In-situ relay catalytic exploitation method for oil shale

Abstract

The present application relates to a kind of oil shale in situ relay catalytic exploitation method, belong to oil shale in situ mining technical field, the exploitation method uses water as heat transfer and mass transfer medium, uses water-soluble metal salt and solid catalyst relay catalytic oil shale in situ cracking, in underground oil shale reservoir, heated to near critical state water has stronger permeability due to its high pressure, can carry water-soluble metal salt into the inside of dense block oil shale, catalytic cheese root cracking generates oil shale oil and gas, solid catalyst moves relatively poor, in fracturing process, it will be filled in the crack generated in fracturing with proppant, catalytic migration to the secondary cracking of oil shale oil generated light oil and gas.The exploitation method described in the present application can effectively shorten the mining cycle of oil shale, and improve the recovery of light oil and gas.

Description

Technical Field

[0001] This invention relates to the field of in-situ oil shale mining technology, specifically to an in-situ relay catalytic mining method for oil shale. Background Technology

[0002] Oil shale is a fine-grained sedimentary rock rich in organic matter (mainly kerogen), with an internal organic matter content generally ranging from 10% to 50%. It can produce oil and gas through pyrolysis. my country has abundant oil shale reserves, equivalent to approximately 47.644 billion tons of oil, ranking second globally. Therefore, oil shale is an ideal supplementary energy source to petroleum.

[0003] Currently, oil shale is mainly developed and utilized through surface retorting technology. However, this technology is costly, causes severe environmental pollution, and is only applicable to shallow oil shale resources. Therefore, research institutions both domestically and internationally have turned to researching in-situ oil shale extraction technology. In-situ oil shale extraction technology refers to the method of injecting heat into the oil shale reservoir through drilling to crack the organic matter, and then extracting the resulting oil and gas to the surface through oil recovery processes.

[0004] Shell has proposed ICP technology (application number CN87100890), which uses an electric heater to heat underground oil shale formations via conduction heating, with a heating cycle typically lasting 2-3 years. CN101871339A discloses a method for in-situ extraction of hydrocarbons from oil shale, proposing the injection of water and inert gas water vapor into the working well to create a near-critical water microenvironment to heat the oil shale formation, thereby producing oil and gas. CN1676870B discloses a method for extracting oil and gas from oil shale using convection heating, injecting high-temperature steam (400-700℃) along a heating well into the oil shale formation, heating the ore layer and causing the kerogen to pyrolyze and form oil and gas. Relatively speaking, the heating rate of convection heating is much higher than that of conduction heating.

[0005] However, existing in-situ oil shale mining technologies and pilot projects have encountered the following two key problems: first, the kerogen pyrolysis rate is low and the heating cycle is long; second, the oil shale oil produced by pyrolysis has poor fluidity and low recovery rate.

[0006] Selecting a suitable catalyst to promote in-situ pyrolysis of oil shale is an effective solution. CN109424345B discloses a method for in-situ oil shale extraction, proposing the use of a proppant containing magnetic nanocatalysts to catalyze oil shale pyrolysis. This catalyst loads the active component onto Fe3O4 particles, which are then combined with a ceramic proppant. Results show that this catalyst effectively reduces the viscosity of oil shale oil. CN108435154A discloses a catalyst for in-situ oil shale extraction and its application method, proposing the use of magnesium sulfate aqueous solution to catalyze hydrothermal pyrolysis of oil shale. This catalyst can reduce the oil extraction temperature and increase oil and gas yield in in-situ oil shale extraction. Similarly, CN114989854B proposes a method to improve the yield of light oil from oil shale pyrolysis, suggesting the use of supercritical water to carry water-soluble transition metal salts into the pore structure of oil shale to catalyze pyrolysis. This catalytic pyrolysis system can promote the pyrolysis of large-molecule heavy oil and inhibit condensation reactions.

[0007] However, the aforementioned methods still failed to effectively solve the two key problems mentioned above. This is because the pyrolysis reaction of kerogen occurs inside the dense, massive oil shale, while the migration and re-pyrolysis of the oil shale oil generated by kerogen pyrolysis occurs in the fractures created by rock fracturing. The two reactions occur in different spaces, so a single catalyst is unlikely to meet the requirements of both reactions.

[0008] In summary, this invention develops an in-situ relay catalytic extraction method for oil shale. Summary of the Invention

[0009] In view of the problems existing in the prior art, the present invention provides an in-situ relay catalytic extraction method for oil shale. This method uses water as a heat and mass transfer medium, and employs water-soluble metal salts and a solid catalyst to relay catalyze the in-situ cracking of oil shale. In underground oil shale reservoirs, water heated to near-critical states has strong permeability due to its high pressure, allowing it to carry water-soluble metal salts into the dense, massive oil shale, catalyzing the cracking of kerogen to generate oil shale oil and gas. The solid catalyst has poor mobility and, during fracturing, fills the fractures created by fracturing along with the proppant, catalyzing the secondary cracking of the oil shale oil that has migrated there to generate light oil and gas. The extraction method of the present invention can effectively shorten the oil shale extraction cycle and improve the recovery rate of light oil and gas.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] The purpose of this invention is to provide an in-situ relay catalytic extraction method for oil shale. The extraction method includes the following steps: using water as a heat and mass transfer medium, water-soluble metal salts catalyze the kerogen inside the tight oil shale, which is then cracked to generate oil shale oil and gas. A solid catalyst catalyzes the oil shale oil that has migrated there to the rock fissures, which is then cracked a second time to generate light oil and gas, thus realizing the relay catalytic in-situ cracking of oil shale by water-soluble metal salts and solid catalysts.

[0012] In the extraction method described in this invention, in a near-critical metal salt aqueous solution environment, metal ions penetrate into the dense interior of oil shale along with the near-critical water, promoting kerogen pyrolysis to produce oil shale oil and gas and expelling it from the oil shale matrix. Meanwhile, the solid catalyst in the rock fissures promotes the secondary pyrolysis of the oil shale oil that has migrated there, producing light oil and gas that are easy to flow and extract.

[0013] As a preferred technical solution of the present invention, the mining method includes the following steps:

[0014] (1) Within the delineated in-situ oil shale mining area, drill at least one heat injection well and at least one production well to the target oil shale layer;

[0015] (2) Prepare a water-based fracturing fluid containing a solid catalyst and a proppant, and then perform downhole hydraulic fracturing between the injection well and the production well, so that the solid catalyst and the proppant are filled together in the rock fractures generated by fracturing.

[0016] (3) Dissolve water-soluble metal salts in water, and inject the resulting metal salt aqueous solution into the fracturing oil shale layer through the hot injection well, while displacing the residual water-based fracturing fluid through the production well.

[0017] (4) Seal the injection well and production well, and use the downhole heater to heat the metal salt aqueous solution in the oil shale layer to a near-critical state, so that the water-soluble metal salt penetrates into the interior of the tight oil shale, catalyzes the cracking of kerogen to generate oil shale oil and gas and discharges the oil shale matrix. The solid catalyst catalyzes the oil shale oil that has migrated to this place in the rock layer fractures, and generates light oil and gas through secondary cracking, realizing the relay catalysis of in-situ cracking of oil shale by water-soluble metal salt and solid catalyst;

[0018] (5) After the heating is completed, the oil, water and gas mixture is extracted to the surface through the production well for separation to obtain the target product light oil and gas.

[0019] It should be noted that the water-based fracturing fluid containing solid catalyst and proppant described in this invention can be obtained by mixing solid catalyst, proppant and water-based fracturing fluid, or by mixing proppant loaded with solid catalyst and water-based fracturing fluid. Those skilled in the art can choose according to the actual situation.

[0020] As a preferred technical solution of the present invention, the water-soluble metal salt includes transition metal salts and / or alkaline earth metal salts, preferably any one or a combination of at least two of ferric chloride, ferrous chloride or calcium chloride.

[0021] As a preferred technical solution of the present invention, the solid catalyst includes any one or a combination of at least two of molecular sieves, transition metal oxides, transition metal sulfides or elemental transition metals, preferably any one or a combination of at least two of cerium-supported HZSM-5 molecular sieves, iron oxide or ferrous sulfide.

[0022] As a preferred technical solution of the present invention, the distance between the injection well and the production well in step (1) is controlled to be 10-20m, and horizontal wells can be drilled between multiple wells.

[0023] It should be noted that the distance between wells described in this invention is 10 to 20m, such as 10m, 11m, 12m, 13m, 14m, 15m, 16m, 17m, 18m, 19m or 20m, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] As a preferred technical solution of the present invention, the amount of solid catalyst added in step (2) is 0.05 to 1 wt% of the target reservoir oil shale mass, such as 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.35 wt%, 0.4 wt%, 0.5 wt%, 0.65 wt%, 0.7 wt%, 0.8 wt%, 0.95 wt%, or 1 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0025] As a preferred technical solution of the present invention, the metal ion concentration of the metal salt aqueous solution in step (3) is 0.04 to 0.12 mol / L, for example, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L or 0.12 mol / L, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0026] It should be noted that the injection volume of the metal salt aqueous solution in this invention can be adjusted according to the actual required pressure, but it is necessary to ensure that the downhole water level is not higher than the top plate of the oil shale layer.

[0027] As a preferred technical solution of the present invention, the heating temperature in step (4) is 300 to 370°C, such as 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C or 370°C, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0028] Preferably, the heating pressure in step (4) is 5 to 20 MPa, such as 5 MPa, 7 MPa, 9 MPa, 10 MPa, 12 MPa, 14 MPa, 15 MPa, 16 MPa, 18 MPa or 20 MPa, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0029] It should be noted that the heating pressure described in this invention is the pressure generated by high temperature.

[0030] Preferably, the heating and heat preservation time in step (4) is 2 to 10 days, such as 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days or 10 days, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0031] As a preferred technical solution of the present invention, the downhole heater in step (4) includes any one or a combination of at least two of resistance heating, electromagnetic heating or microwave heating.

[0032] As a preferred technical solution of the present invention, the water obtained by separation in step (5) is used to dissolve water-soluble metal salts again and inject them into a new heat injection well to realize the recycling of water resources.

[0033] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0034] In the extraction method described in this invention, water heated to near-critical state creates numerous microfractures within the underground oil shale layer. Water-soluble metal salts are then transported into the oil shale along these microfractures, catalyzing the cracking of kerogen to produce oil and gas. A solid catalyst constructs catalytic cracking-migration channels for oil shale oil within the fractures created by rock fracturing, promoting secondary cracking of the oil shale oil and generating light oil and gas. The relay catalysis of oil shale cracking by these two types of catalysts effectively shortens the oil shale extraction cycle and improves the recovery rate of light oil and gas. Attached Figure Description

[0035] Figure 1 This is a well layout diagram of the in-situ relay catalytic extraction method for oil shale described in this invention.

[0036] Figure 2 This is a schematic diagram of the in-situ relay catalytic extraction method for oil shale described in this invention;

[0037] In the diagram: 1-Injection Well 1; 2-Injection Well 2; 3-Injection Well 3; 4-Injection Well 4; 5-Production Well 1; 6-Production Well 2; 7-Production Well 3; 8-Production Well 4; 9-Production Well 5; 10-Production Well 6; 11-Production Well 7; 12-Production Well 8; 13-Production Well 9; 14-Horizontal Well; 15-Controller; 16-Cable; 17-Injection Well; 18-Pressure Sensor; 19-Temperature Sensor; 20- 21-High-pressure water pump; 22-Water tank; 23-Booster; 24-Pressure stabilizing pipe; 25-Pressure sensor; 26-Production well; 27-Separator; 28-Gas storage tank; 29-Oil storage tank; 30-Downhole heater; 31-Shale roof; 32-Shale floor; 33-Oil shale layer; 34-Kerogen; 35-Solid catalyst; 36-Water-soluble metal salt; 37-High molecular weight oil shale oil; 38-Low molecular weight oil shale oil. Detailed Implementation

[0038] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0039] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0040] Embodiments of the present invention provide an in-situ relay catalytic extraction method for oil shale, the extraction method comprising the following steps:

[0041] (1) Within the delineated in-situ oil shale mining area, drill at least one heat injection well and at least one production well to the target oil shale layer;

[0042] (2) Prepare a water-based fracturing fluid containing a solid catalyst and a proppant, and then perform downhole hydraulic fracturing between the injection well and the production well, so that the solid catalyst and the proppant are filled together in the rock fractures generated by fracturing.

[0043] (3) Dissolve water-soluble metal salts in water, and inject the resulting metal salt aqueous solution into the fracturing oil shale layer through the hot injection well, while displacing the residual water-based fracturing fluid through the production well.

[0044] (4) Seal the injection well and production well, and use the downhole heater to heat the metal salt aqueous solution in the oil shale layer to a near-critical state, so that the water-soluble metal salt penetrates into the interior of the tight oil shale, catalyzes the cracking of kerogen to generate oil shale oil and gas and discharges the oil shale matrix. The solid catalyst catalyzes the oil shale oil that has migrated to this place in the rock layer fractures, and generates light oil and gas through secondary cracking, realizing the relay catalysis of in-situ cracking of oil shale by water-soluble metal salt and solid catalyst;

[0045] (5) After the heating is completed, the oil, water and gas mixture is extracted to the surface through the production well for separation to obtain the target product light oil and gas. The separated water is used to dissolve water-soluble metal salts again and injected into a new injection well to realize the recycling of water resources.

[0046] The well distribution diagram of the in-situ relay catalytic extraction method for oil shale described in this invention is as follows: Figure 1 As shown, that is, drilling at least one heat injection well and at least one production well as described in step (1), and horizontal wells can be drilled between multiple wells;

[0047] in, Figure 2 This diagram illustrates the in-situ relay catalytic extraction method for oil shale according to the present invention. An oil shale layer 32 lies between the shale top plate 30 and the shale bottom plate 31. A heat injection well 17 and a production well 25 are installed, extending into the oil shale layer 32. A controller 15 controls the heat injection well 17 via a cable 16. A metal salt aqueous solution from a water tank 21 is injected into the heat injection well 17 via a high-pressure water pump 20. A pressure sensor 18 and a temperature sensor 19 are installed on the pipeline between the high-pressure water pump 20 and the heat injection well 17. A downhole heater 29 is installed downhole in the heat injection well 17. A pressure stabilizing pipe 23 is installed between the production well 25 and the booster 22. A connection is made between the pressure stabilizing pipe 23 and the production well 25. A pressure sensor 24 is installed between the production well 25 and the separator 26. The gas pipe of the separator 26 is connected to the gas storage tank 27. The oil outlet pipe of the separator 26 is connected to the oil storage tank 28. The water outlet pipe of the separator 26 is connected to the water tank 21, realizing the recycling of water resources. The principle of in-situ relay catalysis of oil shale in this invention includes: water-soluble metal salt 35 penetrates into the interior of dense oil shale, catalyzes the cracking of kerogen 33 to generate oil shale oil and gas and discharges it from the oil shale matrix. Solid catalyst 34 catalyzes the oil shale oil that has migrated there in the rock fractures, and generates low molecular weight oil shale oil 37 through secondary cracking of high molecular weight oil shale oil 36. Figure 2 The black arrow located in oil shale layer 32 indicates the direction of catalytic cracking, but it has no practical significance.

[0048] Example 1

[0049] This embodiment provides a method for in-situ relay catalytic extraction of oil shale, the method comprising the following steps:

[0050] (1) Within the designated in-situ oil shale mining area, drill one heat injection well and one production well to the target oil shale layer. The two wells are constructed according to... Figure 1 The positions of the injection well-1 and the production well-5 are arranged, with a distance of 11m between the two wells, and a horizontal well-14 is drilled between the two wells.

[0051] (2) Mix HZSM-5 catalyst (referred to as Ce / HZSM-5) with a Ce loading of 8%, proppant and water-based fracturing fluid. The amount of Ce / HZSM-5 added is 0.1wt% of the target reservoir oil shale mass. Perform downhole hydraulic fracturing on horizontal well 14 so that Ce / HZSM-5 and proppant will fill the rock fractures generated by fracturing together.

[0052] (3) According to Figure 2 After installing the surface equipment and downhole heater 29, a FeCl3 aqueous solution with a metal ion concentration of 0.08 mol / L is prepared in the water tank 21, and the FeCl3 aqueous solution is injected into the fracturing oil shale layer through the hot injection well. At the same time, the residual water-based fracturing fluid is discharged through the production well.

[0053] (4) Seal the injection well and production well, and use downhole heater 29 to heat the FeCl3 aqueous solution in the oil shale formation to a near-critical state, reaching 350℃, with a downhole pressure of 16MPa and a holding time of 5 days. Downhole temperature and pressure are monitored in real time by pressure sensor 18 and temperature sensor 19, and the heating power is adjusted by controller 15. In the near-critical FeCl3 aqueous solution environment, Fe... 3+ As near-critical water penetrates into the interior of tight oil shale, it catalyzes the cracking of kerogen to generate oil and gas, which are then discharged from the oil shale matrix. Meanwhile, the oil shale oil that has migrated to the rock fractures via Ce / HZSM-5 catalyst undergoes secondary cracking to generate light oil and gas that is easy to flow and extract. This process achieves in-situ cracking of oil shale through relay catalysis by water-soluble metal salts and solid catalysts.

[0054] (5) After the heating is completed, the oil, water and gas mixture is pumped to the ground through the production well. The oil, water and gas mixture is separated by the separator 26 to obtain the target product light oil and gas, which are stored in the oil storage tank 28 and the gas storage tank 27 respectively. The separated water is injected into the water tank 21, and FeCl3 is dissolved again before being injected into a new injection well to realize the recycling of water resources.

[0055] Example 2

[0056] This embodiment provides a method for in-situ relay catalytic extraction of oil shale, the method comprising the following steps:

[0057] (1) Within the designated in-situ oil shale mining area, drill two heat injection wells and three production wells to the target oil shale layer, according to... Figure 1 The positions of the injection well 1, injection well 3, and production well 5, production well 2, and production well 3 are arranged in a staggered pattern, with a distance of 14m between each well.

[0058] (2) Mix Fe2O3, proppant and water-based fracturing fluid. The amount of Fe2O3 added is 0.08 wt% of the target reservoir oil shale mass. Perform downhole hydraulic fracturing between two injection wells and three production wells so that Fe2O3 and proppant will fill the rock fractures generated by fracturing together.

[0059] (3) According to Figure 2 After installing the surface equipment and downhole heater 29, a FeCl2 aqueous solution with a metal ion concentration of 0.04 mol / L is prepared in the water tank 21, and the FeCl2 aqueous solution is injected into the fracturing oil shale layer through two hot injection wells. At the same time, the residual water-based fracturing fluid is discharged through the production well.

[0060] (4) Two injection wells and three production wells were sealed off. Downhole heater 29 was used to heat the FeCl2 aqueous solution in the oil shale formation to a near-critical state, reaching 330°C. The downhole pressure was 12.7 MPa, and the holding time was 7 days. Downhole temperature and pressure were monitored in real time using pressure sensor 18 and temperature sensor 19, and the heating power was adjusted by controller 15. In the near-critical FeCl2 aqueous solution environment, Fe... 2+ As near-critical water penetrates into the interior of tight oil shale, it catalyzes the cracking of kerogen to generate oil and gas, which are then discharged from the oil shale matrix. Meanwhile, the oil shale oil that has been transported to this location by Fe2O3 in the rock fissures undergoes secondary cracking to generate light oil and gas that are easy to flow and extract. This process achieves in-situ cracking of oil shale by relay catalysis of water-soluble metal salts and solid catalysts.

[0061] (5) After the heating is completed, the oil, water and gas mixture is pumped to the ground through the production well. The oil, water and gas mixture is separated by the separator 26 to obtain the target product light oil and gas, which are stored in the oil storage tank 28 and the gas storage tank 27 respectively. The separated water is injected into the water tank 21, and FeCl2 is dissolved again before being injected into a new injection well to realize the recycling of water resources.

[0062] Example 3

[0063] This embodiment provides a method for in-situ relay catalytic extraction of oil shale, the method comprising the following steps:

[0064] (1) Within the designated in-situ oil shale mining area, four heat injection wells and nine production wells were drilled to the target oil shale layer, according to... Figure 1 The positions of the injection wells 1, 2, 3, and 4, and the production wells 1, 5, 2, 6, 3, 7, 4, 8, 5, 9, 10, 7, 11, 8, and 9 are arranged in a staggered pattern, with a distance of 12m between each well.

[0065] (2) Mix Fe powder, proppant and water-based fracturing fluid. The amount of Fe powder added is 0.5 wt% of the target reservoir oil shale mass. Perform downhole hydraulic fracturing between four injection wells and nine production wells so that Fe powder and proppant will fill the rock fractures generated by fracturing together.

[0066] (3) According to Figure 2 After installing the surface equipment and downhole heater 29, a CaCl2 aqueous solution with a metal ion concentration of 0.12 mol / L is prepared in the water tank 21, and the CaCl2 aqueous solution is injected into the fracturing oil shale layer through four hot injection wells. At the same time, the residual water-based fracturing fluid is discharged through the production well.

[0067] (4) Four injection wells and nine production wells were sealed off. Downhole heater 29 was used to heat the CaCl2 aqueous solution in the oil shale formation to a near-critical state, reaching 360°C. The downhole pressure was 19.5 MPa, and the holding time was 4 days. Downhole temperature and pressure were monitored in real time using pressure sensor 18 and temperature sensor 19, and the heating power was adjusted by controller 15. In the near-critical CaCl2 aqueous solution environment, Ca... 2+ As near-critical water penetrates into the interior of tight oil shale, it catalyzes the cracking of kerogen to generate oil and gas, which are then discharged from the oil shale matrix. Meanwhile, the oil shale oil, which is transported here by Fe powder in the rock fractures, undergoes secondary cracking to generate light oil and gas that are easy to flow and extract. This achieves the relay catalysis of in-situ cracking of oil shale by water-soluble metal salts and solid catalysts.

[0068] (5) After the heating is completed, the oil, water and gas mixture is pumped to the surface through the production well. The oil, water and gas mixture is separated by the separator 26 to obtain the target product light oil and gas, which are stored in the oil storage tank 28 and the gas storage tank 27 respectively. The separated water is injected into the water tank 21, and after CaCl2 is dissolved again, it is injected into a new injection well to realize the recycling of water resources.

[0069] In summary, in the extraction method described in this invention, water heated to near-critical state generates numerous microfractures within the underground oil shale layer. Water-soluble metal salts are then transported into the oil shale along these microfractures, catalyzing the cracking of kerogen to produce oil and gas. A solid catalyst constructs catalytic cracking-migration channels for oil shale oil within the fractures created by rock fracturing, promoting secondary cracking of the oil shale oil and generating light oil and gas. The relay catalysis of oil shale cracking by these two types of catalysts effectively shortens the oil shale extraction cycle and improves the recovery rate of light oil and gas.

[0070] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0071] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0072] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0073] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for in-situ relay catalytic extraction of oil shale, characterized in that, The mining method includes the following: (1) Drilling at least one heat injection well and at least one production well to the target oil shale layer within the delineated in-situ oil shale mining area; (2) Prepare a water-based fracturing fluid containing a solid catalyst and a proppant, and then perform downhole hydraulic fracturing between the injection well and the production well, so that the solid catalyst and the proppant are filled together in the rock fractures generated by fracturing; (3) Water is used as a heat and mass transfer medium to dissolve water-soluble metal salts in water. The resulting metal salt aqueous solution is injected into the fracturing oil shale layer through the injection well, while the residual water-based fracturing fluid is discharged through the production well. (4) Seal the injection well and production well, and use the downhole heater to heat the metal salt aqueous solution in the oil shale layer to a near-critical state, so that the water-soluble metal salt penetrates into the interior of the tight oil shale, catalyzes the cracking of kerogen to generate oil shale oil and gas and discharges the oil shale matrix. The solid catalyst catalyzes the oil shale oil that has migrated to this place in the rock layer fractures, and generates light oil and gas through secondary cracking, so as to realize the in-situ cracking of oil shale by relay catalysis of water-soluble metal salt and solid catalyst; (5) After the heating is completed, the oil, water and gas mixture is extracted to the surface through the production well for separation to obtain the target product, light oil and gas.

2. The mining method according to claim 1, characterized in that, The water-soluble metal salts include transition metal salts and / or alkaline earth metal salts.

3. The mining method according to claim 2, characterized in that, The water-soluble metal salt is any one or a combination of at least two of ferric chloride, ferrous chloride, or calcium chloride.

4. The mining method according to claim 1, characterized in that, The solid catalyst comprises any one or a combination of at least two of molecular sieves, transition metal oxides, transition metal sulfides, or elemental transition metals.

5. The mining method according to claim 4, characterized in that, The solid catalyst is any one or a combination of at least two of cerium-supported HZSM-5 molecular sieves, iron oxide, or ferrous sulfide.

6. The mining method according to claim 1, characterized in that, The distance between the injection wells and production wells mentioned in step (1) is 10~20m.

7. The mining method according to claim 1, characterized in that, The amount of solid catalyst added in step (2) is 0.05~1wt% of the target reservoir oil shale mass.

8. The mining method according to claim 1, characterized in that, The concentration of metal ions in the aqueous solution of the metal salt in step (3) is 0.04~0.12 mol / L.

9. The mining method according to claim 1, characterized in that, The heating temperature in step (4) is 300~370℃.

10. The mining method according to claim 1, characterized in that, The heating pressure in step (4) is 5~20MPa.

11. The mining method according to claim 1, characterized in that, The heating and heat preservation time in step (4) is 2 to 10 days.

12. The mining method according to claim 1, characterized in that, The downhole heater in step (4) includes any one or a combination of at least two of resistance heating, electromagnetic heating or microwave heating.

13. The mining method according to claim 1, characterized in that, The water obtained in step (5) is used to dissolve water-soluble metal salts again and inject them into new injection wells to achieve the recycling of water resources.

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