Oil and gas field drilling waste liquid low-dose efficient treatment system and method

Abstract

The invention discloses a low-dose efficient treatment system and method for oil and gas field drilling waste liquid, and belongs to the technical field of oil and gas field waste liquid treatment. Comprising a destabilization module which comprises a water inlet lifting device and a mechanical destabilization device which are connected in sequence; the mechanical destabilization device can generate high-frequency oscillation to destroy the stable colloidal state of the waste liquid; the solid-liquid separation module comprises a pipeline mixer and a high-speed centrifugal solid-liquid separation device which are connected in sequence; an inlet of the pipeline mixer is connected with an outlet of the mechanical destabilization device; the recycling module comprises a pressure filtering device and a sludge dewatering device; an inlet of the pressure filtering device is connected with a liquid phase outlet of the high-speed centrifugal solid-liquid separation device; and an inlet of the sludge dewatering device is connected with a solid-phase outlet of the high-speed centrifugal solid-liquid separation device. According to the method, a mechanical destabilization and high-speed centrifugation combined mode is used, so that the use of chemical agents can be greatly reduced, the agent cost is greatly reduced, and the treatment efficiency of the drilling waste liquid is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field waste liquid treatment, and relates to a low-dose and high-efficiency treatment system and method for oil and gas field drilling waste liquid. Background Art

[0002] Oil and natural gas occupy an important position in the national economic development. With the increasing scale of oil and natural gas exploitation, a large amount of waste liquid will be generated in the process of oil and gas development, and drilling waste liquid is one of the main waste liquids. The drilling waste liquid generated during the drilling operation mainly includes drilling waste mud, scattered mud, rock cuttings, drilling equipment flushing water, oil storage tanks and mechanical equipment oil spills, etc. This type of wastewater contains various organic additives and petroleum substances in the drilling fluid. It has complex composition, high calcium and magnesium content, and high viscosity. Improper disposal will cause serious environmental pollution accidents.

[0003] In recent years, the annual generation of drilling waste fluid is about one million cubic meters. The large amount of production has a high risk of water and ecological environment pollution and has become one of the main pollutants in the process of oil and gas development.

[0004] At present, oil and gas fields are mainly developed by large well groups, and the well depth is constantly increasing. The demand for clean water during drilling is very high, but the utilization rate of water resources is low during drilling, oil testing and fracturing operations, which increases the cost of oil and gas extraction. Therefore, in order to further protect water resources, it is necessary to consider treating the drilling waste fluid with low dosage and high efficiency to meet the water requirements of well washing, back-mixing drilling fluid, back-mixing fracturing fluid, flushing equipment, etc. at the drilling site, so as to achieve the goal of reducing costs and increasing efficiency in oil and gas development, which has been a long-term research focus.

[0005] A lot of research has been done on the treatment of drilling wastewater. At present, the treatment methods for drilling wastewater mainly include chemical demulsification, chemical coagulation and sedimentation, flotation separation, etc. The main purpose is to remove oil, particulate pollutants, calcium and magnesium ions, etc. in drilling wastewater, and reuse the treated water. Chemical demulsification is to add an oxidizing demulsifier to the drilling wastewater, and through the chemical oxidation of the demulsifier, the drilling wastewater is demulsified and destabilized. Chemical coagulation and sedimentation is a wastewater solid-liquid separation process. First, a pH regulator is added to the wastewater to adjust the pH of the wastewater to alkaline, providing conditions for coagulation treatment, and then flocculants, coagulants and other agents are added. The fine particle pollutants in the sewage are flocculated by the agent to form large particle flocs, which are separated from the water by sedimentation to achieve the purpose of solid-liquid separation. Flotation separation is also a type of solid-liquid separation. When a chemical coagulant is added, large flocs are formed. With the help of the buoyancy of microbubbles, they float to the surface of the waste liquid to form scum, which is scraped off by a scraping mechanism to achieve solid-liquid separation.

[0006] The above drilling waste fluid treatment technology is currently a commonly used process, but it has some obvious shortcomings:

[0007] (1) The amount of chemical agents used is large and the treatment cost is high;

[0008] (2) The drug has certain hazards to human health, and improper operation can easily cause damage to the skin and respiratory mucosa;

[0009] (3) The dosage of the reagent is crucial to the treatment effect. Therefore, different dosages of reagents need to be determined for wastewater with different pollution levels, which is complicated to operate.

[0010] (4) Flotation and coagulation sedimentation equipment occupy a large area, have a large number of moving equipment, and have a high equipment failure rate. Summary of the invention

[0011] The purpose of the present invention is to solve the technical problems of large amount of chemical agents used, large equipment footprint and high failure rate in the prior art drilling waste fluid treatment process, and to provide a low-dose and efficient treatment system and method for oil and gas field drilling waste fluid.

[0012] In order to achieve the above object, the present invention adopts the following technical solutions:

[0013] In a first aspect, the present invention provides a low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid, comprising:

[0014] A destabilization module, the destabilization module comprising a water inlet lifting device and a mechanical destabilization device connected in sequence; the mechanical destabilization device can generate high-frequency oscillations to destroy the stable colloidal state of the waste liquid;

[0015] A solid-liquid separation module, wherein the solid-liquid separation module comprises a pipeline mixer and a high-speed centrifugal solid-liquid separation device connected in sequence; the inlet of the pipeline mixer is connected to the outlet of the mechanical destabilization device;

[0016] The recovery module comprises a pressure filtering device and a sludge dewatering device; the inlet of the pressure filtering device is connected to the liquid phase outlet of the high-speed centrifugal solid-liquid separation device; the inlet of the sludge dewatering device is connected to the solid phase outlet of the high-speed centrifugal solid-liquid separation device.

[0017] Furthermore, the mechanical destabilization device includes a destabilization cylinder, a vibration unit and a shock absorbing unit; the inlet of the destabilization cylinder is connected to the outlet of the water inlet lifting device, the outlet of the destabilization cylinder is connected to the inlet of the pipeline mixer, and shear particles are arranged in the destabilization cylinder; the destabilization cylinder is rigidly connected to the vibration unit; the shock absorbing unit is arranged below the vibration unit; the vibration unit is externally connected to a control unit and a power unit.

[0018] Furthermore, the shock absorbing unit is composed of shock absorbing springs arranged in double rows.

[0019] Furthermore, the inlet of the pipeline mixer is also connected to a dosing device, and the dosing device is used to add flocculants.

[0020] Furthermore, the high-speed centrifugal solid-liquid separation device adopts a horizontal centrifuge.

[0021] Furthermore, the rotation speed of the horizontal centrifuge is 3000 r / min to 3200 r / min.

[0022] Furthermore, a booster pump is provided between the high-speed centrifugal solid-liquid separation device and the pressure filtration device.

[0023] Furthermore, the pressurized filtration device includes an upper head, a cylinder and a lower head connected in sequence; the top surface of the upper head is connected to the outlet of the booster pump, and an outlet connected to the backwash water tank is arranged at the side wall of the upper head; an outlet is arranged on the side wall of the cylinder for the filtered clean water to flow out and merge into the finished water tank; the outlet of the side wall of the cylinder is also connected to the backwash booster pump, and the clean water flows back through the backwash booster pump into the inlet on the bottom surface of the lower head.

[0024] Furthermore, a flow meter is provided at the inlet of the finished water tank.

[0025] The second invention discloses a method for efficiently treating oil and gas field drilling waste liquid with low dosage using the above system, comprising the following steps:

[0026] The water inlet lifting device is used to allow the waste liquid to enter the destabilization cylinder. Under the action of the vibration unit, high-frequency oscillation is generated, which drives the shear particles inside the destabilization cylinder to shear and collide with the waste liquid.

[0027] The flocculant is added through the dosing device, so that the suspended solids and colloidal substances in the waste liquid form flocs in the pipeline mixer and enter the high-speed centrifugal solid-liquid separation device. Under the use of high-speed centrifugal force, the solid and liquid phases are separated;

[0028] The separated liquid phase is filtered through a pressurized filter to remove fine suspended matter, and the effluent can meet the water requirements for well washing, equipment flushing, back-mixing drilling fluid, and back-mixing fracturing fluid; the separated solid phase is treated harmlessly off-site.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention discloses a low-dose and high-efficiency treatment system and method for waste liquid from drilling in oil and gas fields. A water inlet lifting device is used to allow the waste liquid to enter a destabilization cylinder. High-frequency oscillation is generated under the action of a vibration unit, driving the shear particles inside the destabilization cylinder to shear and colloidal with the waste liquid; thereby destroying its uniform and stable colloidal state, reducing the viscosity of the waste liquid, and creating favorable conditions for subsequent solid-liquid separation. Flocculants are added through a dosing device, so that the suspended solids and colloidal substances in the waste liquid form flocs in a pipeline mixer and enter a high-speed centrifugal solid-liquid separation device. Under the use of high-speed centrifugal force, the solid and liquid phases are separated due to the density difference. The separated liquid phase is filtered through a pressure filter to remove fine suspended matter, and the effluent can meet the indicators of water for well washing, flushing equipment, back-mixing drilling fluid, and back-mixing fracturing fluid; the separated solid phase is treated harmlessly off-site. The present invention uses a combination of mechanical destabilization and high-speed centrifugation, which can greatly reduce the use of chemical agents, significantly reduce agent costs, and improve the treatment efficiency of drilling waste fluid. At the same time, the treatment equipment can be skid-mounted modular design or vehicle-mounted design, and the corresponding treatment module can be selected according to different reuse paths. It occupies a small area and is suitable for the well site operation environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention 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 creative work.

[0032] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0033] Among them: 1-water inlet lifting device; 2-destabilization cylinder; 3-shearing particles; 4-vibration unit; 5-shock absorption unit; 6-dosing device; 7-pipeline mixer; 8-high-speed centrifugal solid-liquid separation device; 9-boosting pump; 10-pressure filtration device; 11-backwashing booster pump; 12-flow meter; 13-sludge dewatering device. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] 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.

[0037] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does 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 cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0038] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0039] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0041] See also Figure 1 The embodiment of the present invention provides a low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid, comprising:

[0042] A destabilization module, the destabilization module comprises a water inlet lifting device 1 and a mechanical destabilization device connected in sequence; the mechanical destabilization device can generate high-frequency oscillations to destroy the stable colloidal state of the waste liquid;

[0043] A solid-liquid separation module, wherein the solid-liquid separation module comprises a pipeline mixer 7 and a high-speed centrifugal solid-liquid separation device 8 connected in sequence; the inlet of the pipeline mixer 7 is connected to the outlet of the mechanical destabilization device;

[0044] The recovery module includes a pressure filter device 10 and a sludge dewatering device 13; the inlet of the pressure filter device 10 is connected to the liquid phase outlet of the high-speed centrifugal solid-liquid separation device 8; the inlet of the sludge dewatering device 13 is connected to the solid phase outlet of the high-speed centrifugal solid-liquid separation device 8. The system can be used to quickly and efficiently treat oil and gas field drilling waste liquid, and the amount of flocculating agent added is reduced from 1500-2000 mg / L required by conventional treatment methods to less than 200 mg / L. The treated effluent can meet the water requirements of well washing, equipment flushing, drilling fluid re-mixing, fracturing fluid re-mixing, etc. at the drilling site, achieving the purpose of low-amount and high-efficiency wastewater.

[0045] In a feasible embodiment of the present invention, the mechanical destabilization device includes a destabilization cylinder 2, a vibration unit 4 and a shock absorbing unit 5; the inlet of the destabilization cylinder 2 is connected to the outlet of the water inlet lifting device 1, the outlet of the destabilization cylinder 2 is connected to the inlet of the pipeline mixer 7, and the destabilization cylinder 2 is provided with shear particles 3; the destabilization cylinder 2 is rigidly connected to the vibration unit 4; the shock absorbing unit 5 is arranged below the vibration unit 4; the vibration unit 4 is externally connected to a control unit and a power unit. The shock absorbing unit 5 is composed of shock absorbing springs arranged in double rows.

[0046] In a feasible embodiment of the present invention, the inlet of the pipeline mixer 7 is also connected to a dosing device 6, and the dosing device 6 is used to add flocculants.

[0047] In a feasible embodiment of the present invention, the high-speed centrifugal solid-liquid separation device 8 is a horizontal centrifuge having a rotation speed of 3000 r / min to 3200 r / min.

[0048] In a feasible embodiment of the present invention, a booster pump 9 is further provided between the high-speed centrifugal solid-liquid separation device 8 and the pressure filtration device 10 .

[0049] In a feasible embodiment of the present invention, the pressure filtration device 10 includes an upper head, a cylinder and a lower head connected in sequence; the top surface of the upper head is connected to the outlet of the booster pump 9, and an outlet is set at the side wall of the upper head to connect to the backwash water tank; an outlet is set at the side wall of the cylinder for the filtered clean water to flow out and merge into the finished water tank; the outlet of the side wall of the cylinder is also connected to the backwash booster pump 11, and the clean water flows back into the inlet of the bottom surface of the lower head through the backwash booster pump 11. A flow meter 12 is also set at the inlet of the finished water tank.

[0050] The embodiment of the present invention also provides a method for efficiently treating oil and gas field drilling waste fluid with low dosage using the above system, comprising the following steps:

[0051] S1, using the water inlet lifting device 1 to allow the waste liquid to enter the destabilization cylinder 2, and generating high-frequency oscillation under the action of the vibration unit 4, driving the shear particles 3 inside the destabilization cylinder 2 to shear and collide with the waste liquid;

[0052] S1, flocculants are added through the dosing device 6, so that the suspended solids and colloidal substances in the waste liquid form flocs in the pipeline mixer 7 and enter the high-speed centrifugal solid-liquid separation device 8, and the solid and liquid phases are separated under the use of high-speed centrifugal force;

[0053] S1, the separated liquid phase is filtered through a pressure filter 10 to remove fine suspended solids, and the effluent can meet the water requirements for well washing, equipment flushing, drilling fluid re-mixing, and fracturing fluid re-mixing; the separated solid phase is treated harmlessly off-site.

[0054] The working principle of the present invention is as follows:

[0055] The present invention adopts a water inlet lifting device 1 to allow the waste liquid to enter the destabilization cylinder 2, and generates high-frequency oscillations under the action of the vibration unit 4, driving the shear particles 3 inside the destabilization cylinder 2 to shear and colloidal with the waste liquid; thereby destroying its uniform and stable colloidal state, reducing the viscosity of the waste liquid, and creating favorable conditions for subsequent solid-liquid separation. Flocculant is added through the dosing device 6, so that the suspended solids and colloidal substances in the waste liquid form flocs in the pipeline mixer 7 and enter the high-speed centrifugal solid-liquid separation device. Under the use of high-speed centrifugal force, the solid and liquid phases are separated due to the density difference. The separated liquid phase is passed through the pressurized filtration device 10 to remove fine suspended matter, and the effluent can meet the indicators of water for well washing, flushing equipment, re-matching drilling fluid and re-matching fracturing fluid; the separated solid phase is harmlessly treated off-site. The present invention uses a combination of mechanical destabilization and high-speed centrifugation, which can greatly reduce the use of chemical agents, significantly reduce agent costs, and improve the treatment efficiency of drilling waste fluid. At the same time, the treatment equipment can be skid-mounted modular design or vehicle-mounted design, and the corresponding treatment module can be selected according to different reuse paths. It occupies a small area and is suitable for the well site operation environment.

[0056] Embodiment 1:

[0057] The waste drilling fluid of an oil field is treated by traditional chemical flocculation and sedimentation process. The treated water is used for well washing, equipment flushing, and back-mixing of drilling fluid. The dosage of the reagents is as follows: PAC dosage 2500mg / L, PAM dosage 100mg / L. The water quality indicators before and after treatment are as follows:

[0058] Table 1

[0059]

[0060] The drilling waste fluid enters the mechanical destabilization device through the water inlet lifting device 1. The vibration frequency of the power unit of the mechanical destabilization device is set to 3500r / min, and the vibration shear time is 6min;

[0061] The wastewater after mechanical destabilization flows into the pipeline mixer 7 by gravity, and the flocculant PAC 300 mg / L is added through the dosing device 2. The wastewater and the agent undergo a coagulation reaction in the pipeline mixer to form a mixed liquid with large particle flocs.

[0062] The mixed liquid containing floccules enters the high-speed centrifugal separation device 8, the centrifuge speed is 3200r / min, the centrifugal time is 5min, and the solid and liquid phases are effectively separated under the action of high-speed centrifugation;

[0063] After solid-liquid separation, the liquid phase enters the pressure filter 10 through the booster pump 9. The filter medium is used to remove fine suspended matter and impurities. The fine filtered water can meet the water requirements for well washing, equipment flushing, and drilling fluid re-mixing, achieving the purpose of low dosage and high efficiency.

[0064] The sludge after solid-liquid separation enters the sludge dewatering device 13, and is processed by plate and frame filter pressing, so that the moisture content of the sludge is controlled below 80%.

[0065] The water quality indicators before and after treatment in this embodiment are as follows:

[0066] Table 2

[0067]

[0068] Compared with the traditional chemical coagulation method, the dosage of the present invention is reduced from 2500 mg / L to 300 mg / L, which has the effect of significantly reducing the dosage of the agent and saving costs, and the water quality index after treatment is better than that of the traditional treatment method.

[0069] Embodiment 2:

[0070] The abandoned drilling supernatant of a gas field was treated by traditional chemical flocculation and sedimentation process. The treated water was used to mix guar fracturing fluid. The dosage of reagents was as follows: PAC dosage 800mg / L, PAM dosage 50mg / L, ion remover dosage 520mg / L. The water quality indicators before and after treatment are as follows:

[0071] Table 3

[0072]

[0073] After being treated by the treatment method of the present invention, it is used to re-mix guar gum fracturing fluid, etc. The general implementation method is consistent with Example 1. The difference is that in this embodiment, the water quality of the drilling supernatant is relatively better than that of the waste drilling fluid. Therefore, the vibration frequency of the power unit of the mechanical destabilization device is set to 3000r / min, and the vibration shear time is 3min.

[0074] In addition, the content of calcium and magnesium ions is the main factor affecting the preparation of fracturing fluid. Therefore, before high-speed centrifugal separation, 300 mg / L of ion remover is added to ensure that the total content of calcium and magnesium ions after treatment is less than 500 mg / L, meeting the requirements for preparing fracturing fluid.

[0075] The water quality indicators before and after treatment in this embodiment are as follows:

[0076] Table 4

[0077]

[0078] Compared with the traditional chemical coagulation method, the present invention does not need to add chemical flocculants under the condition of good raw water quality, thus saving the cost of reagents, and the water quality indicators after treatment are better than those of traditional treatment methods. At the same time, the amount of sludge generated by the inventive method is significantly reduced, thereby greatly reducing the sludge treatment amount and cost.

[0079] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low-dose and high-efficiency treatment system for oil and gas field drilling waste liquid, characterized in that: include: A destabilization module, the destabilization module comprising a water inlet lifting device (1) and a mechanical destabilization device connected in sequence; the mechanical destabilization device can generate high-frequency oscillations to destroy the stable colloidal state of the waste liquid; A solid-liquid separation module, the solid-liquid separation module comprising a pipeline mixer (7) and a high-speed centrifugal solid-liquid separation device (8) connected in sequence; the inlet of the pipeline mixer (7) is connected to the outlet of the mechanical destabilization device; A recovery module, the recovery module comprising a pressurized filtration device (10) and a sludge dewatering device (13); the inlet of the pressurized filtration device (10) is connected to the liquid phase outlet of the high-speed centrifugal solid-liquid separation device (8); and the inlet of the sludge dewatering device (13) is connected to the solid phase outlet of the high-speed centrifugal solid-liquid separation device (8).

2. The low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid according to claim 1 is characterized in that: The mechanical destabilization device comprises a destabilization cylinder (2), a vibration unit (4) and a shock absorbing unit (5); the inlet of the destabilization cylinder (2) is connected to the outlet of the water inlet lifting device (1), the outlet of the destabilization cylinder (2) is connected to the inlet of the pipeline mixer (7), and shear particles (3) are arranged in the destabilization cylinder (2); the destabilization cylinder (2) is rigidly connected to the vibration unit (4); the shock absorbing unit (5) is arranged below the vibration unit (4); and the vibration unit (4) is externally connected to a control unit and a power unit.

3. The low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid according to claim 2 is characterized in that: The shock absorbing unit (5) is composed of shock absorbing springs arranged in double rows.

4. The low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid according to claim 1 is characterized in that: The inlet of the pipeline mixer (7) is also connected to a dosing device (6), and the dosing device (6) is used to add flocculants.

5. The low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid according to claim 4 is characterized in that: The high-speed centrifugal solid-liquid separation device (8) adopts a horizontal centrifuge.

6. A low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid according to claim 5, characterized in that: The horizontal centrifuge has a rotation speed of 3000 r / min to 3200 r / min.

7. The low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid according to claim 1 is characterized in that: A booster pump (9) is also provided between the high-speed centrifugal solid-liquid separation device (8) and the pressure filtering device (10).

8. The low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid according to claim 7 is characterized in that: The pressurized filtering device (10) comprises an upper head, a cylinder and a lower head connected in sequence; the top surface of the upper head is connected to the outlet of the booster pump (9), and an outlet is arranged on the side wall of the upper head to connect to the backwash water tank; the side wall of the cylinder is provided with an outlet for the filtered clean water to flow out and flow into the finished product water tank; The outlet of the side wall of the cylinder is also connected to a backwash booster pump (11), and clean water flows back through the backwash booster pump (11) and enters the inlet of the bottom surface of the lower head.

9. A low-dose and high-efficiency treatment system for oil and gas field drilling waste fluid according to claim 8, characterized in that: A flow meter (12) is also provided at the inlet of the finished product water tank.

10. A method for treating oil and gas field drilling waste liquid with low dosage and high efficiency using the system according to any one of claims 1 to 9, characterized in that: The following steps are involved: A water inlet lifting device (1) is used to allow the waste liquid to enter the destabilization cylinder (2), and a high-frequency oscillation is generated under the action of a vibration unit (4), thereby driving the shear particles (3) inside the destabilization cylinder (2) to shear and collide with the waste liquid; A flocculant is added through a dosing device (6) so that the suspended solids and colloidal substances in the waste liquid form flocs in a pipeline mixer (7) and enter a high-speed centrifugal solid-liquid separation device (8), where the solid and liquid phases are separated under the application of high-speed centrifugal force; The separated liquid phase is filtered through a pressure filter (10) to remove fine suspended matter, and the effluent can meet the water requirements for well washing, equipment flushing, drilling fluid refilling, and fracturing fluid refilling. The separated solid phase is subjected to off-site harmless treatment.

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