Low-permeability sandstone uranium mine vertical shaft multi-node blasting permeability increasing device and construction method thereof

Abstract

The invention provides a low-permeability sandstone uranium mine vertical shaft multi-node blasting permeation increasing device and a construction method thereof. An intelligent flexible directional blasting drill is arranged in a main shaft and used for drilling a plurality of branch wells which are distributed in an umbrella shape with the main shaft as the center; the slant adjustor is arranged in the main shaft and connected with the intelligent flexible directional blasting drill; the underground fracturing device is arranged in the main well, is lowered into a target reservoir and is used for performing perforation gas explosion combined fracturing on the main well and performing blasting fracturing on the branch wells; and the ground pumping and injecting mechanism is connected with the intelligent flexible directional blasting drill and the underground fracturing device and is used for pumping and injecting an additive material into the multilateral well and pumping a chemical permeation enhancing agent into the main well, so that the multilateral well in the target reservoir is drilled, plugged, filled or subjected to blasting fracturing, and the main well in the target reservoir is subjected to blasting fracturing. According to the device and the method, the porosity and the permeability of the low-permeability sandstone uranium mine reservoir around the main shaft can be improved in a large range, so that the mining rate of the uranium mine is improved.

Description

Technical Field

[0001] The present application relates to the field of deep vertical shaft blasting to increase permeability for uranium mining, and in particular to a low-permeability sandstone uranium mine vertical shaft multi-node blasting to increase permeability device and a construction method thereof. Background Art

[0002] Uranium ore is an important raw material for the nuclear industry. It usually comes from open-pit mining, underground mining, in-situ leaching of uranium in uranium-bearing strata, as well as precipitation and adsorption of uranium compounds in the marine environment. my country's onshore sandstone uranium 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 mines with low porosity and poor permeability account for more than 70% of my country's sandstone uranium resources. This results in a small in-situ leaching fluid capacity in the reservoir, few direct interfaces between the in-situ leaching fluid and the sandstone, long reaction time, and low injection-production rate, which greatly limits the mining efficiency of uranium mines, and even makes them impossible to mine due to high costs. Therefore, it is necessary to carry out permeability enhancement transformation of low-permeability sandstone uranium reservoirs to improve their porosity and permeability, and provide guarantees for in-situ leaching of uranium resources.

[0003] At present, the means of permeability enhancement and transformation of low-permeability sandstone uranium reservoirs are mainly divided into two categories: physical and chemical. Among them, the effect of chemical permeability enhancement on the reservoir depends on the seepage channel, and it is usually used as a supplement to physical means. Physical means include hydraulic fracturing, ultrasound, 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 cracks as the gathering channels of oil and gas; the long cracks will make it difficult for the in-situ leaching fluid to fully contact the sandstone reservoir, and the dominant channel will flow out, resulting in extremely insufficient in-situ leaching. The overall energy of ultrasound is relatively small, and it has a certain effect on soft sandstone uranium ores with a high mud content, but the effect on hard low-permeability sandstone uranium ores is difficult to guarantee.

[0004] The existing method of blasting to increase the permeability of low-permeability sandstone uranium deposits is mainly to carry out blasting without an open face in a vertical shaft, and use the impact of the cylindrical stress wave generated by the explosion in the well on the reservoir around the well to fracture and increase the permeability of the low-permeability sandstone. However, due to the characteristic that the cylindrical wave attenuates with the propagation distance, the range of the crushing zone and the fracture zone generated by the blasting is limited. Therefore, in order to achieve a large-scale permeability increase in the reservoir, a large number of vertical shafts are required, and the well spacing is controlled at 20-30m to ensure that the fracture and permeability increase ranges of each well can be connected and communicated. For shallow (depth ≤500m) sandstone uranium mines, the cost can still be controlled, but for deep (depth ≥800m) sandstone uranium mines, the cost is greatly increased, which is not conducive to economic mining. When multiple horizontal wells are extended in the main well to expand the mining range in oil and gas reservoir mining, the blasting will damage the top and bottom plates of the reservoir and cause leakage of in-situ leaching fluid and process failure.

[0005] Therefore, the technical problems in this field are mainly manifested in: ① The uniformity of the main well blasting fracturing method is poor, which cannot achieve a large-scale permeability enhancement effect; ② The engineering cost of developing multiple wells separately is too high; ③ Conventional horizontal well technology is prone to damage to the bottom plate and top plate, affecting in-situ leaching development. Therefore, it is necessary to develop a multi-node blasting permeability enhancement device in a vertical shaft and its construction method. Summary of the invention

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

[0007] The technical solution of this application is:

[0008] A multi-node blasting permeability enhancement device for a low-permeability sandstone uranium mine shaft, comprising 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 on the main well, and the branch wells are connected to the main well, and the downhole fracturing device is arranged on the main well. The intelligent flexible directional blasting drill and the downhole fracturing device are connected to the well and lowered into the target reservoir for performing perforation and gas explosion combined fracturing on the main well and blasting fracturing on the branch wells, so as to connect and communicate the fracture network of the main well and the branch wells distributed in an umbrella shape, so as to form a fracturing and permeability enhancement zone in the target reservoir; the surface pumping mechanism is connected to the intelligent flexible directional blasting drill and the downhole fracturing device, respectively, 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.

[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 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 ground 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 ground pumping mechanism and the drill bit, and the ground pumping mechanism is used to pump additional materials into the charging tube and send them into the branch well.

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

[0011] As a technical solution of the present application, a gamma ray sensor and a gyro inclinometer are installed in the locator, and the gyro inclinometer is electrically connected to the drill bit. The locator is used to determine the position of the drill bit in the formation based on 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, packaged explosives, buffer materials, plugging materials and backfill materials.

[0013] As a technical solution of the present application, the flexible drill rod is formed by hingedly connecting a plurality of drill rod short sections in sequence.

[0014] As a technical solution of the present application, 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.

[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, an injector and a gas explosion packer 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, for controlling the excitation of the perforator and the gas blaster; the surface pumping mechanism is connected to the injector, for pumping a chemical permeability enhancer into the injector; the gas explosion packer is used to plug 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 compression pump, a grouting pump, a mixing device, 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, and is used to fill the pneumatic chamber with packaged 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 compression pump through a valve, and the air compression pump drives the pneumatic chamber to move the pneumatic chamber through compressed air. The packaged explosive in the dynamic chamber is transported 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, and is used to pump drilling fluid into the branch well through the intelligent flexible directional blasting drill; the other ends of the grouting pump 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, and is used to pump chemical permeability enhancers into the main well.

[0017] As a technical solution of the present application, the mixing and preparing device includes three chambers, and the three chambers are used to prepare buffer materials, plugging materials, and backfill materials respectively.

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

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

[0020] 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;

[0021] 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;

[0022] 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;

[0023] 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;

[0024] 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;

[0025] S7, pumping a chemical permeability enhancer into an injector in the downhole fracturing device through the surface pumping mechanism;

[0026] S8, finishing work of the main well is carried out, and the next step of in situ leaching is carried out.

[0027] As a technical solution of the present application, in step S3, the drilling back and hole expansion construction includes the following steps:

[0028] Prepare buffer material, plugging material and backfill material in three chambers of the 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, and use the intelligent flexible directional blasting drill to perform drilling and hole expansion construction, and fill the bottom of the branch well with 0.5-1m thick buffer material;

[0029] 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.

[0030] Beneficial effects of this application:

[0031] The present application provides a multi-node blasting device for sandstone uranium mines, which can realize large-scale permeability enhancement of low-permeability sandstone uranium reservoirs around the main shaft; the device and method use an intelligent flexible directional blasting drill, with the main shaft as the center, to drill from a certain depth to the periphery of the main shaft to form a number of multi-node branch wells with umbrella-shaped distribution, and then combine with a ground pumping mechanism, through the drill withdrawal and hole expansion filling technology, fill the branch wells with packaged explosives, buffer materials, plugging materials, backfill materials, etc., so as to form a multi-node umbrella-shaped distribution in the target reservoir. The multi-level charge structure arrangement with a large range, wherein the packaged explosive is used to provide blasting energy , the buffer material is used to reduce the effect of blasting on the roof and floor, the plugging material is used to plug the boreholes in the roof to prevent the leakage of leachate, and the backfill material is used to fill other sections above the borehole. The main well is combined with the use of downhole fracturing devices to implement perforation-gas explosion joint operation, connect the main well with the target reservoir and fracture a certain area around it, so that the porosity and permeability of the target reservoir can be greatly improved, thereby greatly improving the mining rate of the target reservoir. It can not only provide sufficient blasting energy to increase the permeability of the low-permeability sandstone uranium reservoir, but also provide sufficient protection for the roof and floor of the target reservoir to avoid damage and leakage. In addition, it connects and communicates the main well and the surrounding multi-node and umbrella-shaped branch wells through distributed micro-difference blasting between the main well and the surrounding multi-node and umbrella-shaped branch wells, which can form a large range of fracture and permeability areas in the target reservoir, thereby further improving the porosity and permeability of the target reservoir. At the same time, it injects chemical permeability enhancers into the target reservoir through the surface pumping mechanism combined with the downhole fracturing device, and further transforms the pore and fracture structure of the above-mentioned large-scale fracturing and permeability enhancement area, and finally realizes the large-scale permeability enhancement transformation of the target reservoir around the main well, so that it can finally meet the requirements of the next step of in situ leaching mining, thereby further improving the mining rate of the target reservoir, and providing a new process idea for the permeability enhancement transformation of low-permeability sandstone uranium reservoirs, so that the deep low-permeability sandstone uranium mines that are currently "dead mines" can be fully developed. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the implementation methods of the present application, the drawings required for use in the implementation methods will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 A schematic diagram of the first construction stage of a multi-node blasting permeability enhancement device for a low-permeability sandstone uranium mine shaft provided in an embodiment of the present application;

[0034] Figure 2 A schematic diagram of the second construction phase of a multi-node blasting permeability enhancement device for a low-permeability sandstone uranium mine shaft provided in an embodiment of the present application;

[0035] Figure 3 A schematic diagram of branch wells distributed in an umbrella shape provided in an embodiment of the present application;

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

[0037] Icons: 1-main well; 2-branch well; 3-drill bit; 4-reamer; 5-hydraulic motor; 6-positioner; 7-charging pipe; 8-flexible drill pipe; 9-inclined elbow; 10-chip stopper; 11-downhole tester; 12-perforator; 13-gas blaster; 14-shock absorber; 15-detonation controller; 16-injector; 17-gas blaster; 18-charging tank; 19-pneumatic chamber; 20-air compression pump; 21-grouting pump; 22-mixing mixer; 23-mud pool; 24-chemical injection pump; 25-chemical agent storage tank; 26-target reservoir; 27-top plate; 28-bottom plate; 29-encapsulated explosives; 30-buffer material; 31-plugging material; 32-backfill material. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. The components of the embodiments of the present application described and shown in the 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 for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are 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, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0041] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is usually placed when in use. These are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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 understood as a limitation on the present application.

[0042] In addition, in the present application, unless otherwise clearly specified and limited, 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 being in contact through another feature between them. Moreover, the first feature being above, above, and above the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being below, below, and below the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0043] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0044] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0045] Example:

[0046] Please refer to Figure 1 , with reference Figures 2 to 4The present application provides a multi-node blasting permeability enhancement device for a low-permeability sandstone uranium mine shaft, which mainly includes an intelligent flexible directional blasting drill, an oblique regulator, a downhole fracturing device and a surface pumping mechanism; wherein the intelligent flexible directional blasting drill is arranged in a main well 1, and is used to drill a plurality of branch wells 2 distributed in an umbrella shape around the main well 1 with the main well 1 as the center, and the branch wells 2 extend from the inner wall of the main well 1 to the target reservoir 26 around the main well 1; at the same time, the oblique regulator is arranged in the main well 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 so as to drill the branch wells 2 distributed in an umbrella shape; in addition, the downhole fracturing device The fracturing device is arranged in the main well 1 and lowered into the target reservoir 26, and is used for performing perforation and gas explosion combined fracturing on the main well 1 and blasting fracturing on the branch well 2, so as to connect and communicate the fracture network of the main well 1 and the branch well 2 distributed in an umbrella shape, so as to form a fracturing and permeability enhancement zone in the target reservoir 26; and the ground pumping mechanism is respectively connected to the intelligent flexible directional blasting drill and the downhole fracturing device, and is used for pumping additive materials into the branch well 2 and pumping chemical permeability enhancers into the main well 1, so as to drill, plug, fill or blast fracturing the branch well 2 in the target reservoir 26, and blast fracturing the main well 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, it uses intelligent flexible directional blasting drilling, with the main well 1 as the center, to drill from a certain depth to the periphery of the main well 1 to form a number of multi-node and umbrella-shaped branch wells 2, and then combines the surface pumping mechanism, through the drill back expansion filling technology, the branch well 2 is filled with packaged explosives 29, buffer materials 30, plugging materials 31, backfill materials 32, etc., to form a multi-node umbrella-shaped distribution in the target reservoir 26. Large-scale multi-level charging structure arrangement, wherein the packaged explosives 29 are used to provide Explosion energy, buffer material 30 is used to reduce the effect of blasting on the roof 27 and the bottom plate 28, plugging material 31 is used to plug the borehole of the roof 27 to prevent leakage of leachate, backfill material 32 is used to fill other sections above the borehole, and the main well 1 is perforated and gas exploded in combination with the downhole fracturing device to connect the main well 1 with the target reservoir 26 and fracture a certain area around it, thereby greatly improving the porosity and permeability of the target reservoir 26, thereby greatly improving 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 blaster 13, a shock absorber 14, a detonation controller 15, an injector 16 and a gas explosion packer 17 connected in sequence from bottom to top; the downhole tester 11 is used to test the pressure and temperature in the main well 1, and its sampling frequency is ≥500kHz, and the relative measurement error is ±1.0%. It can adopt the structure in the prior art, and its specific structure and working principle are not repeated here; the perforator 12 is used to measure the target reservoir 26 is perforated, and the perforator 12 uses high-pressure gas to perforate the casing and cementing cement to communicate the main well 1 with the surrounding target reservoir 26. The perforation aperture is 10 mm, and it can adopt the structure in the prior art. Its specific structure and working principle are not repeated here; the detonation controller 15 is electrically connected to the perforator 12 and the gas detonator 13 respectively. It is electronic and is used to control the excitation of the perforator 12 and the gas detonator 13, and can wirelessly detonate the packaged explosive 29 in the branch well 2. The structure in the prior art can be adopted, and its specific structure and working principle are not described in detail here; the gas blaster 13 uses the heat generated by the excitation tube to excite the high-energy gunpowder in the agent chamber to deflagrate or phase change of carbon dioxide, thereby generating a high-pressure gas explosion to fracture the reservoir around the main well 1, and the peak pressure of the gas explosion is ≥500Mpa. The gas blaster 13 can adopt the structure in the prior art, and its specific structure and working principle are not described in detail here; the perforator 12 and the gas blaster 13 can be installed in multiple groups to achieve multi-perforation-gas explosion combined operation; the shock absorber 14 is mainly used to reduce the impact of the vibration caused by detonation on the equipment, and it can adopt the structure in the prior art, and its specific structure and working principle are not described in detail here; the chemical agent storage tank 25 in the ground pumping mechanism is connected to the injector 16, which is used to pump chemical permeability enhancers into the injector 16; the gas explosion packer 17 is used to block the main well 1 to maintain the high gas explosion pressure under the main well 1 to increase the fracturing range of the gas explosion on the target reservoir 26.

[0051] Through distributed micro-difference blasting between the main well 1 and the surrounding branch wells 2 with multiple nodes and umbrella-shaped distribution, the fracture network of the main well 1 and the surrounding branch wells 2 with multiple nodes and umbrella-shaped distribution are connected and communicated, which can form a larger range of fracturing and permeability enhancement area in the target reservoir 26, thereby further improving the porosity and permeability of the target reservoir 26.

[0052] At the same time, the ground pumping mechanism includes a charging tank 18, a pneumatic chamber 19, an air compression pump 20, a grouting pump 21, a mixing device 22, a mud pool 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, and is used to fill the pneumatic chamber 19 with packaged 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 compression pump 20 through a valve, the air compression pump 20 pushes the packaged explosives 29 in the pneumatic chamber 19 through the filling pipe 7 to be transported to the branch well 2 through the compressed air, and the air compression pump 20 provides compressed air power for the pneumatic chamber 19, and the pressure range of its gas input port is 0.5~5bar, which can be increased to 20MPa at most; one end of the grouting pump 21 is connected to the filling pipe 7 through a valve, and is used to fill the pneumatic chamber 19 with packaged explosives 29 through the filling pipe 7. The pipe 7 is installed to pump drilling fluid into the branch well 2, and the grouting pressure is ≥20MPa and the grouting displacement is ≥100L / min; the other end of the grouting pump 21 is connected to the mixing mixer 22 and the mud pool 23 through valves. The mixing mixer 22 includes three chambers, which are used to prepare buffer materials 30, plugging materials 31, and backfill materials 32 respectively. The buffer materials 30, plugging materials 31, backfill materials 32, etc. can be transported into the branch well 2 through the filling pipe 7 through the mixing mixer 22 and the grouting pump 21. The mud pool 23 is used to prepare mud as drilling fluid; the chemical injection pump 24 is connected to the chemical agent storage tank 25 and the injector 16 in sequence through a valve, and is used to pump chemical permeability enhancers into the main well 1 through the injector 16, and its injection pressure is ≥20MPa, the working temperature is -20 to 50°C, and it is corrosion-resistant. The chemical agent storage tank 25 is used for preparing and storing chemical penetration enhancers.

[0053] It injects chemical permeability enhancers into the target reservoir 26 through a surface pumping mechanism in combination with a downhole fracturing device, further transforms the pore and fracture structure of the above-mentioned large-scale fracturing and permeability enhancement area, so that it ultimately meets the requirements of the next step of in situ leaching, thereby further improving the recovery rate of the target reservoir 26.

[0054] In addition, this embodiment also provides a construction method of the multi-node blasting permeability enhancement device for a low-permeability sandstone uranium mine shaft as above, comprising 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] γ=cos -1 (cosθ1cosθ2+sinθ1sinθ2sinΔα);

[0058] βγ=cos -1 [(cosθ1cosΔα-sinθ1cotθ2) / sinΔα];

[0059] Where: θ1 is the initial vertex angle; θ2 is the vertex angle of the lower point; Δα is the azimuth angle 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] X=ΔLsin[(θ1+θ2) / 2]cos[(α1+α2) / 2];

[0063] Y=ΔLsin[(θ1+θ2) / 2]sin[(α1+α2) / 2];

[0064] Z = ΔLcos[(θ1+θ2) / 2];

[0065] Where: θ1 is the initial vertex angle; θ2 is the lower vertex angle; α1 is the initial azimuth angle; α2 is the lower azimuth angle;

[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 SWhen 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 -H C The position of the drill bit 3 is checked according to the measurement while drilling results of the gamma ray sensor to avoid intrusion into the bottom plate 28 of the target reservoir 26. When this condition is met, the grouting pump 21 is turned off and drilling is stopped;

[0067] S3, respectively prepare the buffer material 30, the plugging material 31, and the backfill material 32 in the three chambers of the mixing mixer of the surface pumping mechanism, start the grouting pump 21 of the surface pumping mechanism, open the reamer 4 in the intelligent flexible directional blasting drill, and use the intelligent flexible directional blasting drill to drill back and expand the hole at the same time, and fill the bottom of the branch well 2 with a buffer material 30 (generally foam concrete or bentonite-sand-gravel mixed material) with a thickness of 0.5-1m, and the expanded hole diameter is D L (150 / 170mm), drill retraction speed is V D In order to avoid hole collapse, the injection flow rate Q of the grouting pump 21 is D The following formula must be satisfied:

[0068]

[0069] After the buffer material 30 is filled to a specified thickness according to the total amount of pumping and the drill bit 3 retraction, the pumping of the buffer material 30 is stopped, and the grouting pump 21 is switched to pumping drilling fluid while the intelligent flexible directional blasting drill continues to perform the drilling and hole expansion construction. When the drilling is withdrawn to the bottom of the top plate 27 close to the target reservoir 26, it is stopped; the grouting pump 21 and the reamer 4 are turned off; the packaged explosive 29 is loaded into the pneumatic chamber 19 in the surface pumping mechanism through the charging slot 18; the air compression pump 20 in the surface pumping mechanism is started to fill the pneumatic chamber 19 with compressed air to push the packaged explosive 29 through the intelligent flexible directional blasting. The filling pipe 7 in the drilling is loaded into the branch well 2, and stops when the loading reaches the specified depth (about 1m from the bottom of the top plate 27 of the target reservoir 26); the grouting pump 21 is started again, and the buffer material 30 is continuously pumped into the branch well 2 to the bottom of the top plate 27 of the target reservoir 26, and stops; the drilling is continued to be withdrawn and the grouting pump 21 is switched to pumping the plugging material 31, until the drill bit 3 in the intelligent flexible directional blasting drill is withdrawn to the top of the top plate 27 of the target reservoir 26; the drilling is continued to be withdrawn and the grouting pump 21 is switched to pumping the backfill material 32 (generally mud mixed with crushed stone slag), until the drill bit 3 is withdrawn to the main well 1;

[0070] S4, repeating the operations from step S2 to step S3, continuing to drill multiple other branch wells 2 around the main well 1, and completing the loading of packaged explosives 29, buffer materials 30, plugging materials 31 or backfill materials 32 in each branch well 2, so as 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 oblique regulator, and use liquid nitrogen to clean them to inactivate the remaining explosives therein; design the assembly plan of the downhole fracturing device in advance according to the relevant parameters of the target tight sandstone reservoir including thickness and strength and the strength of the casing, complete the number and arrangement of the perforators 12 and the gas blasters 13 in the downhole fracturing device, lower the downhole fracturing device through the main well 1 to the specified depth in the target reservoir 26, pump drilling fluid into the main well 1 to submerge the downhole fracturing device, and open the gas explosion packer 17 in the downhole fracturing device to enhance the coupling effect of detonation, maintain the high detonation pressure in the well, and improve the detonation and fracturing effect;

[0072] S6, input the pre-designed distributed micro-difference blasting scheme (including blasting sequence and micro-difference interval) of the main well 1 and the branch wells 2 with multiple nodes distributed in an umbrella shape to the detonation controller 15 in the form of instructions, stimulate the perforator 12 and the gas blaster 13 by wired communication, and stimulate the packaged explosives 29 of the branch wells 2 with multiple nodes distributed in an umbrella shape in the form of downhole wireless communication, so as to realize the perforation-gas explosion joint fracturing of the main well 1 and the blasting fracturing of the branch wells, connect and communicate the fracture network of the main well 1 and the branch wells 2 with multiple nodes distributed in an umbrella shape, and form a larger range of fracturing and permeability enhancement area in the target reservoir 26;

[0073] S7, start: pump the pre-configured 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 fracturing device, and enter the fracturing and permeability enhancement area formed in step S6, so as to further improve the fracture and pore structure of the target reservoir 26 and enhance its permeability;

[0074] S8, close the gas explosion packer 17, recover the downhole fracturing device, wash the main well 1, return the waste liquid in the well, put a screen pipe in the well and install a filter, and carry out the next step of in situ leaching.

[0075] In summary, the present application provides a multi-node blasting device for sandstone uranium mines, which can achieve large-scale permeability enhancement of low-permeability sandstone uranium reservoirs around the main shaft. The device and method use an intelligent flexible directional blasting drill, with the main shaft 1 as the center, to drill from a certain depth around the main shaft 1 to form a number of multi-node and umbrella-shaped branch wells 2, and then combine with a ground pumping mechanism, through the drill withdrawal and hole expansion filling technology, to load packaged explosives 29, buffer materials 30, plugging materials 31, backfill materials 32, etc. inside the branch wells 2, so as to form a multi-node umbrella-shaped distribution in the target reservoir 26. The multi-level charge structure arrangement with a large range, wherein the packaged explosive 29 is used to provide blasting energy, the buffer material 30 is used to reduce the effect of blasting on the top plate 27 and the bottom plate 28, and the plugging material 31 is used to plug the drilling holes of the top plate 27 to avoid To prevent leakage of leachate, the backfill material 32 is used to fill other sections of the upper part of the borehole, and the main well 1 is perforated and gas-exploded in combination with the downhole fracturing device. Different numbers and assembly methods of the perforators 12 and gas blasters 13 are used to achieve different fracturing pressure time courses, so that the main well 1 is connected with the target reservoir 26 and a certain area around it is fractured, thereby greatly improving the porosity and permeability of the target reservoir 26, thereby greatly improving the mining rate of the target reservoir 26, which can provide sufficient blasting energy to increase the permeability of the low-permeability sandstone uranium reservoir, and provide sufficient protection for the top plate 27 and the bottom plate 28 of the target reservoir 26 to avoid damage and leakage. In addition, through the distributed micro-difference blasting between the main well 1 and the surrounding multi-node and umbrella-shaped branch wells 2, the main well 1 and the surrounding multi-node and umbrella-shaped branch wells 2 are connected and communicated, which can form a large-scale fracture and permeability area in the target reservoir 26, thereby further improving the porosity and permeability of the target reservoir 26. At the same time, it injects chemical permeability enhancers into the target reservoir 26 through the surface pumping mechanism and the downhole fracturing device, and further transforms the pore and fracture structure of the above-mentioned large-scale fracture and permeability area, and finally realizes the large-scale permeability transformation of the target reservoir 26 around the main well 1, so that it finally meets the requirements of the next step of in-situ leaching mining, thereby further improving the mining rate of the target reservoir 26, and providing a new process idea for the permeability transformation of low-permeability sandstone uranium reservoirs, so that the deep low-permeability sandstone uranium mines that have become "dead mines" can be fully developed.

[0076] The above description is only the 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 modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in 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 to perform 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 to the intelligent flexible directional blasting drill and the downhole fracturing device, and is used to pump additive materials into the branch wells and pump chemical permeability enhancers into the main well, so as to drill, plug, fill or blast fracturing the branch wells in the target reservoir, and perform blasting fracturing on the main well in the target reservoir.

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 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. The multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 1, characterized in that: The surface pumping mechanism includes a charging tank, a pneumatic chamber, an air compression pump, a grouting pump, a mixing and preparing device, 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, and is used to fill the pneumatic chamber with packaged 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 compression pump through a valve, and the air compression pump pushes the packaged explosives in the pneumatic chamber through the intelligent flexible directional blasting drill to be transported to the branch well through the intelligent flexible directional blasting drill by compressed air; one end of the grouting pump is connected to the intelligent flexible directional blasting drill through a valve, and is used to pump 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 and preparing device 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, and is used to pump chemical permeability enhancers into the main well.

10. The multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine shaft according to claim 9, characterized in that: The mixing and preparing device comprises three chambers, and the three chambers are used for preparing buffer material, plugging material and backfill material respectively.

11. 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 10, 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.

12. The construction method of the multi-node blasting permeability enhancement device for low-permeability sandstone uranium mine vertical shaft according to claim 11, 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 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, and use the intelligent flexible directional blasting drill to perform drilling and hole expansion construction, 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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