Device for treating gas field produced water with oil content ranging from 30000mg / L to 300000mg / L

Abstract

The utility model relates to a gas field produced water treatment device with the oil content ranging from 30000 mg / L to 30000 mg / L, and relates to the technical field of produced water treatment. Comprising a pretreatment unit which is used for sequentially carrying out homogenization, demulsification and sedimentation treatment on gas field produced water and is provided with a sewage outlet and a sludge outlet; the sewage treatment unit is connected with the sewage outlet of the pretreatment unit; the sewage treatment adjusting unit is connected with the sewage treatment unit and is used for adjusting the sewage treatment speed according to the sewage content of the sewage outlet of the pretreatment unit; an inlet of the sludge treatment unit is connected with a sludge outlet of the pretreatment unit, and a sewage outlet of the sludge treatment unit is connected with an inlet of the sewage treatment unit. The device disclosed by the utility model can be used for treating the high-content oil and gas field produced water with the oil content of 30000-30000 mg / L in a targeted manner.

Description

Technical Field

[0001] This utility model relates to the field of produced water treatment technology, and in particular to a gas field produced water treatment device for oil content in the range of 30,000 mg / L to 300,000 mg / L. Background Technology

[0002] During gas well production, low acid flowback rates often result in residual acid fracturing fluid remaining in the formation. To increase well production and fully realize capacity, acid fracturing is typically used to modify the well network and develop reservoir fractures. During well production, residual formation fluid is carried to the surface with the gas and undergoes gas-liquid separation before entering subsequent processes. This fluid contains oil and bitumen-like impurities (injected fracturing fluid). To ensure the stable, full-capacity, and efficient operation of natural gas desulfurization units, it is necessary to treat and effectively utilize the produced water from the relevant oil and gas fields.

[0003] The related technology discloses a process and device for treating produced water from oil and gas fields to meet standards for reinjection. The process involves sequentially passing the produced water through sterilization, pH adjustment, addition of flocculants and coagulants, and flotation to purify the water. The device includes a sterilizer, a pipeline mixer, a flotation tank, and a sludge collection tank. These components are connected sequentially by pipelines, each with a drain outlet connected to the sludge collection tank. The sterilizer has a produced water inlet pipeline connected to its inlet, which is also connected to a first dosing tank. The pipeline mixer has a second dosing tank connected to its inlet. The flotation tank has a clear water tank and a dissolved air device connected to its outlet. The dissolved air device has a storage tank connected to its outlet, which is connected to a foamer connected to the inlet of the flotation tank.

[0004] However, the process systems for resource-based treatment of produced water from oil and gas fields provided by related technologies have problems such as poor treatment effect and high treatment cost for produced water from high-content oil and gas fields, such as oil content of 30,000 mg / L-300,000 mg / L. Utility Model Content

[0005] This invention provides a treatment device for produced water from gas fields with an oil content in the range of 30,000 mg / L to 300,000 mg / L. It can at least solve the problems of poor treatment effect and high treatment cost of the process system for resource utilization treatment of produced water from oil and gas fields provided by related technologies for high content, such as oil content of 30,000 mg / L to 300,000 mg / L in produced water from high-oil-content gas fields.

[0006] This utility model provides a gas field produced water treatment device for oil content in the range of 30,000 mg / L to 300,000 mg / L, comprising:

[0007] The pretreatment unit is used to homogenize, demulsify and settle the produced water from the gas field in sequence, and has a wastewater outlet and a sludge outlet.

[0008] A wastewater treatment unit is connected to the wastewater outlet of the pretreatment unit;

[0009] A wastewater treatment regulating unit, connected to the wastewater treatment unit, is used to adjust the wastewater treatment rate according to the wastewater content at the wastewater outlet of the pretreatment unit;

[0010] A sludge treatment unit, wherein the inlet of the sludge treatment unit is connected to the sludge outlet of the pretreatment unit, and the wastewater outlet of the sludge treatment unit is connected to the inlet of the wastewater treatment unit.

[0011] In one embodiment, the wastewater treatment regulating unit includes: a flow meter, a release pipe, and a control valve;

[0012] The release pipe is connected to the wastewater treatment unit;

[0013] The flow meter and the control valve are installed on the release pipe, and the flow meter is used to obtain the sewage inflow of the sewage treatment unit;

[0014] The control valve is used to open or close the release pipe according to the amount of sewage entering the sewage treatment unit.

[0015] In one embodiment, the wastewater treatment unit includes an air flotation device, which includes a dissolved air tank, and the wastewater treatment regulating unit is disposed above the dissolved air tank.

[0016] In one embodiment, the pretreatment unit includes: a homogenization unit, a demulsification unit, and a sedimentation unit connected in series;

[0017] The wastewater outlet of the sedimentation unit is connected to the wastewater treatment unit, and the sludge outlet is connected to the sludge treatment unit.

[0018] In one embodiment, the wastewater treatment unit further includes: a filter;

[0019] The filter inlet is connected to the demulsification unit, and the filter outlet is connected to the sedimentation unit.

[0020] In one embodiment, the demulsification unit includes a demulsifier and a flocculator connected in sequence, the demulsifier being connected to the homogenization unit and the flocculator being connected to the filter.

[0021] In one embodiment, the sludge treatment unit includes at least two sets of plate and frame filter presses;

[0022] The diameter of the filter plates in the first set of plate and frame filter presses is larger than the diameter of the filter plates in the second set of plate and frame filter presses, and the diameter of the filter plates in each set of plate and frame filter presses decreases sequentially from the inlet to the outlet of the plate and frame filter press.

[0023] In one embodiment, the sludge treatment unit further includes a sludge storage tank, the inlet of which is connected to the sludge outlet of the pretreatment unit, and the outlet of which is connected to the sludge outlet of the pretreatment unit.

[0024] In one embodiment, the system further includes a sludge collection tank connected to the sludge outlet of the sludge treatment unit.

[0025] In one implementation, the oil content in the treated gas field produced water is ≤30 mg / L.

[0026] Compared with existing technologies, the advantages of this invention are that the device provided can specifically address the treatment of produced water from high-oil-content gas fields (30,000 mg / L-300,000 mg / L). A pretreatment unit sequentially homogenizes, demulsifies, and settles the produced water. A wastewater treatment unit adjusts the treatment speed based on the oil content at the pretreatment unit's outlet. A sludge treatment unit treats the sludge. This invention treats produced water from gas fields with an oil content in the range of 30,000 mg / L-300,000 mg / L, indicating a high oil content. If the wastewater treatment speed is too fast, the treatment effect may be poor, and the oil may not be completely removed. Therefore, this invention uses a wastewater treatment unit to adjust the treatment speed based on the oil content at the pretreatment unit's outlet, ensuring complete treatment of the produced water while improving the treatment effect, and avoiding the negative impact of excessively fast influent flow rates. Attached Figure Description

[0027] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of the structure of a gas field produced water treatment device with an oil content in the range of 30,000 mg / L to 300,000 mg / L, as described in an embodiment of this utility model.

[0029] Figure label:

[0030] 1-Homogenization unit, 2-Demulsification unit, 3-Sedimentation unit, 4-Air flotation device, 5-Flow meter, 6-Release pipe, 7-Control valve, 8-Filter, 21-Demulsifier, 22-Flocculator, 9-Plate and frame filter press, 10-Sludge temporary storage tank, 11-Sludge collection tank. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] Please see Figure 1 This utility model provides a gas field produced water treatment device for oil content in the range of 30,000 mg / L to 300,000 mg / L, including: a pretreatment unit, a wastewater treatment unit, a wastewater treatment conditioning unit, and a sludge treatment unit.

[0033] The pretreatment unit is used to homogenize, demulsify, and settle the produced water from the gas field in sequence, and has a wastewater outlet and a sludge outlet; the wastewater treatment unit is connected to the wastewater outlet of the pretreatment unit; the wastewater treatment regulation unit is connected to the wastewater treatment unit and is used to adjust the wastewater treatment rate according to the wastewater content at the wastewater outlet of the pretreatment unit; the inlet of the sludge treatment unit is connected to the sludge outlet of the pretreatment unit, and the wastewater outlet of the sludge treatment unit is connected to the inlet of the wastewater treatment unit.

[0034] The device provided by this invention can specifically address the treatment of produced water from high-oil-content gas fields (30,000 mg / L-300,000 mg / L). A pretreatment unit sequentially homogenizes, demulsifies, and settles the produced water. A wastewater treatment unit adjusts the treatment speed based on the oil content at the pretreatment unit's outlet. A sludge treatment unit treats the sludge. This embodiment of the invention treats produced water from gas fields with an oil content in the range of 30,000 mg / L-300,000 mg / L, indicating a very high oil content. If the wastewater treatment speed is too fast, the treatment effect may be poor, and the oil may not be completely removed. Therefore, this embodiment of the invention uses a wastewater treatment unit to adjust the treatment speed based on the oil content at the pretreatment unit's outlet, ensuring complete treatment of the produced water while improving the treatment effect, and avoiding the negative impact of excessively fast influent flow rates.

[0035] The produced water from the gas field treated according to this embodiment of the invention achieved actual values ​​for pH 7.61, suspended solids 12.92%, oil content 17.38%, and median particle size 2.80μm. All four indicators are superior to the requirements of the "Design Specification for Water Treatment and Reinjection Engineering of High-Sulfur Gas Fields" (SY / T 6881-2012). Its application in a series of desulfurization stations in the Western Sichuan Gas Field has proven feasible.

[0036] After treatment according to this embodiment of the utility model, the produced water from the gas field can be reinjected. Before treatment, the hazardous waste cost 2300 yuan per cubic meter. After treatment, each cubic meter of water produces 10% hazardous waste and 90% reinjected water, with reinjection costing 300 yuan per cubic meter. The cost savings per cubic meter of reinjection are 2300 - (2300 * 10% + 300 * 90%) = 1800 yuan, resulting in considerable economic benefits throughout the entire life cycle.

[0037] The device of this utility model embodiment reduces the amount of hazardous waste and "turns waste into treasure". It can process (with less generation) 200 cubic meters of hazardous waste per day * 330 days = 66,000 cubic meters per year, which has practical significance and promotion value for environmental protection.

[0038] In one optional embodiment, the pretreatment unit includes: a homogenization unit 1, a demulsification unit 2, and a sedimentation unit 3 connected in series; the wastewater outlet of the sedimentation unit 3 is connected to the wastewater treatment unit, and the sludge outlet is connected to the sludge treatment unit.

[0039] This embodiment of the invention homogenizes produced water from gas fields using a homogenization unit 1. This homogenization unit 1 can be a gas field water receiving tank. The produced water is placed in the tank, and homogenization is achieved through extensive aeration, breaking down the gel in the system and using microbubbles to remove petroleum contaminants and a large amount of suspended solids. Homogenization of the gas field water removes suspended solids and colloidal substances, thereby improving water quality and reducing the impact on subsequent treatment processes. Through homogenization, the suspended solids content in the produced water can be effectively reduced, improving the transparency and stability of the wastewater and providing better conditions for subsequent treatment processes.

[0040] This embodiment of the invention uses a demulsification unit 2 to demulsify produced water from a gas field. This demulsification unit 2 enables efficient demulsification, sedimentation, and oil-water separation of the produced water, thereby increasing oil and gas production and reducing environmental pollution. For example, the demulsification unit 2 can employ a tubular electrocoagulation demulsification device. Utilizing the special structure of the electrocoagulation reactor, the interaction between the electrode plates and the acoustic field promotes the demulsification and aggregation of emulsified oil droplets.

[0041] In this embodiment of the utility model, the gas field produced water is treated by sedimentation unit 3. For example, sedimentation unit 3 can be a sedimentation tank, in which the gas field produced water is introduced for sedimentation.

[0042] In one optional embodiment, the wastewater treatment regulating unit includes: a flow meter 5, a release pipe 6, and a control valve 7; the release pipe 6 is connected to the wastewater treatment unit; the flow meter 5 and the control valve 7 are disposed on the release pipe 6, the flow meter 5 is used to obtain the wastewater inflow of the wastewater treatment unit; the control valve 7 is used to open or close the release pipe 6 according to the wastewater inflow of the wastewater treatment unit.

[0043] In this embodiment of the invention, the wastewater inflow rate of the wastewater treatment unit is obtained by the flow meter 5. When the wastewater inflow rate of the wastewater treatment unit is greater than the preset inflow rate, for example, greater than 1000 ml / min, the wastewater inflow rate may be too large and thus affect the treatment effect. Therefore, the release pipe 6 is opened by the control valve 7 to release the excess gas field produced water. When the wastewater inflow rate of the wastewater treatment unit is less than the preset inflow rate, for example, less than 1000 ml / min, the release pipe 6 is closed by the control valve 7, and the wastewater treatment unit continues to process the wastewater.

[0044] For example, the release pipe 6 can be installed at the bottom of the wastewater treatment unit. When the inflow of produced water from the gas field is greater than the preset inflow, the release pipe 6 can be opened to release the water.

[0045] In one optional embodiment, the wastewater treatment unit includes an air flotation device 4, which includes a dissolved air tank, and a wastewater treatment regulating unit is disposed above the dissolved air tank.

[0046] It should be noted that the air flotation device 4 introduces air into the produced water of the gas field in the form of microbubbles, so that the microbubbles adhere to the suspended particles in the produced water of the gas field, forming a three-phase mixed system of water-air-particles. After the particles adhere to the air bubbles, their density is less than that of water, so they float to the surface of the water, forming a scum layer, which is then separated from the water.

[0047] The existing air flotation device 4 includes a dissolved air system, a release system, an air flotation tank, and a sludge scraping system. The dissolved air system dissolves air in the produced water from the gas field stored in a tank under pressure, and then releases microbubbles under reduced pressure. The release system, located at the bottom of the tank, releases the dissolved air from the produced water under reduced pressure to form microbubbles. The air flotation tank, located at the top of the tank, allows the bubbles to adhere to suspended particles, forming air-laden particles with a density lower than that of the produced water, which then float to the surface, achieving solid-liquid separation. The sludge scraping system, also located at the top of the tank, uses mechanical devices to scrape away suspended matter floating on the surface, completing the solid-liquid separation.

[0048] In existing dissolved gas systems, a dissolved gas tank is included. In this embodiment of the invention, a wastewater treatment regulating unit is provided above the dissolved gas tank. Furthermore, this embodiment of the invention includes a release pipe 6 in the dissolved gas tank, and a flow meter 5 and a control valve 7 are installed on the release pipe 6. By controlling the dissolved gas rate of the dissolved gas tank, the gas-liquid ratio is adjusted, that is, the rate at which the dissolved gas is released and the rate at which the gas field produced water enters the tank are adjusted.

[0049] In an optional embodiment, the wastewater treatment unit further includes a filter 8; the inlet of the filter 8 is connected to the demulsification unit 2, and the outlet of the filter 8 is connected to the sedimentation unit 3.

[0050] By setting filter 8, large particulate matter that has been demulsified by demulsification unit 2 can be further filtered, reducing the cost and difficulty of subsequent processing.

[0051] In one optional embodiment, the demulsification unit 2 includes a demulsifier 21 and a flocculator 22 connected in sequence. The demulsifier 21 is connected to the homogenization unit 1, and the flocculator 22 is connected to the filter 8.

[0052] In one optional embodiment, the sludge treatment unit includes at least two sets of plate and frame filter presses 9; the diameter of the filter plates in the first set of plate and frame filter presses 9 is larger than the diameter of the filter plates in the second set of plate and frame filter presses 9, and the diameter of the filter plates in each set of plate and frame filter presses 9 decreases sequentially along the direction from the inlet to the outlet of the plate and frame filter presses 9.

[0053] By setting the diameter of the filter plates in the first set of plate and frame filter presses 9 to be larger than the diameter of the filter plates in the second set of plate and frame filter presses 9, and by successively decreasing the diameter of the filter plates, it is possible to treat produced water from gas fields with an oil content in the range of 30,000 mg / L to 300,000 mg / L, and improve the treatment effect. The treated produced water from gas fields meets all the indicators of standard treated water.

[0054] In an optional embodiment, the sludge treatment unit further includes a sludge storage tank 10, the inlet of which is connected to the sludge outlet of the pretreatment unit, and the outlet of which is connected to the sludge outlet of the pretreatment unit.

[0055] In an optional embodiment, a sludge collection tank 11 is also included, which is connected to the sludge outlet of the sludge treatment unit.

[0056] In one alternative embodiment, the oil content in the treated gas field produced water is ≤30 mg / L.

[0057] This invention addresses produced water from gas fields with an oil content ranging from 30,000 mg / L to 300,000 mg / L. A temporary storage tank is used as the receiving and homogenizing tank. After chemical demulsification, flocculation, sedimentation, clarification, and stratification, the wastewater undergoes further treatment via an air flotation device 4 before being reinjected. The sludge is pressed using a plate and frame filter press 9. The oily sludge is treated as hazardous waste and sent to a specialized unit for disposal, while the pressed water is recycled. Specific treatment parameters are shown in Table 1.

[0058] Table 1

[0059]

[0060] As shown in Table 1, the actual water quality of the treated reinjection water is better than the requirements of the "Design Specification for Water Treatment and Reinjection Engineering of High Sulfur Gas Fields" (SY / T 6881-2012). Furthermore, the suspended solids, oil content, and median particle size all meet the specifications.

[0061] Although the present invention has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A treatment device for produced water from gas fields with oil content in the range of 30,000 mg / L to 300,000 mg / L, characterized in that, include: The pretreatment unit is used to homogenize, demulsify and settle the produced water from the gas field in sequence, and has a wastewater outlet and a sludge outlet. A wastewater treatment unit is connected to the wastewater outlet of the pretreatment unit; A wastewater treatment regulating unit, connected to the wastewater treatment unit, is used to adjust the wastewater treatment rate according to the wastewater content at the wastewater outlet of the pretreatment unit; A sludge treatment unit, wherein the inlet of the sludge treatment unit is connected to the sludge outlet of the pretreatment unit, and the wastewater outlet of the sludge treatment unit is connected to the inlet of the wastewater treatment unit.

2. The gas field produced water treatment device according to claim 1 for oil content in the range of 30,000 mg / L-300,000 mg / L, characterized in that, The wastewater treatment regulating unit includes: a flow meter, a release pipe, and a control valve; The release pipe is connected to the wastewater treatment unit; The flow meter and the control valve are installed on the release pipe, and the flow meter is used to obtain the sewage inflow of the sewage treatment unit; The control valve is used to open or close the release pipe according to the amount of sewage entering the sewage treatment unit.

3. The gas field produced water treatment device according to claim 1 for oil content in the range of 30,000 mg / L-300,000 mg / L, characterized in that, The wastewater treatment unit includes an air flotation device, which includes a dissolved air tank, and the wastewater treatment regulating unit is located above the dissolved air tank.

4. The gas field produced water treatment device according to claim 1 for oil content in the range of 30,000 mg / L-300,000 mg / L, characterized in that, The pretreatment unit includes: a homogenization unit, a demulsification unit, and a sedimentation unit connected in series; The wastewater outlet of the sedimentation unit is connected to the wastewater treatment unit, and the sludge outlet is connected to the sludge treatment unit.

5. The gas field produced water treatment device according to claim 4 for oil content in the range of 30,000 mg / L-300,000 mg / L, characterized in that, The wastewater treatment unit also includes: a filter; The filter inlet is connected to the demulsification unit, and the filter outlet is connected to the sedimentation unit.

6. The gas field produced water treatment device according to claim 5 for oil content in the range of 30,000 mg / L-300,000 mg / L, characterized in that, The demulsification unit includes a demulsifier and a flocculator connected in sequence. The demulsifier is connected to the homogenization unit, and the flocculator is connected to the filter.

7. The gas field produced water treatment device according to claim 1 for oil content in the range of 30,000 mg / L-300,000 mg / L, characterized in that, The sludge treatment unit includes at least two sets of plate and frame filter presses; The diameter of the filter plates in the first set of plate and frame filter presses is larger than the diameter of the filter plates in the second set of plate and frame filter presses, and the diameter of the filter plates in each set of plate and frame filter presses decreases sequentially from the inlet to the outlet of the plate and frame filter press.

8. The gas field produced water treatment device according to claim 7 for oil content in the range of 30,000 mg / L-300,000 mg / L, characterized in that, The sludge treatment unit further includes a sludge storage tank, the inlet of which is connected to the sludge outlet of the pretreatment unit, and the outlet of which is connected to the sludge outlet of the pretreatment unit.

9. The gas field produced water treatment device according to claim 1 for oil content in the range of 30,000 mg / L-300,000 mg / L, characterized in that, It also includes a sludge collection tank, which is connected to the sludge outlet of the sludge treatment unit.

10. The gas field produced water treatment device according to claim 1 for oil content in the range of 30,000 mg / L-300,000 mg / L, characterized in that, The oil content in the treated produced water from the gas field is ≤30mg / L.

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