A method and system for the exploitation of oil shale formations

Abstract

The present application provides a kind of exploitation method for oil shale formation, comprising the following steps: step one: from the surface to the target oil shale layer drilling exploitation well, and artificial seam is formed to form fracture in the target oil shale layer, suction passage is formed in exploitation well;Step two: drill injection well in the area corresponding to fracture;Step three: install ground auxiliary equipment device at the wellhead of injection well;Step four: according to the depth of stratum, install heating device in injection well;Step five: start ground auxiliary equipment device, inject high pressure water flow and alkali powder into heating device to generate chemical reaction, thereby releasing heat to heat the external target oil shale layer, the fluid produced by reaction enters fracture, so that fracture is expanded into corrosion crack;Step six: the shale oil produced by target oil shale layer enters exploitation well through corrosion crack, and oil production is carried out through suction passage.The present application also provides an exploitation system used in the above-mentioned exploitation method for oil shale formation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of in-situ exploitation of oil shale formation, and particularly relates to an exploitation method and system for oil shale formation, in particular, an in-situ critical water alkali etching catalytic reaction thermal compound exploitation method and system for oil shale. BACKGROUND

[0002] The increasing demand for energy and the low reserves of oil resources make the exploitation and utilization of alternative energy sources extremely urgent. Oil shale is a fine-grained sedimentary rock rich in organic matter (kerogen), and the internal organic matter can be converted into shale oil and gas after heating. Due to its abundant reserves and wide distribution, it has attracted much attention as a kind of unconventional alternative energy. Compared with direct combustion of oil shale as a power generation fuel for power generation, the more promising approach at present is to produce shale oil and shale gas through surface dry distillation and underground in-situ pyrolysis. Among them, the underground in-situ pyrolysis technology extracts liquid or gaseous hydrocarbons by directly heating the underground oil shale formation, which has the advantages of avoiding environmental pollution and greatly reducing the cost, and is considered to be the most promising oil shale exploitation technology.

[0003] In recent years, more than ten kinds of oil shale in-situ conversion technologies have been proposed at home and abroad, such as the ICP technology of Shell Company, the ElectroFractTM technology of ExxonMobil Company, and the Crush technology of Chevron Company. However, due to the influence of uncertain factors and unfavorable factors such as complex underground equipment, high cost, and long heating time, all the oil shale in-situ conversion technologies are still in the research and development stage, and cannot meet the requirements of commercial exploitation. The existing oil shale in-situ exploitation method has the problems of slow heat transfer rate, low heating efficiency, long exploitation period, and high cost. SUMMARY

[0004] In view of the above technical problems, the present application aims to provide an exploitation method and system for oil shale formation, which can effectively improve the heat transfer rate, improve the heating efficiency, reduce the exploitation period, and significantly improve the output rate of oil shale formation, and effectively reduce the production cost.

[0005] To this end, according to a first aspect of the present application, an exploitation method for oil shale formation is provided, comprising the following steps:

[0006] Step one: drilling an exploitation well from the ground surface to a target oil shale layer, and forming a fracturing fracture in the target oil shale layer by artificial fracture forming through the exploitation well, and forming a suction passage in the exploitation well;

[0007] Step two: drilling a hot injection well in the region corresponding to the fracturing fracture;

[0008] Step 3: Installing ground auxiliary equipment at the wellhead of the heat injection well;

[0009] Step 4: Install a heating device in the heat injection well according to the depth of the formation;

[0010] Step 5: activating the surface support equipment and injecting high-pressure water and alkali powder into the heating device to generate a chemical reaction, thereby releasing heat to heat the target oil shale layer, and the fluid generated by the reaction enters the fracture, causing the fracture to expand into a corrosion fracture;

[0011] Step 6: The shale oil produced from the target oil shale layer enters the production well through the corrosion cracks and is produced through the suction channel.

[0012] In one embodiment, in step one, hydraulic fracturing is used to artificially create fractures.

[0013] In one embodiment, when there are one or two mining wells, the mining wells and the heat injection wells are distributed in a straight line. When there are multiple mining wells, the heat injection well is set at the center position of multiple mining wells so that multiple mining wells are evenly distributed around the heat injection well.

[0014] In one embodiment, in step four, the heating device is extended to correspond to the fracture area of ​​the target oil shale layer.

[0015] In one embodiment, in step five, the fluid generated by the reaction between high-pressure water flow and alkali powder includes critical water, alkaline solution and hydrogen. Part of the heat released by the reaction is directly transferred outward to heat the target oil shale layer, and the other part is transferred with the fluid generated by the reaction and then to the hydraulic fracture to heat the target oil shale formation again.

[0016] In one embodiment, the heat released by the reaction between the high-pressure water flow and the alkali powder can heat the target oil shale layer to 300-500° C., the concentration of the generated alkaline solution is 0.1-1 mol / L, and the pressure of the high-pressure water flow is 3-20 MPa.

[0017] According to a second aspect of the present invention, there is provided a production system for use in the production method for an oil shale formation as described above, comprising:

[0018] The heating device includes a water injection unit, an alkali thermal reaction unit and a heat injection unit connected in sequence from top to bottom, wherein the water injection unit includes a high-pressure water flow channel and an alkali powder injection channel; wherein the high-pressure water flow and alkali powder can be injected into the alkali thermal reaction unit through the high-pressure water flow channel and the alkali powder injection channel respectively, and contact and chemically react in the alkali thermal reaction unit to release heat, and the fluid generated by the reaction enters the fracture through the heat injection unit.

[0019] In one embodiment, the water injection unit includes a main body, a first axial through hole is provided in the center of the main body to form the alkali powder injection channel, and a first axial annular through portion is provided on the radial outside of the alkali powder injection channel to form the high-pressure water flow channel, and a pressure valve is provided at the lower end of the high-pressure water flow channel.

[0020] In one embodiment, the alkali thermal reaction unit includes an alkali thermal reaction chamber outer tube, a baffle disposed inside the alkali thermal reaction chamber outer tube, and a bottom filter plate fixedly connected to the lower end of the baffle.

[0021] In one embodiment, the heat injection unit includes an outer heat injection chamber tube, a heat injection chamber is formed inside the outer heat injection chamber tube, and a plurality of through heat injection holes are evenly opened on the side wall of the outer heat injection chamber tube, and the fluid generated by the reaction enters the fracture through the heat injection holes.

[0022] In one embodiment, a ground auxiliary equipment device is further included for injecting high-pressure water and alkali powder into the heating device, which includes a water supply unit connected to the high-pressure water flow channel and an alkali powder supply unit connected to the alkali powder injection channel.

[0023] In one embodiment, the water supply unit includes a water source, a water pump and a booster pump.

[0024] The water source, the water pump and the booster pump are connected via a water injection pipe, and the tail end of the water injection pipe is connected to the high-pressure water flow channel.

[0025] In one embodiment, the alkali powder supply unit includes a high-pressure conveyor and a high-pressure conveying pipeline, and the high-pressure conveyor is connected to the alkali powder injection channel through the high-pressure conveying pipeline.

[0026] In one embodiment, it also includes an extraction device, which includes an oil storage tank installed at the wellhead of the extraction well, an oil extraction pipeline arranged in the extraction well and extending to the bottom, and an oil extraction pump connected between the oil storage tank and the oil extraction pipeline.

[0027] Compared with the prior art, the advantages of this application are:

[0028] The mining method for oil shale formation according to the present application realizes the in-situ critical water alkali corrosion catalytic reaction heat combined mining of oil shale by combining the mining methods beneficial to the in-situ mining of oil shale such as critical water, alkali corrosion, chemical heating and catalysis. The mining method is carried out by the mining system formed by the heating device, the ground auxiliary equipment device and the mining device, which makes the mining method have the advantages of simple process, short mining period, wide application and high recovery rate. The demineralization treatment of the oil shale formation by alkali corrosion can effectively deal with the thermal expansion problem of oil shale in the heating process. At the same time, the reaction heat released by the reaction of alkali and water, and the products such as alkaline solution and hydrogen generated are fully utilized, and the products such as alkaline solution and hydrogen have catalytic effect on the cracking of oil shale. The high-pressure critical water generated after heating has good dissolution and carrying effect on oil and gas products, which can greatly improve the oil and gas recovery rate. BRIEF DESCRIPTION OF DRAWINGS

[0029] The present application will be described below with reference to the drawings.

[0030] Figure 1 is the schematic diagram of the mining method for oil shale formation according to the present application.

[0031] Figure 2 is the structure of the heating device in the mining system for oil shale formation according to the present application.

[0032] Figure 3 is Figure 2 is the sectional view of the heating device in the mining system for oil shale formation according to the present application with A-A' as the cutting surface.

[0033] Figure 4 is Figure 2 is the local enlarged view of the water injection unit and related parts in the heating device in the mining system for oil shale formation according to the present application.

[0034] In this application, all the drawings are schematic drawings for illustrating the principles of the present application, and are not drawn according to the actual proportions. DETAILED DESCRIPTION

[0035] The present application will be described below with reference to the drawings.

[0036] For the convenience of understanding, in this application, the end close to the wellhead is defined as the upper end, the upstream end or similar terms, and the end away from the wellhead is defined as the lower end, the downstream end or similar terms. At the same time, the length direction along the heating device in the mining system for oil shale formation is called the longitudinal direction, the axial direction or similar terms, and the direction perpendicular thereto is called the transverse direction, the radial direction or similar terms. In addition, it should be noted that the directional terms or limiting terms "upper", "lower", etc. used in this application are all relative to the drawings referred to. Figure 1 The above description is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the devices or elements must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0037] Figure 1 This is a schematic diagram of the principle of the oil shale extraction method according to the present invention. The oil shale extraction method according to the present invention primarily includes the drilling and completion phase, the equipment installation phase, and the production phase. Each phase is described in detail below.

[0038] In the drilling and completion stage, first, a production well 92 is drilled from the surface to the target oil shale layer 7, and artificial fractures are created through the production well 92 to form fractures in the target oil shale layer 7, thereby forming a fracture zone. Figure 1 As shown, the strata in the mining area are, from top to bottom, an overburden stratum 6, an oil shale layer 7, and an underburden stratum 8. A mining well 92 is drilled from the surface, passes through the oil shale layer 7, and extends downward into the underburden stratum 8. A suction channel is formed in mining well 92. In one embodiment, hydraulic fracturing is used to artificially create fractures in mining well 92.

[0039] Then, a heat injection well 91 is drilled in the area corresponding to the fracture. Specifically, the heat injection well 91 is drilled from the surface to the fractured area in the target oil shale layer 7. The heat injection well 91 enters the oil shale layer 7, and the lower end of the heat injection well 91 extends to an area near the bottom of the oil shale layer 7.

[0040] According to the present invention, the specific number of production wells 92 and heat injection wells 91 can be selected based on actual operating conditions. When there are one or two production wells 92, the production wells 92 and the heat injection wells 91 are arranged in a straight line. In particular, when there are two production wells 92, the heat injection well 91 is located in the middle of the line connecting the two production wells 92. When there are multiple production wells 92, the heat injection well 91 is positioned at the center of the multiple production wells 92, so that the multiple production wells 92 are evenly distributed around the heat injection well 91. For example, the multiple production wells 92 can be arranged in a circular shape, such as a triangle, a quadrilateral, a hexagon, or a circle, with the heat injection well 91 as the center.

[0041] After the drilling and completion phase is complete, the equipment installation phase begins. First, the surface support equipment 4 is installed at the wellhead of the heat injection well 91. Simultaneously, the production equipment is installed at the wellhead of the production well 92. The production equipment will be described in detail below.

[0042] Then, according to the depth of the formation, a heating device 100 is installed in the heat injection well 91. The heating device 100 extends to the area corresponding to the fracture of the target oil shale layer 7.

[0043] Afterwards, the production phase begins. During this phase, the ground support equipment 4 is activated, injecting high-pressure water and alkali powder 46 into the heating device 100 to initiate a chemical reaction. This releases heat, heating the target oil shale layer 7 located outside. The fluid generated by the reaction enters the fractures, causing them to expand into corrosion cracks 71. The alkali powder is, for example, nano-alkali powder.

[0044] Afterwards, the shale oil 93 produced from the target oil shale layer 7 enters the production well 92 through the corrosion cracks 71 and is then produced through the suction channel.

[0045] According to the present invention, the fluid generated by the reaction between high-pressure water flow and alkali powder includes critical water, alkaline solution and hydrogen. Part of the heat released by the reaction is directly transferred outward to heat the target oil shale layer 7 outside, and the other part is transferred with the fluid generated by the reaction to form fractures and heat the target oil shale formation 7 again.

[0046] Specifically, upon contact between the high-pressure water flow and the nano-alkali powder 46, a chemical reaction occurs, releasing a large amount of heat and generating a large amount of alkaline solution and hydrogen. The high-pressure water flow then transitions to a critical state. The heat generated by the reaction is carried by the critical water, alkaline solution, and hydrogen through the external connecting pipe 21 (described below) in the heating device 100 and transferred to the external formation, thereby heating the target oil shale layer 7. Simultaneously, the critical water, large amounts of alkaline solution, and hydrogen enter the fractures through the heat injection holes 32 (described below) in the heating device 100, further heating the target oil shale layer 7. The alkaline solution can also corrode quartz minerals in the formation, causing the fractures to expand into corrosion cracks 71. This overcomes the thermal expansion problem caused by the heating of the target oil shale layer 7. Combined with the catalytic effects of the alkali and hydrogen, they promote the cracking of kerogen. Furthermore, the critical water dissolves and extracts organic matter, further facilitating the migration of oil and gas products. Under the combined effects of the above, shale oil 93 produced by the target oil shale layer 7 enters the production well 92 through the corrosion cracks 71. It is then sucked into the oil storage tank 52 by the oil pump 51 in the production device through the oil extraction pipeline 53, thereby achieving the purpose of producing the oil shale formation.

[0047] According to the present invention, during the production phase, the heat released by the reaction between the high-pressure water and the alkaline powder can heat adjacent oil shale layers within the target oil shale layer 7 to 300-500°C. The resulting alkaline solution has a concentration of 0.1-1 mol / L. The pressure of the high-pressure water is 3-20 MPa.

[0048] The present invention also provides a mining system 200 for oil shale formations, which is applied in the mining method for oil shale formations as described above. The mining system 200 includes a heating device 100. Figure 2As shown, the heating device 100 includes a water injection unit 1, an alkali thermal reaction unit 2, and a heat injection unit 3, which are connected in sequence from top to bottom. The water injection unit 1 includes a high-pressure water flow channel 15 and an alkali powder injection channel 25. The high-pressure water and alkali powder can be injected into the alkali thermal reaction unit 2 through the high-pressure water flow channel 15 and the alkali powder injection channel 25, respectively. The high-pressure water and alkali powder can come into contact with each other in the alkali thermal reaction unit 2 to produce a chemical reaction, releasing heat. The fluid produced by the reaction enters the fracture through the heat injection unit 3.

[0049] like Figure 2 As shown, the water injection unit 1 includes a main body, a first axial through hole is provided at the center of the main body to form an alkali powder injection channel 25, and a first axial annular through portion is provided on the radial outside of the alkali powder injection channel 25 to form a high-pressure water flow channel 15, and a pressure valve 14 is provided at the lower end of the high-pressure water flow channel 15.

[0050] like Figures 2 to 4 As shown, in one embodiment, the water injection unit 1 includes an upper joint 11, a water injection connecting pipe 12, a lower joint 13, and a pressure valve 14. The water injection connecting pipe 12 is constructed as a double-layer tube structure including an inner tube 121 and an outer tube 122, with a certain distance between the inner tube 121 and the outer tube 122. The inner tube 121 and the outer tube 122 are connected by a connecting shaft (not shown). This forms an alkali powder injection channel 25 within the inner tube 121 of the water injection connecting pipe 12, and a high-pressure water flow channel 15 between the inner tube 121 and the outer tube 122 of the water injection connecting pipe 12. Threads are provided on the upper and lower sides of the water injection connecting pipe 12, allowing for threaded connection between the upper joint 11, the water injection connecting pipe 12, and the lower joint 13. The outer portion of the upper joint 11 is threadedly connected to the upper inner side of the outer connecting pipe 21 (see below) in the alkali thermal reaction unit 2. The outer diameters of the water injection connecting pipe 12 and the lower joint 13 are the same as the inner diameter of the outer connecting pipe 21. The pressure valve 14 is installed at the bottom of the lower joint 13. The upper joint 11, the water injection connecting pipe 12 and the lower joint 13 together form the main body.

[0051] like Figure 2As shown, the alkali thermal reaction unit 2 includes an external connecting pipe 21, an alkali thermal reaction chamber outer pipe 22, a baffle 23, and a bottom filter plate 24. The upper portion of the external connecting pipe 21 is externally threadedly connected to the upper joint 11, and the lower portion is threadedly connected to the upper portion of the alkali thermal reaction chamber outer pipe 22. The lower portion of the alkali thermal reaction chamber outer pipe 22 is threadedly connected to the upper portion of the heat injection chamber outer pipe 31 (see below) in the heat injection unit 3. The baffle 23 is preferably a strip plate, a cross-arranged plate, or a spiral plate, and is at least partially located inside the alkali thermal reaction chamber outer pipe 22, and the bottom is welded to the bottom filter plate 24. An alkali thermal reaction chamber 26 is formed between the interior of the alkali thermal reaction chamber outer pipe 22 and the bottom filter plate 24. By arranging the baffle 23 in the alkali thermal reaction chamber 26, it is possible to fully contact the high-pressure water flow and the alkali powder 46 in the alkali thermal reaction chamber 26, promoting the chemical reaction and improving the reaction efficiency.

[0052] Preferably, the alkaline thermal reaction chamber outer tube 22, baffle 23, bottom filter plate 24 and heat injection chamber outer tube 31 in the alkaline thermal reaction unit 2 are all made of high-temperature resistant and alkali corrosion resistant materials, or anti-alkali corrosion coatings are added to the outer surfaces to ensure that they have good high-temperature resistance and alkali corrosion resistance.

[0053] In actual use, multiple water injection connecting pipes 12 and alkali thermal reaction chamber outer pipes 22 can be installed according to the depth of the formation until the alkali thermal reaction unit 2 and the heat injection unit 3 can be kept inside the oil shale layer 7.

[0054] like Figure 2 As shown, the heat injection unit 3 includes a heat injection chamber outer tube 31, within which a heat injection chamber 33 is formed. Multiple heat injection holes 32 are evenly distributed along the sidewall of the heat injection chamber outer tube 31. Fluid generated by the reaction enters the fracture through the heat injection holes 32. The upper portion of the heat injection chamber outer tube 31 is threadedly connected to the lower portion of the alkali-thermal reaction chamber outer tube 22.

[0055] According to the present invention, the mining system 200 for oil shale formations also includes a ground auxiliary equipment device 4 for injecting high-pressure water flow and alkali powder into the heating device 100. The ground auxiliary equipment device 4 includes a water supply unit connected to the high-pressure water flow channel 15, and an alkali powder supply unit connected to the alkali powder injection channel 25.

[0056] like Figure 1 As shown, the water supply unit includes a water source 45, a water pump 41, and a booster pump 42. The water source 45, water pump 41, and booster pump 42 are connected by a water injection pipe 44, and the tail end of the water injection pipe 44 is connected to the high-pressure water flow channel 15 in the heating device 100. The alkali powder supply unit includes a high-pressure conveyor 43 and a high-pressure delivery pipe 47. The high-pressure conveyor 43 is connected to the alkali powder injection channel 25 via the high-pressure delivery pipe 47.

[0057] The exploitation system 200 for oil shale stratum according to the present application further comprises an exploitation device, which comprises an oil storage cabin 52 installed at the wellhead of the exploitation well 92, an oil pumping pipe 53 arranged in the exploitation well 92 and extending to the bottom, and an oil pumping pump 51 connected between the oil storage cabin 52 and the oil pumping pipe 53. Specifically, as shown in Figure 1 the upper part of the oil pumping pipe 53 is connected with the front end of the oil pumping pump 51, and the lower part of the oil pumping pipe 53 extends into the shale oil 93. The rear end of the oil pumping pump 51 is connected with the oil storage cabin 52.

[0058] According to the present application, the heating device 100 is assembled into a critical water alkali etching catalytic reaction heat composite heater through the water injection unit 1, the alkali heat reaction unit 2 and the heat injection unit 3, and the ground auxiliary equipment device 4 and the exploitation device constitute the matching equipment of the critical water alkali etching catalytic reaction heat composite heater.

[0059] The exploitation method and the exploitation system 200 for oil shale stratum according to the present application are described in detail below according to different embodiments.

[0060] Embodiment 1:

[0061] In the embodiment 1, two exploitation wells 92 and one heat injection well 91 are drilled to form a three-well form, the quartz content in the oil shale stratum is high, and the injected alkali powder is sodium hydroxide.

[0062] In the drilling and completion stage: first, two exploitation wells 92 are drilled from the ground to the target oil shale stratum 7, artificial fractures are formed in the exploitation wells 92 by hydraulic fracturing to form fractured cracks. Shale oil pumping channels are formed in the exploitation wells 92. Then, a heat injection well 91 is drilled in the center of the two exploitation wells 92 to form a fluid injection channel in the heat injection well 91.

[0063] After the drilling and completion stage is completed, the equipment installation stage is entered: first, the ground auxiliary equipment device 4 is installed at the wellhead of the heat injection well 91, and the water pump 41, the booster pump 42, the high-pressure conveyor 43 and the water injection pipe 44 are installed on the ground at the wellhead of the heat injection well 91. Specifically, the water source 45, the water pump 41 and the booster pump 42 are connected through the water injection pipe 44, and the tail end of the water injection pipe 44 is connected with the high-pressure water flow channel 15. The high-pressure conveyor 43 is connected with the nano alkali powder 46 through the high-pressure conveying pipe 47, and the tail end of the high-pressure conveying pipe 47 is connected with the alkali powder injection channel 25. In this way, the installation of the ground auxiliary equipment device 4 is completed.

[0064] At the same time, the exploitation device is installed at the wellhead of the exploitation well 92. The oil pumping pump 51, the oil storage cabin 52 and the oil pumping pipe 53 are installed on the ground at the wellhead of the exploitation well 92. Specifically, the upper part of the oil pumping pipe 53 is connected with the front end of the oil pumping pump 51, and the lower part of the oil pumping pipe 53 extends into the shale oil 93. The rear end of the oil pumping pump 51 is connected with the oil storage cabin 52. In this way, the installation of the exploitation device is completed.

[0065] Then, a heating device 100 is installed in the heat injection well 91. Specifically, depending on the depth of the formation, an appropriate number of water injection system connecting pipes 12 and alkali-thermal reaction chamber outer pipes 22 are installed to ensure that the heating device 100 extends to the corresponding fracture area of ​​the target oil shale layer 7 and to keep the alkali-thermal reaction unit 2 and heat injection unit 3 of the heating device 100 located within the oil shale layer 7.

[0066] Afterwards, the production phase begins. During this phase, the ground auxiliary equipment 4 is activated, and nano-sodium hydroxide is injected into the alkali thermal reaction chamber 26 through the alkali powder injection channel 25. Simultaneously, high-pressure water is injected into the alkali thermal reaction chamber 26 through the high-pressure water flow channel 15. When the high-pressure water and the nano-sodium hydroxide come into contact within the alkali thermal reaction chamber 26 of the heating device 100, a chemical reaction occurs, releasing a large amount of heat and generating a large amount of alkaline sodium hydroxide solution and hydrogen. The high-pressure water then transitions to a critical state. The ratio of nano-sodium hydroxide to water is adjusted so that the concentration of the generated alkaline sodium hydroxide solution is 0.5 mol / L. The heat released by the reaction heats the target oil shale layer 7 located outside, and the fluid generated by the reaction enters the fractures, causing them to expand into corrosion cracks 71.

[0067] Specifically, under the action of the baffles 23, the large amount of heat generated by the reaction is carried by the critical water, alkaline sodium hydroxide solution, and hydrogen through the flow within the baffles 23 and transferred to the external formation through the external connecting pipe 21, heating the target oil shale layer 7 located outside. Simultaneously, the critical water, a large amount of alkaline sodium hydroxide solution, and hydrogen enter the interior of the heat injection chamber 33 through the bottom filter plate 24. They then enter the fractures through the heat injection holes 32 on the outer pipe 31 of the heat injection chamber, further heating the target oil shale layer 7. Furthermore, the alkaline sodium hydroxide solution corrodes quartz minerals in the formation, causing the fractures to expand into corrosion cracks 71, thereby overcoming the thermal expansion problem caused by the heating of the target oil shale layer 7. Combined with the catalytic effects of the sodium hydroxide and hydrogen, they promote the cracking of kerogen. Furthermore, the critical water dissolves and extracts organic matter, further facilitating the migration of oil and gas products.

[0068] Under the combined effects of the above, shale oil 93 produced by the target oil shale layer 7 enters the production well 92 through the corrosion cracks 71. It is then sucked into the oil storage tank 52 by the oil pump 51 through the oil extraction pipeline 53, thereby achieving the purpose of extracting the oil shale formation and realizing oil production.

[0069] Implementation Case 2:

[0070] In Example 2, three production wells 92 and one heat injection well 91 are drilled to form a well group. The quartz content in the oil shale layer is relatively low, and the injected alkali powder is potassium hydroxide.

[0071] During the drilling and completion phase, three production wells 92 are drilled from the surface toward the target oil shale layer 7 in an equilateral triangle arrangement. Hydraulic fracturing is used to artificially create fractures in production wells 92, creating shale oil extraction channels. A heat injection well 91 is drilled in the center of the three production wells 92, creating a fluid injection channel.

[0072] After the drilling and completion phase is complete, the equipment installation phase begins. First, the ground support equipment assembly 4 is installed at the wellhead of the heat injection well 91. A water pump 41, a booster pump 42, a high-pressure conveyor 43, and a water injection pipeline 44 are installed on the ground at the wellhead of the heat injection well 91. Specifically, a water source 45, water pump 41, and booster pump 42 are connected via a water injection pipeline 44, the tail end of which is connected to the high-pressure water flow channel 15. The high-pressure conveyor 43 is connected to the nano-alkali powder 46 via a high-pressure delivery pipeline 47, the tail end of which is connected to the alkali powder injection channel 25. This completes the installation of the ground support equipment assembly 4.

[0073] At the same time, the extraction equipment is installed at the wellhead of extraction well 92. A wellbore pump 51, an oil storage tank 52, and an extraction pipeline 53 are installed on the ground at the wellhead of extraction well 92. Specifically, the upper portion of the extraction pipeline 53 is connected to the front end of the wellbore pump 51, while the lower portion extends deep into the shale oil 93. The rear end of the wellbore pump 51 is connected to the oil storage tank 52. This completes the installation of the extraction equipment.

[0074] Then, the heating device 100 is installed in the heat injection well 91. Specifically, according to the depth of the formation, an appropriate number of water injection connecting pipes 12 and alkali-thermal reaction chamber outer pipes 22 are installed to ensure that the heating device 100 extends to the corresponding fracture area of ​​the target oil shale layer 7 and to keep the alkali-thermal reaction unit 2 and heat injection unit 3 of the heating device 100 located inside the oil shale layer 7.

[0075] Afterwards, the production phase begins. During this phase, the ground auxiliary equipment 4 is activated, and nano-potassium hydroxide is injected into the alkali thermal reaction chamber 26 through the alkali powder injection channel 25. Simultaneously, high-pressure water is injected into the alkali thermal reaction chamber 26 through the high-pressure water flow channel 15. When the high-pressure water and the nano-potassium hydroxide come into contact within the alkali thermal reaction chamber 26 of the heating device 100, a chemical reaction occurs, releasing a large amount of heat and generating a large amount of alkaline potassium hydroxide solution and hydrogen. The high-pressure water then transitions to a critical state. The ratio of nano-potassium hydroxide to water is adjusted so that the concentration of the generated alkaline potassium hydroxide solution is 0.2 mol / L. The heat released by the reaction heats the target oil shale layer 7 located outside, and the fluid generated by the reaction enters the fractures, causing them to expand into corrosion cracks 71.

[0076] Specifically, under the action of the baffle 23, a large amount of heat generated by the reaction is carried by the critical state water, the alkaline potassium hydroxide solution and the hydrogen gas through the flow in the baffle 23 to the outside formation through the outer connecting pipe 21, heating the target oil shale layer 7 outside. At the same time, the critical state water, the large amount of alkaline potassium hydroxide solution and the hydrogen gas enter the heat injection bin 33 inside through the bottom filter plate 24, and then enter the fracture again through the heat injection hole 32 on the heat injection bin outer pipe 31, heating the target oil shale layer 7 again. At the same time, the alkaline potassium hydroxide solution can corrode the quartz minerals in the formation, so that the fracture is expanded into a corrosion fracture 71, thereby overcoming the thermal expansion problem of the target oil shale layer 7 in the heating process, and the catalysis of potassium hydroxide and hydrogen gas, which together promote the cracking of kerogen. In addition, the critical water has the effect of dissolving and extracting organic matter, which can better help the oil and gas products to migrate outward.

[0077] Under the above-mentioned combined action, the shale oil 93 produced by the target oil shale layer 7 enters the production well 92 through the corrosion fracture 71. Then it is pumped by the oil pump 51 through the oil pumping pipe 53 into the oil storage bin 52, so as to achieve the purpose of exploiting the oil shale formation, thereby realizing oil production.

[0078] The exploitation method for oil shale formation according to the present application realizes the in-situ critical water alkali corrosion catalytic reaction heat complex exploitation of oil shale by combining the in-situ exploitation methods of oil shale which are beneficial to critical water, alkali corrosion, chemical heating and catalysis. The exploitation method is carried out by the exploitation system formed by the heating device 100, the ground auxiliary equipment device 4 and the exploitation device, which makes the exploitation method have the advantages of simple process, short exploitation period, wide use and high recovery rate. The oil shale formation is subjected to the demineralization treatment by alkali corrosion, which can effectively cope with the thermal expansion problem of oil shale in the heating process. At the same time, the reaction heat released by the reaction of alkali and water, and the products such as alkaline solution and hydrogen gas generated are fully utilized, and the products such as alkaline solution and hydrogen gas have catalytic effect on the cracking of oil shale. The high-pressure critical water generated after being heated has good dissolving and carrying effect on oil and gas products, which can greatly improve the oil and gas recovery rate.

[0079] In the description, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0080] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0081] In addition, in the description of this specification, reference to the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0082] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for mining oil shale formations, comprising the following steps: Step 1: drilling a production well (92) from the surface toward the target oil shale layer (7), and artificially creating fractures through the production well (92) to form pressure fractures in the target oil shale layer (7), forming a suction channel in the production well (92); Step 2: Drilling a hot injection well (91) in the area corresponding to the hydraulic fracture; Step 3: Installing a surface auxiliary equipment device (4) at the wellhead of the heat injection well (91); Step 4: Install a heating device (100) in the heat injection well (91) according to the depth of the formation; Step 5: Start the ground auxiliary equipment device (4), inject high-pressure water flow and alkali powder into the heating device (100) to generate a chemical reaction, thereby releasing heat to heat the target oil shale layer (7), and the fluid generated by the reaction enters the pressure fracture, causing the pressure fracture to expand into a corrosion fracture (71). The fluid generated by the reaction between the high-pressure water flow and the alkali powder includes critical water, alkaline solution and hydrogen, a portion of the heat released by the reaction is directly transferred outward to heat the target oil shale layer (7), and the other portion enters the fracture along with the fluid generated by the reaction, thereby heating the target oil shale layer (7) again; Step 6: The shale oil (93) produced from the target oil shale layer (7) enters the production well (92) through the corrosion cracks (71) and is produced through the suction channel.

2. The method for mining oil shale formation according to claim 1, characterized in that: In the step 1, artificial fractures are created by hydraulic fracturing.

3. The method for mining oil shale formation according to claim 1 or 2, characterized in that: When there are one or two mining wells (92), the mining wells (92) and the heat injection wells (91) are distributed in a straight line; when there are multiple mining wells (92), the heat injection well (91) is set at the center of the multiple mining wells (92) so that the multiple mining wells (92) are evenly distributed around the heat injection well (91).

4. The method for mining oil shale formation according to claim 1 or 2, characterized in that: In the fourth step, the heating device (100) is extended to correspond to the fracture area of ​​the target oil shale layer (7).

5. The method for mining oil shale formation according to claim 1 or 2, characterized in that: The heat released by the reaction between the high-pressure water flow and the alkaline powder can heat the target oil shale layer (7) to 300-500°C, and the concentration of the generated alkaline solution is 0.1-1 mol / L. The pressure of the high-pressure water flow is 3-20 MPa.

6. A production system for use in a production method for an oil shale formation according to any one of claims 1 to 5, comprising: A heating device (100) comprising a water injection unit (1), an alkali heat reaction unit (2), and a heat injection unit (3) connected in sequence from top to bottom, wherein the water injection unit (1) comprises a high-pressure water flow channel (15) and an alkali powder injection channel (25); The high-pressure water flow and the alkali powder can be respectively injected into the alkali thermal reaction unit (2) through the high-pressure water flow channel (15) and the alkali powder injection channel (25), and chemically react with each other in the alkali thermal reaction unit (2) to release heat, and the fluid generated by the reaction enters the fracture through the heat injection unit (3).

7. The mining system according to claim 6, characterized in that The water injection unit (1) comprises a main body, a first axial through hole is provided at the center of the main body to form the alkali powder injection channel (25), and a first axial annular through portion is provided radially outside the alkali powder injection channel (25) to form the high-pressure water flow channel (15), and a pressure valve (14) is provided at the lower end of the high-pressure water flow channel (15).

8. The mining system according to claim 6 or 7, characterized in that: The alkali thermal reaction unit (2) comprises an alkali thermal reaction chamber outer tube (22), a baffle (23) arranged inside the alkali thermal reaction chamber outer tube (22), and a bottom filter plate (24) fixedly connected to the lower end of the baffle (23).

9. The mining system according to claim 6 or 7, characterized in that: The heat injection unit (3) comprises a heat injection chamber outer tube (31), a heat injection chamber (33) is formed inside the heat injection chamber outer tube (31), and a plurality of through heat injection holes (32) are evenly opened on the side wall of the heat injection chamber outer tube (31), and the fluid generated by the reaction enters the pressure fracture through the heat injection holes (32).

10. The mining system according to claim 6 or 7, characterized in that: It also includes a ground auxiliary equipment device (4) for injecting high-pressure water flow and alkali powder into the heating device (100), which includes a water supply unit connected to the high-pressure water flow channel (15) and an alkali powder supply unit connected to the alkali powder injection channel (25).

11. The mining system according to claim 10, characterized in that The water supply unit includes a water source (45), a water pump (41) and a booster pump (42). The water source (45), the water pump (41) and the booster pump (42) are connected via a water injection pipe (44), and the tail end of the water injection pipe (44) is connected to the high-pressure water flow channel (15).

12. The mining system according to claim 10, characterized in that The alkali powder supply unit comprises a high-pressure conveyor (43) and a high-pressure conveying pipeline (47), and the high-pressure conveyor (43) is connected to the alkali powder injection channel (25) through the high-pressure conveying pipeline (47).

13. The mining system according to claim 6 or 7, characterized in that: It also includes an extraction device, which includes an oil storage tank (52) installed at the wellhead of the extraction well (92), an oil extraction pipeline (53) arranged in the extraction well (92) and extending to the bottom, and an oil extraction pump (51) connected between the oil storage tank (52) and the oil extraction pipeline (53).

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