An electric pulse well washing device for in-situ leaching uranium drilling

Abstract

The present application belongs to the field of in-situ leaching mining, and particularly relates to a kind of in-situ leaching uranium drilling electric pulse well washing device.A kind of in-situ leaching uranium drilling electric pulse well washing device, wherein, including well device and downhole device, wherein well device is used for the movement and fixation of well washing device, and downhole device is used for washing well in specific drilling area.The present application has the following beneficial effects relative to the prior art: the in-situ leaching uranium drilling electric pulse well washing device of the present application can solve the problems of decreased injection and extraction volume, increased injection pressure, poor effect or high frequency of conventional well washing (air compressor well washing, piston well washing, chemical well washing, etc.), low recovery rate, etc., improve efficiency and ensure stability.

Description

Technical Field

[0001] This invention belongs to the field of in-situ leaching mining, specifically relating to an electric pulse well washing device for in-situ leaching uranium drilling. Background Technology

[0002] In-situ leaching is one of the main processes for uranium mining in China. The permeability of sandstone-type uranium deposits in China is generally low, and the drilling and injection capacity is relatively small. After many years of field practice in in-situ leaching, uranium mining has been scaled up. However, with the increase in the number of years of leaching, a series of problems have emerged due to various reasons, such as a decrease in the amount of injection fluid, high water injection pressure, and low leaching rate. To address or improve this situation, among the existing methods for restoring water supply (injection / pumping) capacity in uranium leaching wells, the commonly used well-washing methods are physical and chemical. Physical well-washing includes air compressor well-washing, piston well-washing (mechanical piston, pneumatic piston), high-pressure jet well-washing, liquid carbon dioxide well-washing, foam well-washing, cavitation jet well-washing, ultrasonic well-washing, and rotating jet sand flushing, etc. Chemical well-washing utilizes the reaction of acid with carbonate rock fragments, rock blocks, and other impurities containing calcium in the pores (fractures) of the aquifer (section) and the well, which can generate soluble salts, gases, or other water-soluble substances. Alternatively, it utilizes the property of chemical solutions to dissolve and destroy the adsorption capacity of mud on the well wall rocks, thereby clearing the seepage channels. Statistics show that the above well-washing operations can alleviate blockage to a certain extent, but repeated operations are required, with nearly 30% of well-washing operations requiring repetition, and the process is cumbersome and costly.

[0003] The principle of high-energy electric pulse technology is that an electric pulse device releases high-energy electric pulses in a water-filled reservoir. Through the electrohydraulic effect, the high-power energy is converted into stress waves to excite and modify the reservoir. The electric pulse device consists of a surface power control cabinet and downhole equipment. The surface power control cabinet provides power and controls the downhole equipment. The downhole high-voltage DC power supply charges the high-energy storage capacitor. When the capacitor reaches its operating value, the energy controller instantly and rapidly transfers the stored electrical energy to the energy converter. The energy converter converts the electrical energy into shock wave energy in the water-filled formation through the electrohydraulic effect. The shock wave acts on the formation through the casing orifice, exerting a powerful impact vibration on the formation and various media within the pores and fractures. Various solid-liquid media are treated by multiple pulse actions, thereby modifying the formation properties.

[0004] In view of the above problems, drawing on the concept and technical principles of high-energy electro-explosive pulse well washing for permeability enhancement in oil and gas field drilling, we will study and develop an electro-pulse well washing method suitable for in-situ leaching uranium drilling. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing an electric pulse well-washing device for uranium drilling in in-situ leaching.

[0006] The specific technical solution adopted in this invention is as follows: an electric pulse well washing device for uranium leaching drilling, comprising an above-ground device and a downhole device, wherein the above-ground device is used for moving and fixing the well washing device, and the downhole device is used for washing a specific drilling area.

[0007] As described above, the above-ground device for uranium leaching drilling includes a chassis frame, a support frame assembly on the chassis frame, a motor on the support frame assembly, the motor being connected to a winch and capable of driving the winch to rotate, a lifting rod at the front end of the winch, a cable laying device below the lifting rod, and a cable on the winch. The cable is fixedly connected to the downhole device through the lifting rod and the cable laying device.

[0008] The above-described in-situ leaching uranium drilling electric pulse well washing device includes a support frame assembly comprising a lower support frame and an upper support frame.

[0009] The above-described in-situ leaching uranium drilling electric pulse well washing device includes tracks installed below the chassis frame.

[0010] The above-described in-situ leaching uranium drilling electric pulse well washing device includes a downhole device comprising a stainless steel pipe connected to the end of a cable, and a shock wave emitting device installed inside the stainless steel pipe.

[0011] As described above, the in-situ leaching uranium drilling electric pulse well washing device includes a shock wave emitting device comprising a gas chamber disposed inside a stainless steel outer cylinder, and two electrodes corresponding to the positions of the gas chamber, namely an adjustable electrode and a fixed electrode, both of which are electrically connected to the outside.

[0012] In the above-described in-situ leaching uranium drilling electric pulse well washing device, insulating components are provided at the points where the adjustable electrode and the fixed electrode are connected to the outside.

[0013] As described above, in an electric pulse well-washing device for uranium leaching drilling, a gap adjustment shim is provided on the adjustable electrode.

[0014] Compared with the prior art, the present invention has the following advantages: the electric pulse well washing device for uranium drilling in in-situ leaching can solve the problems of decreased injection volume, increased injection pressure, poor effect or high frequency of conventional well washing (air compressor well washing, piston well washing, chemical well washing, etc.) and low recovery rate during the process of uranium leaching, thereby improving efficiency and ensuring stability. Attached Figure Description

[0015] Figure 1 Ground walking and lifting devices for pulse well washing equipment;

[0016] Figure 2 Schematic diagram of the working principle of electrical pulse downhole operation;

[0017] Figure 3Self-breakdown ball gap switch (air switch)

[0018] In the diagram: 1 Upper support frame; 2 Motor; 3 Lifting rod; 4 Winch; 5 Brake; 6 Cable puller; 7 Lower support frame; 8 Chassis frame; 9 Tracks; 11 Tracked vehicle loading ground control system, booster unit, energy storage unit, etc.; 12 High-voltage cable; 13 Downhole equipment; 14 Shock wave; 15 Rock formation; 16 Stainless steel pipe; 17 Downhole load (electrode); 18 Stainless steel outer cylinder; 19 Insulator; 20 Adjustable electrode; 21 Gas chamber; 22 Fixed electrode; 23 Insulator; 24 Gap adjustment shim. Detailed Implementation

[0019] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments.

[0020] (1) Mobile device

[0021] The mobile unit consists of a tracked walking mechanism, chassis frame, winch, upper support frame, lower support frame, sprocket drive mechanism, lifting device, and cable laying device. It uses a remote-controlled tracked chassis, which is 1800mm long, 1500mm wide, and 450mm high, with a crossbeam ground clearance of 250mm and a maximum load capacity of 1.5t. It is equipped with two 2200W DC brushless motors. The remote control system consists of a handheld remote controller, a wireless transceiver, and a motor driver. The motor drive power supply uses a 60V DC lead-acid battery.

[0022] (2) Control Module

[0023] The control module consists of a frequency converter, transformer, rectifier, energy storage capacitor, air switch, and current-limiting resistor (discharge resistor). The system includes functions such as moving the hole-cleaning equipment, voltage boosting, hole-cleaning frequency control, capacitor charging / discharging, and cable retraction / deployment. For operational safety, a DC 24V power supply is used as the drive contactor (KM1~KM5) to boost the AC 220V mains voltage to AC 7KV, generating high-energy hole-cleaning power for capacitor charging / discharging. After the hole-cleaning operation is completed, the power circuit breaker (QF3) is turned off, and the selector switch (SA1) is in position 1-3 (closed) to enter the high-voltage cable retraction / deployment operation mode, allowing for the retraction / deployment of the high-voltage cable.

[0024] (3) Energy storage capacitor

[0025] The device is set with a maximum single-charge energy storage of 5kJ and a maximum charging voltage of 10kV. Based on the capacitor energy formula:

[0026]

[0027] In the formula: E is the energy stored in the capacitor, C is the capacitance value, and U is the capacitor charging voltage.

[0028] (4) Transformers and rectifiers

[0029] Low-voltage AC power needs to be transmitted underground for step-up and rectification. The size and frequency of the transformer are determined by a formula, and in conjunction with a frequency converter, the transformer's operating frequency is set at 300–500 Hz.

[0030] Combining a transformer with a full-wave rectifier results in an input of single-phase two-wire AC low voltage and an output of single-phase two-wire DC high voltage. The input and output are electrically isolated, and the casing does not require grounding. With a rated capacity of 4kVA and an input voltage of 500V AC, the rectifier outputs 10kV DC high voltage, with an equivalent turns ratio of 20.

[0031] (5) Discharge switch

[0032] As one of the most critical components in a pulse power device, the performance of the switch directly affects the overall performance of the device. When turned off, it isolates the charging and discharging circuits, ensuring a highly efficient charging process; when turned on, it instantly releases the stored energy to the load, generating a burst of high power.

[0033] The structure of the self-penetrating ball gap switch is as follows: Figure 3 As shown, the switch consists of a pair of metal hemispheres, one of which is a fixed electrode and the other is an adjustable electrode. By adjusting the gap between the two electrodes, the breakdown voltage of the intermediate air gap is changed, thereby altering the discharge voltage of the capacitor. The metal hemispheres are fixed to the stainless steel outer cylinder by insulating components.

[0034] (6) Current-limiting resistor (discharge resistor)

[0035] A resistor is connected in series in a circuit to limit the current in a branch circuit, or to release electrical energy as internal energy or heat after well cleaning operations are completed, to prevent damage to electrical appliances or for safety reasons. It can also control the discharge rate of capacitors to ensure circuit stability and personnel safety.

[0036] (7) Electrode loaded in water

[0037] The underwater load is the energy storage and release component of the entire system. Its function is to convert the electrical energy stored in the capacitor into shock wave energy through pulse discharge. Therefore, the underwater load is also called the discharge electrode. The discharge electrode is the core component of the entire system. It generates shock waves downhole, which then act on the downhole reservoir. The shearing and fracturing effects of the shock waves are used to unblock and enhance permeability, thereby increasing the reservoir's permeability.

[0038] The underwater load of this device uses a water gap. Since underwater discharge requires a strong electric field, the discharge electrodes are generally designed in a "point-to-point" shape. The electrodes are conical with a base diameter of 25mm. To reduce the impact of electrode erosion, a copper-tungsten alloy is used for the electrode tip, combining the toughness of copper with the erosion resistance of tungsten.

Claims

1. A device for electropulse well washing in uranium mining drilling, characterized in that: It includes surface equipment and downhole equipment, where surface equipment is used for moving and fixing well-washing equipment, and downhole equipment is used for washing wells in specific drilling areas.

2. The in-situ leaching uranium drilling electropulse well washing device as described in claim 1, characterized in that: The above-ground device includes a chassis frame (8), a support frame assembly is provided on the chassis frame (8), a motor (2) is provided on the support frame assembly, the motor (2) is connected to the winch (4) and can drive the winch (4) to rotate, a lifting rod (3) is provided at the front end of the winch (4), a cable laying device (6) is provided below the lifting rod (3), a cable is provided on the winch (4), and the cable is fixedly connected to the downhole device through the lifting rod (3) and the cable laying device (6).

3. The in-situ leaching uranium drilling electropulse well washing device as described in claim 2, characterized in that: The support frame assembly includes a lower support frame (7) and an upper support frame (1).

4. The in-situ leaching uranium drilling electropulse well washing device as described in claim 3, characterized in that: Tracks (9) are installed below the chassis frame (8).

5. The in-situ leaching uranium drilling electropulse well washing device as described in claim 4, characterized in that: The downhole device includes a stainless steel pipe (16), which is connected to the end of a cable, and a shock wave emitting device is installed inside the stainless steel pipe (16).

6. The in-situ leaching uranium drilling electropulse well washing device as described in claim 5, characterized in that: The shock wave emitting device includes an air chamber (21) set inside a stainless steel outer cylinder (18), and two electrodes corresponding to the positions of the air chamber (21) are set, namely an adjustable electrode (20) and a fixed electrode (22), both of which are electrically connected to the outside.

7. The in-situ leaching uranium drilling electropulse well washing device as described in claim 6, characterized in that: Insulators are provided at the points where the adjustable electrode (20) and the fixed electrode (22) are connected to the outside.

8. The in-situ leaching uranium drilling electropulse well washing device as described in claim 7, characterized in that: A gap adjustment shim (24) is provided on the adjustable electrode (20).

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