Single-well injection and production method for low-permeability sandstone type uranium mine

Abstract

The invention discloses a low-permeability sandstone type uranium mine single-well injection and production method, and belongs to the technical field of in-situ leaching uranium mining. The method comprises the steps that an injection and production well is drilled from the ground to a uranium mine layer; pumping liquid carbon dioxide into the uranium ore layer and soaking; a leaching agent is injected into the uranium ore layer in stages, and soaking is carried out every time the leaching agent is injected; extracting the leachate until the uranium concentration in the leachate is reduced by 10% compared with the initial concentration or the uranium concentration in the leachate is reduced to the preset concentration; carbon dioxide and a leaching agent are supplemented into tail liquid formed after uranium recovery is conducted on the leachate, the tail liquid reaches a saturated state, and the tail liquid in the saturated state is reinjected into the uranium ore layer; and a cycle operation step.

Description

Technical Field

[0001] This application belongs to the technical field of in-situ leaching of uranium, and particularly relates to a single-well injection and production method for low-permeability sandstone-type uranium ore. Background Art

[0002] As a key strategic resource, uranium plays an irreplaceable core role in the field of nuclear power generation. With the continuous advancement of the "deep exploration and blind area search" work in uranium ore exploration in China, multiple complex sandstone uranium ores such as low-permeability and isolated island-like ones have been discovered. How to effectively develop such uranium deposits has become a technical problem that urgently needs to be overcome in the field of in-situ leaching development.

[0003] Conventional in-situ leaching development requires the coordinated operation of injection wells and production wells. This method has significant drawbacks: for low-permeability uranium ore layers, it is difficult to establish effective communication between injection and production wells, resulting in low mining efficiency; in small-scale, isolated island-like distributed uranium ore areas, the cost of building multiple wells for coordinated development is too high, which is not reasonable from an economic perspective. In addition, the conventional coordinated development mode requires long-term continuous cyclic injection and production, with huge energy consumption, making the mining cost remain high.

[0004] The development experience in the field of oil and gas reservoirs shows that for low-permeability reservoirs, reservoir stimulation methods such as fracturing can effectively improve reservoir permeability and ore recovery rate. This method has important reference significance for the development of low-permeability uranium ore deposits. However, due to the lack of effective coordination technology, conventional stimulation methods are difficult to achieve the expected effect. Even if certain fractures can be formed, without an effective leaching system and enhanced leaching means, the spreading range of the leaching agent in the uranium ore layer is still limited and cannot evenly diffuse to the entire target area, seriously affecting the leaching efficiency, and further restricting the mining efficiency and economic benefits of low-permeability sandstone-type uranium ore.

[0005] Therefore, it is extremely urgent to develop a single-well injection and production method for low-permeability sandstone-type uranium ore. This method needs to rely on the synergistic effect of single-well reservoir stimulation, enhanced leaching and shut-in well technology to achieve the economic and efficient development of complex sandstone uranium ores such as low-permeability and isolated island-like ones. Summary of the Invention

[0006] In view of this, the present application provides a single-well injection and production method for low-permeability sandstone-type uranium ore, with the main purpose of overcoming many deficiencies of conventional methods in the exploitation of complex sandstone uranium ores such as low permeability and isolated islands. Specifically, for the low-permeability uranium ore layer, it is difficult to establish effective communication and the exploitation efficiency is low in the collaborative development of conventional two wells (injection well and leaching well). Through the single-well injection and production method, by means of the synergistic effect of single-well reservoir transformation, enhanced leaching (operations such as pumping liquid carbon dioxide into the uranium ore layer and injecting lixiviant in stages), and well soaking technology, the permeability of the uranium ore layer and the leaching effect are improved, thereby solving the problem of communication between wells and enhancing the exploitation efficiency. For small-scale (isolated island-shaped) uranium ore areas, the cost of conventionally drilling two wells is too high, while this method adopts single-well injection and production, avoiding the high-cost investment of drilling two wells, which is more reasonable from an economic perspective and reduces the exploitation cost.

[0007] To achieve the above object, the present application mainly provides the following technical solutions:

[0008] The present application provides a single-well injection and production method for low-permeability sandstone-type uranium ore, including:

[0009] Drill an injection-production well from the ground into the uranium ore layer;

[0010] Pump liquid carbon dioxide into the uranium ore layer and then soak the well;

[0011] Inject lixiviant into the uranium ore layer in stages, and soak the well each time after the injection of lixiviant is completed;

[0012] Extract the leaching solution until the uranium concentration in the leaching solution is reduced by 10% compared to the initial concentration or the uranium concentration in the leaching solution is reduced to a preset concentration;

[0013] For the tail liquid formed after uranium recovery from the leaching solution, add carbon dioxide and lixiviant to make the tail liquid reach a saturated state, and inject the saturated tail liquid back into the uranium ore layer;

[0014] Repeat the steps of injecting lixiviant into the uranium ore layer in stages, soaking the well each time after the injection of lixiviant is completed, extracting the leaching solution until the uranium concentration in the leaching solution is reduced by 10% compared to the initial concentration or the uranium concentration in the leaching solution is reduced to a preset concentration, and for the tail liquid formed after uranium recovery from the leaching solution, adding carbon dioxide and lixiviant to make the tail liquid reach a saturated state, and injecting the saturated tail liquid back into the uranium ore layer.

[0015] Optionally, the pumping pressure of the liquid carbon dioxide is 1.1 to 1.2 times the fracture pressure of the uranium ore layer.

[0016] Optionally, in the step of pumping liquid carbon dioxide into the uranium ore layer and soaking the well, the well soaking time is 48 to 72 hours to ensure the formation of a large-scale complex fracture network structure suitable for in-situ leaching in the uranium ore layer.

[0017] Optionally, the step of injecting the leaching agent into the uranium ore layer in stages and soaking the well after each injection of the leaching agent includes:

[0018] The first-stage injection of the leaching agent and soaking the well;

[0019] The second-stage injection of the leaching agent and soaking the well.

[0020] Optionally, in the step of injecting the leaching agent into the uranium ore layer in stages and soaking the well after each injection of the leaching agent, the injection volume of the second stage of the leaching agent is the same as that of the first stage of the leaching agent, or the injection volume of the second stage of the leaching agent is proportionally reduced compared with that of the first stage of the leaching agent.

[0021] Optionally, in the step of the first-stage injection of the leaching agent and soaking the well, the soaking time is 24 to 48 hours; in the step of the second-stage injection of the leaching agent and soaking the well, the soaking time is 96 to 168 hours.

[0022] Optionally, in the step of injecting the leaching agent into the uranium ore layer in stages and soaking the well after each injection of the leaching agent, when the soaking time after the first-stage injection of the leaching agent is 48 hours, the injection volume of the second stage of the leaching agent is the same as that of the first stage of the leaching agent.

[0023] Optionally, in the step of injecting the leaching agent into the uranium ore layer in stages and soaking the well after each injection of the leaching agent, when the soaking time after the first-stage injection of the leaching agent is less than 48 hours, the injection volume of the second stage of the leaching agent is proportionally reduced compared with that of the first stage of the leaching agent.

[0024] Optionally, in the step of injecting the leaching agent into the uranium ore layer in stages and soaking the well after each injection of the leaching agent, when the soaking time after the first-stage injection of the leaching agent is 24 hours, the injection volume of the second stage of the leaching agent is one-half of that of the first stage of the leaching agent.

[0025] Optionally, in the step of injecting the leaching agent into the uranium ore layer in stages and soaking the well after each injection of the leaching agent, the leaching agent used is a hydrogen peroxide solution with a mass concentration of 3% to 5% or a potassium permanganate solution with a mass concentration of 0.1% to 0.3%, and the injection rate of the leaching agent in each stage is 0.1 to 0.5 cubic meters per hour.

[0026] By means of the above technical solutions, the present application has at least the following beneficial effects:

[0027] In the embodiments of the present application, the single-well injection and production method for low-permeability sandstone-type uranium ore is adopted. The single-well injection and production method does not require the construction of a wellfield injection and production structure with at least two pumping and injection wells as in the conventional method, reducing the drilling cost. At the same time, it avoids the huge energy consumption brought by the long-term uninterrupted cyclic injection and production in the conventional collaborative development mode, reduces the operating cost, is more reasonable economically, and is especially suitable for the exploitation of complex sandstone uranium ores such as low-permeability and isolated island-like ores. Specifically, by pumping liquid carbon dioxide into the uranium ore layer and soaking the well, and injecting the leaching agent in stages and soaking the well, it helps to achieve reservoir transformation under single-well conditions, promote the formation and expansion of fractures in the uranium ore layer, improve the permeability of the uranium ore layer, enable the leaching agent to diffuse more evenly throughout the target area, and fully contact with uranium elements, thereby enhancing the leaching efficiency and further improving the mining efficiency. By taking the reduction of the uranium concentration in the leaching liquid by 10% compared with the initial concentration or the reduction of the uranium concentration in the leaching liquid to a preset concentration as the standard when pumping out the leaching liquid, the mining process can be accurately controlled, avoiding over-mining or under-mining, and ensuring the reasonable development and utilization of uranium ore resources. By treating the tail liquid formed after uranium recovery from the leaching liquid, adding carbon dioxide and leaching agent to make it reach a saturated state and then reinjecting it into the uranium ore layer, the recycling of resources is realized, reducing resource waste and environmental pollution, and improving the sustainability of the entire mining process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flowchart of the single-well injection and production method for low-permeability sandstone-type uranium ore according to an optional embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present application will be described in detail below with reference to the drawings and in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0030] In this embodiment, a single-well injection and production method for low-permeability sandstone-type uranium ore is provided. Refer to Figure 1 As shown, the method includes:

[0031] Step S101: Drill an injection and production well from the ground into the uranium ore layer.

[0032] The single-well injection and production method for low-permeability sandstone-type uranium ore provided by the embodiments of the present application can be applied to fields such as in-situ leaching of uranium, and specifically can be applied to the mining operations of low-permeability ore layers or isolated island-like ore sections. When carrying out the mining operations of low-permeability ore layers or isolated island-like ore sections, first, survey the geological conditions, determine the specific location of the low-permeability sandstone-type uranium ore layer to be mined, and arrange drill holes in the length direction from the surface to the uranium ore layer. Here, a professional drilling device is used to drill vertically or obliquely from the ground into the underground uranium ore layer to form an injection and production well. It should be noted that this injection and production well is the channel for all subsequent operations, used to inject various substances into the uranium ore layer and extract the leaching liquid.

[0033] Step S201: Pump liquid carbon dioxide into the uranium ore layer and shut in the well.

[0034] In this embodiment, a high-pressure pump can be used to inject liquid carbon dioxide into the uranium ore layer through the injection-production well. After the liquid carbon dioxide enters the uranium ore layer, physical and chemical changes will occur under the action of pressure and temperature. Shutting in the well means that after injecting the liquid carbon dioxide, the wellhead of the injection-production well is closed, allowing the carbon dioxide to diffuse in the uranium ore layer for a period of time, so that the carbon dioxide has sufficient time to diffuse to the far end of the uranium ore layer, and a range that can be effectively affected by the leaching agent is constructed in a wider area.

[0035] It should be noted that the pumping pressure of the liquid carbon dioxide is 1.1 to 1.2 times the fracture pressure of the uranium ore layer. By setting the pumping pressure of the liquid carbon dioxide higher than the fracture pressure of the uranium ore layer, when pumping the liquid carbon dioxide into the uranium ore layer, using its strong impact force, it can initially cause fractures to occur in the uranium ore layer. When the liquid carbon dioxide successfully enters the uranium ore layer, it will continuously diffuse in the formed fractures. At the same time, due to the change of temperature and pressure conditions, the liquid carbon dioxide gradually gasifies into a gaseous state, and the volume expands significantly. The force of this volume expansion will further open up the fractures, causing the fractures to continuously extend and branch in the uranium ore layer, effectively increasing the degree of fracture spread, and finally forming a multi-fracture morphology. As the fracture network becomes richer, the affected range of the leaching agent in the uranium ore layer is greatly expanded, and it can penetrate more comprehensively into the uranium ore area, greatly increasing the contact area and reaction opportunity between the leaching agent and the uranium ore. This enables the uranium element to react more fully with the leaching agent, significantly improving the leaching efficiency of the uranium element, and finally achieving the purpose of improving the mining efficiency of low-permeability sandstone-type uranium ore and increasing economic benefits.

[0036] In some actual cases, through actual measurement, the fracture pressure of the uranium ore layer is 12 MPa. Based on this, during actual operation, the pumping pressure of liquid carbon dioxide is controlled at 13.2 MPa, the injection rate is set at 1.5 cubic meters per minute, and the injection continues for 30 minutes. Subsequently, with the help of microseismic monitoring technology, it can be found that the fracturing operation successfully forms a network of microfractures with a radius ranging from 1.2 to 1.8 meters, and the longitudinal span is effectively controlled within 4.2 meters. During this process, the waterproof layers of the roof and floor are not damaged. When the injection of liquid carbon dioxide is completed, the pressure-maintaining soaking operation is immediately carried out. The soaking time set for this soaking operation is 60 hours. The temperature of this uranium ore layer is stable at 20 °C. In such a temperature environment, the injected liquid carbon dioxide can quickly vaporize into gaseous carbon dioxide. The gaseous carbon dioxide reacts with the water in the formation to generate carbonic acid. This chemical reaction causes the pH value in the ore layer to decrease from the initial 7.42 to 6.71, thus creating a weakly acidic groundwater environment. Thereby, the possibility of the subsequent injected lixiviant reacting with the surrounding rock and generating precipitation can be greatly reduced. During the 60-hour soaking period, the gaseous carbon dioxide continuously diffuses towards the far end of the ore layer through the microfractures formed by the previous fracturing, and gradually builds a range where the lixiviant can fully act in a wider area, creating extremely favorable preconditions for the subsequent leaching and mining operation.

[0037] Step S301: Inject the lixiviant into the uranium ore layer in stages, and perform a soaking operation after each injection of the lixiviant.

[0038] In this embodiment, the lixiviant can be a hydrogen peroxide solution with a mass concentration in the range of 3% to 5%, or a potassium permanganate solution with a mass concentration in the range of 0.1% to 0.3%. It should be noted that whether it is a hydrogen peroxide solution with a mass concentration of 3% to 5% or a potassium permanganate solution with a mass concentration of 0.1% to 0.3%, when used to oxidize uranium, a certain reaction time is required to complete this oxidation process. During this period, if the lixiviant is in excess, it will react with other minerals in the uranium ore. Taking iron ions as an example, the excess lixiviant will react with iron and oxidize it to trivalent iron, thereby generating precipitation. In view of this, in this embodiment, the method of injecting the lixiviant in stages can, on the one hand, ensure the effective utilization of the lixiviant, enable the reaction of oxidizing uranium to proceed fully, and improve the leaching efficiency of uranium; on the other hand, by controlling the injection amount of the lixiviant in each stage, the reaction of the excess lixiviant with other metals can be effectively inhibited, thereby avoiding the blockage of the ore layer pores caused by precipitation and ensuring the fluidity of the lixiviant in the uranium ore layer, creating favorable conditions for the smooth progress of the subsequent mining operation. And performing a soaking operation after each injection of the lixiviant is to allow sufficient time for the lixiviant to react with the uranium ore, improve the dissolution efficiency of uranium elements, enable the lixiviant to diffuse more evenly to all parts of the uranium ore layer, and react with the uranium ore as much as possible.

[0039] Here, taking the case where the leaching agent is injected into the uranium ore layer in two times as an example, the injection amount of the leaching agent in each stage will be described. In the actual application scenario, the soaking time after the first-stage injection of the leaching agent is within a range interval, and there is an upper limit value and a lower limit value in this interval. The specific value can be flexibly determined according to the treatment amount of the leaching solution, and this application does not make any limitations on this. When the soaking time after the first-stage injection of the leaching agent reaches the upper limit value, the injection amount of the second stage of the leaching agent is equal to that of the first stage. This is because a longer soaking time can enable the leaching agent injected in the first stage to be consumed more fully, and the reaction is more complete. There is still a large space and demand in the ore layer to accommodate the same amount of leaching agent as in the first stage, so a large amount of injection can still be carried out in the second stage. When the soaking time after the first-stage injection of the leaching agent is less than the upper limit value, the injection amount of the second stage of the leaching agent will be proportionally reduced compared with the first stage. This is because a shorter soaking time makes the leaching agent injected in the first stage not fully react and be consumed, and the concentration of the remaining leaching agent in the ore layer is relatively high. If the injection amount of the second stage is still the same as that of the first stage, it will cause an excessive amount of leaching agent, not only resulting in waste of resources, but also possibly causing adverse consequences such as excessive reaction with other minerals to produce precipitation, which will affect subsequent mining operations. Specifically, when the soaking time after the first-stage injection of the leaching agent is the lower limit value, the injection amount of the second stage of the leaching agent is reduced to one-half of the injection amount of the first stage.

[0040] Furthermore, in this embodiment, there are clear settings for the soaking time after the injection of the leaching agent in each stage: the soaking time range after the first-stage injection of the leaching agent is 24 to 48 hours; the soaking time range after the second-stage injection of the leaching agent is 96 to 168 hours. It should be noted that after the first-stage injection of the leaching agent, the main purpose is to initially prompt the uranium ore to contact the leaching agent and initiate the oxidation dissolution reaction. Within 24 to 48 hours, the leaching agent rapidly diffuses in the ore layer and reacts with the uranium ore initially, and some easily soluble uranium elements can be dissolved in a short time. In the second stage, after the first-stage reaction, the remaining refractory uranium ore needs a longer time to fully react with the leaching agent. As the reaction progresses, the reaction environment inside the ore layer becomes more complex, and the reaction rate gradually decreases. A soaking time as long as 96 to 168 hours is required to enable the leaching agent to continuously penetrate into finer pores and deeper parts of the ore layer, fully react with the residual uranium ore, and improve the overall leaching rate of uranium elements.

[0041] In some actual cases, the parameters are as follows: In the first stage, the leaching agent injected is hydrogen peroxide solution with a mass concentration of 5%. The injection process is carried out at a rate of 0.3 cubic meters per hour, and the cumulative injection volume reaches 8 cubic meters. Subsequently, a soaking well operation is carried out, and the soaking well duration is 48 hours. In the second stage, the leaching agent injected is also hydrogen peroxide solution with a mass concentration of 5%. The injection rate is set at 0.2 cubic meters per hour, and the injection volume is also 8 cubic meters. After the injection is completed, the soaking well time is as long as 168 hours.

[0042] Step S401: Pump out the leaching solution until the uranium concentration in the leaching solution decreases by 10% compared to the initial concentration or the uranium concentration in the leaching solution decreases to a preset concentration.

[0043] In this embodiment, a submersible pump can be used to pump the leaching solution containing uranium elements from the uranium ore layer to the ground through the injection-production well. During the pumping process, the uranium concentration in the leaching solution is continuously monitored. When the uranium concentration in the leaching solution decreases by 10% compared to the initial concentration at the beginning of the pumping, or the uranium concentration in the leaching solution decreases to a pre-set lower concentration value, the pumping stops. This step is to control the leaching degree of the uranium ore, ensure a certain mining efficiency and economic benefits, and avoid over-mining and resource waste.

[0044] In some actual cases, a submersible pump is used for pumping the leaching solution, and the pumping rate is set at 3 cubic meters per hour. The real-time monitoring data of the uranium concentration shows that within the first 24 hours after the start of the pumping, the average uranium concentration in the leaching solution is 96 mg / L. After that, as the pumping operation continues, the uranium concentration shows a gradually decreasing trend. When the continuous pumping duration reaches 72 hours, the uranium concentration in the leaching solution has dropped to 86 mg / L.

[0045] Step S501: For the tail liquid formed after uranium recovery from the leaching solution, add carbon dioxide and leaching agent to make the tail liquid reach a saturated state, and inject the saturated tail liquid back into the uranium ore layer.

[0046] In this embodiment, after recovering uranium elements from the leaching solution, the remaining tail liquid still contains some unreacted components and possibly lost carbon dioxide and leaching agent. Adding carbon dioxide and leaching agent to the tail liquid to make it reach a saturated state means making the various components in the tail liquid reach the optimal concentration that can effectively leach uranium elements again. Then, the saturated tail liquid is injected back into the uranium ore layer through the injection-production well to achieve the recycling of resources, reduce environmental pollution, and also reduce the mining cost.

[0047] In some actual cases, add carbon dioxide (to make its concentration reach 300 mg / L) and hydrogen peroxide (to make its concentration reach 1%) to the tail liquid. After the addition is completed, inject the treated tail liquid back into the original uranium ore layer.

[0048] Step S601: Repeatedly perform the step of injecting a leaching agent into the uranium ore layer in stages, and after each injection of the leaching agent, carry out a soaking well and extract the leaching solution until the uranium concentration in the leaching solution is reduced by 10% compared to the initial concentration or the uranium concentration in the leaching solution is reduced to a preset concentration, and for the tail solution formed after uranium recovery from the leaching solution, add carbon dioxide and a leaching agent to make the tail solution reach a saturated state, and inject the saturated tail solution back into the uranium ore layer.

[0049] In this embodiment, it is continuously cycled and repeated in the order of steps S301, S401, and S501 to continuously carry out leaching mining on the uranium ore layer to maximize the extraction of uranium elements in the uranium ore until the uranium resources in the uranium ore layer are mined to the extent that it is no longer economically or technically feasible. Through this cyclic operation, the mining efficiency of uranium ore can be continuously improved, resources can be fully utilized, and sustainable mining of low-permeability sandstone-type uranium ore can be achieved.

[0050] In some actual cases, in accordance with the sequence of steps S301 (injecting a leaching agent into the uranium ore layer in stages, and carrying out a soaking well after each injection of the leaching agent), S401 (extracting the leaching solution until the uranium concentration in the leaching solution is reduced by 10% compared to the initial concentration or the uranium concentration in the leaching solution is reduced to a preset concentration), and S501 (for the tail solution formed after uranium recovery from the leaching solution, adding carbon dioxide and a leaching agent to make the tail solution reach a saturated state, and injecting the saturated tail solution back into the uranium ore layer), it was cycled and repeated 3 times. During the entire leaching process, the average concentration of leached uranium reached 80.2 mg / L. Thus, it can be seen that the single-well injection and production method for low-permeability sandstone-type uranium ore provided in this embodiment effectively improves the leaching concentration of uranium ore in low-permeability sandstone reservoirs, and effectively achieves the goals of reducing mining costs and improving mining benefits.

[0051] By applying the technical solution of this embodiment, the single-well injection-production method is adopted, which does not require the construction of a wellfield injection-production structure with at least two wells for pumping and injection as in the conventional method, reducing the drilling cost. At the same time, it avoids the huge energy consumption brought by the long-term uninterrupted cyclic injection-production in the conventional collaborative development mode, reduces the operation cost, is more reasonable economically, and is especially suitable for the exploitation of complex sandstone uranium ores such as low-permeability and isolated island-shaped ones. Specifically, by pumping liquid carbon dioxide into the uranium ore layer and soaking the well, and injecting the leaching agent in stages and soaking the well, it helps to realize reservoir transformation under single-well conditions, promote the formation and expansion of fractures in the uranium ore layer, improve the permeability of the uranium ore layer, enable the leaching agent to diffuse more evenly to the entire target area, and fully contact with uranium elements, thereby enhancing the leaching efficiency and further improving the mining efficiency. By taking the reduction of the uranium concentration in the leaching solution by 10% compared with the initial concentration or the reduction of the uranium concentration in the leaching solution to a preset concentration as the standard when pumping out the leaching solution, the mining process can be accurately controlled, avoiding over-mining or under-mining, and ensuring the reasonable development and utilization of uranium ore resources. By treating the tail liquid formed after uranium recovery from the leaching solution, adding carbon dioxide and leaching agent to make it reach the saturated state and then reinjecting it into the uranium ore layer, the recycling of resources is realized, reducing resource waste and environmental pollution, and improving the sustainability of the entire mining process.

[0052] It is easy for those skilled in the art to understand that, on the premise of no conflict, the above-mentioned advantageous ways can be freely combined and superimposed.

[0053] The above are only the preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of this application shall be included in the protection scope of this application. The above is only the preferred implementation manner of this application. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of this application, several improvements and variations can still be made, and these improvements and variations should also be regarded as the protection scope of this application.

Claims

1. A single-well injection-production method for low-permeability sandstone-type uranium ore, characterized in that, Including: Drilling injection-production wells from the ground into the uranium ore layer; Pumping liquid carbon dioxide into the uranium ore layer and soaking the well; Injecting the leaching agent into the uranium ore layer in stages, and soaking the well after each injection of the leaching agent; Extracting the leaching solution until the uranium concentration in the leaching solution is reduced by 10% compared to the initial concentration or the uranium concentration in the leaching solution is reduced to a preset concentration; For the tail liquid formed after uranium recovery from the leaching solution, adding carbon dioxide and the leaching agent to make the tail liquid reach a saturated state, and injecting the saturated tail liquid back into the uranium ore layer; Repeatedly execute the steps of injecting the leaching agent into the uranium ore layer in stages, soaking the well after each injection of the leaching agent, extracting the leaching solution until the uranium concentration in the leaching solution is reduced by 10% compared to the initial concentration or the uranium concentration in the leaching solution is reduced to a preset concentration, and for the tail liquid formed after uranium recovery from the leaching solution, adding carbon dioxide and the leaching agent to make the tail liquid reach a saturated state, and injecting the saturated tail liquid back into the uranium ore layer.

2. The single-well injection and production method for low-permeability sandstone-type uranium ore according to claim 1, characterized in that The pumping pressure of the liquid carbon dioxide is 1.1 to 1.2 times the fracture pressure of the uranium ore layer.

3. The single-well injection and production method for low-permeability sandstone-type uranium ore according to claim 1, characterized in that In the step of pumping liquid carbon dioxide into the uranium ore layer and soaking the well, the soaking time is 48 to 72 hours to ensure the formation of a large-scale complex fracture network structure suitable for in-situ leaching in the uranium ore layer.

4. The single-well injection and production method for low-permeability sandstone-type uranium ore according to claim 1, characterized in that, The injecting the leaching agent into the uranium ore layer in stages, and soaking the well after each injection of the leaching agent includes: The first-stage injection of the leaching agent and soaking the well; The second-stage injection of the leaching agent and soaking the well.

5. The single-well injection and production method for low-permeability sandstone-type uranium ore according to claim 4, characterized in that, In the step of injecting the leaching agent into the uranium ore layer in stages, and soaking the well after each injection of the leaching agent, the injection amount in the second stage of the leaching agent is the same as that in the first stage of the leaching agent or the injection amount in the second stage of the leaching agent is proportionally reduced compared to that in the first stage of the leaching agent.

6. The single-well injection and production method for low-permeability sandstone-type uranium ore according to claim 4, characterized in that, In the step of the first-stage injection of the leaching agent and soaking the well, the soaking time is 24 to 48 hours; in the step of the second-stage injection of the leaching agent and soaking the well, the soaking time is 96 to 168 hours.

7. The single-well injection and production method for low-permeability sandstone-type uranium ore according to claim 6, characterized in that In the step of injecting the leaching agent into the uranium ore layer in stages, and soaking the well after each injection of the leaching agent, when the soaking time after the first-stage injection of the leaching agent is 48 hours, the injection amount in the second stage of the leaching agent is the same as that in the first stage of the leaching agent.

8. The single-well injection and production method for low-permeability sandstone-type uranium ore according to claim 6, characterized in that In the step of injecting the leaching agent into the uranium ore layer in stages, and soaking the well after each injection of the leaching agent, when the soaking time after the first-stage injection of the leaching agent is less than 48 hours, the injection amount in the second stage of the leaching agent is proportionally reduced compared to that in the first stage of the leaching agent.

9. The single-well injection and production method for low-permeability sandstone-type uranium ore according to claim 8, characterized in that, In the step of injecting the leaching agent into the uranium ore layer in stages, and soaking the well after each injection of the leaching agent, when the soaking time after the first-stage injection of the leaching agent is 24 hours, the injection amount in the second stage of the leaching agent is one-half of the injection amount in the first stage of the leaching agent.

10. The single-well injection and production method for low-permeability sandstone-type uranium ore according to claim 1, characterized in that, In the step of injecting the leaching agent into the uranium ore layer in stages and soaking the well after each injection of the leaching agent, the leaching agent used is a hydrogen peroxide solution with a mass concentration of 3% to 5% or a potassium permanganate solution with a mass concentration of 0.1% to 0.3%, and the injection rate of the leaching agent in each stage is 0.1 to 0.5 cubic meters per hour.

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