Physical permeability increasing device and method for improving permeability of sandstone type uranium ore layer

Abstract

The invention discloses a physical permeation increasing device and method for improving the permeability of a sandstone type uranium ore layer, relates to the technical field of in-situ leaching uranium mining, and aims to solve the problems that in the sandstone type uranium ore layer process, due to the fact that the permeability of an ore layer is poor, the drilling hole liquid pumping and injecting amount is affected, and the productivity is seriously affected in the existing mining technology. The device comprises a cavitation pipe column inserted into a casing pipe, the cavitation pipe column comprises an oil pipe arranged in the casing pipe, a filter is arranged on the lower portion of the cavitation pipe column, a cavitator is arranged at the bottom of the cavitation pipe column, the top of the cavitation pipe column is connected with the bottom of a Christmas tree, and water return pipelines are connected to the two sides of the Christmas tree respectively. The Christmas tree is connected with the water storage tank through a water return pipeline, the top of the Christmas tree is connected with a high-pressure water faucet pipe, and pump injection equipment is arranged between the high-pressure water faucet pipe and the water storage tank.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of in-situ leaching of uranium, and particularly relates to a physical permeability increasing device and method for improving the permeability of sandstone type uranium ore bed. BACKGROUND

[0002] Sandstone type uranium ore is one of the important uranium resources in China, and is mainly mined by in-situ leaching process. After years of development, China has made great progress in the mining process of acid in-situ leaching of uranium and neutral in-situ leaching of uranium, and has mature in-situ leaching technology of uranium. In the in-situ leaching of uranium, the prepared leaching solution is injected into the underground loose sandstone type uranium ore bed through the injection well, and penetrates along the ore bed under the artificial hydraulic drive. Through the diffusion convection effect, chemical reaction occurs with the naturally buried uranium minerals to generate leaching solution containing uranium elements, which is then lifted to the surface through the pumping well for uranium mining process.

[0003] The in-situ leaching of uranium process is used to mine sandstone type uranium ore bed. Some of this type of uranium ore has poor natural permeability, which makes uranium mining uneconomical or even infeasible. At the same time, during the in-situ leaching process, the hydraulic gradient will cause the fine particles such as mud and silt in the ore bed to move and gather along the pores, resulting in physical plugging. The injected solution in the underground will produce new minerals, mainly clay minerals such as kaolinite, illite and montmorillonite. These clay minerals will block the pores after swelling, causing the pumping and injection volume of the well to decrease and affecting the production capacity.

[0004] In view of the problem of decreasing pumping and injection volume of the well, the existing technology has carried out well washing methods such as high-pressure intermittent air compressor well washing, high-pressure air piston well washing, high-pressure intermittent air compressor acid well washing, soft piston acid well washing and chemical well washing. The above well washing methods can remove different types of blockages and temporarily solve the problem of well plugging, but these well washing methods can only solve the plugging around the well, resulting in short maintenance time of well washing effect and being unable to fundamentally solve the problem of decreasing pumping and injection volume of the well. In recent years, due to the high intensity of well washing, the increase of well washing cost and the long and complicated work, well washing has become the most important factor restricting the production and operation of in-situ leaching mines. The liquid flow cavitation technology is widely used in oil field reservoir permeability enhancement, which can effectively increase the production capacity of oil production wells and reduce the pressure of water injection wells. However, there are differences in well structure, casing material and well depth between the in-situ leaching of uranium process and the oil exploitation process. SUMMARY

[0005] The present application aims to provide a physical permeability increasing device and method for improving the permeability of sandstone type uranium ore bed, which solves the problem of poor permeability of the ore bed in the existing mining technology, affecting the pumping and injection volume of the well and seriously affecting the production capacity.

[0006] The technical scheme adopted by the present application to solve its technical problems is: a physical permeability increasing device for improving the permeability of sandstone type uranium ore bed, wherein the device comprises: a cavitation pipe column inserted into a casing pipe, the casing pipe comprises: a filter installed at the bottom, the cavitation pipe column comprises: a tubing pipe arranged in the casing pipe, the bottom of the cavitation pipe column is provided with a cavitation device, the top of the cavitation pipe column is connected with the bottom of a Christmas tree, two water return pipelines are respectively connected with the two sides of the Christmas tree, the Christmas tree is connected with a water storage tank through the water return pipelines, a high-pressure water hose is connected with the top of the Christmas tree, and a pump injection device is arranged between the high-pressure water hose and the water storage tank.

[0007] The physical permeability increasing device for improving the permeability of sandstone type uranium ore bed, wherein the cavitation device has the following parameters: a diameter less than 80 mm, a pressure resistance value greater than 125 MPa, and an internal pressure yield strength greater than 50 MPa.

[0008] The physical permeability increasing device for improving the permeability of sandstone type uranium ore bed, wherein the cavitation pipe column is a steel grade tubing pipe.

[0009] A physical permeability increasing method for improving the permeability of sandstone type uranium ore bed, wherein the method comprises:

[0010] Step one: selecting cavitation points, for the existing bare hole design of in-situ leaching of uranium, only a filter and a casing pipe are arranged in the hole, and a plurality of cavitation points are arranged at intervals at the filter in the hole;

[0011] Step two: connecting ground pipelines, installing a Christmas tree at the wellhead, connecting an inlet high-pressure water hose with the upper end of the Christmas tree, and connecting one end of two water return pipelines with the two sides of the Christmas tree respectively, and connecting the other ends of the two water return pipelines with a water storage tank;

[0012] Step three: well operation, connecting the upper end of the cavitation pipe column with the lower end of the Christmas tree in the existing drilling casing pipe, then lowering the cavitation pipe column into the drilling hole until the cavitation pipe column reaches the bottom end of the filter, and if the lowering depth of the cavitation pipe column cannot reach the bottom end of the filter, sand washing treatment is performed;

[0013] Step four: cavitation pipe column pressure test operation, then performing pressure test on the cavitation pipe column, the pump injection pressure range of the pressure test is set to be 18-22 MPa, after the pressure test is completed, pressure stabilization is performed, and the pressure test operation is completed after the system pressure drop is less than or equal to 0.7 MPa;

[0014] Step five: lowering the cavitation device, after the cavitation pipe column pressure test is completed, the cavitation pipe column is lifted, the cavitation device is installed at the bottom of the cavitation pipe column, and then the cavitation device is connected with the cavitation pipe column and lowered to the bottommost cavitation point designed in step one;

[0015] Step six: ground pipeline pressure test, one end of the inlet high pressure hose is connected with the pump injection device, the other end is connected with the upper end of the Christmas tree at the wellhead, then the high pressure hose is tested again, the pump injection pressure range is set to be 20-25 MPa, and the high pressure hose test operation is completed after the loop pressure drop is less than or equal to 0.7 MPa; one end of the water return pipeline is connected with the Christmas tree at the wellhead, and the other end is connected with the water storage tank, the water return pipeline is tested, the pump injection pressure range is set to be 8-15 MPa, and the water return pipeline test operation is completed after the system pressure drop is less than or equal to 0.7 MPa;

[0016] Step seven: liquid flow cavitation operation, the operation drilling construction pressure range is 18-25 MPa, and the displacement is 1.8-2.5 m 3 / min, the leakage amount needs to be paid attention to in the operation process, if the leakage amount is greater than 100 m 3 , the operation of the cavitation point position is completed, the cavitation point spacing is designed according to step one, the construction sequence is from bottom to top, the cavitation pipe column is lifted to the next cavitation point for operation according to the sequence in turn after each cavitation point operation is completed, and the cavitation operation of all points is completed.

[0017] Step eight: lifting the cavitation pipe column, after the operation of all cavitation points is completed, the cavitation pipe column is lifted out, and then the wellhead device is installed.

[0018] The physical permeability increasing method for improving the permeability of the sandstone type uranium ore bed, wherein the cavitation point spacing in step one is 0.5 m.

[0019] The physical permeability increasing method for improving the permeability of the sandstone type uranium ore bed, wherein the pressure test operation in steps four and six needs to be carried out.

[0020] The physical permeability increasing method for improving the permeability of the sandstone type uranium ore bed, wherein the operation time of each cavitation point is preferably 2 hours.

[0021] Compared with the prior art, the physical permeability increasing device and method for improving the permeability of the sandstone type uranium ore bed has the beneficial effects that: through the device structure design and the matching method, the permeability of the required mining ore bed is increased, the problems of the drilling liquid pumping and injection amount reduction are solved, and the economic efficiency of the in-situ leaching uranium mining is improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The physical permeability increasing device for improving the permeability of the sandstone type uranium ore bed is shown in the schematic view.

[0023] BRIEF DESCRIPTION OF DRAWINGS 1. Water storage tank; 2. Water return pipeline; 3. Pump injection equipment; 4. High-pressure water hose; 5. Christmas tree; 6. Cavitation string; 7. Cavitation device; 8. Filter; 9. Casing. DETAILED DESCRIPTION

[0024] In order to solve the problem that the poor permeability of the ore bed affects the liquid injection and extraction amount of the borehole and seriously affects the production capacity in the process of the existing mining technology in the sandstone type uranium ore bed, an embodiment of the present application provides a physical permeability increasing device and method for improving the permeability of the sandstone type uranium ore bed. Figure 1 As shown in the figure, the device comprises: a cavitation string 6 inserted into a casing 9, a filter 8 installed at the bottom of the casing 9, and the cavitation string 6 comprising: an oil pipe arranged in the casing, the bottom of the cavitation string 6 being provided with a cavitation device 7, the cavitation device 7 having the following parameters: a diameter less than 80 mm, a pressure resistance greater than 125 MPa, and an internal pressure yield strength greater than 50 MPa. The top of the cavitation string 6 is connected to the bottom of a Christmas tree 5, the two sides of the Christmas tree 5 are respectively connected to two water return pipelines 2, the Christmas tree 5 is connected to a water storage tank 1 through the water return pipelines 2, and the top of the Christmas tree 5 is connected to a high-pressure water hose 4, and the high-pressure water hose 4 is provided with pump injection equipment 3 between the Christmas tree 5 and the water storage tank 1.

[0025] A physical permeability increasing method for improving the permeability of the sandstone type uranium ore bed, the method comprising:

[0026] Step one: selecting cavitation points, for the existing bare hole design of in-situ leaching of uranium, only a filter 8 and a casing 9 are arranged in the hole, and a plurality of cavitation points are arranged at intervals at the filter 8 in the hole, and the interval between the cavitation points is 0.5 meters;

[0027] Step two: connecting the ground pipeline, installing a Christmas tree 5 at the wellhead, connecting an inlet high-pressure water hose 4 to the upper end of the Christmas tree 5, and connecting one end of two water return pipelines 2 to the two sides of the Christmas tree 5 respectively, and connecting the other end of the two water return pipelines 2 to a water storage tank 1;

[0028] Step three: well operation, after connecting the upper end of the cavitation string 6 to the lower end of the Christmas tree 5 in the existing drilling casing, lowering the cavitation string 6 into the borehole until the cavitation string 6 reaches the bottom end of the filter 8, and if the lowering depth of the cavitation string 6 cannot reach the bottom end of the filter 8, sand washing treatment is performed;

[0029] Step four: cavitation string 6 pressure test operation, then the cavitation string 6 is pressure tested, the pump injection pressure range of the pressure test is set to be 18-22 MPa, after the pressure test is completed, pressure stabilization is performed, the pressure stabilization time is 10 minutes, and the pressure drop needs to be observed during the pressure stabilization, and the pressure test operation is completed after the system pressure drop is less than or equal to 0.7 MPa;

[0030] Step five: lower the cavitation device 7, after the cavitation pipe column 6 is tested, the cavitation pipe column 6 is taken out, the cavitation device 7 is installed at the bottom of the cavitation pipe column 6, and then the cavitation device 7 is connected with the cavitation pipe column 6 and is lowered to the bottommost cavitation point designed in step one;

[0031] Step six: ground pipeline pressure test, one end of the inlet high-pressure hose 4 is connected with the pump injection equipment 3, the other end is connected with the upper end of the Christmas tree 5 at the wellhead, then the high-pressure hose 4 is tested again, the pump injection pressure range is set to be 20-25 MPa, the pressure stabilizing time is 10 minutes, and the pressure drop needs to be paid attention to during the pressure stabilizing, and the high-pressure hose 4 is tested after the loop pressure drop is less than or equal to 0.7 MPa; one end of the water return pipeline 2 is connected with the Christmas tree 5 at the wellhead, and the other end is connected with the water storage tank 1, the water return pipeline 2 is tested, the pump injection pressure range is set to be 8-15 MPa, the pressure stabilizing time is 10 minutes, and the pressure drop needs to be paid attention to during the pressure stabilizing, and the water return pipeline 2 is tested after the system pressure drop is less than or equal to 0.7 MPa;

[0032] Step seven: liquid flow cavitation operation, the operation drilling construction pressure range is 18-25 MPa, and the displacement is 1.8-2.5 m 3 / min, the leakage needs to be paid attention to during the operation, if the leakage is greater than 100 m 3 , the operation of the cavitation point position is completed, the cavitation point interval is designed according to step one, the construction sequence is from bottom to top, the cavitation pipe column 6 is sequentially lifted to the next cavitation point for operation after each cavitation point operation is completed, and the cavitation operation of all points is completed; the operation time of each cavitation point is preferably 2 hours.

[0033] Step eight: lift the cavitation pipe column, after the operation of all cavitation points is completed, the cavitation pipe column 6 is lifted, and then the wellhead device is installed.

[0034] The liquid flow cavitation technology utilizes the formation, development and collapse of bubbles in liquid when the local pressure of the liquid is reduced, the cavitation effect, sound wave and vibration wave are generated when the bubbles collapse, and various energies act on the ore bed, so that micro cracks are generated in the ore bed, and the permeability of the ore bed is increased. The physical permeability increasing device for improving the permeability of the sandstone type uranium ore bed provided by the present application optimizes the existing casing structure, lowers the steel oil pipe (cavitation pipe column) in the existing casing for bearing heavy pressure, and lowers the cavitation device 7 into the filter 8 during operation, so that the ore bed around the filter 8 is affected. When the physical permeability increasing device and method for improving the permeability of the sandstone type uranium ore bed are used in the field to construct the operation hole, the construction pressure is about 21 MPa, the displacement is about 1.8 m 3 / min, and the flow rate is increased from 3.62 m 3 / h to 5.89 m 3 / h, the pumping well flow rate from the target well 35 meters away was increased from 2.58 m 3 / h to 6.11 m 3 / h. The target well had a significant increase in flow rate after the liquid flow cavitation operation.

[0035] It should be noted that the combination of various technical features in the embodiments of the present application is not limited to the combination of the embodiments of the present application or the combination of the specific embodiments described in the present application. All technical features described in the present application can be freely combined or combined in any manner, unless contradictory to each other.

[0036] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, 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 physical permeation enhancement device for improving the permeability of sandstone-type uranium ore layers, characterized in that, The device includes: a cavitation string (6) inserted into a casing (9), the casing (9) including: a filter (8) installed at the bottom, the cavitation string (6) including: an oil pipe installed in the casing, a cavitator (7) installed at the bottom of the cavitation string (6), the top of the cavitation string (6) being connected to the bottom of a tree (5), return water lines (2) being connected to both sides of the tree (5), the tree (5) being connected to a water storage tank (1) through the return water lines (2), a high-pressure water hose (4) being connected to the top of the tree (5), and a pumping device (3) being installed between the high-pressure water hose (4) and the water storage tank (1).

2. The physical permeation enhancement device for improving the permeability of sandstone-type uranium ore layers according to claim 1, characterized in that, The cavitation device (7) has the following specifications: diameter less than 80mm, pressure resistance greater than 125MPa, and internal pressure yield strength greater than 50MPa.

3. The physical permeation enhancement device for improving the permeability of sandstone-type uranium ore layers according to claim 1, characterized in that, The cavitation tubing (6) is a steel-grade tubing.

4. A physical permeability enhancement method for improving the permeability of sandstone-type uranium ore layers, characterized in that, The method includes: Step 1: Select cavitation points. Based on the existing bare hole design for in-situ uranium leaching, there are only filters (8) and casings (9) inside the hole. At the filter (8) inside the hole, several cavitation points are set at intervals. Step 2: Connect the ground pipelines and install the wellhead tree (5). The upper end of the wellhead tree (5) is connected to the inlet high-pressure water hose (4). Two return water pipelines (2) are connected to one end on each side of the wellhead tree (5). The other end of the two return water pipelines (2) is connected to the water storage tank (1). Step 3: Well cleaning operation. After connecting the upper end of the cavitation string (6) to the lower end of the production tree (5) inside the existing borehole casing (9), the cavitation string (6) is lowered into the borehole until the cavitation string (6) reaches the bottom of the filter (8). If the cavitation string (6) cannot reach the bottom of the filter (8) when it is lowered, sand flushing is performed. Step 4: Pressure test operation of cavitation string (6). Then, pressure test is performed on cavitation string (6). The pump injection pressure range for the pressure test is set to 18-22MPa. After the pressure test is completed, the pressure is stabilized. The pressure test operation is completed when the system pressure drop is less than or equal to 0.7MPa. Step 5: Lower the cavitation device (7). After the cavitation tube (6) has been pressure tested, remove the cavitation tube (6). After installing the cavitation device (7) at the bottom of the cavitation tube (6), lower the cavitation device (7) through the cavitation tube (6) to the bottommost cavitation point designed in Step 1. Step 6: Pressure test of surface pipelines. Connect one end of the inlet high-pressure water hose (4) to the pumping equipment (3) and the other end to the upper end of the wellhead tree (5). Then, pressure test the high-pressure water hose (4) again. The pumping pressure range is set to 20-25MPa. After the loop pressure drop is less than or equal to 0.7MPa, the pressure test operation of the high-pressure water hose (4) is completed. Connect one end of the return water pipeline (2) to the wellhead tree (5) and the other end to the water storage tank (1). Pressure test the return water pipeline (2). The pumping pressure range is set to 8-15MPa. After the system pressure drop is less than or equal to 0.7MPa, the pressure test operation of the return water pipeline (2) is completed. Step 7: Cavitation operation, with drilling pressure ranging from 18-25 MPa and displacement from 1.8-2.5 m³ / h. 3 / min, during the operation, the leakage rate needs to be monitored. If the leakage rate is greater than 100m 3 If the cavitation point is completed, the work at that cavitation point location is completed. The construction is carried out according to the spacing of the cavitation points designed in step one. The construction sequence is from bottom to top. After each cavitation point is completed, the cavitation pipe column (6) is lifted up in sequence to the next cavitation point for work, until the cavitation work of all points is completed. Step 8: Remove the cavitation string. After completing the work at all cavitation points, remove the cavitation string (6) and then install the wellhead equipment.

5. A physical permeability enhancement method for improving the permeability of sandstone-type uranium ore layers according to claim 4, characterized in that, The cavitation points in step one are set at a spacing of 0.5 meters.

6. A physical permeation enhancement method for improving the permeability of sandstone-type uranium ore layers according to claim 4 or 5, characterized in that, In both steps four and six of the pressure test, a pressure stabilization operation is required. The stabilization time is 10 minutes, and the pressure drop should be monitored during the stabilization period.

7. A physical permeability enhancement method for improving the permeability of sandstone-type uranium ore layers according to claim 4, characterized in that, The optimal operating time for each cavitation point is 2 hours.

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