CN113371895A - Process method and system for resourceful treatment of oil and gas field produced water - Google Patents
Process method and system for resourceful treatment of oil and gas field produced water Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/46104—Devices therefor; Their operating or servicing
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- C—CHEMISTRY; METALLURGY
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- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
- C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/10—Nature of the water, waste water, sewage or sludge to be treated from quarries or from mining activities
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
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Abstract
The invention discloses a process method and a system for resourceful treatment of produced water of an oil-gas field, wherein the process method sequentially comprises the following steps: and (3) hardness removal: adding a medicament into the produced water to remove scaling ions in the produced water; an electrochemical oxidation step: performing electrolytic treatment on the produced water, controlling the pH value of the inlet water to be between 8 and 9, and removing ammonia nitrogen and reducing COD in the water by adopting direct-current voltage of 4.0V to 6.0V for the electrolytic treatment; iron-carbon microelectrolysis: enabling the produced water to flow through an iron-carbon filler, and adding an acid agent to control the pH value of the inlet water to be between 5.5 and 6.0 so as to further remove ammonia nitrogen in the water and reduce COD; reverse osmosis: the produced water passes through a reverse osmosis membrane to further remove conductive ions and reduce COD, and the treated finished product effluent is obtained. The invention has the advantages of short process flow, relatively simple operation, low energy consumption, strong shock resistance and small construction investment, can effectively solve the defects of the prior art and has industrial practicability.
Description
Technical Field
The invention belongs to the technical field of oil and gas field ground engineering, and particularly relates to a process method and a system for resource treatment of oil and gas field produced water.
Background
Most of produced water of oil and gas fields has the characteristics of high COD (chemical oxygen demand) and difficult degradation. The characteristics are more prominent in the produced water of the gas field, taking a plain gas field as an example, the analysis result of a three-dimensional fluorescence spectrometer of the produced water is shown in figure 1, and areas I, II, III, IV and V are tyrosine-like substances, tryptophan-like substances, fulvic acid-like substances, soluble microbial degradation byproducts and humic acid-like substances respectively. Wherein, the areas I, II and IV belong to degradable substances, and the areas III and V belong to non-degradable substances.
From the conditions of the components in the figure, about 80 percent of produced water is refractory substances, mainly aromatic compounds, and the B/C of the produced water is measured to be below 0.2, so that the overall biodegradability of the produced water is poor.
In the related technology, the produced water of the COD oil and gas field with high salt content, high ammonia nitrogen content and difficult degradation is treated by the following processes of hardness removal, deamination, evaporation, advanced oxidation, micro/ultrafiltration and reverse osmosis:
1) through pretreatment (mainly removing suspended substances, oil and H)2S, and the like) produced water of the oil and gas field firstly enters a hardness removal device to remove the hardness of the produced water;
2) the hardness-removed effluent enters a deamination tower to remove ammonia nitrogen;
3) the water discharged from the deamination tower enters a multi-effect evaporation device for desalting and removing part of COD;
4) the evaporated water enters a high-grade oxidation (mainly adopting Fenton, ozone or combined process) reaction device to further remove COD in the water;
5) the produced water after advanced oxidation treatment enters a micro/ultrafiltration membrane for filtration;
6) and (4) treating the produced water subjected to micro/ultrafiltration treatment by using a reverse osmosis membrane to obtain qualified effluent.
The related technology can achieve the purpose of recycling the produced water of the oil and gas field, but has the defects of long process chain, more equipment and high operation cost; secondly, secondary pollution and the like caused by large sludge production amount in the Fenton process in the advanced oxidation process. How to seek a high-efficiency and low-consumption treatment process becomes the direction of research and development in the industry.
Disclosure of Invention
In order to solve or partially solve the technical problems, the invention provides a process method for recycling produced water of an oil and gas field, which sequentially comprises the following steps: and (3) hardness removal: adding a medicament into the produced water to remove scaling ions in the produced water; an electrochemical oxidation step: performing electrolytic treatment on the produced water, controlling the pH value of the inlet water to be between 8 and 9, and removing ammonia nitrogen and reducing COD in the water by adopting direct-current voltage of 4.0V to 6.0V for the electrolytic treatment; iron-carbon microelectrolysis: enabling the produced water to flow through an iron-carbon filler, and adding an acid agent to control the pH value of the inlet water to be between 5.5 and 6.0 so as to further remove ammonia nitrogen in the water and reduce COD; reverse osmosis: the produced water passes through a reverse osmosis membrane to further remove conductive ions and reduce COD, and the treated finished product effluent is obtained.
In some embodiments, the produced water has a COD of less than 1500mg/L, a mineralization of less than 30000mg/L, and ammonia nitrogen of less than 300 mg/L.
In some embodiments, in the hardness removal step, the added medicaments comprise an alkaline agent, a coagulant and a flocculant, the pH value of the effluent is controlled to be above 10, the addition amount of the coagulant is not less than 50mg/L, and the addition amount of the flocculant is not less than 3 mg/L.
In some embodiments, in the iron-carbon micro-electrolysis step, the thickness of the filter layer of the iron-carbon filler is not less than 1.0m, and the filter speed is controlled to be between 6m/h and 10 m/h.
In some embodiments, the reverse osmosis step comprises: high-pressure reverse osmosis treatment with the operating pressure of 3-7 MPa and low-pressure reverse osmosis treatment with the operating pressure of less than 1 MPa.
In some embodiments, the middle reverse osmosis membrane of the high pressure reverse osmosis treatment is a pipe-grid type high pressure reverse osmosis membrane and/or a disc type high pressure reverse osmosis membrane, and the flux is between 8L/m2·h~20 L/m2H.
The invention also provides a system for resourceful treatment of the produced water of the oil and gas field, which comprises: the stirring and clarifying device is used for removing scaling ions in the produced water; the electrochemical oxidation device comprises an electrolytic cell, a water treatment device and a water treatment device, wherein the electrolytic cell is used for carrying out electrolytic treatment on produced water, removing ammonia nitrogen in the water and reducing COD; the iron-carbon filtering device contains iron-carbon filler and is used for further removing ammonia nitrogen in water and reducing COD; and the reverse osmosis device is used for further removing conductive ions in the water and reducing COD (chemical oxygen demand) to obtain treated finished product effluent.
In some embodiments, the stirring and clarifying device comprises a reaction zone, a separation zone, a clarifying zone and a stirrer, produced water and the medicament are mixed and flow upwards through the stirrer, meanwhile, the precipitated floc is recycled from the separation zone, and supernatant enters the clarifying zone to overflow.
In some embodiments, the electrolytic cell comprises a plurality of cathode and anode sleeves, wherein the anodes in the cathode and anode sleeves are rod-shaped, the cathodes are perforated sleeves, and the cathodes are sleeved outside the anodes; the electrolytic cell is also connected with a buffer water tank and a circulating pump, and the buffer water tank and the circulating pump are used for enabling produced water in the electrolytic cell to circularly flow.
In some embodiments, the reverse osmosis device comprises a high-pressure reverse osmosis device with the operating pressure of 3 MPa-7 MPa and a low-pressure reverse osmosis device with the operating pressure of 1MPa or less.
The process method and the system adopt the method of 'hardness removal + electrochemical oxidation + iron-carbon micro-electrolysis + reverse osmosis' aiming at the characteristic of the difficultly degraded COD component in the produced water of the oil-gas field, and the finished product effluent can reach the conditions that the CODcr of the inlet water is less than or equal to 1500mg/L and the ammonia nitrogen is less than or equal to 300mg/L, and the CODcr of the outlet water is less than or equal to 60mg/L and the ammonia nitrogen is less than or equal to 10 mg/L. Meanwhile, the degradation and removal of volatile phenol and other organic components in the extracted water can be realized, and the water quality requirement of the supplementary water for the circulating cooling water is met (part 2 of the water management technical requirement: circulating water Q/SH 0628.2-2014). The system has the advantages of short flow, relatively simple operation, low energy consumption, strong shock resistance and small construction investment, can effectively overcome the defects of the prior art, and has industrial practicability.
Drawings
FIG. 1 shows the results of three-dimensional fluorescence spectroscopy analysis of produced water to be treated in the present invention.
FIG. 2 is a schematic illustration of the process steps of the present invention.
FIG. 3 is a schematic diagram of a system according to an embodiment of the present invention.
Fig. 4A and 4B show a report sheet of analysis results of produced water and finished product water in an embodiment of the invention.
Symbolic illustration in the drawings:
100 produced water;
200, discharging water from the finished product;
10 stirring and clarifying device;
11 a stirrer;
12 a reaction zone;
13 a separation zone;
14 a clarification zone;
15 a dosing line;
20 an electrochemical oxidation device;
21 an electrolytic cell;
211 an electrode;
22 a buffer water tank;
23 circulating pump;
24 acid addition lines;
30 iron carbon filtering device;
31 an iron carbon filler;
32 feed lines;
40 reverse osmosis unit;
41 high pressure reverse osmosis unit;
411 an intermediate water tank;
412 a lift pump;
413 a high pressure pump;
414 a reverse osmosis membrane;
415 a concentrated water discharge line;
42 low pressure reverse osmosis unit;
421 an intermediate water tank;
422 a booster pump;
423 reverse osmosis membrane;
424 a drain line;
s001 to S004.
Detailed Description
The technical solution of the present invention will be described below by way of specific examples. It is to be understood that one or more of the steps mentioned in the present invention does not exclude the presence of other methods or steps before or after the combined steps, or that other methods or steps may be inserted between the explicitly mentioned steps. It should also be understood that these examples are intended only to illustrate the invention and are not intended to limit the scope of the invention. Unless otherwise indicated, the numbering of the method steps is only for the purpose of identifying the method steps, and is not intended to limit the arrangement order of each method or the scope of the implementation of the present invention, and changes or modifications of the relative relationship thereof may be regarded as the scope of the implementation of the present invention without substantial technical change.
Example 1
The present embodiment provides a process method for resource treatment of produced water in an oil and gas field, as shown in fig. 2, which sequentially includes steps S001 to S004.
And a hardness removal step S001, adding a medicament into the produced water to remove scaling ions in the produced water.
And an electrochemical oxidation step S002, performing electrolytic treatment on the produced water, controlling the pH value of the inlet water to be between 8 and 9, and performing the electrolytic treatment by adopting direct current voltage of 4.0V to 6.0V to remove ammonia nitrogen in the water and reduce COD.
And S003, carrying out iron-carbon micro-electrolysis, namely enabling the produced water to flow through an iron-carbon filler, and adding an acid agent to control the pH value of the inlet water to be 5.5-6.0 so as to further remove ammonia nitrogen in the water and reduce COD.
And a reverse osmosis step S004, wherein the produced water passes through a reverse osmosis membrane to further remove conductive ions in the water and reduce COD, so that treated finished product effluent is obtained.
Wherein, direct current passes through the produced water that contains high salt, high chloride ion concentration in the electrochemistry oxidation step S002, take place redox reaction on negative and positive electrode, generate strong oxidizing property material hydroxyl free radical and get rid of the COD in aqueous, chloride ion is by the hypochlorous acid of oxidation simultaneously and get rid of with the ammonia nitrogen to the aquatic, realize the effect of synchronous removal COD and ammonia nitrogen, shortened process flow, reduced equipment quantity, this process step normal operating process only consumes the electric energy, need not other medicaments, the auxiliary material consumption, secondary pollution such as not producing mud, reduce operation maintenance work load.
And an iron-carbon micro-electrolysis step S003, wherein the residual difficultly-degraded COD after the biochemical treatment is further removed by utilizing the potential difference generated in the iron-carbon reaction process, and meanwhile, the iron-carbon filler is formed by high-temperature sintering, has a good adsorption effect and can also be used for removing difficultly-degraded substances in water. Along with the filtration, the filler of the micro-electrolysis device needs to be backwashed and regenerated at regular intervals, and the filler can be regenerated on line by soaking the filler in hydrogen peroxide with higher concentration.
The invention carries out resource treatment on the produced water of an oil and gas field, wherein the COD of the produced water to be treated is below 1500mg/L, the mineralization is below 30000mg/L, and ammonia nitrogen is below 300mg/L, and the treated finished product effluent reaches part 2 of the technical requirement of water management: circulating Water "Q/SH 0628.2-2014) requires: CODCr is less than or equal to 60mg/L, ammonia nitrogen is less than or equal to 10mg/L, and conductivity is less than or equal to 1200 mu S/cm.
Preferably, before the hardness removing step S001, a pretreatment step is further included for primarily removing suspended matters, oil and H in the produced water2S and the like.
Preferably, in the hardness removal step S001, the added medicaments comprise an alkaline agent, a coagulant and a flocculant, the pH value of the effluent is controlled to be more than 10, the addition amount of the coagulant is not less than 50mg/L, and the addition amount of the flocculant is not less than 3 mg/L. Optionally, carbonate and/or magnesium agent can be selectively added according to the characteristics of water quality, wherein the carbonate mainly removes calcium, magnesium and strontium ions in the water through precipitation reaction, and the magnesium agent is added for removing silicic acid compounds in the water. Preferably, the retention time of the water in the hardness removing step S001 is not less than 4h, and the total hardness of the effluent can be controlled within 200 mg/L.
Preferably, in the electrochemical oxidation step S002, the treatment time is not less than 30min, and the treated effluent COD isCrCan be reduced to below 300mg/L, and the ammonia nitrogen is reduced to within 10 mg/L.
Preferably, in the step S003 of iron-carbon micro-electrolysis, the thickness of the filter layer of the iron-carbon filler is not less than 1.0m, the filtration rate is controlled to be between 6m/h and 10m/h, and the COD of the treated effluent is reduced to be less than 200 mg/L.
Preferably, the reverse osmosis step S004 comprises a high-pressure reverse osmosis treatment with the pressure of 3 MPa-7 MPa and a low-pressure reverse osmosis treatment with the pressure of 1MPa or less, and the recovery rate of the water product effluent is improved by two-stage reverse osmosis treatment, wherein in the high-pressure reverse osmosis treatment, the reverse osmosis membrane is preferably a pipe network type high-pressure reverse osmosis membrane and/or a disc type high-pressure reverse osmosis membrane, and the flux is 8L/m2·h~20 L/m2And h, the comprehensive recovery rate of the finished product effluent can be more than 50%.
Example 2
The embodiment provides a system for resourceful treatment of oil and gas field produced water, as shown in fig. 3, includes: a stirring and clarifying device 10, an electrochemical oxidation device 20, an iron-carbon filtering device 30 and a reverse osmosis device 40. Wherein, the stirring and clarifying device 10 is used for removing scaling ions in the produced water; the electrochemical oxidation device 20 comprises an electrolytic cell 21 for carrying out electrolytic treatment on the produced water 100 to remove ammonia nitrogen and COD in the water; the iron-carbon filtering device 30 contains iron-carbon filler 31 for further removing ammonia nitrogen and COD in the water; the reverse osmosis device 40 is used for further removing COD and conductive ions in the produced water 100 to obtain a treated finished product effluent 200.
Preferably, in this embodiment, the stirring and clarifying device 10 is an integrated device (as shown in fig. 3), and has a tank body, which includes a reaction zone 12, a separation zone 13, a clarifying zone 14 and a stirrer 11, the produced water 100 and the chemical are mixed and flow upward through the stirrer 11, meanwhile, the precipitated flocs are recycled from the separation zone 13, and the supernatant enters the clarifying zone 14 to overflow and then enters the electrochemical oxidation device 20 for further treatment. Wherein, inside the medicament added stirring clarification device 10 through the medicine pipeline 15 with jar body intercommunication, the stirring clarification device 10 that adopts the integration can realize removing silicon, strontium in step and remove firmly, and the point of offeing medicine is arranged in jar internal improvement medicament and is mixed and the sludge concentration efficiency, has avoided the jam problem of front end pipeline, and separation zone floc part backward flow utilizes, improves reaction zone 12 flocculation efficiency, reduces the dose. The stirring and clarifying device 10 in the embodiment integrates hardness removal and clarification, and reduces the occupied area. When the hardness removal step S001 is performed by using the integrated stirring and clarifying device 10 in this embodiment, preferably, the stirring rotation speed is not lower than 50r/min, the water retention time is not less than 4h, the pH of the effluent is controlled to be above 10, the addition amount of the coagulant is not lower than 50mg/L, the addition amount of the flocculant is not lower than 3mg/L, and the total hardness of the effluent can be controlled within 200 mg/L.
In this embodiment, the water inlet pipeline of the electrochemical oxidation apparatus 20 is further connected with an acid adding pipeline 24 for adjusting the pH value of the produced water entering the electrolytic cell 21, and preferably, the pH value of the inlet water is controlled to be between 8 and 9.
In this embodiment, the electrolytic cell 21 includes a plurality of electrodes 211, preferably, the electrodes 211 are cathode and anode sleeves (not shown), the anode in the cathode and anode sleeves is rod-shaped, the cathode is a perforated sleeve, the cathode is sheathed outside the anode, and the electrodes 211 adopt a perforated sleeve structure to improve the water flow in the electrolytic cell 21 to form a turbulent flow pattern, thereby reducing concentration polarization. Preferably, the anode is a rod-shaped titanium oxide ceramic electrode, and the cathode is a perforated-tube sleeve-shaped hastelloy electrode. In this embodiment, the electrolytic cell 21 is further connected to a buffer water tank 22 and a circulating pump 23, so as to enable the produced water in the electrolytic cell 21 to flow circularly, increase the flow velocity of the water flow, further eliminate concentration polarization, and reduce the scaling tendency of the electrodes. The effluent treated by the electrochemical oxidation device 20 enters the iron-carbon filtering device 30 for further treatment.
In this embodiment, the water inlet line of the iron-carbon filtering device 30 is further communicated with a feeding line 32 for adding an acid agent therein to adjust the pH value of the produced water entering the iron-carbon filtering device 30 to be acidic, preferably, the pH value is within 5.5 to 6.0; preferably, the thickness of the filtering layer of the iron carbon filler 31 in the iron carbon filtering device 30 is not less than 1.0m, and the COD of the treated effluent can be reduced to below 200mg/L by controlling the filtering speed of the produced water within 6-10 m/h. The effluent water treated by the iron-carbon filtering device 30 enters a reverse osmosis device 40 for further treatment. Along with the filtering, the iron-carbon filler 31 needs to be periodically backwashed and regenerated, and the filler can be regenerated on line by soaking the filler in high-concentration hydrogen peroxide (with the industrial content of 28%).
Preferably, the reverse osmosis device 40 in this embodiment comprises a high pressure reverse osmosis device 41 and a low pressure reverse osmosis device 42. Wherein, the high pressure reverse osmosis device 41 comprises an intermediate water tank 411, a lift pump 412, a high pressure pump 413 and a reverse osmosis membrane 414, the inlet water to be treated firstly enters the intermediate water tank 411, then passes through the reverse osmosis membrane 414 through the conveying and pressurizing effects of the lift pump 412 and the high pressure pump 413, and the concentrated water generated by the high pressure reverse osmosis filtration is discharged out of the system through a concentrated water discharge pipeline 415. The low-pressure reverse osmosis device 42 comprises a middle water tank 421, a booster pump 422 and a reverse osmosis membrane 423, inlet water to be treated firstly enters the middle water tank 421 and then is conveyed by the booster pump 422And the pressurized water passes through the reverse osmosis membrane 423, and the concentrated water produced by the low pressure reverse osmosis filtration enters the intermediate water tank 411 through the drain line 424 for further treatment. Preferably, the high-pressure reverse osmosis can adopt a pipe network type high-pressure reverse osmosis membrane (STRO) or a disc type high-pressure reverse osmosis membrane (DTRO), a primary two-section operation mode is adopted, and the flux of the STRO membrane is easy to control to be 8-15L/m2Within h, the flux of the DTRO membrane can be increased to 10-20L/m2H, preferably, the operation pressure is within 3-7 MPa, the recovery rate is about 60%, and the desalination rate is more than 95%; the low-pressure reverse osmosis effluent adopts a roll-type low-pressure reverse osmosis membrane, preferably, the operating pressure is within 1MPa, the recovery rate is more than 85 percent, and the desalination rate is about 98 percent; the low-pressure reverse osmosis concentrated water returns to the middle water tank 411 of the high-pressure reverse osmosis device 41, the comprehensive recovery rate of the water produced by the high-pressure and low-pressure reverse osmosis process section is more than 50%, and the treated finished product effluent 200 meets the water quality requirement of the water quality standard of industrial circulating water (part 2 of the water management technical requirement: circulating water Q/SH 0628.2-2014). Through setting up high low pressure two-stage reverse osmosis, can synthesize the quality of water of guaranteeing the quality of water simultaneously to improve the rate of recovery that the finished product goes out water.
It should be noted that, in order to better show the technical features of the present invention, the cleaning and dosing systems in the iron-carbon micro-electrolysis device 30, the high-pressure reverse osmosis device 41 and the low-pressure reverse osmosis device 42 in fig. 3 are omitted.
The process method and the system of the invention are processed by the ordinary optical division company of the oilfield in China petrochemical industry with the processing scale of 1m3The test in the/h pilot test. Please see fig. 4A and 4B for water quality detection of produced water and finished product effluent, wherein in the analysis result report sheet, sample No. 2020-08-SQ01 in serial No. 1 is produced water, and sample No. 2020-08-SQ02 in serial No. 2 is finished product effluent, and it can be seen that the produced water has an electrical conductivity of 2.9 × 104Mu S/cm, COD (chemical oxygen demand) of 895mg/L, ammonia nitrogen of 15.6 mg/L and total hardness of 657 mg/L, and after the treatment by the system, the conductivity of the finished product effluent is 64 mu S/cm, the COD is 4mg/L, the ammonia nitrogen is 1.15 mg/L and the total hardness is 19 mg/L. It can also be seen from fig. 4B that the process and system of the present invention also have excellent removal of suspended matter, chloride, volatile phenols, and BOD (biological oxygen demand) in the produced water.
The process method and the system adopt the method of 'hardness removal + electrochemical oxidation + iron-carbon micro-electrolysis + reverse osmosis' aiming at the characteristic of the difficultly degraded COD component in the produced water of the oil-gas field, and the finished product effluent can reach the conditions that the CODcr of the inlet water is less than or equal to 1500mg/L and the ammonia nitrogen is less than or equal to 300mg/L, and the CODcr of the outlet water is less than or equal to 60mg/L and the ammonia nitrogen is less than or equal to 10 mg/L. Meanwhile, the degradation and removal of volatile phenol and other organic components in the extracted water can be realized, and the water quality requirement of the supplementary water for the circulating cooling water is met (part 2 of the water management technical requirement: circulating water Q/SH 0628.2-2014). The invention has the advantages of short process flow, relatively simple operation, low energy consumption, strong shock resistance and small construction investment, can effectively solve the defects of the prior art and has industrial practicability.
The above embodiments are provided only to illustrate some embodiments of the technical features of the present invention, and the present invention includes embodiments not limited thereto, and it will be apparent to those skilled in the art that several modifications and improvements can be made without departing from the inventive concept of the present invention, and the scope of the present invention should be determined by what is defined in the claims.
Claims (10)
1. A process method for resourceful treatment of produced water of an oil-gas field is characterized by sequentially comprising the following steps:
and (3) hardness removal: adding a medicament into the produced water to remove scaling ions in the produced water;
an electrochemical oxidation step: performing electrolytic treatment on the produced water, controlling the pH value of the inlet water to be between 8 and 9, wherein the electrolytic treatment adopts direct-current voltage of 4.0V to 6.0V to remove ammonia nitrogen in the water and reduce COD;
iron-carbon microelectrolysis: enabling the produced water to flow through an iron-carbon filler, and adding an acid agent to control the pH value of the inlet water to be between 5.5 and 6.0 so as to further remove ammonia nitrogen in the water and reduce COD;
reverse osmosis: the produced water passes through a reverse osmosis membrane to further remove conductive ions and reduce COD, and the treated finished product effluent is obtained.
2. The process method for resource treatment of produced water in oil and gas fields as claimed in claim 1, wherein the COD of the produced water is below 1500mg/L, the mineralization is below 30000mg/L, and the ammonia nitrogen is below 300 mg/L.
3. The process method for recycling produced water from oil and gas fields as claimed in claim 1, wherein in the step of hardness removal, the added agents comprise alkaline agents, coagulants and flocculants, the pH value of the produced water is controlled to be above 10, the addition amount of the coagulants is not less than 50mg/L, and the addition amount of the flocculants is not less than 3 mg/L.
4. The process method for resource treatment of produced water in oil and gas fields as claimed in claim 1, wherein in the step of iron-carbon micro-electrolysis, the thickness of the filter layer of the iron-carbon filler is not less than 1.0m, and the filter speed is controlled between 6m/h and 10 m/h.
5. The process for resource treatment of produced water from oil and gas fields as claimed in claim 1, wherein the reverse osmosis step comprises: high-pressure reverse osmosis treatment with the operating pressure of 3-7 MPa and low-pressure reverse osmosis treatment with the operating pressure of less than 1 MPa.
6. The process method for resource treatment of produced water in oil and gas fields as claimed in claim 5, wherein the middle reverse osmosis membrane of the high pressure reverse osmosis treatment is a pipe network type high pressure reverse osmosis membrane and/or a disc type high pressure reverse osmosis membrane, and the flux is 8L/m2·h~20 L/m2H.
7. A system for resourceful treatment of oil and gas field produced water is characterized by comprising:
the stirring and clarifying device is used for removing scaling ions in the produced water;
the electrochemical oxidation device comprises an electrolytic cell, a water treatment device and a water treatment device, wherein the electrolytic cell is used for carrying out electrolytic treatment on produced water, removing ammonia nitrogen in the water and reducing COD;
the iron-carbon filtering device contains iron-carbon filler and is used for further removing ammonia nitrogen in water and reducing COD;
and the reverse osmosis device is used for further removing conductive ions in the water and reducing COD (chemical oxygen demand) to obtain treated finished product effluent.
8. The system for resource treatment of the oil and gas field produced water as claimed in claim 7, wherein the stirring and clarifying device comprises a reaction zone, a separation zone, a clarifying zone and a stirrer, the stirrer is used for mixing the produced water with the medicament and raising the flow, meanwhile, the precipitated flocs are recycled from the separation zone, and the supernatant enters the clarifying zone to overflow.
9. The system for resource treatment of the oil and gas field produced water as claimed in claim 7, wherein the electrolytic cell comprises a plurality of cathode and anode sleeves, the anode in the cathode and anode sleeves is rod-shaped, the cathode is a perforated sleeve, and the cathode is sleeved outside the anode; the electrolytic cell is also connected with a buffer water tank and a circulating pump, and is used for enabling produced water in the electrolytic cell to circularly flow.
10. The oil and gas field produced water resource treatment system of claim 7, wherein the reverse osmosis device comprises a high-pressure reverse osmosis device with the operating pressure of 3 MPa-7 MPa and a low-pressure reverse osmosis device with the operating pressure of 1MPa or less.
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Effective date of registration: 20221114 Address after: 100027 Chaoyangmen North Street, Chaoyang District, Chaoyang District, Beijing Applicant after: SINOPEC Group Applicant after: SINOPEC OILFIELD SERVICE Corp. Applicant after: SINOPEC PETROLEUM ENGINEERING Corp. Address before: 100020 Building 2, Chaoyang Gate office area, Sinopec, 9 jishikou Road, Chaoyang District, Beijing Applicant before: SINOPEC OILFIELD SERVICE Corp. Applicant before: SINOPEC PETROLEUM ENGINEERING Corp. |