Gas fracturing and fused salt assisted in-situ heating shale oil in-situ conversion mining method and device

Abstract

The invention provides a gas fracturing and fused salt assisted in-situ heating shale oil in-situ conversion mining method and device, and the mining method comprises the steps: drilling a target shale layer, and carrying out gas fracturing to obtain a fractured well with a seam net structure; molten salt with the melting temperature slightly higher than the formation temperature is selected, and the molten salt is injected into the fractured well and pressurized; after the pressure is stable, the fractured well is sealed to heat the stratum; in the heating process, the shale hydrocarbon generation amount and the thermal field action range are simulated and calculated; and after the edge temperature of the fracture network of the fractured well reaches the hydrocarbon generation stage temperature, stopping heating, reducing the temperature of the fractured well to the melting temperature interval of the fused salt, and then carrying out reverse discharging and suction to obtain an oil-gas mixed product. The mining method and device are used for achieving in-situ heating shale oil in-situ conversion mining assisted by fracturing and molten salt, cost is reduced through single-well heating mining, the hydrocarbon generation temperature of shale oil is reduced through catalytic hydrocarbon generation, economical efficiency is improved, self-sealing of a shale layer and efficient heat transfer hydrocarbon generation are achieved, and therefore the thermal field wave and the volume are improved, and the economical exploitability of shale oil is improved.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration and relates to a method and apparatus for in-situ conversion and extraction of shale oil by gas fracturing and molten salt-assisted in-situ heating. Background Technology

[0002] With the development of the national economy, my country's oil and gas demand and imports have continued to climb over the past decade, with oil dependence exceeding 70%. According to the National Energy Administration's Oil and Gas Strategy Research Center, under my country's "dual carbon" (carbon peaking and carbon neutrality) goals, my country's energy has transitioned to new energy sources, but its oil and gas demand remains insufficient. Assessments predict that by 2060, my country's oil demand will still reach 230-240 million tons, exceeding its domestic production capacity. Even with the vigorous development of medium-to-high maturity shale oil, my country's annual crude oil production barely maintains around 200 million tons, facing numerous challenges. Finding major replacement areas for oil and gas exploration and development is crucial for ensuring national energy security. Preliminary estimates suggest that China's medium-to-low shale oil resources exceed 20 billion tons. A breakthrough in the in-situ conversion of medium-to-low shale oil would make my country a major energy power, reduce its dependence on imported crude oil, and significantly improve its energy security situation. Currently, most global shale oil in-situ conversion technologies are in the theoretical stage, a small number are only in the pilot stage, and only Shell's ICP method has entered the field trial stage.

[0003] Domestic and international in-situ shale conversion methods are mainly physical methods, which can be further subdivided according to the heating mechanism into heat conduction (Shell: CN87100890A, ExxonMobil: CN10163655A); heat convection + conduction (Chevron and Taiyuan University of Technology: CN103114831A) and radiation + heat conduction (Raytheon: CN116335610A). Based on the assimilation and absorption of foreign methods, domestic scholars have proposed chemical-based methods (CN105840162B); localized chemical methods (CN103790563B; 202111291684; CN113374460B); biochar-assisted heating of oil shale for shale oil and gas extraction (CN109184649B); and in-situ conversion systems and methods using supercritical water oxidation (CN115263). 260B). These methods mainly focus on exploring heating methods, conduction fluids, and heat source materials, with most methods focusing only on a single heat transfer method. Although in recent years some scholars have begun to focus on the combination of modification processes and heating methods, for example, China Petroleum & Chemical Corporation (publication number CN107178350A) proposed a method of combining modification with high-temperature supercritical fluids for in-situ extraction of shale oil, that is, modifying heating wells and production wells to increase formation permeability, and injecting high-temperature supercritical fluids with catalytic metals into the heating wells; Wang Youping et al. (CN109424345B) proposed a method of combining catalyst proppant fracturing and heating for in-situ extraction of oil shale; Zhao Jinmin et al. (CN201310152533.7) proposed a method of combining in-situ vertical well fracturing and chemical distillation for extracting oil shale oil.

[0004] However, to date, there is still insufficient attention paid to the most important core problem of efficient heat transfer in in-situ conversion of medium and low-maturity shale (how to expand the thermal field range and improve efficiency in in-situ regeneration of non-high thermal conductivity shale). In particular, the need to drill multiple wells, low heating efficiency, and poor economic efficiency are prominent issues. There is an urgent need to propose revolutionary technologies to address these problems in order to achieve economically recoverable shale. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a method and apparatus for in-situ conversion and extraction of shale oil using gas fracturing and molten salt-assisted in-situ heating. This extraction method and apparatus are used to achieve in-situ conversion and extraction of shale oil using fracturing and molten salt-assisted in-situ heating. By heating extraction through a single well, costs are reduced; by catalytic hydrocarbon generation, the hydrocarbon generation temperature of shale oil is lowered, improving economic efficiency; and by achieving self-sealing of the shale layer and efficient heat transfer for hydrocarbon generation, the thermal sweep volume is increased, thereby enhancing the economic recoverability of shale oil.

[0006] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0007] One objective of this invention is to provide a method for in-situ conversion and extraction of shale oil using gas fracturing and molten salt-assisted heating, the method comprising:

[0008] Drilling and gas fracturing were performed on the target shale formation to obtain a fractured well with a fracture network structure;

[0009] Select molten salt with a melting temperature slightly higher than the formation temperature, inject the molten salt into the fractured well and pressurize it;

[0010] After the pressure stabilizes, the fracturing well is sealed to heat the formation;

[0011] During the heating process, the amount of hydrocarbon generation from shale and the range of thermal field effect were simulated and calculated.

[0012] Once the temperature at the edge of the fracture network in the fractured well reaches the hydrocarbon generation stage temperature, heating is stopped. The temperature of the fractured well is then reduced to the melting temperature range of the molten salt before reverse runoff and extraction are performed to obtain a mixture of oil and gas products.

[0013] As a preferred technical solution of the present invention, the gas used in gas fracturing includes carbon dioxide and / or liquefied petroleum gas.

[0014] As a preferred technical solution of the present invention, the melting temperature T of the molten salt is... i min With formation temperature T s Satisfying relation 5 < T i min -T s <50.

[0015] As a preferred technical solution of the present invention, the pressure P applied is... b With formation fracture pressure P m Satisfying relation P m -P b =1~10MPa.

[0016] As a preferred technical solution of the present invention, the parameters for simulating and calculating the hydrocarbon generation of shale and the range of thermal field include formation thickness, heating program, heating length, rock thermal conductivity, molten salt thermal conductivity, and heating power.

[0017] As a preferred technical solution of the present invention, the heating rate of the formation is 2-5°C / day.

[0018] As a preferred technical solution of the present invention, the oil and gas mixture is subjected to three-phase separation to obtain molten salt, shale oil and shale gas.

[0019] The second objective of this invention is to provide an in-situ heating shale oil conversion and extraction device with gas fracturing and molten salt assistance. This extraction device is used in the in-situ electric heating shale oil conversion and extraction method with gas fracturing and molten salt assistance provided in the first objective. The extraction device includes a gas fracturing device, a molten salt device, a pressure device, a heating device, a simulation device, and a production device.

[0020] As a preferred technical solution of the present invention, the mining device also includes a three-phase separation device and a collection device.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] This invention provides a method and apparatus for in-situ conversion and extraction of shale oil using gas fracturing and molten salt-assisted in-situ heating. This extraction method and apparatus are used to realize in-situ conversion and extraction of shale oil using fracturing and molten salt-assisted in-situ heating. By heating extraction through a single well, costs are reduced. Catalytic hydrocarbon generation lowers the hydrocarbon generation temperature of shale oil and improves economic efficiency. The method and apparatus achieve self-sealing of shale formations and efficient heat transfer for hydrocarbon generation, thereby increasing the thermal sweep volume and improving the economic recoverability of shale oil. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process for the in-situ conversion and extraction of shale oil using gas fracturing and molten salt-assisted in-situ heating, as provided in Embodiment 1 of the present invention.

[0024] Figure 2 The figure shows the experimental results of molten salt thermal conductivity and melting temperature in Example 1 of this invention.

[0025] Figure 3 This is a distribution diagram of the 300°C temperature lines at different times under simulated 600°C heating conditions in Embodiment 1 of the present invention;

[0026] Figure 4 This is a schematic diagram of the structure of the gas fracturing and molten salt-assisted in-situ heating shale oil conversion and extraction device provided in Embodiment 2 of the present invention;

[0027] Figure 5 This is a field schematic diagram of the in-situ heating shale oil conversion and extraction device with gas fracturing and molten salt assistance in Embodiment 2 of the present invention.

[0028] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0029] The technical solution of this application will be further described below through specific implementation methods.

[0030] This invention provides a method for in-situ conversion and extraction of shale oil using gas fracturing and molten salt-assisted heating, the method comprising:

[0031] Drilling and gas fracturing were performed on the target shale formation to obtain a fractured well with a fracture network structure;

[0032] Select molten salt with a melting temperature slightly higher than the formation temperature, inject the molten salt into the fractured well and pressurize it;

[0033] After the pressure stabilizes, the fracturing well is sealed to heat the formation;

[0034] During the heating process, the amount of hydrocarbon generation from shale and the range of thermal field effect were simulated and calculated.

[0035] Once the temperature at the edge of the fracture network in the fractured well reaches the hydrocarbon generation stage temperature, heating is stopped. The temperature of the fractured well is then reduced to the melting temperature range of the molten salt before reverse runoff and extraction are performed to obtain a mixture of oil and gas products.

[0036] In one specific embodiment of the present invention, the selection criteria for the target shale layer include: a maturity level in the low to medium evolutionary stage (R... o <0.9%), with strong current hydrocarbon generation potential (S1+S2>300mg / g) and high thickness (h>20m).

[0037] In one specific embodiment of the present invention, drilling is performed on the target shale layer, and the drilling method includes horizontal drilling or vertical drilling.

[0038] In one specific embodiment of the present invention, the gas used in gas fracturing includes carbon dioxide and / or liquefied petroleum gas. The formation fracturing pressure P is recorded during the gas fracturing process. m .

[0039] In one specific embodiment of the present invention, the fractured well has a complex fracture network structure, and the fracture height within the shale range needs to be controlled within the shale range to ensure that the fracture network does not connect to sandstone layers outside the shale layer.

[0040] In one specific embodiment of the present invention, a heater, preferably an electric heater, is inserted into the tubing and plugged into the fractured well section. The length of the heater is approximately equal to the length of the fractured section (L). h >L f ).

[0041] In one specific embodiment of the present invention, the molten salt is preferably a nitrate (a series of mixed salts). Thermal conductivity tests and melting experiments of the series of mixed salts are conducted on nitrates with different ratios to determine the thermal conductivity values ​​and melting temperature range (T) of the series of nitrates. i min ~T i max(where i represents different proportions of salt).

[0042] In one specific embodiment of the present invention, the melting temperature T of the molten salt is selected through a series of mixed salt melting experiments. i min With formation temperature T s Satisfying relation 5 < T i min -T s <50.

[0043] In one specific embodiment of the present invention, the melting of molten salt is carried out in a molten salt apparatus, and the heating temperature of the molten salt apparatus is constant at T. sh , with T i max Satisfying the relation 10 < T sh -T i max <20.

[0044] In this invention, molten salt with physicochemical characteristics such as high thermal conductivity, phase change temperature close to formation temperature, and cooling ability to achieve self-sealing of shale layers is used to realize integrated single-well stimulation heating and production, catalyze hydrocarbon generation, reduce costs and increase efficiency, effectively increase heat transfer range and heat transfer efficiency, thereby overcoming the current shortcomings of poor economic efficiency and realizing efficient heat transfer and economical shale oil extraction.

[0045] In one specific embodiment of the present invention, the molten salt is melted and pumped into a fracturing well equipped with a heater, and the pressure P is applied. b With formation fracture pressure P m Satisfying relation P m -P b = 1 to 10 MPa, such as 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa or 10 MPa, but not limited to the listed values. Other unlisted values ​​within this range also apply.

[0046] In one specific embodiment of the present invention, a heater is used to heat the formation, and the heating rate of the formation is 2 to 5°C / day, such as 2°C / day, 2.5°C / day, 3°C / day, 3.5°C / day, 4°C / day or 4.5°C / day, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] In one specific embodiment of the present invention, during the heating process, a simulation device is used to simulate and calculate the hydrocarbon generation rate and the range of the thermal field in the shale. The parameters used to simulate and calculate the hydrocarbon generation rate and the range of the thermal field include the formation thickness h, the heating program PT, the heating length L, and the rock thermal conductivity λ. R and the thermal conductivity λ of molten salt S and heating power Ph wait.

[0048] In one specific embodiment of the present invention, heating is stopped after the temperature at the edge of the fracture network in the fracturing well reaches the hydrocarbon generation stage temperature. The hydrocarbon generation stage temperature is mainly determined by conducting pyrolysis experiments on the shale in this area at heating rates of 10℃ / min, 20℃ / min, 30℃ / min, and 40℃ / min. Based on the hydrocarbon content, temperature, and heating rate, the activation energy Ei and the pre-exponential factor A are fitted according to Formula 1.

[0049] X=∑(1-e Ai×RT2 / β(Ei+2RT)e-Ei / RT ) Formula 1,

[0050] Where X represents the hydrocarbon generation conversion rate; Ai represents the pre-exponential factor; R and β represent constants; T represents temperature; and Ei represents the hydrocarbon generation activation energy. Then, when X represents a hydrocarbon generation conversion rate of 60%, it is considered that the hydrocarbon generation stage temperature has been reached, and the hydrocarbon generation temperature T can be calculated by back-calculating from Formula 1.

[0051] In one specific embodiment of the present invention, after heating is stopped, the temperature of the fracturing well is reduced to the melting temperature range of the molten salt (T). i min ~T i max The well is then reverse-flowed and pumped to begin producing shale oil and gas, at which point the heating well becomes a production well.

[0052] In one specific embodiment of the present invention, the oil and gas mixture is subjected to three-phase separation to obtain molten salt, shale oil, and shale gas. The molten salt is returned to the molten salt unit for recycling, while the shale oil and shale gas are collected in their respective storage devices.

[0053] The present invention provides a gas fracturing and molten salt-assisted in-situ heating shale oil in-situ conversion and extraction device. The extraction device is used in the above-mentioned gas fracturing and molten salt-assisted in-situ electrically heated shale oil in-situ conversion and extraction method. The extraction device includes a gas fracturing device, a molten salt device, a pressure device, a heating device, a simulation device, and a production device.

[0054] In one specific embodiment of the present invention, a gas fracturing device is used to fracture and transform shale formations to form complex fracture networks. After horizontal or vertical drilling of the target shale formation, gas fracturing is performed to form a complex fracture network structure. The gas fracturing used includes carbon dioxide fracturing and liquefied petroleum gas.

[0055] In one specific embodiment of the present invention, a molten salt device is used to melt mixed molten salt. For example, the main structure of the molten salt device can be a cylindrical vessel resistant to high temperature and pressure, with dimensions of an inner diameter of 4 meters, a height of 5 meters, and a thickness of 5 decimeters. Heating wires and an insulation jacket can be fitted externally for heating and temperature control.

[0056] In one specific embodiment of the present invention, the pressure device is used to pressurize molten salt in shale formations and pump the molten salt into the fracture network of the fracturing section.

[0057] In one specific embodiment of the present invention, the heating device is a device for heating the formation, mainly including a heater and an oil pipe, which can heat the formation.

[0058] In one specific embodiment of the present invention, the simulation device is used to simulate the distribution and evolution of the underground temperature field, and can estimate the range of influence and temperature distribution of the underground thermal field.

[0059] In one specific embodiment of the present invention, the extraction device is used to extract oil and gas generated from in-situ conversion of shale to the surface, including means such as pumping and lifting.

[0060] In one specific embodiment of the present invention, the mining apparatus further includes a three-phase separation device and a collection device.

[0061] In one specific embodiment of the present invention, a three-phase separation device is used to separate the oil and gas generated from the in-situ conversion of shale extracted to the ground, to obtain molten salt, shale oil and shale gas.

[0062] 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:

[0063] Example 1

[0064] This invention provides a method for in-situ conversion and extraction of shale oil using gas fracturing and molten salt-assisted heating, the process of which is as follows: Figure 1 As shown, the mining method includes:

[0065] (1) After horizontal and vertical drilling of the target shale formation, gas fracturing was carried out to form a complex fracture network structure. The fracturing gases used included carbon dioxide fracturing and liquefied petroleum gas, and the formation fracturing pressure P was recorded. m Complex fracture networks require controlling the fracture height within the shale layer to ensure the network does not connect to sandstone layers outside the shale layer. The heater is inserted into the tubing and plugged into the fractured well section. The heater length is approximately equal to the length of the fractured section (L). h >L f );

[0066] The target shale layer is located in Zhengning County, Qingyang City, Gansu Province, in the Ordos Basin. The target shale layer is 73m long, 30m thick, and 500m long.

[0067] (2) Molten salt screening was conducted, and thermal conductivity tests and melting experiments of nitrates with different ratios (a series of mixed salts) were carried out to determine the thermal conductivity values ​​and melting temperature ranges (T) of the series of nitrates.i min ~T i max ),like Figure 2 As shown;

[0068] After conducting the above nitrate melting experiments, the melting temperature T was selected. i min Slightly higher than the formation temperature T s Mixed salts (5 < T) i min -T s <50) Place it in a molten salt apparatus for melting;

[0069] The selected molten salt formulation is a nitrate complex. In Zhengning County, Qingyang City, Gansu Province, in the southern Ordos Basin, the selected nitrate complex is a compound salt of potassium nitrate and sodium nitrite, with a mass ratio of 55:45.

[0070] The molten salt device uses a combination of wind and solar energy for heating, and the heating temperature of the molten salt device is constant at T. sh Slightly greater than T i max (10 < T) sh -T i max <20);

[0071] (3) After melting the selected nitrate, the molten salt is pumped into the fracturing well equipped with a heater using a molten salt pump and pressurized. The pumping pressure is P. b With rock fracture pressure P m The relationship between them conforms to the formula (P) m -P b =1~10MPa), after sealing, turn on the heater to heat, the heating program is 2~5℃ / day, and the final temperature is 600℃;

[0072] (4) For the simulation device used in the above heating process, according to the formation thickness h, heating program PT, heating length L, and rock thermal conductivity λ R and the thermal conductivity λ of molten salt S Heating power Ph and other parameters are calculated through simulation to determine the range of the thermal field, such as... Figure 3 As shown; heating is stopped after the edge temperature of the hydraulic fracturing network reaches the hydrocarbon generation stage temperature of 360℃;

[0073] (5) After heating is stopped, the temperature in the area of ​​the well to be heated drops to the salt melting temperature range (T). i min ~T i max After the reverse flow and pumping start, the heated well becomes a production well;

[0074] (6) During the production process, the high-temperature substances produced are separated by a three-phase separator. After separation, the salt is inspected and qualified, and then directly returned to the molten salt unit for recycling. The shale oil and shale gas are stored separately.

[0075] Example 2

[0076] This embodiment provides a method for in-situ conversion and extraction of shale oil using gas fracturing and molten salt-assisted heating, the structure of which is as follows: Figure 4 and Figure 5 As shown:

[0077] The mining equipment includes a gas fracturing unit, a molten salt unit, a pressure unit, a heating unit, a production unit, a three-phase separation unit, and a collection unit;

[0078] Gas fracturing equipment is used to fracture and transform shale formations into complex fracture networks. After horizontal and vertical drilling of the target shale formation, gas fracturing is performed to form a complex fracture network structure. The gas fracturing used includes carbon dioxide fracturing and liquefied petroleum gas.

[0079] The molten salt device is used to melt mixed molten salt. The main structure of the molten salt device adopts a cylindrical vessel that is resistant to high temperature and high pressure, with an inner diameter of 4 meters, a height of 5 meters, and a thickness of 5 decimeters. It is equipped with heating wires and insulation sleeves on the outside for heating and temperature control.

[0080] The pressure device is used to pressurize molten salt in shale formations and pump the molten salt into the fracture network of the fracturing section.

[0081] A heating device is a device used to heat a formation, mainly consisting of a heater and an oil pipe, which can heat the formation.

[0082] The simulation device is used to simulate the distribution and evolution of the underground temperature field, and can estimate the range of influence and temperature distribution of the underground thermal field;

[0083] Production equipment is used to extract oil and gas generated from in-situ conversion of shale to the surface, including methods such as pumping and lifting;

[0084] The mining equipment also includes a three-phase separation device and a collection device;

[0085] The three-phase separation unit is used to separate the oil and gas generated from the in-situ conversion of shale extracted to the surface, obtaining molten salt, shale oil, and shale gas.

[0086] As can be seen from Examples 1 and 2, the gas fracturing and molten salt-assisted in-situ heating method and apparatus for shale oil in-situ conversion and extraction provided by this invention, based on calculations, saves 50-60% in cost compared to the direct electric heating in-situ conversion method. The main cost saving is drilling cost, which is reduced by 75% of the original drilling cost, although the use of molten salt increases the process cost by about 30%. Considering the benefits of salt-catalyzed hydrocarbon generation and the increased oil production from the effective thermal field calculated based on the current crude oil price of $70 / barrel, it is estimated that this method directly improves the economic benefits of shale oil extraction by 90-150% compared to the direct electric heating in-situ conversion method and the thermal convection method.

[0087] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but 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 selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0088] 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.

[0089] 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.

[0090] 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 conversion and extraction of shale oil using gas fracturing and molten salt-assisted in-situ heating, characterized in that, The mining method includes: Drilling and gas fracturing were performed on the target shale formation to obtain a fractured well with a fracture network structure; Select molten salt with a melting temperature slightly higher than the formation temperature, inject the molten salt into the fractured well and pressurize it; After the pressure stabilizes, the fracturing well is sealed to heat the formation; During the heating process, the amount of hydrocarbon generation from the shale and the range of the thermal field are simulated and calculated. Once the temperature at the edge of the fracture network in the fractured well reaches the hydrocarbon generation stage temperature, heating is stopped. The temperature of the fractured well is then reduced to the melting temperature range of the molten salt before reverse runoff and absorption are performed to obtain a mixture of oil and gas products.

2. The mining method according to claim 1, characterized in that, The gases used in the gas fracturing include carbon dioxide and / or liquefied petroleum gas.

3. The mining method according to claim 1, characterized in that, The pressure fracture height of the fracture network structure is within the shale range and does not reach the sandstone layer.

4. The mining method according to claim 1, characterized in that, The melting temperature T of the molten salt imin With formation temperature T s Satisfying relation 5 < T imin -T s <50.

5. The mining method according to claim 1, characterized in that, The pressure P applied b With formation fracture pressure P m Satisfying relation P m -P b =1~10MPa.

6. The mining method according to claim 1, characterized in that, The parameters used in the simulation calculation of shale hydrocarbon generation and thermal field range include formation thickness, heating program, heating length, rock thermal conductivity, molten salt thermal conductivity, and heating power.

7. The mining method according to claim 1, characterized in that, The heating rate of the formation is 2-5°C / day.

8. The mining method according to claim 1, characterized in that, The oil and gas mixture is subjected to three-phase separation to obtain molten salt, shale oil and shale gas.

9. A gas fracturing and molten salt-assisted in-situ heating shale oil conversion and extraction device, characterized in that, The extraction apparatus is used in the in-situ heating and in-situ conversion extraction method for shale oil with gas fracturing and molten salt assistance as described in any one of claims 1-8. The extraction apparatus includes a gas fracturing device, a molten salt device, a pressure device, a heating device, a simulation device, and an extraction device.

10. The mining apparatus according to claim 1, characterized in that, The mining apparatus also includes a three-phase separation device and a collection device.

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