Well group type brine solution mining system and solution mining method

Abstract

The well group type brine solution mining system comprises an extraction well (1), an auxiliary well (2), a horizontal well (22), a gas fracturing device (3), a solvent supplementing device (4) and a brine mining device (5), the extraction well is arranged in a solution mining area (6), the lower end of the extraction well extends into a target salt mine layer (61), and the auxiliary well is arranged in the solution mining area and keeps a certain distance from the extraction well; and the lower end of the auxiliary well extends into the target salt mine layer. The horizontal well is arranged in the target salt mine layer and located at the bottom of the target salt mine layer, the two ends of the horizontal well communicate with the extraction well and the auxiliary well correspondingly, and the gas fracturing device fractures the target salt mine layer above the horizontal well to form a first crack (62). And the solvent supplementing device is communicated with the auxiliary well. And the brine mining device is used for mining ore dissolving brine in the extraction well. According to the method, the solvent can rapidly permeate into a target salt mine layer, and the ore dissolving efficiency and the target mineral content are improved.

Description

Technical Field

[0001] The present invention relates to a well group type brine solution mining system, and particularly to the solution mining efficiency of the well group type brine solution mining system. Background Art

[0002] Brine is rich in elements such as potassium, magnesium, and sodium, and is one of the important raw materials for the production of potassium chloride. The existing brine mining methods mainly rely on shallow canal mining supplemented by deep well mining. Shallow canal mining means directly mining the brine in the salt ore layer through a brine mining canal. With long-term mining, the content and quality of brine in the salt ore layer gradually decline, unable to meet the production demand. Therefore, there is a mining method of solid-liquid conversion, that is, by the method of large-area flooding with a solvent, the external solvent is replenished into the solution mining area, so that the target mineral (potassium) in the target salt ore layer in the solution mining area dissolves into the solvent, and then it is mined by a combined method of canal mining and well mining.

[0003] With the vigorous development of salt lake resources, the brine level in the solution mining area has dropped significantly, forming a large-scale drained area. The potassium resources in the shallow salt ore layer (shallower than 18 m in depth) have been depleted. However, there are a large number of potassium salt resources in the deep salt ore layer (deeper than 18 m in depth). Due to the limitations of large formation burial depth, low porosity and other conditions, the deep salt ore layer mainly consists of loose sediments such as some fine sand layers and silt layers containing salt and salt layers with low porosity, and has low permeability. Due to the influence of the blockage of fine sand, powder and other debris in the deep salt ore layer, it is difficult for the solvent to enter the deep salt ore layer, the increase rate of the target mineral is relatively slow, the ore dissolution effect is not ideal, resulting in difficulty in dissolving and mining the solid ore containing a large amount of potassium chloride in the deep layer, and relatively serious resource waste.

[0004] Therefore, the existing solid-liquid conversion mining method mainly dissolves the shallow salt ore layer. Although deep well mining can carry out partial mining of the deep salt ore layer. However, there are still problems such as large development difficulty, insufficient water inflow, and high cost in the large-area deep and precise ore dissolution mining project, and it is difficult to achieve large-scale, engineering, and sustainable brine mining.

[0005] The purpose of the present invention is to provide a well group type brine solution mining system to solve the problems of large mining difficulty, low ore dissolution efficiency, and low content of target minerals in brine when using a method of solid-liquid conversion to mine brine in the deep salt ore layer. Summary of the Invention

[0006] To solve the above problems, the present invention provides a well group type brine solution mining system, including a pumping well 1, an auxiliary well 2, a horizontal well 22, a gas fracturing device 3, a solvent replenishing device 4, and a brine mining device 5. The pumping well 1 is arranged in the solution mining area 6, and the lower end extends into the target salt ore layer 61. The auxiliary well 2 is arranged in the solution mining area 6, keeps a certain distance from the pumping well 1, and the lower end of the auxiliary well 2 extends into the target salt ore layer 61 for injecting the solvent 21 into the target salt ore layer 61.

[0007] The horizontal well 22 is arranged in the target salt ore layer 61, at the bottom of the target salt ore layer 61, and is connected to the extraction well 1 and the auxiliary well 2 at both ends respectively. The gas fracturing device 3 is used to fracture the target salt ore layer 61 above the horizontal well 22 to form a first fracture 62 in the target salt ore layer 61. The solvent replenishing device 4 is connected to the auxiliary well 2 and is used to inject the solvent 21 into the auxiliary well 2 to dissolve the target minerals in the target salt ore layer 61 to form the ore-dissolving brine 12. The brine extraction device 5 is used to extract the ore-dissolving brine 12 in the extraction well 1.

[0008] In the solution mining area 6 of the present invention, an extraction well 1, an auxiliary well 2 and a horizontal well 22 are arranged. The gas fracturing device 3 fractures the target salt ore layer 61 above the horizontal well 22 to form a first fracture 62 in the target salt ore layer 61. By means of the first fracture 62, the permeability of the target salt layer is increased, and the solvent 21 is promoted to pass through the loose sediment and the salt layer with low porosity in the target salt ore layer 61 and quickly infiltrate into the target salt ore layer 61. After the target minerals in the target salt ore layer 61 are dissolved, the ore-dissolving brine 12 is obtained, the permeability and fluidity of the solvent 21 are improved, the ore-dissolving efficiency and effect are improved, the content of the target minerals in the ore-dissolving brine 12 is increased, and thus the quality of the ore-dissolving brine is improved. Through the horizontal well 22, the ore-dissolving brine 12 after dissolving the target minerals in the target salt ore layer 61 can be quickly converged into the extraction well 1. The present invention can solve the problems of large mining difficulty, low ore-dissolving efficiency and low content of target minerals in the ore-dissolving brine 12 when mining deep potassium salt ore by the method of solid-liquid conversion.

[0009] Preferably, eight auxiliary wells 2 are correspondingly arranged around the outer periphery of the extraction well 1, and the eight auxiliary wells 2 are evenly arranged in four directions around the outer periphery of the extraction well 1.

[0010] Preferably, an auxiliary well 2 is arranged every 250 m around the extraction well 1. Therefore, in the present invention, the penetration radius of the solvent 21 of each auxiliary well 2 can be in a suitable range, thereby improving the ore-dissolving efficiency and the content of the target minerals in the ore-dissolving brine 12.

[0011] Preferably, a perforated casing pipe 23 is arranged in the area of the well wall of the extraction well 1 in the target salt ore layer 61, and a non-perforated solid pipe 24 is arranged on the well wall in the remaining areas. A perforated casing pipe is arranged in the area of the well wall of the auxiliary well 2 in the target salt ore layer 61, and a non-perforated solid pipe is arranged on the well wall in the remaining areas.

[0012] The perforated pipe 23 and the solid pipe 24 without holes can support the well walls of the extraction well 1 and the auxiliary well 2, prevent the well walls from collapsing and causing blockages, and protect the salt ore layer from being damaged. By arranging the perforated pipe 23 in the area of the target salt ore layer 61 on the well wall of the extraction well 1, after the solvent 21 enters the auxiliary well 2, it can only dissolve and displace the target minerals in the target salt ore layer 61, effectively preventing the upper salt layer from polluting the solvent 21, enabling the solvent 21 to have a high dissolution and displacement efficiency, and achieving the purpose of precise solution mining of deep brine.

[0013] Preferably, the lower end of the extraction well 1 extends through the target salt ore layer 61 to the upper part of the target salt ore floor layer 63, and the lower end of the auxiliary well 2 extends through the target salt ore layer 61 to the upper part of the target salt ore floor layer 63.

[0014] Preferably, a liquid level gauge 11 is arranged in both the auxiliary well 2 and the extraction well 1, and the liquid level of the solvent 21 in the auxiliary well 2 is higher than the liquid level of the ore-dissolving brine 12 in the extraction well 1.

[0015] In the present invention, by continuously replenishing the solvent 21 into the auxiliary well 2, a hydraulic gradient is created between the extraction well 1 and the auxiliary well 2. The solvent 21 in the auxiliary well 2 naturally converges towards the extraction well 1 by gravity. Finally, only the ore-dissolving brine 12 needs to be extracted from the extraction well 1, achieving the purpose of cost reduction and efficiency improvement, and realizing green and low-carbon mining.

[0016] Preferably, the brine extraction device 5 includes a brine extraction pump 51 and a brine extraction pipe 52. The water inlet of the brine extraction pump 51 is connected to the extraction well 1 through the brine extraction pipe 52, and the water outlet of the brine extraction pump 51 is used to be connected to the brine transportation pipeline.

[0017] Preferably, the solvent 21 is a high-sodium and low-potassium solution. When the high-sodium and low-potassium solution enters the deep salt ore layer, potassium ions in the deep salt ore layer are precipitated. After the sodium ions in the solvent 21 are mixed with the sodium ions in the ore layer and become supersaturated, they precipitate, and the salt is left in the deep salt ore layer, thus ensuring the safety of the solution mining area 6 and preventing the solution mining area 6 from collapsing.

[0018] Preferably, the first fracture 62 extends vertically in the target salt ore layer 61 above the horizontal well 22. Since the horizontal well 22 is located at the bottom of the salt layer, the vertical fracture can increase the permeability of the target salt layer, thereby improving the quality of the ore-dissolving brine and increasing the water inflow of the extraction well 1.

[0019] The well group type precise brine solution mining method includes: the first step S11, excavating the extraction well 1 and a corresponding plurality of auxiliary wells 2 in the solution mining area 6. The lower ends of the extraction well 1 and the auxiliary wells 2 extend into the target salt ore layer 61, and a horizontal well 22 is arranged in the target salt ore layer 61 to connect the extraction well 1 and the corresponding plurality of auxiliary wells 2. The second step S12, fracturing the target salt ore layer 61 above the horizontal well 22 through the gas fracturing device 3 to form a vertically extending first fracture 62 in the target salt ore layer 61.

[0020] In the third step S13, a solvent is injected into the auxiliary well 2 through the solvent supply device 4, and the solvent passes through the first fracture 62 to dissolve the target minerals in the target salt ore layer 61, forming a leaching brine 12, and the leaching brine 12 is collected in the extraction well 1. In the fourth step S14, the leaching brine 12 in the extraction well 1 is exploited through the brine extraction device 5.

[0021] A brine leaching system includes an extraction well 1, an auxiliary well 2, a gas fracturing device 3, a solvent supply device 4, and a brine extraction device 5. The extraction well 1 is arranged in a leaching area 6, and the lower end extends into the target salt ore layer 61. The auxiliary well 2 is arranged in the leaching area 6, keeping a certain distance from the extraction well 1, and the lower end of the auxiliary well 2 extends into the target salt ore layer 61 for injecting a solvent 21 into the target salt ore layer 61.

[0022] The gas fracturing device 3 is used to fracture the target salt ore layer 61 around the auxiliary well 2 to form a second fracture 62a in the target salt ore layer 61. The solvent supply device 4 is connected to the auxiliary well 2 for injecting the solvent 21 into the auxiliary well 2 to dissolve the target minerals in the target salt ore layer 61, forming a leaching brine 11. The brine extraction device 5 is used to extract the leaching brine 11 in the extraction well 1.

[0023] In the present invention, by arranging the extraction well 1 and the auxiliary well 2 in the leaching area 6, the gas fracturing device 3 fractures the target salt ore layer 61 around the auxiliary well 2 to form a second fracture 62a in the target salt ore layer 61. The permeability of the target salt layer is increased through the second fracture 62a, promoting the solvent 21 to pass through the loose sediment and low-porosity salt layer in the target salt ore layer 61 and quickly infiltrating into the target salt ore layer 61. After dissolving the target minerals in the target salt ore layer 61, a leaching brine 11 is obtained, improving the permeability and fluidity of the solvent 21, enhancing the leaching efficiency and effect, increasing the content of the target minerals in the leaching brine 11, and thus improving the quality of the leaching brine 11. The present invention can solve the problems of large mining difficulty, low leaching efficiency, and low content of target minerals in the leaching brine 11 when using the solid-liquid conversion method to mine deep potassium salt ore.

[0024] Preferably, eight auxiliary wells 2 are correspondingly arranged on the outer periphery of each extraction well 1, and the eight auxiliary wells 2 are evenly arranged in four directions around the outer periphery of the extraction well 1.

[0025] Preferably, an auxiliary well 2 is arranged every 100 m around the extraction well 1. Therefore, in the present invention, the penetration radius of the solvent 21 of each auxiliary well 2 can be in a suitable range, thereby improving the leaching efficiency and increasing the content of the target minerals in the leaching brine 11.

[0026] Preferably, the lower end of the extraction well 1 penetrates through the target salt ore layer 61 and extends to the upper part of the target salt ore floor layer 63. The lower end of the auxiliary well 2 penetrates through the target salt ore layer 61 and extends to the upper part of the target salt ore floor layer 63.

[0027] Preferably, a liquid level gauge 22 is provided in both the auxiliary well 2 and the extraction well 1, and the liquid level of the solvent 21 in the auxiliary well 2 is higher than the liquid level of the ore-dissolving brine 11 in the extraction well 1.

[0028] In the present invention, by continuously replenishing the solvent 21 into the auxiliary well 2, a hydraulic gradient is created between the extraction well 1 and the auxiliary well 2. The solvent 21 in the auxiliary well 2 naturally converges towards the extraction well 1 by gravity. Finally, only the ore-dissolving brine 11 needs to be extracted from the extraction well 1, achieving the purpose of cost reduction and efficiency improvement, and realizing green and low-carbon mining.

[0029] Preferably, the brine extraction device 5 includes a brine extraction pump 51 and a brine extraction pipe 52. The water inlet of the brine extraction pump 51 is connected to the brine extraction well through the brine extraction pipe 52, and the water outlet of the brine extraction pump 51 is used to be connected to the brine transportation pipeline.

[0030] Preferably, the solvent 21 is a high-sodium and low-potassium solution. The high-sodium and low-potassium solution enters the deep salt ore layer, precipitating potassium ions in the deep salt ore layer. After the sodium ions in the solvent 21 are mixed with the sodium ions in the ore layer and become supersaturated, they precipitate, and the salt remains in the deep salt ore layer, thus ensuring the safety of the solution mining area 6 and preventing the collapse of the solution mining area 6.

[0031] Preferably, the second fracture 62a extends horizontally in a direction perpendicular to the auxiliary well 2. Through the horizontally extending second fracture 62a, the solvent 21 can quickly penetrate into the target salt ore layer 61, quickly dissolve the target minerals in the target salt layer to obtain the ore-dissolving brine 11, and make the ore-dissolving brine 11 flow into the extraction well 1. In the present invention, horizontal wells do not need to be set, which can reduce the engineering quantity and improve the construction efficiency.

[0032] Preferably, it includes an excavation step S21 of excavating the extraction well 1 and a corresponding plurality of auxiliary wells 2 in the solution mining area 6, so that the lower ends of the extraction well 1 and the auxiliary wells 2 extend into the target salt ore layer 61. A fracturing step S22 of fracturing the target salt ore layer 61 on the outer periphery of the wellbore of the auxiliary well 2 by a gas fracturing device 3 to form a horizontally extending second fracture 62a in the target salt ore layer 61.

[0033] A dissolving step S23 of injecting the solvent 21 into the auxiliary well 2 through a solvent replenishing device 4, so that the solvent 21 passes through the second fracture 62a to dissolve the target minerals in the target salt ore layer 61 to form the ore-dissolving brine 11, and making the ore-dissolving brine 11 gather in the extraction well 1. A mining step S24 of mining the ore-dissolving brine 11 in the extraction well 1 by a brine extraction device 5. Description of the Drawings

[0034] Figure 1Schematic diagram of the well group type brine solution mining system in Embodiment 1; Figure 2 Schematic diagram of the installation of the perforated screen pipe and non-perforated solid pipe inside the extraction well in Embodiment 1; Figure 3 Schematic diagram of the distribution positions of the extraction wells and auxiliary wells in the solution mining area; Figure 4 Schematic diagram of the well group type brine solution mining method in Embodiment 1; Figure 5 Schematic diagram of the well group type brine solution mining system in Embodiment 2; Figure 6 Schematic diagram of the well group type brine solution mining method in Embodiment 2.

[0035] In the figure, 1. Extraction well, 11. Liquid level gauge, 12. Solution mining brine, 2. Auxiliary well, 21. Solvent, 22. Horizontal well, 23. Perforated screen pipe, 24. Non-perforated solid pipe, 25. Liquid level gauge, 3. Gas fracturing device, 4. Solvent replenishing device, 5. Brine extraction device, 51. Brine extraction pump, 52. Brine extraction pipe, 6. Solution mining area, 61. Target salt ore layer, 62. Fracture, 63. Target salt ore bottom layer, 64. Target salt layer top layer, 62a. Second fracture. Detailed implementation manners

[0036] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0037] Embodiment 1 In this embodiment, extraction wells, auxiliary wells and horizontal wells are arranged in the solution mining area, and a first fracture is arranged in the target salt ore layer above the horizontal well. The permeability of the target salt layer is improved through the first fracture, so that the solvent can quickly penetrate into the target salt ore layer, improving the solution mining efficiency and solution mining effect, and increasing the content of the target mineral in the solution mining brine. The following is a detailed description of this embodiment.

[0038] As shown in Figure 1 and Figure 2 , the well group type brine solution mining system includes an extraction well 1, an auxiliary well 2, a horizontal well 22, a gas fracturing device 3, a solvent replenishing device 4 and a brine extraction device 5.

[0039] The extraction well 1 is arranged in the solution mining area 6 and is vertically arranged. The lower end penetrates through the target salt ore layer 61 and extends into the target salt ore bottom layer 63. The extraction well 1 is used to converge the solution mining brine 12.

[0040] Eight auxiliary wells 2 are correspondingly arranged on the outer periphery of the extraction well 1, and the eight auxiliary wells 2 are evenly arranged in four directions around the outer periphery of the extraction well 1.

[0041] The auxiliary well 2 is arranged in the solution mining area 6, maintaining a certain distance from the extraction well 1. The auxiliary well 2 is vertically arranged, with its lower end passing through the target salt ore layer 61 and extending into the target salt ore bottom layer 63. The auxiliary well 2 is used to inject the solvent 21 into the target salt ore layer 61.

[0042] When selecting the excavation positions of the extraction well and the auxiliary well in the solution mining area, first explore the content of the target mineral (potassium) in the target salt ore layer, and excavate the extraction well and the auxiliary well in the area where the content of the target mineral is relatively high, so as to achieve precise solution mining.

[0043] In this embodiment, an auxiliary well 2 is arranged every 250 m around the extraction well 1 (refer to Figure 3 ). In other embodiments, the distance between the extraction well 1 and the auxiliary well 2 can be set according to the soil quality and the content of the target mineral in the target salt ore layer 61, such as 100 m, 150 m or other distances, as long as the penetration radius of the solvent 21 of each auxiliary well 2 is within a suitable range, so as to improve the ore dissolution efficiency and increase the content of the target mineral in the ore dissolution brine 12.

[0044] The solvent 21 is a high-sodium and low-potassium solution. When the high-sodium and low-potassium solution enters the deep salt ore layer, potassium ions in the deep salt ore layer are precipitated. After the sodium ions in the solvent 21 are mixed with the sodium ions in the ore layer and become supersaturated, they precipitate, and the salt remains in the deep salt ore layer, thus ensuring the safety of the solution mining area 6 and preventing the solution mining area 6 from collapsing.

[0045] The horizontal well 22 is arranged in the target salt ore layer 61, at the bottom of the target salt ore layer 61, and is connected to the extraction well 1 and the auxiliary well 2 at both ends respectively. That is, each auxiliary well 2 is connected to the extraction well 1 through the horizontal well 22. Through the horizontal well 22, the ore dissolution brine 12 after dissolving the target mineral in the target salt ore layer 61 can be quickly converged into the extraction well 1.

[0046] By arranging the horizontal well 22, the rapid flow of the solvent in the target salt ore layer 61 can be promoted, the ore dissolution range of the target salt ore layer 61 can be increased, and the ore dissolution efficiency can be improved.

[0047] Perforated casing pipes 23 are arranged in the area of the well wall of the extraction well 1 located in the target salt ore layer 61, and non-perforated solid pipes 24 are arranged on the well walls of the remaining areas (that is, the inner sides of the target salt ore layer roof layer 64 and the target salt ore layer bottom layer 63). Perforated casing pipes are arranged in the area of the well wall of the auxiliary well 2 located in the target salt ore layer 61, and non-perforated solid pipes are arranged on the well walls of the remaining areas.

[0048] Gravel is filled between the perforated casing pipes and the non-perforated solid pipes and the target salt ore layer 61 to support the ore layer and achieve the extraction of the brine.

[0049] The well walls of the extraction well 1 and the auxiliary well 2 can be supported by perforated flower pipes and solid pipes without holes, preventing the well walls from collapsing and causing blockages, and protecting the salt ore layer from being damaged. By setting perforated flower pipes in the area of the target salt ore layer 61 on the well wall of the extraction well 1, after the solvent 21 enters the auxiliary well 2, it can only dissolve and displace the target minerals in the target salt ore layer 61, effectively preventing the upper salt layer from polluting the solvent 21, enabling the solvent 21 to have a high dissolution and displacement efficiency, and achieving the purpose of precise solution mining of deep brine.

[0050] Level gauges 11 are installed in both the auxiliary well 2 and the extraction well 1, and the liquid level of the solvent 21 in the auxiliary well 2 is higher than the liquid level of the ore - dissolving brine 12 in the extraction well 1.

[0051] By continuously replenishing the solvent 21 into the auxiliary well 2, a hydraulic gradient is created between the extraction well 1 and the auxiliary well 2, forming a liquid level difference. The solvent 21 in the auxiliary well 2 naturally converges towards the extraction well 1 by gravity. Finally, only the ore - dissolving brine 12 needs to be extracted from the extraction well 1, achieving the purpose of cost reduction and efficiency improvement, and realizing green and low - carbon mining.

[0052] The gas fracturing device 3 is used to fracture the target salt ore layer 61 above the horizontal well 22, forming the first fracture 62 in the target salt ore layer 61.

[0053] The gas fracturing device 3 mainly includes a gas generator, a packer, an ignition system, pressure control equipment, and a monitoring and control system. During fracturing, the gas generator, packer, sensors, etc. are combined and lowered to the target position. Then, the non - target intervals are isolated using the packer. In a remote ignition mode, the gas rapidly expands to generate fractures (the pressure can reach 50 - 200 MPa). The fracture propagation effect is evaluated through sensors.

[0054] The gas fracturing device 3 uses gunpowder combustion to generate high - temperature and high - pressure gas, and the high - pressure gas fractures the target salt ore layer 61 to obtain multiple irregular fissures, thereby increasing the permeability of the salt layer.

[0055] After high - energy gas fracturing, due to the action of residual stress, the fractures remain open to a certain extent without the need to add proppants. Moreover, the main components of the gas generated by gunpowder combustion are CO2, CO, and H2O, which cause little pollution to the salt layer and the original brine, and have the characteristics of environmental protection, energy conservation, and low reservoir damage.

[0056] High - energy gas fracturing generates high - pressure gas through the rapid combustion of gunpowder or chemical agents, forming a dynamic shock wave. This instantaneous loading can overcome the tensile strength of the rock and form fractures at the perforation holes.

[0057] The first fracture 62 extends vertically in the target salt ore layer 61 above the horizontal well 22. Since the horizontal well 22 is located at the bottom of the salt layer, the vertical fracture can increase the permeability of the target salt layer, thereby improving the quality of the ore-dissolving brine and increasing the water inflow of the extraction well 1.

[0058] By using the gas fracturing device 3 to fracture the target salt ore layer 61 above the horizontal well 22, the first fracture 62 is formed in the target salt ore layer 61. Through the first fracture 62, the permeability of the target salt layer is increased, thereby improving the quality of the ore-dissolving brine, promoting the solvent 21 to penetrate through the loose sediment and low-porosity salt layer in the target salt ore layer 61, quickly infiltrating into the target salt ore layer 61, dissolving the target minerals in the target salt ore layer 61 to obtain the ore-dissolving brine 12, improving the permeability and fluidity of the solvent 21, enhancing the ore-dissolving efficiency and effect, and increasing the content of the target minerals in the ore-dissolving brine 12.

[0059] The solvent replenishing device 4 is connected to the auxiliary well 2 and is used to inject the solvent 21 into the auxiliary well 2 to dissolve the target minerals in the target salt ore layer 61, forming the ore-dissolving brine 12.

[0060] The brine extraction device 5 is used to extract the ore-dissolving brine 12 in the extraction well 1. The brine extraction device 5 includes a brine extraction pump 51 and a brine extraction pipe 52. The water inlet of the brine extraction pump 51 is connected to the extraction well 1 through the brine extraction pipe 52, and the water outlet of the brine extraction pump 51 is used to be connected to the brine transportation pipeline.

[0061] As Figure 4 shown, the well group type brine ore-dissolving method includes the first step S11 of excavating the extraction well 1 and a corresponding plurality of auxiliary wells 2 in the ore-dissolving area 6. The lower ends of the extraction well 1 and the auxiliary wells 2 extend into the target salt ore layer 61, and a horizontal well 22 is arranged in the target salt ore layer 61 to connect the extraction well 1 and the corresponding plurality of auxiliary wells 2.

[0062] The second step S12 is to fracture the target salt ore layer 61 above the horizontal well 22 through the gas fracturing device 3 to form a vertically extending first fracture 62 in the target salt ore layer 61.

[0063] The third step S13 is to inject the solvent 21 into the auxiliary well 2 through the solvent replenishing device 4, so that the solvent 21 passes through the first fracture 62 formed by fracturing to dissolve the target minerals in the target salt ore layer 61, forming the ore-dissolving brine 12, and causing the ore-dissolving brine 12 to gather in the extraction well 1.

[0064] The fourth step S14 is to extract the ore-dissolving brine 12 in the extraction well 1 through the brine extraction device 5.

[0065] In this embodiment, a production well 1, an auxiliary well 2, and a horizontal well 22 are arranged in the solution mining area 6. The gas fracturing device 3 is used to fracture the target salt ore layer 61 above the horizontal well 22 to form a first fracture 62 in the target salt ore layer 61, so as to increase the permeability of the target salt layer, thereby improving the quality of the solution mining brine 12, promoting the solvent 21 to penetrate through the loose sediment and low-porosity salt layer in the target salt ore layer 61, quickly infiltrating into the target salt ore layer 61, dissolving the target minerals in the target salt ore layer 61 to obtain the solution mining brine 12, improving the permeability and fluidity of the solvent 21, improving the solution mining efficiency and solution mining effect, and increasing the content of the target minerals in the solution mining brine 12.

[0066] Embodiment 2 The difference between this embodiment and Embodiment 1 is that in this embodiment, no horizontal well and first fracture are provided, and only a horizontally extending second fracture is provided in the target salt ore layer on the outer periphery of the auxiliary well wall. Thus, under the condition of reducing the construction workload, the target minerals in the target salt ore layer are quickly dissolved to obtain the solution mining brine, and the quality of the solution mining brine is improved.

[0067] For the convenience of understanding, the same structures in this embodiment and Embodiment 1 adopt the same names and numbers.

[0068] As Figure 5 shown, the well group type brine solution mining system includes a production well 1, an auxiliary well 2, a gas fracturing device 3, a solvent replenishing device 4, and a brine production device 5.

[0069] The production well 1 is arranged in the solution mining area 6, vertically arranged, and the lower end passes through the roof layer 64 of the target salt ore layer and the target salt ore layer 61 and extends into the bottom layer 63 of the target salt ore. The production well 1 is used to converge the solution mining brine 11.

[0070] Eight auxiliary wells 2 are correspondingly arranged on the outer periphery of the production well 1, and the eight auxiliary wells 2 are evenly arranged in four directions around the outer periphery of the production well 1.

[0071] The auxiliary well 2 is arranged in the solution mining area 6, keeping a certain distance from the production well 1. The auxiliary well 2 is vertically arranged, and the lower end passes through the roof layer 64 of the target salt ore layer and the target salt ore layer 61 and extends into the bottom layer 63 of the target salt ore. The auxiliary well 2 is used to inject the solvent 21 into the target salt ore layer 61.

[0072] In this embodiment, an auxiliary well 2 is arranged every 100 m around the production well 1 (refer to Figure 3 ). In other embodiments, the distance between the production well 1 and the auxiliary well 2 can be set according to the soil quality and the content of the target minerals in the target salt ore layer 61, such as 100 m, 150 m or other distances, as long as the penetration radius of the solvent 21 of each auxiliary well 2 is within a suitable range, so as to improve the solution mining efficiency and increase the content of the target minerals in the solution mining brine 11.

[0073] The solvent 21 is a high-sodium and low-potassium solution. The high-sodium and low-potassium solution enters the deep salt ore layer, precipitating potassium ions in the deep salt ore layer. After the sodium ions in the solvent 21 are mixed with the sodium ions in the ore layer and become supersaturated, they precipitate, and the salt formed remains in the deep salt ore layer, thus ensuring the safety of the solution mining area 6 and preventing the collapse of the solution mining area 6.

[0074] Level gauges 22 are provided in both the auxiliary well 2 and the extraction well 1, and the liquid level of the solvent 21 in the auxiliary well 2 is higher than the liquid level of the ore-dissolving brine 11 in the extraction well 1.

[0075] By continuously replenishing the solvent 21 into the auxiliary well 2, a hydraulic gradient is created between the extraction well 1 and the auxiliary well 2 to form a liquid level difference. The solvent 21 in the auxiliary well 2 naturally converges towards the extraction well 1 by gravity. Finally, only the ore-dissolving brine 11 needs to be extracted from the extraction well 1, achieving the purpose of cost reduction and efficiency increase and realizing green and low-carbon mining.

[0076] The gas fracturing device 3 is used to fracture the target salt ore layer 61 around the auxiliary well 2 to form a second fracture 62a in the target salt ore layer 61.

[0077] The gas fracturing device 3 is the same as that in the foregoing embodiment and will not be elaborated here.

[0078] The second fracture 62a extends horizontally in the target salt ore layer 61 on the outer periphery of the wellbore of the auxiliary well 2. Through the horizontally extending second fracture 62a, the solvent 21 can quickly penetrate into the target salt ore layer 61, quickly dissolve the target minerals in the target salt layer to obtain the ore-dissolving brine 11, and cause the ore-dissolving brine 11 to flow into the extraction well 1. The present invention does not need to set up horizontal wells, which can reduce the engineering quantity and improve the construction efficiency.

[0079] The solvent replenishing device 4 is connected to the auxiliary well 2 and is used to inject the solvent 21 into the auxiliary well 2 to dissolve the target minerals in the target salt ore layer 61 to form the ore-dissolving brine 11.

[0080] The brine extraction device 5 is used to extract the ore-dissolving brine 11 in the extraction well 1. The brine extraction device 5 includes a brine extraction pump 51 and a brine extraction pipe 52. The water inlet of the brine extraction pump 51 is connected to the brine extraction well through the brine extraction pipe 52, and the water outlet of the brine extraction pump 51 is used to be connected to the brine transportation pipeline.

[0081] Preferably, it includes an excavation step S21 of excavating the extraction well 1 and a corresponding plurality of auxiliary wells 2 in the solution mining area 6, so that the lower ends of the extraction well 1 and the auxiliary wells 2 extend into the target salt ore layer 61.

[0082] A fracturing step S22 of fracturing the target salt ore layer 61 around the wellbore of the auxiliary well 2 by the gas fracturing device 3 to form a horizontally extending second fracture 62a in the target salt ore layer 61.

[0083] Dissolution step S23: Inject solvent 21 into auxiliary well 2 through solvent supply device 4, so that solvent 21 passes through second fracture 62a to dissolve target minerals in target salt ore layer 61, forming ore-dissolving brine 11, and making ore-dissolving brine 11 converge in production well 1.

[0084] Mining step S24: Mine ore-dissolving brine 11 in production well 1 through brine mining device 5.

[0085] In this embodiment, by arranging production well 1 and auxiliary well 2 in solution mining area 6, fracturing target salt ore layer 61 around auxiliary well 2 through gas fracturing device 3 to form second fracture 62a in target salt ore layer 61, increasing the permeability of the target salt layer through second fracture 62a, promoting solvent 21 to pass through the loose sediment and low-porosity salt layer in target salt ore layer 61, quickly infiltrating into target salt ore layer 61, dissolving target minerals in target salt ore layer 61 to obtain ore-dissolving brine 11, improving the permeability and fluidity of solvent 21, improving the ore-dissolving efficiency and effect, increasing the content of target minerals in ore-dissolving brine 11, and thus improving the quality of ore-dissolving brine 11. The present invention can solve the problems of great mining difficulty, low ore-dissolving efficiency, and low content of target minerals in ore-dissolving brine 11 when mining deep potassium salt ore by solid-liquid conversion method.

[0086] It should be noted that the above embodiments illustrate the present invention rather than limit the present invention.

Claims

1. Well group type brine solution mining system, characterized in that, It includes a gas extraction well (1), an auxiliary well (2), a horizontal well (22), a gas fracturing device (3), a solvent replenishing device (4) and a brine extraction device (5). The gas extraction well (1) is arranged in the solution mining area (6), and its lower end extends into the target salt ore layer (61). The auxiliary well (2) is arranged in the solution mining area (6), keeping a certain distance from the gas extraction well (1). The lower end of the auxiliary well (2) extends into the target salt ore layer (61) for injecting solvent into the target salt ore layer (61). The horizontal well (22) is arranged in the target salt ore layer (61), at the bottom of the target salt ore layer (61), and its two ends are respectively communicated with the gas extraction well (1) and the auxiliary well (2). The gas fracturing device (3) is used to fracture the target salt ore layer (61) above the horizontal well (22) to form a first fracture (62) in the target salt ore layer (61). The solvent replenishing device (4) is communicated with the auxiliary well (2) for injecting solvent into the auxiliary well (2) to dissolve the target minerals in the target salt ore layer (61) to form dissolved ore brine. The brine extraction device (5) is used to extract the dissolved ore brine in the gas extraction well (1).

2. The well group type brine solution mining system according to claim 1, wherein Eight auxiliary wells (2) are correspondingly arranged around the outer periphery of the gas extraction well (1). The eight auxiliary wells (2) are evenly arranged in four directions around the outer periphery of the gas extraction well (1).

3. The well group type brine solution mining system according to claim 2, characterized in that, One auxiliary well (2) is arranged every 250 m around the gas extraction well (1).

4. The well group type brine solution mining system according to claim 3, characterized in that, Perforated casing pipes (23) are arranged in the area of the well wall of the gas extraction well (1) in the target salt ore layer (61), and non-perforated solid pipes (24) are arranged on the well wall in the remaining areas. Perforated casing pipes are arranged in the area of the well wall of the auxiliary well (2) in the target salt ore layer (61), and non-perforated solid pipes are arranged on the well wall in the remaining areas.

5. The well group type brine solution mining system according to claim 4, wherein The lower end of the gas extraction well (1) passes through the target salt ore layer (61) and extends to the upper part of the bottom layer (63) of the target salt ore layer (61). The lower end of the auxiliary well (2) passes through the target salt ore layer (61) and extends to the upper part of the bottom layer (63) of the target salt ore layer (61).

6. The well group type brine solution mining system according to claim 5, characterized in that, Level gauges (11) are arranged in both the auxiliary well (2) and the gas extraction well (1). The liquid level of the solvent in the auxiliary well (2) is higher than the liquid level of the dissolved ore brine in the gas extraction well (1).

7. The well group type brine solution mining system according to claim 6, characterized in that, The brine extraction device (5) includes a brine extraction pump (51) and a brine extraction pipe (52). The water inlet of the brine extraction pump (51) is communicated with the gas extraction well (1) through the brine extraction pipe (52), and the water outlet of the brine extraction pump (51) is used to be communicated with the brine transportation pipeline.

8. The well group type brine solution mining system according to claim 7, characterized in that, The solvent is a high-sodium and low-potassium solution.

9. The well group type brine solution mining system according to any one of claims 1 to 8, characterized in that, The first fracture (62) vertically extends in the target salt ore layer (61) above the horizontal well (22).

10. Well-group brine solution mining method, characterized in that, It includes the first step (S1): Excavate the gas extraction well (1) and a corresponding plurality of auxiliary wells (2) in the solution mining area (6). The lower ends of the gas extraction well (1) and the auxiliary wells (2) extend into the target salt ore layer (61), and a horizontal well (22) is arranged in the target salt ore layer (61) to communicate the gas extraction well (1) and the corresponding plurality of auxiliary wells (2). The second step (S2): Using a gas fracturing device (3) to fracture the target salt ore layer (61) above the horizontal well (22) to form a vertically extending first fracture (62) in the target salt ore layer (61). The third step (S3): Using a solvent supplement device (4) to inject a solvent into the auxiliary well (2), enabling the solvent to pass through the first fracture (62) to dissolve the target minerals in the target salt ore layer (61) to form a mineral - dissolved brine, and collecting the mineral - dissolved brine in the extraction well (1). The fourth step (S4): Using a brine extraction device (5) to extract the mineral - dissolved brine in the extraction well (1).

11. Well-group type brine solution mining system, characterized in that, It includes an extraction well (1), an auxiliary well (2), a gas fracturing device (3), a solvent supplement device (4), and a brine extraction device (5). The extraction well (1) is arranged in the solution mining area (6), and its lower end extends into the target salt ore layer (61). The auxiliary well (2) is arranged in the solution mining area (6), maintaining a certain distance from the extraction well (1). The lower end of the auxiliary well (2) extends into the target salt ore layer (61) for injecting a solvent into the target salt ore layer (61). The gas fracturing device (3) is used to fracture the target salt ore layer (61) around the auxiliary well (2) to form a second fracture (62a) in the target salt ore layer (61). The solvent supplement device (4) is connected to the auxiliary well (2) and is used to inject a solvent into the auxiliary well (2) to dissolve the target minerals in the target salt ore layer (61) to form a mineral - dissolved brine. The brine extraction device (5) is used to extract the mineral - dissolved brine in the extraction well (1).

12. The well group type brine solution mining system according to claim 11, wherein, Eight auxiliary wells (2) are correspondingly arranged on the outer periphery of each extraction well (1). The eight auxiliary wells (2) are evenly arranged in four directions around the outer periphery of the extraction well (1).

13. The well group type brine solution mining system according to claim 12, wherein, An auxiliary well (2) is arranged every 100 m around the extraction well (1).

14. The well group type brine solution mining system according to claim 13, characterized in that, The lower end of the extraction well (1) passes through the target salt ore layer (61) and extends to the upper part of the bottom layer 63 of the target salt ore. The lower end of the auxiliary well (2) passes through the target salt ore layer (61) and extends to the upper part of the bottom layer 63 of the target salt ore.

15. The well group type brine solution mining system according to claim 14, characterized in that, A liquid level gauge (22) is arranged in both the auxiliary well (2) and the extraction well (1). The liquid level of the solvent in the auxiliary well (2) is higher than the liquid level of the mineral - dissolved brine in the extraction well (1).

16. The well group type brine solution mining system according to claim 15, characterized in that, The brine extraction device (5) includes a brine extraction pump (51) and a brine extraction pipe (52). The water inlet of the brine extraction pump (51) is connected to the extraction well through the brine extraction pipe (52), and the water outlet of the brine extraction pump (51) is used to be connected to a brine transportation pipeline.

17. The well group type brine solution mining system according to claim 16, characterized in that, The solvent is a high - sodium and low - potassium solution.

18. The well group type brine solution mining system according to any one of claims 11 to 17, characterized in that, The second fracture (62a) extends horizontally in a direction perpendicular to the auxiliary well (2).

19. Well group type brine solution mining method, characterized in that, It includes an excavation step (S21): Excavating the extraction well (1) and a corresponding number of auxiliary wells (2) in the solution mining area (6) so that the lower ends of the extraction well (1) and the auxiliary wells (2) extend into the target salt ore layer (61). The fracturing step (S22): Using a gas fracturing device (3) to fracture the target salt ore layer (61) on the outer periphery of the well wall of the auxiliary well (2) to form a horizontally extending second fracture (62a) in the target salt ore layer (61). Dissolution step (S23): Inject a solvent into the auxiliary well (2) through a solvent supply device (4), so that the solvent passes through the second fracture (62a) to dissolve the target minerals in the target salt ore layer (61) to form a brine solution for dissolving minerals, and the brine solution for dissolving minerals is collected in the extraction well (1); Mining step (S24): Mine the brine solution for dissolving minerals in the extraction well (1) through a brine mining device (5).

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