer after being heated by microwaves to a temperature of 250°C. Finally, supercritical water at 520°C was injected. The mass ratio of the injected hydrogen donor solvent to supercritical water was 0.05:1, and the volume ratio of supercritical water to CO was 2.1:1. Example 6

[0046] Based on the principles and structural design described in Example 1, a system for underground hydrogenation and liquefaction of oil shale was established.

[0047] High-pressure water was introduced into the fracturing well 4 to perform drilling and fracturing on the oil shale layer 1. A mixture of 9,10-diphenylphenanthrene and 9,10-diphenylanthracene was selected as the hydrogen supply solvent in a volume ratio of 1:1.4. Copper nitrate and iron oxide were selected as metal catalysts in a mass ratio of 1:1.7. The mass of the catalyst corresponding to 1 L of the hydrogen supply solvent was 120 g. The introduced CO was heated to 300° C. by microwave and then introduced into the oil shale layer. Finally, 550° C. supercritical water was injected. The mass ratio of the injected hydrogen supply solvent to supercritical water was 0.06:1, and the volume ratio of supercritical water to CO was 2.5:1.

[0048] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A system for underground hydroliquefaction of oil shale, characterized by: In the oil shale mining area, an injection well (3), a fracturing well (4) and a production well (6) are arranged; the injection well (3), the fracturing well (4) and the production well (6) are all drilled from the surface into the oil shale layer (1), and the fracturing well (4) is arranged between the injection well (3) and the production well (6) and close to the injection well (3); The injection well (3) is used to inject supercritical water into the oil shale formation (1); the fracturing well (4) is used to inject fracturing medium, a mixed suspension of hydrogen supply solvent and catalyst, and CO into the oil shale formation (1); and the production well (6) is used to discharge oil and gas products from in-situ hydrogenation and liquefaction of the oil shale.

2. The system for underground hydroliquefaction of oil shale according to claim 1, characterized in that: A double-layer casing structure is arranged in the fracturing well (4), wherein the double-layer casing (5) comprises an outer tube (501), an inner tube (502), a support assembly (503), a temperature sensor (504) and an exhaust valve (505); The inner tube (502) is fixed to the inside of the outer tube (501) via a support assembly (503); a microwave heating device is provided inside the inner tube (502); and a cavity formed between the outer wall of the inner tube (502) and the inner wall of the outer tube (501) is used for injecting CO; An exhaust port is provided at the bottom of the outer tube (501), an exhaust valve (505) is provided at the exhaust port, and a temperature sensor (504) is provided on the inner wall of the bottom of the outer tube (501).

3. The oil shale underground hydroliquefaction system according to claim 2, characterized in that: The microwave heating device comprises a magnetron (506) and a waveguide (507). The magnetron (506) is arranged at the inlet of the inner tube (502). The inner tube (502) is made of ceramic material. A plurality of waveguides (507) are arranged on the inner wall of the inner tube (502).

4. The oil shale underground hydroliquefaction system according to claim 3, characterized in that: It includes a water tower (7) arranged on the ground, a supercritical water generator (8), a microwave control room (9), a pressure pump (10), a CO storage tank (11), a hydrogen supply solvent and catalyst suspension storage tank (12), an oil-water separator (13), a gas-liquid separator (14), and an exhaust pump (15); The outlet pipe of the water tower (7) is connected to the inlet end of the supercritical water generator (8) and the inlet end of the pressure pump (10), respectively; the outlet end of the supercritical water generator (8) is connected to the injection well (3); the microwave control chamber (9) is used to control the microwave emission frequency in the fracturing well (4); the CO storage tank (11) and the hydrogen supply solvent and catalyst suspension storage tank (12) are all connected to the fracturing well (4); the inlet end and the outlet end of the exhaust pump (15) are connected to the production well (6) and the gas-liquid separator (14), respectively; and the outlet end of the gas-liquid separator (14) is connected to the oil-water separator (13).

5. A method for underground hydroliquefaction of oil shale, characterized in that: The system for underground hydroliquefaction of oil shale according to claim 4 comprises: Step 1: After the fracturing medium is pressurized by a pressure pump (10), it is injected into the oil shale layer (1) through a fracturing well (4) for fracturing, thereby forming a fracturing crack network and generating oil and gas channels (18); Step 2: injecting the hydrogen supply solvent and catalyst mixed suspension in the hydrogen supply solvent and catalyst suspension storage tank (12) into the oil shale formation (1) through the fracturing well (4); then heating CO through microwaves in the fracturing well (4) and passing it into the underground oil shale formation (1); sealing the wellhead of the fracturing well (4); and finally injecting supercritical water into the oil shale formation (1) through the injection well (3); In the fracture network and pores of the oil shale formation (1), supercritical water and CO undergo a supercritical water-gas shift reaction, and the oil shale is in situ hydrogenated and liquefied under the action of the supercritical shift reaction, hydrogen-donating solvent, and catalyst to generate oil and gas products; In step three, the oil and gas products are discharged to the surface through the production well (6) and separated by the gas-liquid separator (14) and the oil-water separator (13).

6. The method for underground hydroliquefaction of oil shale according to claim 5, characterized in that: In step 2, the temperature of the CO after microwave heating is 200-300°C, and the temperature of the supercritical water is 450-550°C.

7. The method for underground hydroliquefaction of oil shale according to claim 5 or 6, characterized in that: In step 2, the catalyst is a combination of any two of the oxides, sulfates, chlorides or nitrates of iron, nickel, copper or zinc.

8. The method for underground hydroliquefaction of oil shale according to claim 7, characterized in that: In step 2, the hydrogen-donating solvent is anthracene or phenanthrene and its derivatives.

9. The method for underground hydroliquefaction of oil shale according to claim 8, characterized in that: In step 2, the mass of the catalyst corresponding to 1 L of hydrogen supply solvent is 50-120 g.

10. The method for underground hydroliquefaction of oil shale according to claim 9, characterized in that: In step 2, the volume ratio of supercritical water and CO is (1.5-2.5):1, and the mass ratio of hydrogen donor solvent and supercritical water is: (0.02-0.06):1.

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