A system and method for in-situ hydro-liquefaction of oil shale

Abstract

The application discloses an oil shale underground hydrogenation liquefaction system and method, and belongs to the technical field of oil shale in-situ mining. The oil shale underground hydrogenation liquefaction system is provided with an injection well, a fracturing well and a production well in an oil shale mining area. A fracturing medium is injected into an oil shale layer through the fracturing well to generate an oil and gas passage; a hydrogen-donor solvent and a catalyst mixed suspension liquid are injected into the oil shale layer through the fracturing well, then CO is injected into the fracturing well and is heated by microwaves to be introduced into the underground oil shale layer, and the wellhead of the fracturing well is closed; finally, supercritical water is injected into the oil shale layer from the injection well; the supercritical water and the CO in the fracture network and the pore of the oil shale layer undergo a supercritical water-gas shift reaction, and the oil shale is in-situ hydrogenation liquefied under the action of the supercritical shift reaction, the hydrogen-donor solvent and the catalyst to generate oil and gas products. The oil and gas products are discharged to the ground through the production well, are separated through a gas-liquid separator and an oil-water separator, and the oil shale underground hydrogenation liquefaction mining is completed.

Description

Technical Field

[0001] This invention belongs to the field of in-situ oil shale mining technology, specifically, it relates to a system and method for underground hydrogenation liquefaction of oil shale. Background Technology

[0002] Currently, in-situ mining has become the inevitable path for the development and utilization of oil shale. Oil shale is characterized by low thermal conductivity, low permeability, and low grade, leading to common key problems in in-situ mining such as low heating efficiency, low recovery rate, and poor oil quality. Therefore, there is an urgent need to find a clean and efficient method for oil shale mining to promote its large-scale development and utilization.

[0003] Supercritical water possesses a low dielectric constant, weak hydrogen bonds, and a high ionization constant, exhibiting strong solvation and extraction effects on the organic matter of oil shale. In-situ extraction of oil shale using supercritical water has become a promising development method in recent years, significantly improving oil and gas recovery rates. However, supercritical water struggles to undergo hydrogenation reactions with organic matter, and pyrolysis reactions are often incomplete, resulting in oil containing large amounts of high-viscosity and high-density colloids and asphaltenes. This severely blocks oil and gas mass transfer channels, reducing the efficiency of in-situ extraction. 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 hydrogenation liquefaction of oil shale is provided, wherein injection wells, fracturing wells and production wells are arranged in an oil shale mining area; the injection wells, fracturing wells and production wells are all drilled from the surface to the oil shale layer, and the fracturing wells are located between the injection wells and production wells and 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 supply solvent and catalyst, and CO into the oil shale formation sequentially; and the production well is used to discharge the oil and gas products from the in-situ hydrogenation and liquefaction of oil shale.

[0006] Furthermore, a double-casing structure is arranged inside the fracturing well, the double-casing including an outer casing, an inner casing, a support assembly, a temperature sensor, and an exhaust valve; The inner tube is fixed inside the outer tube by 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 for CO injection. An exhaust port is located at the bottom of the outer tube, an exhaust valve is located at the exhaust port, and a temperature sensor is located on the inner wall at the bottom of the outer tube.

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

[0008] Furthermore, it includes a water tower, a supercritical water generator, a microwave control room, a pressurization 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, all located on the ground. The outlet pipe of the water tower is connected to the inlet of the supercritical water generator and the inlet of the booster pump, respectively. The outlet 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 both connected to the fracturing well. The inlet and outlet of the exhaust pump are connected to the production well and the gas-liquid separator, respectively. The outlet 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 hydrogenation liquefaction of oil shale is provided, employing the above-described system for underground hydrogenation liquefaction of oil shale, comprising: Step 1: After being pressurized by a booster pump, the fracturing medium is injected into the oil shale layer through a fracturing well to fracturing the rock, forming a network of fracturing fractures and generating oil and gas channels; the fracturing medium is preferably high-pressure water.

[0010] Step two involves injecting the hydrogen supply solvent and catalyst suspension from the hydrogen supply solvent and catalyst suspension storage tank into the oil shale formation through a fracturing well. Then, CO is introduced into the underground oil shale formation through microwave heating in the fracturing well, and the wellhead of the fracturing well is sealed. Finally, supercritical water is injected into the oil shale formation through the injection well. In the fracture network and pores of oil shale formations, supercritical water and CO undergo a supercritical water-gas shift reaction. Under the action of the supercritical shift reaction, hydrogen-donating solvent and catalyst, oil shale is hydrogenated and liquefied in situ to generate oil and gas products.

[0011] During in-situ oil shale extraction, both the supercritical shift reaction and the hydrogen-donating solvent release active hydrogen under heating conditions. This hydrogen 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 synergistic effect of the hydrogen-donating solvent and the shift system prolongs and improves the efficiency and effectiveness of hydrogen supply, significantly improving the quality and yield of the product oil.

[0012] Step 3: Oil and gas products are discharged to the surface through production wells and separated by gas-liquid separators and oil-water separators.

[0013] Furthermore, in step two, the CO is heated to a temperature of 200-300°C by microwave heating, and the supercritical water temperature is 450-550°C. The supercritical water pressure is above 22.1 MPa.

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

[0015] Furthermore, in step two, the hydrogen-donating solvent is anthracene or phenanthrene and its 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 two, the mass of catalyst corresponding to 1L of hydrogen-donating solvent is 50~120g. This ensures sufficient contact between the active sites in the catalyst and the hydrogen-donating solvent, thereby enhancing hydrogen migration efficiency.

[0017] Furthermore, in step two, the volume ratio of supercritical water to CO is (1.5~2.5):1, and the mass ratio of hydrogen-supplying 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] This invention injects a mixed suspension of supercritical water, carbon monoxide, catalyst, and hydrogen-donating solvent into an oil shale layer. CO is preheated using microwave heating. Under these conditions, supercritical water and carbon monoxide undergo a supercritical water-gas shift reaction in the combined action of the hydrogen-donating solvent and catalyst, thereby promoting the hydroliquefaction process of oil shale and generating more light oil.

[0019] In this invention, microwaves within a double-layer casing are used to preheat CO. Compared to surface heating, this method offers faster heating speeds and avoids heat loss within the wellbore, resulting in less heat loss. Once the high-temperature CO enters the oil shale formation, it heats the suspension of the catalyst and hydrogen-supplying solvent, bringing it to a boiling state and ensuring a more uniform distribution of the catalyst and hydrogen-supplying solvent within the oil shale formation.

[0020] In this invention, supercritical water and carbon monoxide undergo a water-gas shift reaction (H₂O + CO → CO₂ + H₂) to produce an active hydrogen intermediate. Simultaneously, the hydrogen-donating solvent, at high temperatures, also provides active hydrogen, stabilizing free radicals in the reaction, promoting the cracking of large organic molecules in oil shale, inhibiting polymerization reactions, and improving the quality of the oil products. The hydrogen-donating solvent and catalyst have a synergistic effect, jointly promoting the shift reaction and oil shale liquefaction, reducing the density and viscosity of the product oil, and improving the efficiency of oil and gas product recovery. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of underground hydrogenation liquefaction of oil shale provided by the present invention; Figure 2 This is a schematic diagram of the structure of the double-layer sleeve described in this invention; Figure 3This is a schematic diagram showing the connection between the outer tube and the inner tube in the double-layer sleeve described in this invention.

[0022] In the diagram, 1-oil shale layer; 2-other rock layers; 3-injection well; 4-fractured well; 5-double casing; 501-outer casing; 502-inner casing; 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-pressurization 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 passage. Detailed Implementation

[0023] Microwave heating offers rapid heating and high energy efficiency, penetrating directly into the gas to shorten heating time and improve efficiency. Preheated CO is introduced into the oil shale formation and undergoes a water-gas shift reaction (H₂O + CO → CO₂ + H₂) with supercritical water to produce active hydrogen. Furthermore, the hydrogen-donating solvent also provides active hydrogen at high temperatures. This active hydrogen can then undergo a hydrogenation reaction 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 can catalyze 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 this invention is to inject supercritical water and microwave-heated CO into oil shale formations to carry out a water-gas shift reaction. Under the synergistic effect of hydrogen-supplying solvent and catalyst, the organic matter in the oil shale undergoes in-situ hydrogenation and liquefaction, effectively alleviating the problem of heavy oil blocking oil and gas migration channels. Example 1

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

[0026] Fracturing well 4 has a double-casing structure, such as Figure 2 As shown, the double-layer sleeve 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 sleeve 5 is a microwave heating device system, including a magnetron 506 disposed 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 CO injection. The inner tube (502) is fixed inside the outer tube (501) by a support assembly (503). Figure 3 ).

[0028] like Figure 2 As shown, the lower part of the double-layer sleeve has an inverted frustum-shaped structure. 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 after 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 pressurization 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, all located on the ground.

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

[0031] The hydrogen supply solvent and catalyst mixed suspension 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 injected into the oil shale formation 1 after being microwave heated by the CO storage tank 11 through the fracturing well 4. The water in the water tower 7 is transformed into a supercritical state by the supercritical water generator 8 and injected into the oil shale formation 1 through the injection well 3.

[0032] After well completion, fracturing medium is injected into oil shale layer 1 through fracturing well 4 to fracture oil shale layer 1, creating a network of fracturing fractures and generating oil and gas channels 18.

[0033] After fracturing is completed, a double-layer casing 5 is installed 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 to cement the well.

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

[0035] In the fracture network and pores of oil shale formation 1, supercritical water and CO undergo a supercritical water-gas shift reaction under the action of hydrogen-supplying solvent and catalyst. The oil shale is then hydrogenated and liquefied in situ under the action of supercritical shift reaction, hydrogen-supplying solvent and catalyst to generate oil and gas products. The oil and gas products are discharged to the surface through 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] In Examples 2-6, the oil shale layer 1 is buried at a depth of 1000m, with an average grade of 12.00%~20.00% and a thickness of 11m~20m. Example 2

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

[0039] High-pressure water was introduced into fracturing well 4 to drill and fracture oil shale layer 1. A mixture of 9-anthracene methanol and 9-phenanthrene methanol was selected as the hydrogen donor solvent with a volume ratio of 1:1.2. Copper oxide and ferric chloride were selected as the metal catalysts with a mass ratio of 1:1.3. The mass of catalyst corresponding to 1L of hydrogen donor solvent was 50g. CO was introduced into the oil shale layer after being microwave-heated to 200℃. Finally, supercritical water at 450℃ 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 liquefaction of oil shale was established.

[0041] High-pressure water was introduced into fracturing well 4 to drill and fracture oil shale layer 1. A mixture of 9-anthracarboxylic acid and 9-phenanthrenecarboxylic acid was selected as the hydrogen donor solvent with a volume ratio of 1:1.3. Ferric sulfate and zinc nitrate were selected as the metal catalyst with a mass ratio of 1:1.4. The mass of catalyst corresponding to 1L of hydrogen donor solvent was 80g. CO was introduced into the oil shale layer after being microwave-heated to 270℃. Finally, supercritical water at 480℃ 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 liquefaction of oil shale was established.

[0043] High-pressure water was introduced into fracturing well 4 to drill and fracture oil shale layer 1. A mixture of 9,10-dihydroanthracene and 9,10-dihydrophenanthrene was selected as the hydrogen donor solvent, with a volume ratio of 1:1.5. Ferric nitrate and copper chloride were selected as the metal catalysts, with a mass ratio of 1:1.6. The mass of catalyst corresponding to 1L of hydrogen donor solvent was 80g. CO was introduced into the oil shale layer after being microwave-heated to 280℃. Finally, 500℃ supercritical water was injected. The mass ratio of the injected hydrogen donor 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 liquefaction of oil shale was established.

[0045] High-pressure water was introduced into fracturing well 4 to drill and fracture oil shale layer 1. A mixture of 9,10-dibromoanthracene and 9,10-dibromophenanthrene was selected as the hydrogen donor solvent, with a volume ratio of 1:1.3. Copper nitrate and zinc chloride were selected as the metal catalysts, with a mass ratio of 1:1.5. The mass of catalyst corresponding to 1L of hydrogen donor solvent was 110g. CO was introduced into the oil shale layer after being microwave-heated to 250℃. Finally, supercritical water at 520℃ 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 liquefaction of oil shale was established.

[0047] High-pressure water was introduced into fracturing well 4 to drill and fracture oil shale layer 1. A mixture of 9,10-diphenylphenanthrene and 9,10-diphenylanthracene was selected as the hydrogen donor solvent, with a volume ratio of 1:1.4. Copper nitrate and iron oxide were selected as the metal catalysts, with a mass ratio of 1:1.7. The mass of catalyst corresponding to 1L of hydrogen donor solvent was 120g. CO was introduced into the oil shale layer after being microwave-heated to 300℃. Finally, supercritical water at 550℃ was injected. The mass ratio of the injected hydrogen donor 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 embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for underground hydrogenation liquefaction of oil shale, characterized in that, The system is applied to underground hydrogenation liquefaction of oil shale. In the oil shale mining area, the system is arranged with injection well (3), fracturing well (4) and production well (6). The injection well (3), fracturing well (4) and production well (6) are all drilled from the surface to the oil shale layer (1). The fracturing well (4) is set 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 layer (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 layer (1) in sequence; the production well (6) is used to discharge the oil and gas products from the in-situ hydrogenation and liquefaction of the oil shale; the fracturing well (4) is equipped with a double-casing structure, the double-casing (5) including an outer pipe (501), an inner pipe (502), a support assembly (503), a temperature sensor (504), and an exhaust valve (505); The inner tube (502) is fixed inside the outer tube (501) by a support assembly (503). A microwave heating device is installed inside the inner tube (502). The cavity formed between the outer wall of the inner tube (502) and the inner wall of the outer tube (501) is used for CO injection. An exhaust port is provided at the bottom of the outer tube (501), an exhaust valve (505) is located at the exhaust port, and a temperature sensor (504) is located on the inner wall at the bottom of the outer tube (501); the exhaust valve (505) is automatically opened after the CO temperature reaches the required temperature. The microwave heating device includes a magnetron (506) and waveguides (507). The magnetron (506) is located at the inlet of the inner tube (502). The inner tube (502) is made of ceramic material, and multiple waveguides (507) are arranged on the inner wall of the inner tube (502). The method includes the following steps: Step 1: After being pressurized by the booster pump (10), the fracturing medium is injected into the oil shale layer (1) through the fracturing well (4) to perform fracturing, forming a fracturing fracture network and generating oil and gas channels (18); Step 2: The hydrogen supply solvent and catalyst suspension in the hydrogen supply solvent and catalyst suspension storage tank (12) is injected into the oil shale layer (1) through the fracturing well (4). Then, CO is introduced into the underground oil shale layer (1) through microwave heating in the fracturing well (4), and the wellhead of the fracturing well (4) is sealed. Finally, supercritical water is injected into the oil shale layer (1) through the injection well (3). In the fracture network and pores of the oil shale layer (1), supercritical water and CO undergo a supercritical water-gas shift reaction. Under the action of supercritical shift reaction, hydrogen-supplying solvent and catalyst, the oil shale is hydrogenated and liquefied in situ to generate oil and gas products. The hydrogen-donating solvent is any combination of two of anthracene or phenanthrene and their derivatives, and the catalyst is any combination of two of oxides, sulfates, chlorides or nitrates of iron, nickel, copper, or zinc; the mass of catalyst corresponding to 1L of hydrogen-donating solvent is 50~120g; 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. Step 3: 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).

2. The method for underground hydrogenation liquefaction of oil shale according to claim 1, characterized in that: In step two, the CO is heated to a temperature of 200-300°C by microwave heating, and the supercritical water is heated to a temperature of 450-550°C.

3. The method for underground hydrogenation liquefaction of oil shale according to claim 2, characterized in that: Includes a ground-mounted water tower (7), a supercritical water generator (8), a microwave control room (9), a pressurization 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 booster pump (10), respectively. The outlet end of the supercritical water generator (8) is connected to the injection well (3). The microwave control room (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 both connected to the fracturing well (4). The inlet end and outlet end of the exhaust pump (15) are connected to the production well (6) and the gas-liquid separator (14), respectively. The outlet end of the gas-liquid separator (14) is connected to the oil-water separator (13).

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