A shale oil and gas exploitation fracturing flow-back fluid treatment device

Abstract

This utility model relates to a treatment device for fracturing flowback fluid in shale oil and gas extraction, comprising a mounting bracket, a reaction unit, and a power supply unit. The reaction unit includes a box fixedly connected to the mounting bracket, with an open top and an inlet and outlet. The box contains multiple anode plates and multiple cathode plates. The anode plates divide the box interior into multiple reaction chambers. The cathode plates are rotatably mounted within the box and staggered with the anode plates. The power supply unit includes a DC power supply, with its positive terminal electrically connected to the anode plate and its negative terminal electrically connected to the cathode plate. This utility model, by employing a rotating cathode design, fundamentally changes the problem of traditional fixed cathodes being easily covered by scale, allowing the electrode plates to maintain an activated surface for a long time, resulting in stable electrochemical efficiency, greatly extending the continuous operation cycle, and reducing frequent downtime for cleaning and maintenance.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, specifically a treatment device for fracturing flowback fluid from shale oil and gas extraction. Background Technology

[0002] In oil and gas extraction, formation modification is often necessary to increase permeability and improve oil and gas production. Hydraulic fracturing, as one of the core technologies for this type of resource extraction, injects high-pressure water into the formation to create fractures, thereby increasing the channels for oil and gas flow. However, this process generates a large amount of fracturing flowback fluid, and its treatment and disposal have become a key environmental challenge restricting the green development of shale gas fields.

[0003] Fracturing flowback fluid is a high-salt, high-COD, and high-hardness wastewater, containing large amounts of salts, heavy metals, organic matter, and colloidal oils. Direct discharge into the environment without treatment will cause serious harm to the ecosystem. Common treatment methods include physical, chemical, and biological methods, but these suffer from low treatment efficiency, high operating costs, and susceptibility to scaling and clogging. While electrochemical methods have some application, electrode scaling affects continuous operation, and the combination of flotation and electrochemical processes is insufficient for efficient simultaneous treatment. Utility Model Content

[0004] The purpose of this invention is to provide a treatment device for fracturing flowback fluid in shale oil and gas extraction, which aims to improve the electrochemical method to reduce the scaling problem on the electrode plates and enhance the treatment effect.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a treatment device for fracturing flowback fluid in shale oil and gas extraction, comprising a mounting bracket, a reaction unit, and a power supply unit. The reaction unit includes a box fixedly connected to the mounting bracket, with an open top and an inlet and an outlet. The box contains multiple anode plates and multiple cathode plates, the anode plates dividing the box into multiple reaction chambers. The cathode plates are rotatably disposed within the box and are staggered with the anode plates. The power supply unit includes a DC power supply, the positive terminal of which is electrically connected to the anode plate, and the negative terminal of which is electrically connected to the cathode plate.

[0006] In a preferred embodiment, an overflow cavity is provided at the upper end of the box, and the overflow cavity is sequentially connected to an overflow trough and a waste liquid tank disposed outside the box.

[0007] In a preferred embodiment, the cathode plate is a disc-shaped plate structure.

[0008] In a preferred embodiment, the reaction unit further includes a drive unit, which includes a rotating spindle and a geared motor. The rotating spindle is rotatably supported on the two side walls of the housing via bearing seats, and the geared motor is connected to the rotating spindle for transmission. The plurality of cathode plates are all fixedly mounted on the rotating spindle.

[0009] In a preferred embodiment, the rotating spindle has a conductive section corresponding to the cathode plate, and the surface of the non-conductive section of the rotating spindle is covered with an insulating layer.

[0010] In a preferred embodiment, the negative terminal of the power supply unit is electrically connected to the rotating spindle via a brush slip ring mechanism.

[0011] In a preferred embodiment, the positive terminal of the power supply unit is electrically connected to all anode plates via a conductive plate.

[0012] In a preferred embodiment, the height of the plurality of anode plates gradually decreases from the inlet to the outlet.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] 1. The shale oil and gas fracturing flowback fluid treatment device provided by this utility model fundamentally changes the problem of traditional fixed cathodes being easily covered and encased by scale by adopting a rotating cathode scheme. The continuous rotation of the cathode plate forms a stable tangential water flow on its surface, which effectively shears and scours the newly formed microscale layer, making it difficult for it to adhere firmly to the electrode plate surface. This allows the electrode plate to maintain an activated surface for a long time, with stable electrochemical efficiency, greatly extending the continuous operation cycle and reducing frequent shutdowns for cleaning and maintenance.

[0015] 2. The multi-stage descending reaction chamber design guides the water flow to flow smoothly from top to bottom, increases the residence time of wastewater in the reaction zone, improves the efficiency of electrochemical reaction, and facilitates the accumulation of precipitates at the bottom, reducing the risk of clogging. Attached Figure Description

[0016] Figure 1 A side view of the device for treating fracturing flowback fluid in shale oil and gas extraction provided by this utility model;

[0017] Figure 2 A top view schematic diagram of the shale oil and gas extraction fracturing flowback fluid treatment device provided by this utility model;

[0018] The meanings of the labels in the diagram are as follows:

[0019] 1. Mounting bracket; 2. Housing; 21. Inlet; 22. Outlet; 3. Anode plate; 4. Cathode plate; 5. Overflow tank; 6. Waste liquid tank; 7. Gear motor; 8. Brush slip ring mechanism; 9. DC power supply; 10. Rotary spindle; 11. Overflow chamber; 12. Water pump; 13. Conductive plate. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0022] See Figures 1-2 This embodiment discloses a treatment device for fracturing flowback fluid in shale oil and gas extraction, including a mounting bracket 1, a reaction unit fixedly connected to the mounting bracket, and a power supply unit connected to the reaction unit.

[0023] Mounting bracket 1 is used to provide a stable supporting foundation for the entire device.

[0024] The reaction unit includes an electrochemical reaction chamber 2, which is made of a non-conductive and corrosion-resistant material. In this embodiment, fiberglass is preferred, but in other embodiments, polyethylene (PE) or polypropylene (PP) can also be used. The electrochemical reaction chamber 2 is fixedly connected to the mounting bracket 1 and has an open-top design, forming an electrochemical reaction space inside. The electrochemical reaction chamber 2 has an inlet 21 and an outlet 22. The inlet 21 is used to introduce the wastewater to be treated and is connected to an inlet pipe and a water pump 12. The outlet 22 is located at the lower end of the electrochemical reaction chamber 2 and is used to discharge the treated purified water. In this embodiment, the electrochemical reaction chamber 2 also has an overflow chamber 11, located at the upper end of the electrochemical reaction chamber 2. This overflow chamber 11 is constructed as a cavity formed by a horizontal partition at the end of the chamber 2. The overflow chamber 11 is sequentially connected to an overflow trough 5 and a waste liquid tank 6 located outside the chamber 2.

[0025] The reaction unit further includes an anode plate 3 and a cathode plate 4 disposed within the electrochemical reaction chamber 2. In practical applications, a reduction reaction occurs on the cathode plate 4, where calcium and magnesium ions are released from the fracturing flowback fluid, thereby reducing hardness. An oxidation reaction occurs on the anode plate 3 to remove COD from the fracturing flowback fluid. Simultaneously, under the action of current, the liquid undergoes electrolysis, generating tiny hydrogen bubbles. These bubbles act as flotation agents for insoluble and difficult-to-settle colloids and oils in the wastewater, causing them to condense on the surface of the wastewater. Under the action of water flow, the bubbles gradually flow to the overflow chamber 11 and then into the waste liquid tank 6 via the overflow trough 5.

[0026] Specifically, in this embodiment, multiple sets of anode plates 3 and cathode plates 4 are arranged in an alternating pattern. The anode plates 3 are preferably made of 316L stainless steel, and each anode plate 3 is vertically fixed to the bottom of the electrochemical reaction chamber 2. Thus, the interior of the electrochemical reaction chamber 2 is divided into multiple independent reaction chambers by multiple parallel and spaced anode plates 3. It is understood that in other embodiments, the anode plates 3 can also be titanium-based coated electrodes with higher catalytic activity or lower-cost graphite electrodes. In this embodiment, the height of the anode plates 3 gradually decreases from the inlet 21 to the outlet 22. This design forms a multi-stage descending reaction chamber, guiding the water flow smoothly from top to bottom, increasing the residence time of wastewater in the reaction zone, improving the electrochemical reaction efficiency, and facilitating the accumulation of precipitates at the bottom, reducing the risk of clogging.

[0027] The cathode plates 4 are staggered between the anode plates 3, creating an effective electric field region within each reaction chamber. In this embodiment, the cathode plates 4 are preferably made of 316L stainless steel and are constructed as a disc-shaped plate structure, and the cathode plates 4 are rotatable. The disc-shaped structure of the cathode plates 4 allows them to rotate smoothly in the liquid, avoiding eddies or vibrations. Furthermore, the constant distance from the edge of the disc to the center of rotation ensures that the distance between the plates and the anode plates 3 remains consistent, which is beneficial for forming a uniform electric field distribution and thus ensuring the stability of the electrochemical reaction efficiency. It should also be noted that the use of rotatable cathode plates 4 in this embodiment prevents scale-like substances generated by the electrochemical reaction from accumulating on the cathode plate 4 surface. The tangential water flow provided by the rotation washes away the scale-like substances, preventing them from accumulating and allowing them to settle to the bottom of the tank. Once a certain amount has accumulated, the scale can be discharged through the drain port at the bottom of the tank 2.

[0028] Furthermore, the reaction unit also includes a drive unit for mounting and driving the cathode plate 4 to rotate. The drive unit includes a rotating spindle 10 and a geared motor 7 for driving the rotating spindle 10 to rotate. The rotating spindle 10 is a metal shaft. In this embodiment, the cathode plate 4 has a shaft hole at its center, and the rotating spindle 10 passes through the shaft holes of all the cathode plates 4 in sequence, so that the cathode plates 4 are fixedly connected to the rotating spindle 10. Preferably, the rotating spindle 10 has a conductive section at the mounting position corresponding to the cathode plate 4. The conductive section can be integrally machined with the rotating spindle 10, or it can be a metal sleeve that is interference-fitted onto the rotating spindle 10. The cathode plate 4 is sleeved on the conductive section through its central shaft hole, so that the cathode plate 4 and the conductive section maintain a tight metal contact to ensure that the current can be conducted efficiently. The non-conductive sections of the rotating spindle 10 are all covered with insulating material. This design ensures that current can only flow into the cathode plate 4 through the preset conductive sections, and that no irrelevant electrochemical reactions occur in the main body of the rotating spindle 10, effectively preventing corrosion of the rotating spindle 10 and unnecessary current consumption.

[0029] Furthermore, in this embodiment, the rotating main shaft 10 is disposed above the anode plate 3 and is rotatably supported on both side walls of the electrochemical reaction chamber 2 via bearing seats. The geared motor 7 is fixedly connected to the outer end plate of the electrochemical reaction chamber 2 or to the mounting bracket 1 via a fixing frame, and its output shaft is connected to the end of the rotating main shaft 10 via a coupling, thereby transmitting power to the rotating main shaft 10 and driving all cathode plates 4 to rotate synchronously.

[0030] The power supply unit includes an adjustable DC power supply 9. Its positive terminal is connected to all anode plates 3 via cables. It should be noted that, to facilitate the connection between the cables and each anode plate 3, in a preferred embodiment, the bottom ends of each anode plate 3 are electrically connected via a uniform conductive plate 13. This conductive plate 13 is fixedly connected to the bottom end of the housing 2, and the cables are connected to this conductive plate 13. This arrangement greatly simplifies the cable arrangement inside the housing 2, reduces connection points, and lowers the failure rate. The negative terminal is fixedly connected to the other end of the rotating spindle 10 via a brush slip ring mechanism 8, achieving electrical connection with the rotating spindle 10. The brush slip ring mechanism 8 adopts existing technology. Current flows from the brush slip ring mechanism 8 into the rotating spindle 10, is conducted through the metal rotating spindle 10 to the conductive section at each installation location, and then through the tight metal contact surface to each cathode plate 4. The voltage and current output of the DC power supply 9 should be adjusted according to the water quality of the returned liquid and the treatment target to control the appropriate current density and achieve the best treatment effect.

[0031] In practical applications, the feedwater pump 12 is first turned on, and the fracturing flowback fluid to be treated is injected into the electrochemical reaction tank 2 through the inlet 21. After the predetermined liquid level is reached, the geared motor 7 is started to rotate. Subsequently, the DC power supply 9 is turned on, and the voltage is gradually increased to the preset value, so that the system operates at the set current density. During the flowback fluid through the multi-stage reaction chamber, calcium and magnesium ions are precipitated on the surface of the rotating cathode plate 4 to form soft scale, which is then washed off in time; organic matter is oxidized and decomposed on the surface of the anode plate 3; at the same time, the tiny hydrogen bubbles generated by the anode form a flotation effect on the insoluble colloids and greases, causing them to condense on the surface of the wastewater. Finally, the treated clean water is discharged through the drain outlet, and the surface scum overflows into the overflow chamber 11 and enters the waste liquid tank 6 through the overflow trough 5.

[0032] This embodiment utilizes a rotatable cathode design to prevent scale-like substances from accumulating on the plate surface. Combined with the microbubble flotation effect generated by the anode, and by setting a reasonable water flow pattern and channel, it can reduce the hardness of the liquid while also removing grease, colloids, and other difficult-to-settle substances. This achieves efficient and stable treatment of high-difficulty fracturing flowback fluid, and has significant advantages such as strong continuous operation capability and simple maintenance.

[0033] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A device for treating fracturing flowback fluid in shale oil and gas extraction, characterized in that, include: Mounting bracket (1); The reaction unit includes a box (2) fixedly connected to the mounting bracket (1), with an open top and an inlet (21) and an outlet (22). The box (2) is provided with multiple anode plates (3) and multiple cathode plates (4). The anode plates (3) divide the inside of the box (2) into multiple reaction chambers. The cathode plates (4) are rotatably disposed in the box (2) and are staggered with the anode plates (3). The power supply unit includes a DC power supply (9), whose positive terminal is electrically connected to the anode plate (3) and whose negative terminal is electrically connected to the cathode plate (4).

2. The shale oil and gas extraction fracturing flowback fluid treatment device according to claim 1, characterized in that, An overflow chamber (11) is provided at the upper end of the box (2), and the overflow chamber (11) is connected in sequence to an overflow trough (5) and a waste liquid tank (6) located outside the box (2).

3. The shale oil and gas extraction fracturing flowback fluid treatment device according to claim 1, characterized in that, The cathode plate (4) has a disc-shaped plate structure.

4. The shale oil and gas extraction fracturing flowback fluid treatment device according to claim 1, characterized in that, The reaction unit further includes a driving unit, the driving unit comprising: The rotating spindle (10) is rotatably supported on the two side walls of the housing (2) via bearing seats; A geared motor (7) is connected to the rotating main shaft (10) for transmission. The plurality of cathode plates (4) are all fixedly mounted on the rotating spindle (10).

5. The shale oil and gas extraction fracturing flowback fluid treatment device according to claim 4, characterized in that, The rotating spindle (10) is provided with a conductive section corresponding to the cathode plate (4), and the surface of the non-conductive section of the rotating spindle (10) is covered with an insulating layer.

6. The shale oil and gas extraction fracturing flowback fluid treatment device according to claim 4, characterized in that, The negative terminal of the power supply unit is electrically connected to the rotating spindle (10) through the brush slip ring mechanism (8).

7. The device for treating fracturing flowback fluid in shale oil and gas extraction according to claim 1, characterized in that, The positive terminal of the power supply unit is electrically connected to all the anode plates (3) through a conductive plate (13).

8. The processing apparatus according to claim 1, characterized in that, The height of the plurality of anode plates (3) gradually decreases from the inlet (21) to the outlet (22).

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