Gas field produced water treatment device

Abstract

The utility model discloses a gas field produced water treatment device, and relates to the technical field of water treatment equipment. The gas field produced water treatment device comprises a jet device, an aeration oxidation pond, a booster pump, a silicon carbide filtering assembly, a backwashing water tank, a cleaning water pump, a cleaning water tank, a scale inhibitor dosing tank, a scale inhibitor dosing pump, a pipeline mixer and a compressed air storage tank, wherein the jet device is arranged at the liquid inlet end of the aeration oxidation pond, the liquid outlet end of the aeration oxidation pond is communicated and connected with the silicon carbide filtering assembly through the booster pump, and the output end of the silicon carbide filtering assembly is communicated and connected with the input end of the backwashing water tank, the input end of the cleaning water tank and the input end of the pipeline mixer. The utility model has the advantages of no need of flocculation dosing, high filtering efficiency, less self-water consumption, stable and excellent effluent, small occupied area, low operation cost, less sludge amount and high automation degree.

Description

Technical Field

[0001] The utility model relates to the technical field of water treatment equipment, in particular to a device for treating produced water in a gas field. Background Art

[0002] The low-cost, safe and efficient disposal of produced water from gas fields has become the main factor restricting the stable and increased production of natural gas in my country. Solving the problem of water disposal in gas field development is of great significance to ensuring national energy security. Natural gas has contributed low-carbon and clean energy to my country's economic and social development, but the "flood" of gas fields has become the top problem in natural gas development, which is mainly reflected in the water production of gas wells. Most of the gas fields distributed in the four basins are facing a sharp increase in water production in gas fields, especially in the peak period of gas production in winter. The increase in water production in gas fields means that the natural gas recovery rate will be greatly reduced, the intensity of measures and expenses for implementing drainage and gas production will increase, the investment and energy consumption of produced water treatment in gas fields will increase, and some high-water-content wells will be forced to shut down. There are 7 major onshore wells in my country. Large oil and gas basins, among which natural gas is mainly distributed in the Sichuan Basin, Ordos Basin, Tarim Basin and Qaidam Basin. In 2021, the natural gas production of the four basins accounted for about 80% of the country's total natural gas production. As the largest oil and gas production and supply company in China, China National Petroleum Corporation, the natural gas production of the four basins accounted for 87% of its total domestic natural gas production in 2021. my country's gas reservoir types are diverse, and the geological, geomorphological, hydrological and climatic conditions are complex and changeable. The gas field produced water (raw water) reinjection treatment method is an important way to reduce environmental pollution and improve the economic benefits of oil fields during gas field development. With the increasing attention of national and local environmental protection departments to environmental protection issues, the treatment of produced water is inevitable in the current production process of gas fields.

[0003] For gas field produced water with high mineralization, oil, iron ions, high hardness, high alkalinity and other characteristics, the current conventional treatment process is sedimentation + filtration. After (multi-stage) natural or flocculation sedimentation, (multi-stage) filtration, flotation and other process treatments, the suspended matter concentration and oil content in the water are still exceeded, and the reinjection transmission pipeline is seriously scaled, which seriously affects the environment and production. At the same time, the fluctuation of water quality of gas field produced water, the addition of flocculants + lime hardness removal + acid and alkali agents, lead to high operating costs, large amounts of mud, and many control and maintenance points, which pose challenges to personnel, processes, equipment operation management, and sludge disposal. Therefore, we proposed a gas field produced water treatment device to solve the above-mentioned problems. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides a produced water treatment device for a gas field, which solves the problem of produced water, reduces pollution, reduces energy consumption and costs, and ensures the long-term stable and efficient development of the gas field.

[0005] To achieve the above purpose, the utility model is implemented through the following technical solutions: a device for treating produced water in a gas field, comprising an ejector, an aeration oxidation tank, a booster pump, a silicon carbide filter assembly, a backwash water tank, a cleaning water pump, a cleaning water tank, an antiscalant dosing box, an antiscalant dosing pump, a pipeline mixer and a compressed air storage tank;

[0006] The ejector is arranged at the liquid inlet end of the aeration oxidation tank, the liquid outlet end of the aeration oxidation tank is conductively connected to the silicon carbide filter assembly through a booster pump, and the output end of the silicon carbide filter assembly is conductively connected to the input end of the backwash water tank, the input end of the cleaning water tank and the input end of the pipeline mixer;

[0007] A scale inhibitor dosing box is provided on one side of the cleaning water tank, and the output end of the scale inhibitor dosing box is conductively connected to the pipeline mixer through a scale inhibitor dosing pump;

[0008] The output end of the cleaning water tank is connected with a cleaning water pump.

[0009] Preferably, a branch fishbone-shaped air inlet pipe is arranged at the bottom of the aeration oxidation pond, and air holes are spaced apart at a downward angle of 45 degrees.

[0010] Preferably, the silicon carbide filter assembly uses a silicon carbide membrane for filtration and is equipped with air-water backwashing.

[0011] Preferably, the water backwashing adopts a pneumatic water backwashing device.

[0012] Beneficial Effects

[0013] The utility model provides a device for treating produced water in a gas field. Compared with the prior art, the utility model has the following beneficial effects:

[0014] The produced water treatment device for gas fields is provided with an ejector and an aeration oxidation pond so that oxygen and produced water are fully contacted and mixed, and iron ions in the water are oxidized. The iron ions in the water are separated from the water in a manner of being hydrolyzed to form solids, thereby reducing the addition of sodium hypochlorite or similar oxidizing agents, reducing the operating cost, and not adding ions to the water. The device is filtered through a silicon carbide ceramic membrane with high filtration accuracy and good effect. The self-consumption of water for air pressure backwashing is small, the concentration of suspended solids in backwashing drainage is high, and no coagulant needs to be added. The operating cost is low and the amount of mud is small. Scaling is reduced by adding a scale inhibitor, and pipeline blockage can be effectively avoided or alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the system principle diagram of the device of the utility model.

[0016] In the figure: 1. Ejector; 2. Aeration oxidation tank; 3. Booster pump; 4. Silicon carbide filter assembly; 5. Backwash water tank; 6. Cleaning water pump; 7. Cleaning water tank; 8. Antiscalant dosing box; 9. Antiscalant dosing pump; 10. Pipeline mixer; 11. Compressed air storage tank. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] See also Figure 1 The utility model provides a technical solution: a device for treating produced water in a gas field, comprising an ejector 1, an aeration oxidation tank 2, a booster pump 3, a silicon carbide filter assembly 4, a backwash water tank 5, a cleaning water pump 6, a cleaning water tank 7, a scale inhibitor dosing box 8, a scale inhibitor dosing pump 9, a pipeline mixer 10 and a compressed air storage tank 11; wherein the ejector 1 is arranged at the liquid inlet end of the aeration oxidation tank 2, the liquid outlet end of the aeration oxidation tank 2 is connected to the silicon carbide filter assembly 4 through the booster pump 3, the output end of the silicon carbide filter assembly 4 is connected to the input end of the backwash water tank 5, the input end of the cleaning water tank 7 and the input end of the pipeline mixer 10; a scale inhibitor dosing box 8 is arranged on one side of the cleaning water tank 7, and the output end of the scale inhibitor dosing box 8 is connected to the pipeline mixer 10 through the scale inhibitor dosing pump 9; the output end of the cleaning water tank 7 is connected to the cleaning water pump 6;

[0019] By setting up ejectors and aeration oxidation tanks, oxygen and produced water are fully contacted and mixed, and the iron ions in the water are oxidized. The iron ions in the water are separated from the water by hydrolysis to form solids, which reduces the addition of sodium hypochlorite or similar oxidizing agents, reduces operating costs, and does not add new ions to the water. It is filtered through silicon carbide ceramic membranes with high filtration accuracy and good effects. The air pressure backwashing consumes little water, and the backwash drainage has a high suspended solids concentration. There is no need to add coagulants, so the operating cost is low and the amount of mud is small. By adding scale inhibitors, scaling is reduced, which can effectively avoid or alleviate pipeline blockage.

[0020] See also Figure 1 A branch fishbone-shaped air inlet pipe is arranged at the bottom of the aeration oxidation tank 2, and air vents are arranged at intervals of 45 degrees downward. The air in the compressed air storage tank can be evenly aerated in the tank body through the air distribution pipe.

[0021] See also Figure 1The silicon carbide filter component 4 uses a silicon carbide membrane for filtration and is equipped with air-water backwashing. The water backwashing uses an air pressure water backwashing device. Compressed air is passed into the backwash water tank to provide power for the backwashing of the silicon carbide component. The water volume and water pressure are controlled by the tank pressure.

[0022] During operation, in the first step, the produced water from the gas field enters the aeration oxidation tank 2 after preliminary contact with oxygen in the compressed air through the pipeline ejector 1. The aeration oxidation tank 2 is provided with an aeration tank and a water outlet tank. In the aeration tank, the produced water contacts with the air in the uniformly distributed air pipeline at the bottom again. The divalent iron ions in the water undergo an oxidation-reduction reaction with oxygen and become trivalent iron ions. The water is hydrolyzed into solids and becomes solid suspended matter in the form of ions and gathers together. A floating oil collection pipeline is provided on the upper part of the liquid surface of the aeration tank, and the oil is discharged to the sludge collection tank regularly according to the water quality.

[0023] In the second step, the produced water after air mixing and aeration flows into the outlet pool of the aeration oxidation pool through the holes in the walls of the aeration pool and the collection pool; it is lifted by the booster pump 3 and enters the silicon carbide filter assembly 4;

[0024] In the third step, the produced water from the gas field is filtered through the silicon carbide ceramic membrane in the silicon carbide filter assembly 4, and the produced water is mixed with the scale inhibitor through the pipeline mixer, and the water is collected to the produced water return water;

[0025] In the fourth step, during the filtration process of the silicon carbide ceramic membrane, the pollutants trapped on the membrane surface are backwashed by air-water mixture, and then discharged into the sludge collection tank by the backwash water, wherein the compressed air in the compressed air storage tank 11 can directly enter the water production pipeline of the silicon carbide ceramic membrane for air-water backwashing; the compressed air in the compressed air storage tank 11 can enter the backwash water tank, provide the backwash water pressure, and control the backwash water volume, so as to backwash the silicon carbide ceramic membrane with water;

[0026] In the fifth step, when the flux recovery of the pollutants intercepted by the silicon carbide ceramic membrane does not meet the designed flux after backwashing, the silicon carbide ceramic membrane can be chemically cleaned to fully restore the membrane performance.

[0027] In summary, the device has the advantages of no need for flocculation and dosing, high filtration efficiency, low self-use water consumption, excellent stable water output, small footprint, low operating cost, small sludge volume and high degree of automation.

[0028] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A gas field produced water treatment device, characterized in that: It comprises an ejector (1), an aeration oxidation tank (2), a booster pump (3), a silicon carbide filter assembly (4), a backwash water tank (5), a cleaning water pump (6), a cleaning water tank (7), an antiscalant dosing box (8), an antiscalant dosing pump (9), a pipeline mixer (10) and a compressed air storage tank (11); The ejector (1) is arranged at the liquid inlet end of the aeration oxidation pond (2), the liquid outlet end of the aeration oxidation pond (2) is conductively connected to the silicon carbide filter assembly (4) via a booster pump (3), and the output end of the silicon carbide filter assembly (4) is conductively connected to the input end of the backwash water tank (5), the input end of the cleaning water tank (7) and the input end of the pipeline mixer (10); A scale inhibitor dosing box (8) is provided on one side of the cleaning water tank (7), and the output end of the scale inhibitor dosing box (8) is conductively connected to the pipeline mixer (10) via a scale inhibitor dosing pump (9); The output end of the cleaning water tank (7) is connected to a cleaning water pump (6).

2. A gas field produced water treatment device according to claim 1, characterized in that: A branch fishbone-shaped air intake pipe is arranged at the bottom of the aeration oxidation pond (2), and air vents are arranged at intervals of 45 degrees downward.

3. The produced water treatment device for a gas field according to claim 1, characterized in that: The silicon carbide filter assembly (4) uses a silicon carbide membrane for filtering and is equipped with air-water backwashing.

4. A gas field produced water treatment device according to claim 3, characterized in that: The water backwashing adopts a pneumatic water backwashing device.

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