Oil and gas field wastewater pretreatment integrated device and treatment method

Abstract

The invention relates to the technical field of oil and gas field wastewater treatment, in particular to an oil and gas field wastewater pretreatment integrated device and a treatment method.The oil and gas field wastewater pretreatment integrated device comprises a treatment box body, a water inlet pipe opening and a ventilation pipe opening are formed in the top of the treatment box body, a straight sedimentation structure is arranged at the bottom of the treatment box body, and a transverse barrier plate is fixed between the inner walls of the treatment box body; at least three transverse barrier plates are arranged in the treatment box body, leakage holes are formed in the transverse barrier plates, an absorption assembly is arranged above the treatment box body, a closing mechanism for closing the leakage holes is arranged at the bottom of each transverse barrier plate, the absorption assembly comprises a transverse box body fixed on the inner wall of the treatment box body, and a relay pipe is fixed at one end of the transverse box body; according to the device, the separated transverse barrier plates are used for separating wastewater, meanwhile, the treatment efficiency is improved, the absorption assembly is used for carrying out upper-layer treatment on the wastewater, the absorption treatment effect is better, use is flexible, regional separation exists between the absorption assembly and a lower straight sedimentation structure, mutual interference can be reduced when the wastewater is pumped out, and the treatment speed is not affected.

Description

Technical Field

[0001] The invention relates to an integrated device, in particular to an integrated device for pre-treating oil and gas field wastewater and a treatment method, belonging to the technical field of oil and gas field wastewater treatment. Background Art

[0002] During the exploitation of oil and gas fields, water in the formation will be carried to the ground as the exploitation progresses, especially in the later stages of oil field exploitation, the amount of water produced will increase, and during drilling and exploitation, a large amount of drilling fluid and water are required to cool the drill bit and facilitate the discharge of cuttings, etc. These waters will also become wastewater after use. Oil and gas field wastewater contains a large amount of petroleum substances and suspended solids, as well as some metal ions and various chemical agents. Therefore, if it is discharged directly, it will cause strong pollution to the environment, and it is not friendly to production equipment, affecting the healthy operation of the equipment.

[0003] For example, the Chinese invention patent document with application number CN202111232977.2 discloses an integrated device for pretreatment of oil and gas field wastewater, which integrates demulsification, gel breaking, coagulation, flocculation, oil separation, sedimentation, and flotation. It has highly integrated multiple functions, greatly improves the pretreatment effect of oil and gas wastewater, reduces equipment investment cost and floor space, and is easy to transport and install; hydraulic flocculation is carried out through baffles, which not only reduces power consumption, but also the through holes on the baffles can divide the colloidal block floccules to avoid large flocs clogging the tank body; oil substances first pass through the inclined plate oil separation sedimentation area, so that oils with a density greater than water are removed by sedimentation, and oils with a density less than water float naturally, and oils with a density closer to water are removed by subsequent flotation processes, with good oil removal effect, low energy consumption, and good effluent quality; the inclined plate oil separation sedimentation area can increase the sedimentation area and improve the sedimentation effect by setting an inclined plate, and the bottom of the inclined plate can be backwashed for automatic cleaning after sludge sedimentation.

[0004] The above document improves the sedimentation effect by using inclined plates, but using a large number of inclined plates will cause a complex structure and limit the flow rate of the liquid stored in the inclined plate oil separation sedimentation area, affecting the treatment efficiency.

[0005] For example, the Chinese invention patent application document with application number CN201510571147.0 discloses a method for deep treatment of oil and gas field wastewater, which includes the following steps: the first step is to physically pretreat the oil field wastewater; the second step is to sequentially perform anaerobic treatment and aerobic treatment; the third step is to perform electrochemical treatment and ozone treatment; the fourth step is to finally perform ultraviolet disinfection treatment. The present invention provides a method for deep treatment of oil and gas field wastewater, firstly, physically pretreating the wastewater to remove most of the petroleum substances and solid pollutants in the wastewater, thus creating conditions for the subsequent processes, then treating the pretreated wastewater by anaerobic and aerobic treatment to further reduce the organic content in the sewage, thus reducing the organic load of the subsequent treatment, and finally, by electrochemical treatment and ozone treatment, further degrading various pollutants in the wastewater, and then after disinfection, the wastewater can be directly discharged or injected back into the oil field.

[0006] In order to further improve production efficiency and facilitate the addition of chemical reagents to wastewater, it is convenient for subsequent treatment processes.

[0007] In view of this, the present invention is proposed. Summary of the invention

[0008] The purpose of the present invention is to provide an integrated oil and gas field wastewater pretreatment device and treatment method in order to solve the above-mentioned problems, which can better carry out comprehensive treatment of wastewater. In the treatment box, various dosing pipes can be used to conveniently add chemicals, and separated horizontal baffles can be used to separate the wastewater, while improving the treatment efficiency. Each absorption component can perform upper layer treatment on the wastewater, and the absorption treatment effect is better and flexible to use. There is regional separation with the lower direct sedimentation structure, which can also reduce mutual interference when pumping out wastewater without affecting the treatment speed.

[0009] The present invention achieves the above-mentioned purpose through the following technical scheme: an integrated device for pre-treatment of oil and gas field wastewater, including a treatment box, a water inlet and a ventilation pipe opening are provided on the top of the treatment box, the water inlet needs to be connected to a water pumping device for receiving wastewater, the water pumping device needs to adjust the water pumping amount according to the single treatment capacity in the treatment box, the ventilation pipe opening needs to be connected to an air pressure control device, and the functions of air replenishment and air pumping and pressure reduction are performed when necessary, the bottom of the treatment box is provided with a direct sedimentation structure, the direct sedimentation structure is used to directly receive solids that are deposited due to gravity, and the inner walls of the treatment box are fixed with a gas pressure control device. There is a transverse blocking plate, which is provided with leakage holes, and there are at least three transverse blocking plates. An absorption component is provided above the processing box body, and a closing mechanism for closing the leakage holes is provided at the bottom of the transverse blocking plate. The closing mechanism, the absorption component and the transverse blocking plate are arranged correspondingly. The absorption component includes a transverse box body fixed on the inner wall of the processing box body, and a relay pipe is fixed at one end of the transverse box body. The relay pipe extends outside the processing box body and is connected to an oil drain pipe. The oil drain pipe needs to be connected to an external water pump. A power connector is provided on one side of the processing box body through a power cord.

[0010] Furthermore, in order to facilitate the absorption and discharge of floating objects after they are generated and accumulated on the upper layer of wastewater, absorption holes are opened on both side walls of the horizontal box body, and the horizontal box body is arranged to avoid the bottom of the water inlet pipe mouth. An opening and closing mechanism for blocking the absorption holes is installed in the horizontal box body.

[0011] Furthermore, in order to facilitate the control of the closing and opening of the absorption hole, the opening and closing mechanism includes a blocking shell that is slidably engaged on the inner wall of the horizontal box body, and a passage is provided on the outer wall of the blocking shell. A conversion cylinder is fixed on the outer wall of the processing box body, and one end of the conversion cylinder passes through the processing box body and the horizontal box body, and is connected to one end of the blocking shell. A distance is left between one end of the blocking shell and one end of the horizontal box body, and the side wall of the blocking shell is in contact with the inner wall of the horizontal box body.

[0012] Furthermore, in order to facilitate the addition of various reagents into the wastewater, a dosing device is provided at the bottom of the horizontal shell, and the dosing device includes a dosing pipe fixed at the bottom of the horizontal shell, one end of the dosing pipe extends outside the treatment box body, and the dosing pipe is provided with a bent portion for avoiding the conversion cylinder, and a spray branch pipe is fixed on the side wall of the dosing pipe, one end of the spray branch pipe extends obliquely downward, and a spray hole is provided at the end of the spray branch pipe.

[0013] Furthermore, in order to facilitate the control of the opening and closing of the leakage hole, the waste water can be retained above the horizontal baffle plate when closed, and the closing mechanism includes limit blocks fixed on both sides of the bottom of the horizontal baffle plate, and the limit blocks are provided with limit grooves, and a bottom blocking plate is slidably engaged in the limit grooves, and a strip-shaped through hole is provided on the bottom blocking plate. A side thrust ear plate is fixed on one side of the bottom blocking plate, and a side thrust cylinder is fixed on the outer wall of the treatment box body, and one end of the side thrust cylinder and the side thrust ear plate are fixed to each other.

[0014] Furthermore, in order to facilitate the sedimentation and discharge of solid matter, the direct sedimentation structure includes an inverted cone shell fixed to the bottom of the treatment box, a stabilizing shell is fixed to the bottom of the inverted cone shell, the bottom of the stabilizing shell is connected to a waste discharge pipe, a support column is fixed to the bottom of the inverted cone shell, an internal vertical plate group is fixed on the inner wall of the stabilizing shell, and an extraction mechanism is provided on one side of the inverted cone shell, which can extract the pre-treated wastewater.

[0015] Furthermore, in order to prevent solid matter from being extracted, the extraction mechanism includes an extraction channel connected to the inverted cone shell, the top of the extraction channel extends obliquely upward, one end of the extraction channel is provided with an extraction pipe mouth, and an oblique baffle is fixed between the inner walls of the extraction channel.

[0016] A method for pre-treating wastewater from oil and gas fields, S1: isolating solids: collecting wastewater from the oil and gas fields, placing the collected wastewater in a fixed sedimentation tank or using filtering equipment for solid removal treatment, and then performing sedimentation and filtration to remove large solids, thereby reducing the treatment intensity of the equipment and avoiding damage to the equipment;

[0017] S2: stirring reaction: the wastewater except solids is introduced into the treatment box body, the time interval is 5 minutes, and the water level reaches the top of the horizontal box body, and then chemical reagents are added to the wastewater, and the wastewater passes through the horizontal baffles for stirring. The reagents discharged by the dosing pipes at different heights are different. The side thrust cylinder controls the fall of the wastewater. The wastewater can be stirred when passing through each horizontal baffle. At the same time, when the wastewater leaks, high-pressure gas can be introduced into the ventilation pipe port to assist the wastewater to leak. Similarly, the dosing pipe can be used to introduce gas into the treatment box body, and the gas can be used to assist the stirring of the wastewater;

[0018] S3: Remove floating objects: After the wastewater reacts with chemical reagents, it floats on the surface. The oil layer is absorbed by the horizontal box body, and the oil layer and floating objects are discharged. The upper oil layer and floating objects are coordinated by the water inlet and the extraction mechanism, so that the horizontal box body can completely suck out the floating objects. Specifically, the amount of wastewater added and the amount of wastewater extracted are coordinated and controlled;

[0019] S4: Solid deposition: The wastewater with sediment is deposited in the inverted cone shell and the internal vertical plate group, and the solids finally fall into the waste pipe;

[0020] S5: Wastewater extraction: The treated wastewater is led to the extraction channel. When the wastewater flows, the solid matter at the bottom can be blocked by the inclined baffle to further prevent the solid matter from being sucked out.

[0021] Furthermore, in order to facilitate the treatment of wastewater, the chemical reagents include polyaluminium chloride, dodecyldimethylbenzyl ammonium chloride, chromate, hydrogen peroxide and scale inhibitors. Polyaluminium chloride is used as a flocculant to facilitate the precipitation of substances. Dodecyldimethylbenzyl ammonium chloride is used as a bactericide to avoid environmental pollution. Chromate is used as a corrosion inhibitor to protect the inner wall of the equipment. Hydrogen peroxide is used to remove organic matter in the wastewater and reduce the chemical oxygen demand. The scale inhibitor is used to prevent mineral scaling in the wastewater.

[0022] The technical effects and advantages of the present invention are as follows: the device can better carry out comprehensive treatment of wastewater, each dosing pipe can be used to conveniently add chemicals in the treatment box, and the separated horizontal baffle plates can be used to separate the wastewater, while improving the treatment efficiency. Each absorption component can perform upper layer treatment on the wastewater, the absorption treatment effect is better, and it is flexible to use. There is regional separation with the direct sedimentation structure at the bottom, which can also reduce mutual interference when pumping out the wastewater without affecting the treatment speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0024] Figure 2 It is a schematic diagram of the internal structure of the processing box of the present invention;

[0025] Figure 3 It is a schematic diagram of the structure of the absorption component of the present invention;

[0026] Figure 4 It is a schematic diagram of the opening and closing mechanism structure of the present invention;

[0027] Figure 5 It is a schematic diagram of the bottom blocking plate structure of the present invention;

[0028] Figure 6 for Figure 5 A schematic diagram of the enlarged structure at A in the middle;

[0029] Figure 7 It is a schematic diagram of the structure of the internal vertical plate group of the present invention;

[0030] Figure 8 is a flow chart of the method of the present invention;

[0031] In the figure: 1. treatment box; 101. water inlet; 102. ventilation pipe; 103. horizontal blocking plate; 104. leakage hole; 2. straight sedimentation structure; 201. inverted cone shell; 202. stabilizing shell; 203. waste pipe; 204. internal vertical plate group; 3. absorption component; 301. horizontal box; 302. relay pipe; 303. oil discharge pipeline; 304. absorption hole; 4. closing machine Structure; 401, limit block; 402, bottom blocking plate; 403, side push ear plate; 404, side push cylinder; 5, opening and closing mechanism; 501, blocking shell; 502, passage; 503, conversion cylinder; 6, dosing device; 601, dosing pipe; 602, bending part; 603, spray branch pipe; 7, extraction mechanism; 701, extraction channel; 702, extraction pipe mouth; 703, inclined baffle. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0033] See also Figure 1-Figure 7 As shown, an integrated device for pre-treatment of wastewater from oil and gas fields comprises a treatment box 1, a water inlet port 101 and a ventilation port 102 are provided on the top of the treatment box 1, the water inlet port 101 needs to be connected to a water pumping device for receiving wastewater, the water pumping device needs to adjust the water pumping amount according to the single treatment capacity in the treatment box 1, the ventilation port 102 needs to be connected to an air pressure control device for performing the functions of air replenishment and air pumping and pressure reduction when necessary, a direct sedimentation structure 2 is provided at the bottom of the treatment box 1, the direct sedimentation structure 2 is used to directly receive solids that are deposited due to gravity, and a horizontal baffle plate 103 is fixed between the inner walls of the treatment box 1, and the horizontal baffle plate A leakage hole 104 is opened on 103, at least three transverse baffles 103 are provided, an absorption component 3 is provided above the processing box body 1, and a closing mechanism 4 for closing the leakage hole 104 is provided at the bottom of the transverse baffle 103. The closing mechanism 4 and the absorption component 3 and the transverse baffle 103 are arranged correspondingly. The absorption component 3 includes a transverse box body 301 fixed on the inner wall of the processing box body 1, and a relay pipe 302 is fixed at one end of the transverse box body 301. The relay pipe 302 extends to the outside of the processing box body 1 and is connected with an oil discharge pipe 303. The oil discharge pipe 303 needs to be connected with an external water pump. A power connector is provided on one side of the processing box body 1 through a power cord.

[0034] Absorption holes 304 are provided on both side walls of the horizontal box body 301, and the horizontal box body 301 is arranged to avoid the bottom of the water inlet pipe 101. An opening and closing mechanism 5 for blocking the absorption holes 304 is installed in the horizontal box body 301, so that floating objects can be easily absorbed and discharged after they are generated and accumulated on the upper layer of wastewater.

[0035] The opening and closing mechanism 5 includes a blocking shell 501 which is slidably engaged with the inner wall of the horizontal box body 301, and a passage 502 is provided on the outer wall of the blocking shell 501. A conversion cylinder 503 is fixed on the outer wall of the processing box body 1. One end of the conversion cylinder 503 passes through the processing box body 1 and the horizontal box body 301, and is connected to one end of the blocking shell 501. There is a distance between one end of the blocking shell 501 and one end of the horizontal box body 301, and the side wall of the blocking shell 501 fits with the inner wall of the horizontal box body 301, so that the closing and opening of the absorption hole 304 can be easily controlled.

[0036] A dosing device 6 is provided at the bottom of the horizontal shell, and the dosing device 6 includes a dosing pipe 601 fixed at the bottom of the horizontal shell, one end of the dosing pipe 601 extends to the outside of the treatment box 1, and a bending portion 602 is provided on the dosing pipe 601 to avoid the conversion cylinder 503. A spray branch pipe 603 is fixed on the side wall of the dosing pipe 601, one end of the spray branch pipe 603 extends obliquely downward, and a spray hole is provided at the end of the spray branch pipe 603, so that various reagents can be easily added to the wastewater.

[0037] The closing mechanism 4 includes a limit block 401 fixed on both sides of the bottom of the horizontal blocking plate 103, and a limit groove is provided on the limit block 401. A bottom blocking plate 402 is slidably connected in the limit groove. The bottom blocking plate 402 is provided with a strip-shaped through hole, and a side push ear plate 403 is fixed on one side of the bottom blocking plate 402. A side push cylinder 404 is fixed on the outer wall of the processing box body 1, and one end of the side push cylinder 404 and the side push ear plate 403 are fixed to each other, so that it is convenient to control the opening and closing of the leakage hole 104, and the wastewater can be retained above the horizontal blocking plate 103 when closed.

[0038] The direct sedimentation structure 2 includes an inverted cone shell 201 fixed at the bottom of the treatment box 1, a stabilizing shell 202 is fixed at the bottom of the inverted cone shell 201, a waste discharge pipe 203 is connected to the bottom of the stabilizing shell 202, a support column is fixed at the bottom of the inverted cone shell 201, an internal vertical plate group 204 is fixed on the inner wall of the stabilizing shell 202, and an extraction mechanism 7 is provided on one side of the inverted cone shell 201, and the extraction mechanism 7 can extract the pre-treated wastewater, which can facilitate the deposition and discharge of solids.

[0039] The extraction mechanism 7 includes an extraction channel 701 connected to the inverted cone shell 201. The top of the extraction channel 701 extends obliquely upward. An extraction pipe mouth 702 is provided at one end of the extraction channel 701. An oblique baffle 703 is fixed between the inner walls of the extraction channel 701 to prevent solid matter from being extracted.

[0040] See also Figure 8 As shown, the pretreatment method of oil and gas field wastewater, solid isolation: collect oil and gas field wastewater, the collected wastewater can be placed in a fixed sedimentation tank or use filtering equipment for solid removal treatment, and then precipitate and filter to remove large solids, which can reduce the treatment intensity of the equipment and avoid damage to the equipment, stirring reaction: the wastewater without solids is passed into the treatment box 1, the time interval is 5 minutes, and the water level reaches the top of the horizontal box body 301, and then chemical reagents are added to the wastewater. The wastewater passes between the horizontal baffles 103 for stirring. The dosing pipes 601 at different heights discharge different agents. The side thrust cylinder 404 controls the fall of the wastewater. The wastewater can be stirred when passing through each horizontal baffle 103. At the same time, when the wastewater leaks, high-pressure gas can be passed into the ventilation pipe port 102 to assist the wastewater to leak. Similarly, the dosing pipe 601 can be used to introduce gas into the treatment box 1, and the gas can be used to assist in stirring the wastewater to remove floating objects: after the wastewater reacts with the chemical reagent, it floats on the top, and the horizontal box body 301 is used to absorb the oil layer and discharge the oil layer and floating objects. The upper oil layer and floating objects are coordinated with the water inlet port 101 and the extraction mechanism 7, so that the horizontal box body 301 can completely suck out the floating objects, specifically, the amount of wastewater added and the amount of wastewater extracted are coordinated and controlled. Solid deposition: the wastewater with sediment is deposited at the inverted cone shell 201 and the internal vertical plate group 204, and the solid matter finally falls into the waste discharge pipe 203. Wastewater extraction: the treated wastewater is led to the extraction channel 701. When the wastewater flows, the solid matter at the bottom can be blocked by the inclined baffle 703 to further prevent the solid matter from being sucked out.

[0041] Chemical reagents include polyaluminium chloride, dodecyldimethylbenzyl ammonium chloride, chromate, hydrogen peroxide and scale inhibitors. Polyaluminium chloride as a flocculant is beneficial to the precipitation of substances. Dodecyldimethylbenzyl ammonium chloride is used as a bactericide to avoid environmental pollution. Chromate is used as a corrosion inhibitor to protect the inner wall of the equipment. Hydrogen peroxide is used to remove organic matter in wastewater and reduce chemical oxygen demand. Scale inhibitors are used to prevent mineral scaling in wastewater, which makes it easier to treat wastewater.

[0042] The present device can better carry out comprehensive treatment of wastewater. In the treatment box 1, each dosing tube 601 can be used to conveniently add chemicals, and the separated horizontal baffle plates 103 can be used to separate the wastewater, while improving the treatment efficiency. Each absorption component 3 can perform upper layer treatment on the wastewater, and the absorption treatment effect is better and flexible to use. There is a regional separation with the lower direct sedimentation structure 2, which can also reduce mutual interference when pumping out the wastewater without affecting the treatment speed.

[0043] When in use, the wastewater first enters the top of the horizontal blocking plate 103. At this time, the side push cylinder 404 can push the bottom blocking plate 402 to make the strip-shaped through holes detach from the corresponding leakage holes 104, and then the oil discharge pipe 303 and the negative pressure source can be connected. Then the floating layer can be drawn out by the absorption hole 304 on the horizontal box body 301. When the wastewater is injected, the conversion cylinder 503 can control the movement of the blocking shell 501 to make the blocking shell 501 block the absorption hole 304. At the same time, the wastewater can also be flexibly treated, specifically, the wastewater is gradually leaked down and then the chemical agent is introduced through the dosing pipe 601, and then the wastewater is filled on the two layers of the horizontal blocking plates 103, and the floating objects are removed by the absorption component 3 above.

[0044] After adding the flocculant, precipitates will appear, and the precipitates can pass through the internal vertical plate group 204 and then be pumped out by the waste pipe 203, and the treated wastewater can be gradually led out by the pumping channel 701 to complete the pretreatment.

[0045] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0046] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An integrated device for pre-treatment of oil and gas field wastewater, comprising a treatment box (1), wherein a water inlet (101) and a ventilation pipe (102) are provided on the top of the treatment box (1), characterized in that: A straight settling structure (2) is provided at the bottom of the processing box (1); a transverse blocking plate (103) is fixed between the inner walls of the processing box (1); a leakage hole (104) is opened on the transverse blocking plate (103); at least three transverse blocking plates (103) are provided; an absorption component (3) is provided above the processing box (1); a closing mechanism (4) for closing the leakage hole (104) is provided at the bottom of the transverse blocking plate (103); the absorption component (3) comprises a transverse box body (301) fixed on the inner wall of the processing box (1); a relay pipe (302) is fixed at one end of the transverse box body (301); the relay pipe (302) extends to the outside of the processing box (1) and is connected to the oil discharge pipe (303); a power connector is provided on one side of the processing box (1) through a power cord.

2. The integrated device for pretreatment of oil and gas field wastewater according to claim 1, characterized in that: Both side walls of the transverse box body (301) are provided with absorption holes (304), the transverse box body (301) is arranged to avoid the lower side of the water inlet pipe (101), and an opening and closing mechanism (5) for blocking the absorption holes (304) is installed in the transverse box body (301).

3. The integrated device for pretreatment of oil and gas field wastewater according to claim 2, characterized in that: The opening and closing mechanism (5) comprises a blocking shell (501) slidably engaged with the inner wall of the horizontal box body (301), a passage opening (502) being provided on the outer wall of the blocking shell (501), a conversion cylinder (503) being fixed on the outer wall of the processing box body (1), one end of the conversion cylinder (503) passing through the processing box body (1) and the horizontal box body (301), and being connected to one end of the blocking shell (501).

4. The integrated device for pretreatment of oil and gas field wastewater according to claim 3 is characterized in that: A dosing device (6) is provided at the bottom of the transverse shell, and the dosing device (6) comprises a dosing pipe (601) fixed at the bottom of the transverse shell, one end of the dosing pipe (601) extends to the outside of the processing box (1), and the dosing pipe (601) is provided with a bent portion (602) for avoiding the conversion cylinder (503), and a spray branch pipe (603) is fixed on the side wall of the dosing pipe (601).

5. The integrated device for pretreatment of oil and gas field wastewater according to claim 1, characterized in that: The closing mechanism (4) comprises limit blocks (401) fixed on both sides of the bottom of the horizontal blocking plate (103), the limit blocks (401) are provided with limit grooves, a bottom blocking plate (402) is slidably engaged in the limit grooves, the bottom blocking plate (402) is provided with strip-shaped through holes, a side push ear plate (403) is fixed on one side of the bottom blocking plate (402), a side push cylinder (404) is fixed on the outer wall of the processing box (1), and one end of the side push cylinder (404) and the side push ear plate (403) are fixed to each other.

6. The integrated device for pre-treatment of oil and gas field wastewater according to claim 1, characterized in that: The direct sedimentation structure (2) comprises an inverted cone shell (201) fixed to the bottom of the processing box (1), a stabilizing shell (202) is fixed to the bottom of the inverted cone shell (201), the bottom of the stabilizing shell (202) is connected to a waste discharge pipe (203), a supporting column is fixed to the bottom of the inverted cone shell (201), an internal vertical plate group (204) is fixed on the inner wall of the stabilizing shell (202), and a pull-out mechanism (7) is provided on one side of the inverted cone shell (201).

7. The integrated device for pre-treatment of oil and gas field wastewater according to claim 6, characterized in that: The extraction mechanism (7) comprises an extraction channel (701) connected to the inverted cone shell (201), the top of the extraction channel (701) extends obliquely upward, one end of the extraction channel (701) is provided with an extraction pipe opening (702), and an oblique baffle (703) is fixed between the inner walls of the extraction channel (701).

8. A method for pretreatment of oil and gas field wastewater, based on the pretreatment method of the integrated device according to any one of claims 1 to 7, characterized in that: S1: Isolation of solids: The oil and gas field wastewater is collected and then precipitated and filtered to remove large solids; S2: stirring reaction: the wastewater except solids is passed into the treatment box (1) at a time interval of 5 minutes, until the water level reaches the top of the horizontal box (301), and then chemical reagents are added to the wastewater. The wastewater passes between the horizontal baffles (103) for stirring. The reagents discharged from the dosing pipes (601) at different heights are different, and the side thrust cylinder (404) controls the fall of the wastewater; S3: Removal of floating objects: After the wastewater reacts with the chemical reagent, it floats on the surface. The oil layer is absorbed by the horizontal box (301) to discharge the oil layer and floating objects; S4: Solid deposition: The wastewater with sediment is deposited on the inverted cone shell (201) and the internal vertical plate group (204), and the solids finally fall into the waste discharge pipe (203); S5: Wastewater extraction: The treated wastewater is led to the extraction channel (701). When the wastewater flows, the solid matter at the bottom can be blocked by the inclined baffle (703), further preventing the solid matter from being sucked out.

9. The method for pretreating oil and gas field wastewater according to claim 8, characterized in that: The chemical reagents include polyaluminium chloride, dodecyldimethylbenzyl ammonium chloride, chromate, hydrogen peroxide and antiscalant.

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