A multi-node blasting permeability increasing device for low-permeability sandstone uranium mine shafts and its construction method

Abstract

The present application provides a multi-node blasting permeability increasing device for a low-permeability sandstone uranium mine shaft and a construction method thereof. The intelligent flexible directional blasting drill is arranged in the main shaft and is used for drilling a plurality of branch wells distributed in an umbrella shape with the main shaft as the center; the oblique adjuster is arranged in the main shaft and is connected with the intelligent flexible directional blasting drill; the downhole fracturer is arranged in the main shaft and lowered to the target reservoir, and is used for respectively carrying out perforation and gas explosion combined fracturing on the main shaft and blasting fracturing on the branch wells; the ground pumping mechanism is respectively connected with the intelligent flexible directional blasting drill and the downhole fracturer, and is used for respectively pumping additive materials into the branch wells and pumping chemical permeability increasing agents into the main shaft, so as to drill, plug, fill or blast-fracture the branch wells in the target reservoir, and blast-fracture the main shaft in the target reservoir. The device and the method can greatly improve the porosity and permeability of the low-permeability sandstone uranium ore reservoir around the main shaft, thereby improving the uranium ore recovery rate.

Description

Technical Field

[0001] This application relates to the field of deep shaft blasting for enhanced permeability in uranium ore mining, and particularly to a multi-node blasting device for enhanced permeability in low-permeability sandstone uranium ore shafts and its construction method. Background Art

[0002] Uranium ore is an important raw material for the nuclear industry, usually sourced from open-pit mining, underground mining, and in-situ leaching of uranium-bearing strata, as well as methods such as precipitation and adsorption of uranium compounds in the marine environment. In China, onshore sandstone-type uranium ore resources account for 43% of the total proven uranium resources, the highest proportion among all storage types, and are mainly mined by in-situ leaching. However, low-permeability sandstone uranium ores with low porosity and poor permeability account for more than 70% of China's sandstone-type uranium ore resources. This results in a small capacity of the reservoir to hold in-situ leaching solution, a small direct interaction interface between the in-situ leaching solution and the sandstone, a long reaction time, and a low injection-production rate, greatly limiting the uranium ore mining efficiency and even making it unmineable due to excessive costs. Therefore, it is necessary to carry out enhanced permeability transformation on low-permeability sandstone uranium ore reservoirs to improve their porosity and permeability, providing guarantee for the in-situ leaching mining of uranium ore resources.

[0003] Currently, the enhanced permeability transformation methods for low-permeability sandstone uranium ore reservoirs are mainly divided into physical and chemical categories. Among them, the effect of chemical enhanced permeability on the reservoir depends on the seepage channels and is usually used as a supplement to physical means. Physical means include hydraulic fracturing, ultrasonic waves, blasting, etc.; among them, hydraulic fracturing has been widely used in the field of oil and gas reservoir exploitation, but the direct fracturing process will form long and large fractures as the gathering channels for oil and gas; the long and large fractures will instead cause the in-situ leaching solution to be difficult to fully contact with the sandstone reservoir, resulting in the outflow through the dominant channels and causing extremely insufficient in-situ leaching mining. The overall energy of ultrasonic waves is relatively small, which has a certain effect on soft sandstone uranium ores with a high shale content, but the effect on hard low-permeability sandstone uranium ores is difficult to guarantee.

[0004] The existing blasting methods for enhanced permeability in low-permeability sandstone uranium deposits mainly carry out blasting without a free face in the shaft, using the impact of the cylindrical stress wave generated by the explosion in the shaft on the reservoir around the shaft to fracture and enhance the permeability of the low-permeability sandstone. However, due to the characteristic of the cylindrical wave attenuating with the propagation distance, the range of the crushed zone and the fractured zone generated by the blasting is limited. Therefore, in order to achieve large-scale enhanced permeability of the reservoir, a large number of shafts are required, and the well spacing needs to be controlled within 20 - 30 m to ensure that the fracture and enhanced permeability ranges of each well can be connected and communicated. For shallow (depth ≤ 500 m) sandstone uranium ores, the cost can still be controlled, but for deep (depth ≥ 800 m) sandstone uranium ores, the cost is greatly increased, which is not conducive to economic mining. When extending multiple horizontal wells in the main well in oil and gas reservoir exploitation to expand the mining range, the blasting will damage the roof and floor of the reservoir and cause in-situ leaching solution leakage and process failure.

[0005] Therefore, the technical problems in this field are mainly manifested as follows: ① The uniformity of the main shaft blasting fracturing method is poor, and it cannot achieve the effect of large-scale permeability enhancement; ② The engineering cost of using multiple wells for separate development is too high; ③ The conventional horizontal well technology is prone to damage the floor and roof, affecting in-situ leaching development. Therefore, it is necessary to develop a multi-node blasting permeability enhancement device in the vertical shaft and its construction method. Summary of the Invention

[0006] One of the purposes of this application is to provide a multi-node blasting device for sandstone uranium ore, which is suitable for carrying out large-scale permeability enhancement transformation on deep low-permeability and high-aquifer sandstone uranium ore reservoirs, and can effectively improve the production rate of in-situ leaching.

[0007] The technical solution of this application is as follows:

[0008] A multi-node blasting permeability enhancement device for low-permeability sandstone uranium ore vertical shafts includes an intelligent flexible directional blasting drill, an inclined regulator, a downhole fracturing device, and a surface pumping mechanism; the intelligent flexible directional blasting drill is arranged in the main shaft and is used to drill a plurality of branch wells distributed in an umbrella shape centered on the main shaft around the main shaft, and the branch wells extend from the inner wall of the main shaft to the target reservoir around the main shaft; the inclined regulator is arranged in the main shaft and is connected to the intelligent flexible directional blasting drill, and is used to guide the intelligent flexible directional blasting drill to change direction to drill the branch wells distributed in an umbrella shape; the downhole fracturing device is arranged in the main shaft and lowered into the target reservoir, and is used to perform perforation and gas explosion combined fracturing on the main shaft and blasting fracturing on the branch wells respectively, so that the fracture networks of the main shaft and the branch wells distributed in an umbrella shape are connected and communicated to form a fractured permeability enhancement area in the target reservoir; the surface pumping mechanism is respectively connected to the intelligent flexible directional blasting drill and the downhole fracturing device, and is used to pump additives into the branch wells and pump chemical permeability enhancers into the main shaft respectively, so as to drill, plug, fill or perform blasting fracturing on the branch wells in the target reservoir, and perform blasting fracturing on the main shaft in the target reservoir.

[0009] As a technical solution of the present application, the intelligent flexible directional blasting drill includes a drill bit, a reamer, a hydraulic motor, a locator, a filling pipe and a flexible drill pipe; the drill bit, the reamer, the hydraulic motor, the locator and the filling pipe are sequentially arranged in the flexible drill pipe from bottom to top; the surface pumping mechanism is connected to the hydraulic motor for pumping drilling fluid into the hydraulic motor; the hydraulic motor is respectively connected to the drill bit and the reamer in a transmission manner for driving the drill bit to rotate and drill or driving the reamer to ream the target reservoir; the locator is electrically connected to the drill bit for determining the position of the drill bit in the formation; both ends of the filling pipe are respectively communicated with the surface pumping mechanism and the drill bit, and the surface pumping mechanism is used for pumping additive materials into the filling pipe and feeding them into the branch well.

[0010] As a technical solution of the present application, the drill bit includes a PDC coring bit, and the diameter of the drilled hole is 75 or 91 mm.

[0011] As a technical solution of the present application, a gamma ray sensor and a gyroscopic inclinometer are installed in the locator, the gyroscopic inclinometer is electrically connected to the drill bit, and the locator is used for determining the position of the drill bit in the formation respectively according to the gamma radiation of the rock formation and the inclination angle of the drill bit.

[0012] As a technical solution of the present application, the additive materials include drilling fluid, encapsulated explosives, buffer materials, plugging materials and backfill materials.

[0013] As a technical solution of the present application, the flexible drill pipe is formed by sequentially hinging a plurality of drill pipe short joints.

[0014] As a technical solution of the present application, the diverter includes a deflecting elbow and a chip blocking packer; the chip blocking packer is arranged in the main well for separating the intelligent flexible directional blasting drill from the lower section of the main well; the deflecting elbow is installed on the top of the chip blocking packer and sleeved on the intelligent flexible directional blasting drill for guiding the intelligent flexible directional blasting drill to change direction.

[0015] As a technical solution of the present application, the downhole fracturing device includes a downhole tester, a perforator, a gas blaster, a shock absorber, a detonation controller, a jet injector and a gas blasting packer which are sequentially connected from bottom to top; the downhole tester is used for testing the pressure and temperature in the main well; the perforator is used for perforating the target reservoir; the detonation controller is respectively electrically connected to the perforator and the gas blaster for controlling the firing of the perforator and the gas blaster; the surface pumping mechanism is connected to the jet injector for pumping chemical permeability enhancer into the jet injector; the gas blasting packer is used for plugging the main well.

[0016] As a technical solution of the present application, the ground pumping mechanism includes a charging tank, a pneumatic chamber, an air compressor pump, a grouting pump, a mixing mixer, a mud pit, a chemical injection pump, and a chemical agent storage tank; the charging tank is connected to the top of the pneumatic chamber through a valve for filling the pneumatic chamber with encapsulated explosives; one end of the pneumatic chamber is connected to the intelligent flexible directional blasting drill through a valve, and the other end is connected to the air compressor pump through a valve. The air compressor pump pushes the encapsulated explosives in the pneumatic chamber through the intelligent flexible directional blasting drill and transports them into the branch well; one end of the grouting pump is connected to the intelligent flexible directional blasting drill through a valve for pumping drilling fluid into the branch well through the intelligent flexible directional blasting drill; the other end of the grouting pump is respectively connected to the mixing mixer and the mud pit through valves; the chemical injection pump is sequentially connected to the chemical agent storage tank and the downhole fracturing device through valves for pumping a chemical permeability enhancer into the main well.

[0017] As a technical solution of the present application, the mixing mixer includes three chambers, and the three chambers are respectively used for preparing buffer materials, plugging materials, and backfilling materials.

[0018] A construction method of a multi-node blasting permeability enhancement device for a low-permeability sandstone uranium ore shaft as described above includes the following steps:

[0019] S1, install the multi-node blasting permeability enhancement device for the low-permeability sandstone uranium ore shaft;

[0020] S2, drill through the intelligent flexible directional blasting drill to form a branch well extending from the inner wall of the main well to the target reservoir around the main well;

[0021] S3, perform back-drilling and reaming construction through the intelligent flexible directional blasting drill, and respectively load encapsulated explosives, buffer materials, plugging materials, or backfilling materials in the branch well according to the design plan;

[0022] S4, repeat the operations in steps S2 to S3, continue to drill other multiple branch wells around the main well, and complete the loading of encapsulated explosives, buffer materials, plugging materials, or backfilling materials for each branch well to form multiple branch wells distributed in an umbrella shape in the target reservoir;

[0023] S5, recover the intelligent flexible directional blasting drill and the inclined regulator, complete the assembly of the perforator and the air blasting device in the downhole fracturing device according to the design plan, lower the downhole fracturing device through the main well to a specified depth in the target reservoir, pump drilling fluid into the main well until the downhole fracturing device is submerged, and open the air blasting packer in the downhole fracturing device;

[0024] S6. Set the millisecond difference t of the initiation controller in each of the branch wells as the time difference between different branch wells, and start the combined millisecond blasting of the main well and the branch wells. In the main well, the combined operation blasting is performed through the perforator and the gas blaster, and in the branch wells, the blasting is performed through the encapsulated explosives.

[0025] S7. Pump the chemical permeability enhancer into the injector of the downhole fracturer through the surface pumping mechanism.

[0026] S8. Conduct the finishing work of the main well and carry out the next step of in-situ leaching mining.

[0027] As a technical solution of the present application, in step S3, the drill-back and reaming construction includes the following steps:

[0028] Prepare the buffer material, plugging material, and backfill material in the three chambers of the mixing and preparation device of the surface pumping mechanism respectively. Start the grouting pump of the surface pumping mechanism, open the reamer in the intelligent flexible directional blasting drill, and conduct the drill-back and reaming construction while retreating the intelligent flexible directional blasting drill. Fill the bottom of the branch well with 0.5 - 1 m thick buffer material.

[0029] After judging that the buffer material is filled to the specified thickness according to the total amount of pump injection and the drill bit retraction, stop pumping the buffer material, and switch the grouting pump to pump drilling fluid while continuing to retreat and ream the intelligent flexible directional blasting drill. Stop when retreating to the bottom of the roof of the target reservoir. Close the grouting pump and the reamer. Load the encapsulated explosives into the pneumatic chamber of the surface pumping mechanism through the charging tank of the surface pumping mechanism. Start the air compressor pump in the surface pumping mechanism and fill the pneumatic chamber with compressed air to push the encapsulated explosives to be loaded into the branch well through the filling pipe in the intelligent flexible directional blasting drill. Stop when loaded to the specified depth. Start the grouting pump again and continue to pump the buffer material into the branch well until reaching the bottom of the roof of the target reservoir and then stop. Continue to retreat the drill and switch the grouting pump to pump the plugging material until the drill bit in the intelligent flexible directional blasting drill retreats to the top of the roof of the target reservoir. Continue to retreat the drill and switch the grouting pump to pump the backfill material until the drill bit retreats into the main well.

[0030] The beneficial effects of the present application:

[0031] The present application provides a multi-node blasting device for sandstone uranium ore, which can achieve large-scale permeability enhancement of low-permeability sandstone uranium ore reservoirs around the main shaft. The device and method use an intelligent flexible directional blasting drill to drill from a certain depth around the main well to form several multi-node and umbrella-shaped distributed branch wells centered on the main well. Then, combined with a ground pumping mechanism, through the technology of withdrawing the drill and expanding the hole for filling, encapsulated explosives, buffer materials, plugging materials, backfill materials, etc. are loaded inside the branch wells to form a multi-level charge structure layout with a large range of multi-node and umbrella-shaped distribution in the target reservoir. Among them, the encapsulated explosives are used to provide blasting energy, the buffer materials are used to reduce the impact of blasting on the roof and floor, the plugging materials are used to plug the boreholes in the roof to prevent leachate leakage, and the backfill materials are used to fill other sections above the boreholes. By using an underground fracturer to perform perforation-gas explosion combined operation on the main well, the main well is communicated with the target reservoir and a certain area around it is fractured, so as to greatly improve the porosity and permeability of the target reservoir, and further improve the recovery rate of the target reservoir. It can not only provide sufficient blasting energy for permeability enhancement and transformation of low-permeability sandstone uranium ore reservoirs, but also provide sufficient protection for the roof and floor of the target reservoir to avoid damage and leakage. In addition, through the distributed millisecond blasting between the main well and the multi-node and umbrella-shaped distributed branch wells around it, the fracture networks of the main well and the multi-node and umbrella-shaped distributed branch wells around it are connected and communicated, and a large-range fractured and permeability-enhanced area can be formed in the target reservoir, thereby further improving the porosity and permeability of the target reservoir. At the same time, through the ground pumping mechanism and combined with the underground fracturer, a chemical permeability enhancer is injected into the target reservoir to further transform the pore and fracture structures of the above-mentioned large-range fractured and permeability-enhanced area, and finally achieve large-scale permeability enhancement and transformation of the target reservoir around the main well, so that it finally meets the requirements of the next in-situ leaching mining, thereby further improving the recovery rate of the target reservoir, providing a new technological idea for the permeability enhancement and transformation of low-permeability sandstone uranium ore reservoirs, and enabling the full development of deep low-permeability sandstone uranium ore, which is currently a "dormant ore". BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0033] Figure 1 Schematic diagram of the first construction stage of the multi-node blasting and permeability enhancement device for low-permeability sandstone uranium ore shaft provided by the embodiment of the present application;

[0034] Figure 2 Schematic diagram of the second construction stage of the multi-node blasting and permeability enhancement device for low-permeability sandstone uranium ore shaft provided by the embodiment of the present application;

[0035] Figure 3 Schematic diagram of a branched well provided in an embodiment of the present application and distributed in an umbrella shape

[0036] Figure 4 Flow chart of the construction method of a multi-node blasting permeability increasing device for a low-permeability sandstone uranium mine vertical shaft provided in an embodiment of the present application

[0037] Icons: 1 - main shaft; 2 - branched well; 3 - drill bit; 4 - reamer; 5 - hydraulic motor; 6 - locator; 7 - filling pipe; 8 - flexible drill pipe; 9 - whipstock; 10 - chip baffle packer; 11 - downhole tester; 12 - perforator; 13 - gas detonator; 14 - shock absorber; 15 - detonation controller; 16 - injector; 17 - gas explosion packer; 18 - charge slot; 19 - pneumatic chamber; 20 - air compressor pump; 21 - grouting pump; 22 - mixing blender; 23 - mud pit; 24 - chemical injection pump; 25 - chemical agent storage tank; 26 - target reservoir; 27 - roof; 28 - floor; 29 - encapsulated explosive; 30 - buffer material; 31 - plugging material; 32 - backfill material Detailed implementation manners

[0038] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and shown in the accompanying drawings here can be arranged and designed in various different configurations

[0039] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application

[0040] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings

[0041] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is usually placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application

[0042] In addition, in this application, unless otherwise clearly specified and defined, the first feature being above or below the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but in contact through additional features therebetween. Moreover, the first feature being above, on top of, and over the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being below, beneath, and under the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0043] In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging vertically, but may be slightly inclined. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but may be slightly inclined.

[0044] In the description of this application, it should also be noted that, unless otherwise clearly specified and defined, the terms "arranged", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0045] Embodiment:

[0046] Please refer to Figure 1 and, in conjunction with reference to Figures 2 to 4, this application provides a multi-node blasting and permeability-increasing device for low-permeability sandstone uranium mine shafts, which mainly includes an intelligent flexible directional blasting drill, an oblique adjuster, an underground fracturer, and a ground pumping mechanism; among them, the intelligent flexible directional blasting drill is arranged in the main shaft 1 and is used to drill a plurality of branch shafts 2 that are distributed in an umbrella shape centered on the main shaft 1. The branch shafts 2 extend from the inner wall of the main shaft 1 to the target reservoir 26 around the main shaft 1; at the same time, the oblique adjuster is arranged in the main shaft 1 and is connected to the intelligent flexible directional blasting drill, and is used to guide the intelligent flexible directional blasting drill to change direction to drill the branch shafts 2 distributed in an umbrella shape; in addition, the underground fracturer is arranged in the main shaft 1 and lowered to the target reservoir 26, and is used to respectively perform perforation and gas explosion combined fracturing on the main shaft 1 and blasting fracturing on the branch shafts 2, so that the fracture networks of the main shaft 1 and the branch shafts 2 distributed in an umbrella shape are connected and communicated to form a fracturing and permeability-increasing area in the target reservoir 26; and, the ground pumping mechanism is respectively connected to the intelligent flexible directional blasting drill and the underground fracturer, and is used to pump additives into the branch shafts 2 and pump chemical permeability-increasing agents into the main shaft 1 respectively, so as to drill, plug, fill or perform blasting fracturing on the branch shafts 2 in the target reservoir 26, and perform blasting fracturing on the main shaft 1 in the target reservoir 26.

[0047] Furthermore, the intelligent flexible directional blasting drill comprises a drill bit 3, a reamer 4, a hydraulic motor 5, a positioner 6, a charging tube 7 and a flexible drill rod 8; wherein the drill bit 3, the reamer 4, the hydraulic motor 5, the positioner 6 and the charging tube 7 are sequentially arranged in the flexible drill rod 8 from bottom to top; the drill bit 3 comprises a PDC coring drill bit 3, and the borehole diameter is 75 or 91 mm, and the inside thereof is connected with the charging tube 7; the reamer 4 adopts the existing technology, and has the function of opening or retracting, and is used for The tight sandstone reservoir is expanded to increase the charge amount, and the expanded hole diameter is 216mm; at the same time, the grouting pump 21 in the surface pumping mechanism is connected to the hydraulic motor 5, and the drilling fluid is pumped into the hydraulic motor 5 through the mud pool 23 connected to the grouting pump 21; in addition, the hydraulic motor 5 is respectively connected to the drill bit 3 and the reamer 4 through the transmission shaft, which is used to drive the drill bit 3 to rotate and drill or drive the reamer 4 to expand the target reservoir 26, which uses the grouting pump 21 in the surface pumping mechanism. The pressure of the drilling fluid injected into the well drives the rotor thereon to rotate, thereby providing power for the transmission shaft. The hydraulic motor 5 adopts the existing technology, and its pressure drop is ≥4.0MPa, the working torque is ≥5000N·m, and the drilling speed range is 50-200rpm; and the positioner 6 is equipped with a gamma ray sensor and a gyro inclinometer, which is electrically connected to the drill bit 3. The positioner 6 is used to determine the position of the drill bit 3 in the formation according to the gamma radiation of the rock formation and the inclination angle of the drill bit 3, and to locate the position of the drill bit 3 in the formation. The accuracy is ±2.0%, and the existing technology can be used. Its specific structure and working principle are not described here. One end of the filling pipe 7 is connected to the pneumatic chamber 19 and the grouting pump 21 in the ground pumping mechanism through a valve and a connecting pipe, and the other end is connected to the core hole on the front of the drill bit 3. The pneumatic chamber 19 is used to pump drilling fluid into the filling pipe 7, and the grouting pump 21 is used to pump packaged explosives 29, buffer materials 30, plugging materials 31 and backfill materials 32 into the filling pipe 7. In addition, the flexible drill pipe 8 is formed by hingedly connecting multiple drill pipe short sections in sequence.

[0048] The oblique regulator includes an inclination elbow 9 and a chip stopper 10; wherein, the chip stopper 10 is arranged in the main well 1, and is used to separate the flexible drill pipe 8 from the lower section of the main well 1, so as to prevent the casing window and the drilling debris of the branch well 2 from affecting the use of the main well 1; the inclination elbow 9 is installed on the top of the chip stopper 10, and is sleeved on the flexible drill pipe 8, and is used to guide the flexible drill pipe 8 to change direction so as to realize the drilling of the branch well 2. There is a gyro inclinometer inside, and its installation angle is adjustable to realize different inclination angles and corresponding drilling trajectories of the branch well 2.

[0049] Therefore, through an intelligent flexible directional blasting drill, with the main well 1 as the center, several branched wells 2 with multiple nodes and an umbrella-shaped distribution are drilled from a certain depth around the main well 1. Then, in combination with the surface pump injection mechanism, through the technique of back-drilling and hole expansion for filling, explosive charges 29, buffer materials 30, plugging materials 31, backfill materials 32, etc. are loaded inside the branched wells 2 to form a large-scale multi-level charge structure layout with an umbrella-shaped distribution of multiple nodes in the target reservoir 26. Among them, the explosive charges 29 are used to provide blasting energy, the buffer materials 30 are used to reduce the impact of blasting on the roof 27 and the floor 28, the plugging materials 31 are used to plug the boreholes in the roof 27 to prevent the leakage of leachate, and the backfill materials 32 are used to fill other sections above the boreholes. By combining the use of downhole fracturing devices to perform perforation-gas explosion combined operations on the main well 1, the main well 1 is connected to the target reservoir 26 and a certain area around it is fractured, thereby greatly improving the porosity and permeability of the target reservoir 26, and further greatly increasing the recovery rate of the target reservoir 26.

[0050] In addition, the downhole fracturing device includes a downhole tester 11, a perforator 12, a gas exploder 13, a shock absorber 14, a detonation controller 15, an injector 16, and a gas explosion packer 17, which are connected in sequence from bottom to top; the downhole tester 11 is used to test the pressure, temperature, etc. inside the main well 1, its sampling frequency ≥500 kHz, the measurement relative error is ±1.0%, it can adopt the structure in the existing technology, and its specific structure and working principle will not be elaborated here; the perforator 12 is used to perforate the target reservoir 26, and the perforator 12 uses high-pressure gas to perforate through the casing and the cement sheath to connect the main well 1 and the surrounding target reservoir 26, its perforation aperture is 10 mm, it can adopt the structure in the existing technology, and its specific structure and working principle will not be elaborated here; the detonation controller 15 is electrically connected to the perforator 12 and the gas exploder 13 respectively, it is electronic, used to control the firing of the perforator 12 and the gas exploder 13, and can wirelessly detonate the explosive charges 29 inside the branched wells 2, it can adopt the structure in the existing technology, and its specific structure and working principle will not be elaborated here; the gas exploder 13 uses the heat generated by the firing tube to excite the high-energy gunpowder in the medicine chamber to deflagrate or the phase change of carbon dioxide, thereby generating high-pressure gas for gas explosion to fracture the reservoir around the main well 1, the peak gas explosion pressure ≥500 Mpa, the gas exploder 13 can adopt the structure in the existing technology, and its specific structure and working principle will not be elaborated here; the perforator 12 and the gas exploder 13 can be selectively installed in multiple groups for multiple perforation-gas explosion combined operations; the shock absorber 14 is mainly used to reduce the impact of the vibration caused by detonation on the equipment, it can adopt the structure in the existing technology, and its specific structure and working principle will not be elaborated here; the chemical agent storage tank 25 in the surface pump injection mechanism is connected to the injector 16 to pump chemical permeability enhancer into the injector 16; the gas explosion packer 17 is used to block the main well 1 to maintain a high gas explosion pressure below the main well 1 to increase the fracture range of the gas explosion on the target reservoir 26.

[0051] Through the distributed millisecond blasting between the main well 1 and the branch wells 2 with multiple nodes distributed in an umbrella shape around it, the fracture networks of the main well 1 and the branch wells 2 with multiple nodes distributed in an umbrella shape around it are connected and communicated, enabling the formation of a large-scale fracture and permeability enhancement area in the target reservoir 26, and further improving the porosity and permeability of the target reservoir 26.

[0052] Meanwhile, the surface pumping mechanism includes a charging tank 18, a pneumatic chamber 19, an air compressor pump 20, a grouting pump 21, a mixing and preparation device 22, a mud pit 23, a chemical injection pump 24, and a chemical agent storage tank 25; the charging tank 18 is connected to the top of the pneumatic chamber 19 through a valve for filling the pneumatic chamber 19 with encapsulated explosives 29; one end of the pneumatic chamber 19 is connected to the filling pipe 7 through a valve, and the other end is connected to the air compressor pump 20 through a valve. The air compressor pump 20 pushes the encapsulated explosives 29 in the pneumatic chamber 19 through compressed air to be transported into the branch well 2 through the filling pipe 7. The air compressor pump 20 provides compressed air power for the pneumatic chamber 19, and the pressure range at its gas inlet is 0.5 - 5 bar, which can be increased to a maximum of 20 MPa; one end of the grouting pump 21 is connected to the filling pipe 7 through a valve for pumping drilling fluid into the branch well 2 through the filling pipe 7, with a grouting pressure ≥ 20 MPa and a grouting displacement ≥ 100 L / min; the other end of the grouting pump 21 is respectively connected to the mixing and preparation device 22 and the mud pit 23 through valves. The mixing and preparation device 22 includes three chambers, which are respectively used for preparing buffer material 30, plugging material 31, and backfill material 32. Through the mixing and preparation device 22 and the grouting pump 21, the buffer material 30, plugging material 31, backfill material 32, etc. can be respectively transported into the branch well 2 through the filling pipe 7. The mud pit 23 is used for preparing mud as drilling fluid; the chemical injection pump 24 is sequentially connected to the chemical agent storage tank 25 and the injector 16 through valves for pumping chemical permeability enhancer into the main well 1 through the injector 16, with an injection pressure ≥ 20 MPa, a working temperature of -20 - 50 °C, and corrosion resistance. The chemical agent storage tank 25 is used for preparing and storing chemical permeability enhancer.

[0053] It injects chemical permeability enhancer into the target reservoir 26 through the surface pumping mechanism in combination with downhole fracturing devices, further transforming the pore and fracture structures of the above large-scale fracture and permeability enhancement area to finally meet the requirements of the next in-situ leaching mining, thereby further improving the recovery rate of the target reservoir 26.

[0054] In addition, this embodiment also provides a construction method for the multi-node blasting and permeability enhancement device of the low-permeability sandstone uranium mine shaft as described above, including the following steps:

[0055] S1, the wellhead preparation work is completed on the ground, the drilling rig enters the site, the derrick, overhead crane, turntable, winch, etc. are built, the mud pool 23 is excavated, the drilling fluid is prepared in it, the relevant pipelines of the surface pumping mechanism are installed, the water and electricity are turned on, and the installation of the multi-node blasting permeability enhancement device for the low-permeability sandstone uranium mine shaft is completed;

[0056] S2, lower the oblique regulator to the specified depth H S And fix it, open the chip blocking packer 10, adjust the installation angle of the deflecting elbow 9, including the full bending angle γ and the installation azimuth angle β, and calculate it according to the following formula:

[0057] ;

[0058] ;

[0059] Where: θ 1 is the initial vertex angle; θ 2 is the vertex angle of the lower point; Δα is the azimuth increment;

[0060] Intelligent flexible directional blasting drilling down the well, at a depth of H S The position is to open a window in the casing according to the angle guided by the deflecting elbow 9;

[0061] The grouting pump 21 is started to pump drilling fluid into the flexible drill pipe 8, and the hydraulic motor 5 is driven to drive the drill bit 3 to continue drilling to form a branch hole. At the same time, the drilled core is taken out by a rope coring tool. The relationship between the directional drilling trajectory and the footage is calculated as follows:

[0062] ;

[0063] ;

[0064] ;

[0065] Where: θ 1 is the initial vertex angle; θ 2 is the vertex angle of the lower point; α 1 is the initial azimuth; α 2 is the lower azimuth;

[0066] Let the top depth of the target tight sandstone reservoir roof 27 be H C , the top depth of the bottom plate 28 is H B ; Calculate the drilling trajectory according to the above formula and check the position of the drill bit 3 according to the measurement results of the gamma ray sensor while drilling. When Z=H C -H S When the drilling is completed, it indicates that the top plate 27 of the target reservoir 26 has been drilled, and the drilling trajectory needs to be adjusted to penetrate the top plate 27 and gradually vertically drill into the target reservoir 26; the drilling trajectory needs to satisfy ΔZ≤H B -HC Based on the measurement results of the gamma-ray sensor during drilling, the position of the drill bit 3 is checked to avoid invading the bottom plate 28 of the target reservoir 26. After this condition is met, the grouting pump 21 is shut down and drilling stops.

[0067] S3. In the three chambers of the mixing mixer 22 of the surface grouting mechanism, the buffer material 30, the plugging material 31, and the backfill material 32 are respectively prepared. The grouting pump 21 of the surface grouting mechanism is started, and the reamer 4 in the intelligent flexible directional blasting drill is opened. The intelligent flexible directional blasting drill is constructed with reaming while withdrawing the drill. A buffer material 30 with a thickness of 0.5 - 1 m (usually foam concrete or bentonite - sand - gravel mixture) is filled at the bottom of the branch well 2, and its reaming diameter is D L (150 / 170 mm), and the drill withdrawal speed is V D , then to avoid hole collapse, the pumping flow rate Q of the grouting pump 21 D needs to satisfy the following formula:

[0068] ;

[0069] After judging that the buffer material 30 is filled to the specified thickness according to the total grouting volume and the drill bit 3's retraction, the pumping of the buffer material 30 is stopped, and the grouting pump 21 is switched to pump drilling fluid while the intelligent flexible directional blasting drill continues to retract and ream. When retracting to the bottom of the roof 27 near the target reservoir 26, stop; shut down the grouting pump 21 and the reamer 4; load the encapsulated explosive 29 into the pneumatic chamber 19 in the surface grouting mechanism through the charging groove 18; start the air compressor pump 20 in the surface grouting mechanism, and fill the pneumatic chamber 19 with compressed air to push the encapsulated explosive 29 to be loaded into the branch well 2 through the filling pipe 7 in the intelligent flexible directional blasting drill. When loaded to the specified depth (about 1 m from the bottom of the roof 27 of the target reservoir 26), stop; start the grouting pump 21 again, and continue to pump the buffer material 30 into the branch well 2 until reaching the bottom of the roof 27 of the target reservoir 26 and then stop; continue to retract the drill and switch the grouting pump 21 to pump the plugging material 31 until the drill bit 3 in the intelligent flexible directional blasting drill retracts to the top of the roof 27 of the target reservoir 26; continue to retract the drill and switch the grouting pump 21 to pump the backfill material 32 (usually mud mixed with crushed stone) until the drill bit 3 retracts into the main well 1;

[0070] S4. Repeat the operations in steps S2 to S3, continue to drill other multiple branch wells 2 around the main well 1, and complete the loading of the encapsulated explosive 29, buffer material 30, plugging material 31, or backfill material 32 in each branch well 2 to form multiple branch wells 2 distributed in an umbrella shape in the target reservoir 26;

[0071] S5. Recover the intelligent flexible directional blasting drill and the inclined regulator, and clean them with liquid nitrogen to inactivate the remaining explosives. According to the relevant parameters of the target tight sandstone reservoir, including thickness, strength, and the strength of the casing, etc., design the assembly plan of the downhole fracturer in advance, complete the quantity and layout of the perforator 12 and the gas blaster 13 in the downhole fracturer, lower the downhole fracturer through the main well 1 to the designated depth in the target reservoir 26, pump drilling fluid into the main well 1 until the downhole fracturer is submerged, and open the gas blast packer 17 in the downhole fracturer to enhance the coupling effect of detonation, maintain the high detonation pressure in the well, and improve the detonation fracturing effect.

[0072] S6. Input the pre-designed distributed differential blasting plan (including blasting sequence and differential interval) of the main well 1 and the branch wells 2 with multiple nodes distributed in an umbrella shape around it into the detonation controller 15 in the form of instructions, activate the perforator 12 and the gas blaster 13 through wired communication, and activate the encapsulated explosives 29 of the branch wells 2 with multiple nodes distributed in an umbrella shape around it through wireless communication in the well, so as to realize the perforation-gas blast combined fracturing of the main well 1 and the blasting fracturing of the branch holes, connect and communicate the fracture networks of the main well 1 and the branch wells 2 with multiple nodes distributed in an umbrella shape around it, and form a large-scale fracture and permeability enhancement area in the target reservoir 26.

[0073] S7. Start: Pump the pre-prepared chemical permeability enhancer (oxalic acid, mud acid, acetic acid, hydrofluoric acid, etc.) stored in the chemical agent storage tank 25 into the injector 16 in the downhole fracturer, and enter the fracture and permeability enhancement area formed in step S6 to further improve the fracture and pore structure of the target reservoir 26 and enhance its permeability.

[0074] S8. Close the gas blast packer 17, recover the downhole fracturer, wash the main well 1, backflow the waste liquid in the well, lower a screen pipe in the well and install a filter, and carry out the next step of in-situ leaching mining.

[0075] In summary, the present application provides a multi-node blasting device for sandstone uranium ore, which can achieve large-scale permeability enhancement of low-permeability sandstone uranium ore reservoirs around the main shaft. The device and method use an intelligent flexible directional blasting drill to drill from a certain depth around the main well 1 to form several multi-node and umbrella-shaped distributed branch wells 2 centered on the main well 1. Then, combined with the surface pumping mechanism, through the technology of withdrawing the drill and expanding the hole for filling, explosive charges 29, buffer materials 30, plugging materials 31, backfill materials 32, etc. are loaded inside the branch wells 2 to form a multi-level charge structure layout with a large range of multi-node umbrella-shaped distribution in the target reservoir 26. Among them, the explosive charges 29 are used to provide blasting energy, the buffer materials 30 are used to reduce the impact of blasting on the roof 27 and the floor 28, the plugging materials 31 are used to plug the boreholes in the roof 27 to prevent the leakage of leaching solution, and the backfill materials 32 are used to fill other sections of the upper part of the borehole. By combining the use of downhole fracturing devices to perform perforation-gas explosion joint operations on the main well 1, and realizing different fracture pressure time histories through different numbers and assembly methods of the perforator 12 and the gas detonator 13, the main well 1 is connected to the target reservoir 26 and the surrounding area is fractured, thereby greatly improving the porosity and permeability of the target reservoir 26, and further greatly improving the recovery rate of the target reservoir 26. It can not only provide sufficient blasting energy for permeability enhancement and transformation of low-permeability sandstone uranium ore reservoirs, but also provide sufficient protection for the roof 27 and the floor 28 of the target reservoir 26 to avoid damage and leakage. In addition, through the distributed millisecond blasting between the main well 1 and the surrounding multi-node and umbrella-shaped distributed branch wells 2, the fracture networks of the main well 1 and the surrounding multi-node and umbrella-shaped distributed branch wells 2 are connected and communicated, enabling a large range of fractured and permeability-enhanced areas to be formed in the target reservoir 26, and further improving the porosity and permeability of the target reservoir 26. At the same time, through the surface pumping mechanism and combined with the downhole fracturing device, chemical permeability enhancer is injected into the target reservoir 26 to further transform the pore and fracture structures of the above-mentioned large range of fractured and permeability-enhanced areas, finally realizing large-scale permeability enhancement and transformation of the target reservoir 26 around the main well 1, making it finally meet the requirements of the next in-situ leaching mining, thereby further improving the recovery rate of the target reservoir 26, providing a new technological idea for the permeability enhancement and transformation of low-permeability sandstone uranium ore reservoirs, and enabling the deep low-permeability sandstone uranium ore, which is currently a "dormant ore", to be fully developed.

[0076] The foregoing is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A multi-node blasting permeability enhancement device for a low-permeability sandstone uranium mine shaft, characterized in that: It comprises an intelligent flexible directional blasting drill, an oblique regulator, a downhole fracturing device and a surface pumping mechanism; the intelligent flexible directional blasting drill is arranged in a main well, and is used to drill a plurality of branch wells distributed in an umbrella shape around the main well with the main well as the center, and the branch wells extend from the inner wall of the main well to the target reservoir around the main well; the oblique regulator is arranged in the main well and connected to the intelligent flexible directional blasting drill, and is used to guide the intelligent flexible directional blasting drill to change direction so as to drill the branch wells distributed in an umbrella shape; The downhole fracturing device is arranged in the main well and lowered into the target reservoir, and is used for performing perforation and gas explosion combined fracturing on the main well and blasting fracturing on the branch wells, so that the main well and the branch wells distributed in an umbrella shape are connected and communicated with each other, so as to form a fracturing and permeability enhancement zone in the target reservoir; the surface pumping mechanism is respectively connected with the intelligent flexible directional blasting drill and the downhole fracturing device, and is used for pumping additional materials into the branch wells and pumping chemical permeability enhancers into the main well, so as to drill, plug, fill or blast fracturing the branch wells in the target reservoir, and blast fracturing the main well in the target reservoir; the surface pumping mechanism includes a charging tank, a pneumatic chamber, an air compression pump, a grouting pump, a mixing mixer, a mud pool, a chemical injection pump and a chemical agent storage tank; the charging tank is connected to the top of the pneumatic chamber through a valve. part, used for filling packaged explosives into the pneumatic chamber; one end of the pneumatic chamber is connected to the intelligent flexible directional blasting drill through a valve, and the other end is connected to the air compression pump through a valve, the air compression pump pushes the packaged explosives in the pneumatic chamber through compressed air and transports them to the branch well via the intelligent flexible directional blasting drill; one end of the grouting pump is connected to the intelligent flexible directional blasting drill through a valve, used for pumping drilling fluid into the branch well through the intelligent flexible directional blasting drill; the other ends of the grouting pumps are respectively connected to the mixing mixer and the mud pool through valves; the chemical injection pump is connected to the chemical agent storage tank and the downhole fracturing device in sequence through a valve, used for pumping chemical permeability enhancers into the main well; the mixing mixer includes three chambers, and the three chambers are respectively used for preparing buffer materials, plugging materials, and backfill materials.

2. The multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 1 is characterized in that: The intelligent flexible directional blasting drill includes a drill bit, a reamer, a hydraulic motor, a positioner, a charging tube and a flexible drill pipe; the drill bit, the reamer, the hydraulic motor, the positioner and the charging tube are arranged in the flexible drill pipe from bottom to top in sequence; the surface pumping mechanism is connected to the hydraulic motor for pumping drilling fluid into the hydraulic motor; the hydraulic motor is respectively connected to the drill bit and the reamer for driving the drill bit to rotate and drill or to drive the reamer to reame the target reservoir; the positioner is electrically connected to the drill bit for determining the position of the drill bit in the formation; the two ends of the charging tube are respectively connected to the surface pumping mechanism and the drill bit, and the surface pumping mechanism is used to pump additional materials into the charging tube and send them into the branch well.

3. The multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 2 is characterized in that: The drill bit comprises a PDC coring drill bit, and the borehole diameter is 75 mm or 91 mm.

4. The multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 2, characterized in that: The locator is equipped with a gamma ray sensor and a gyro inclinometer, the gyro inclinometer is electrically connected to the drill bit, and the locator is used to determine the position of the drill bit in the formation according to the gamma radiation of the rock formation and the inclination angle of the drill bit respectively.

5. The multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 2, characterized in that: The additive materials include drilling fluid, packaged explosives, buffer materials, plugging materials and backfill materials.

6. The multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 2, characterized in that: The flexible drill rod is formed by hingedly connecting a plurality of drill rod short sections in sequence.

7. The multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 1, characterized in that: The oblique adjuster includes an oblique elbow and a chip stopper; the chip stopper is arranged in the main well to separate the intelligent flexible directional blasting drill from the lower section of the main well; the oblique elbow is installed on the top of the chip stopper and is sleeved on the intelligent flexible directional blasting drill to guide the intelligent flexible directional blasting drill to change direction.

8. The multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 1, characterized in that: The downhole fracturing device includes a downhole tester, a perforator, a gas blaster, a shock absorber, a detonation controller, an injector and a gas explosion packer which are connected in sequence from bottom to top; the downhole tester is used to test the pressure and temperature in the main well; the perforator is used to perforate the target reservoir; the detonation controller is electrically connected to the perforator and the gas blaster respectively, and is used to control the excitation of the perforator and the gas blaster; the surface pumping mechanism is connected to the injector, and is used to pump a chemical permeability enhancer into the injector; the gas explosion packer is used to plug the main well.

9. A construction method for a multi-node blasting permeability enhancement device for a low-permeability sandstone uranium mine shaft according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, installing the multi-node blasting permeability enhancement device for the low-permeability sandstone uranium mine shaft; S2, drilling by the intelligent flexible directional blasting drill to form the branch well extending from the inner wall of the main well to the target reservoir around the main well; S3, performing drill backing and hole expansion construction by using the intelligent flexible directional blasting drill, and filling the branch well with packaged explosives, buffer materials, plugging materials or backfill materials according to the design plan; S4, repeating the operations in step S2 to step S3, continuing to drill the other multiple branch wells around the main well, and completing the filling of packaged explosives, buffer materials, plugging materials or backfill materials in each branch well, so as to form a plurality of branch wells distributed in an umbrella shape in the target reservoir; S5, recovering the intelligent flexible directional blasting drill and the oblique regulator, completing the assembly of the perforator and the gas blaster in the downhole fracturing device according to the design plan, lowering the downhole fracturing device through the main well to a designated depth in the target reservoir, pumping drilling fluid into the main well until the downhole fracturing device is submerged, and opening the gas blasting packer in the downhole fracturing device; S6, setting the micro-difference t of the detonation controller in each branch well as the time difference between different branch wells, starting the joint micro-difference blasting of the main well and the branch wells, and performing joint blasting in the main well by the perforator and the gas blaster, and performing blasting in the branch wells by packaged explosives; S7, pumping a chemical permeability enhancer into an injector in the downhole fracturing device through the surface pumping mechanism; S8, finishing work of the main well is carried out, and the next step of in situ leaching is carried out.

10. The construction method of the multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 9, characterized in that: In step S3, the drilling back and hole expansion construction includes the following steps: Prepare buffer material, plugging material and backfill material in three chambers of the mixing mixer of the surface pumping mechanism respectively, start the grouting pump of the surface pumping mechanism, open the reamer in the intelligent flexible directional blasting drill, perform drilling and hole reaming construction while withdrawing the intelligent flexible directional blasting drill, and fill the bottom of the branch well with 0.5-1m thick buffer material; After the buffer material is filled to a specified thickness according to the total amount of pumping and the drill bit withdrawal, the pumping of the buffer material is stopped, and the grouting pump is switched to pumping drilling fluid while the intelligent flexible directional blasting drill continues to withdraw the drill and expand the hole. When the drill is withdrawn to the bottom of the top plate close to the target reservoir, it is stopped; the grouting pump and the reamer are turned off; the packaged explosive is loaded into the pneumatic chamber of the surface pumping mechanism through the charging slot in the surface pumping mechanism; the air compression pump in the surface pumping mechanism is started to fill the pneumatic chamber with compressed air. The gas is used to push the packaged explosive through the filling pipe in the intelligent flexible directional blasting drill to be loaded into the branch well, and the filling is stopped when the specified depth is reached; the grouting pump is started again, and the buffer material is continued to be pumped into the branch well and stopped when it reaches the bottom of the roof of the target reservoir; the drill is continued to be withdrawn and the grouting pump is switched to pump the plugging material until the drill bit in the intelligent flexible directional blasting drill is withdrawn to the top of the roof of the target reservoir; the drill is continued to be withdrawn and the grouting pump is switched to pump backfill material until the drill bit is withdrawn to the main well.

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