Filter material cleaning process and device for oilfield produced water filter

Abstract

The invention belongs to the technical field of filter material cleaning of filters for oil fields, and discloses a process and a device for cleaning a filter material of an oilfield produced water filter. The process comprises the following steps: injecting water into a medicine dissolving buffer tank; according to components of a filter material scale sample, a descaling agent is prepared through experimental debugging, and the descaling agent is added into a dissolved agent buffer tank to be dissolved to obtain a descaling cleaning solution; heating the descaling cleaning liquid; the descaling cleaning liquid is pumped into the filter, so that the whole filter is full of the descaling cleaning liquid, and the filter material is soaked; the descaling cleaning liquid is discharged from the filter to reach the filtering device, and returns to the medicine dissolving buffer tank after being filtered; and circularly cleaning until the cleaning is thorough. An existing filter backwashing process device is used for online cleaning, filter materials do not need to be cleaned, and water injection and chemical feeding are conducted through the front-end chemical dissolving buffer tank, so that the problems that a produced water treatment filtering device is high in scaling rate and large in descaling difficulty, the shutdown construction period of a traditional cleaning technology is long, and continuous operation of oil field production cannot be guaranteed are solved. The filtered water quality is stable and reaches the standard.

Description

Technical Field

[0001] The invention belongs to the technical field of cleaning filter media for oilfield filters, and in particular relates to a cleaning process and device for filter media of oilfield produced water filters. Background Art

[0002] After a long period of operation, the pores of the filter media in the oilfield produced water treatment system will be filled with dirty oil and impurities. At this time, the filter basically loses its filtering capacity, which is manifested in the deterioration of the filtered water quality or the total pressure drop of the filter layer exceeding the standard value. In order to restore the filtering capacity of the filter media, it is necessary to regenerate the polluted and ineffective filter media with certain technology.

[0003] At present, the filter materials used in oil fields are mostly quartz sand, ceramsite, anthracite, walnut shells, etc., with a small amount of corundum or modified filter materials. When the filter material is seriously polluted, the filter should be stopped and thoroughly cleaned. Most of the cleaning methods use manual cleaning of the contaminated filter material, and then simple physical stirring cleaning, sedimentation filtration, and screen to remove impurities, and then rely on manual reinstallation into the filter for continued use, or replenish with new filter material. The above methods currently have the following problems: ① The manual cleaning and physical stirring cleaning process is complicated and will cause a large loss of filter material; ② Physical cleaning or conventional chemical cleaning is difficult to remove the silicon scale adsorbed on the surface of the filter material, affecting the filtering effect of the filter material; ③ The cleaning cycle is long, generally 5-7 days, and can only be carried out in summer; ④ Cleaning the filter material is prone to secondary pollution of oil pollution, and the cleaning process is relatively dangerous. Therefore, there is an urgent need for a cleaning process and device for oilfield produced water filters that can meet the needs of rapid and thorough cleaning of filter materials.

[0004] Patent document CN213853255U discloses an integrated high-efficiency filter material circulation cleaning and filtering device for oilfield produced water, including a filter tank body, a water inlet is provided on the top of the filter tank body, a water outlet is provided on the bottom, and a filter assembly is provided inside; the bottom of the filter tank body is also connected to a backwash pipe, and a cleaning port facing the filter assembly is also provided on the side wall, the cleaning port is connected to a scrubbing circulation assembly through a pipeline, and the outlet of the scrubbing circulation assembly is connected to the upper part of the filter tank body through a reflux pipe, and a sewage outlet is provided on the filter tank body. The technical solution of this patent can improve the filtering treatment effect of the device and equipment, extend the service life of the filter material, and the cleaning effect is thorough and the amount of water used for cleaning is small. However, the method of this patent is to scrub the filter material in vitro, which is not suitable for the current scale formation of filters in the construction oil field, especially silica scale. The scale blocks are large and difficult to break manually, and the scrubbing effect in vitro is not good, which is similar to manual cleaning.

[0005] Patent document CN115700132A discloses a filter material cleaning process for a multi-tank filter system. Based on the design of a filter tank, a suction pump and a pipeline system, the filter material in two or more filter tanks or multiple filter tanks is sucked and transported by a pump, so that all the filter material in the tank is stirred in the tank, screened and washed in the pipeline outside the tank, and then returned to the tank in a cyclic cleaning process between the system formed by the tank and the cleaning pipeline. It has the advantages of high backwashing intensity, high oil removal efficiency, and less backwashing water. However, the technical solution of this patent is still an in vitro scrubbing type, which is not suitable for all filter material cleaning. For example, the fiber ball filter material is fragile, and it is basically unusable after in vitro scrubbing and returning to the filter tank.

[0006] Patent document CN111013246A discloses an anti-pollution and energy-saving filtering device and method for oilfield produced water, which adopts a two-stage backwashing method of small flow rate filter screen washing and large flow rate filter material washing, and the backwashing time is automatically controlled according to the turbidity of the backwashing effluent, which solves the problems of poor cleaning effect caused by the fixed filter material cleaning time in the prior art, and at the same time causes filter material loss and waste of water and electricity for backwashing. However, the method of the patent is daily online backwashing, and its cleaning method is not suitable for cleaning large scale or compacted filter materials. At the same time, the method of the patent requires real-time monitoring of the inlet and outlet water pressure and controlling the electric valves of each pipeline through a frequency conversion controller. The pipeline design is complex, and many equipment and instruments are invested. The water and electricity energy consumed for cleaning is high, and the operation cost is high. Summary of the invention

[0007] The present invention aims to solve at least one technical problem existing in the background technology, and provides an oilfield produced water filter cleaning process and device, which utilizes the existing filter backwashing process equipment for online cleaning, does not need to clean the filter material, and injects water and medicine through the front-end solvent buffer tank to solve the problems of fast scaling rate and difficulty in descaling of produced water treatment filtration equipment, long shutdown construction period of traditional cleaning technology, and inability to ensure continuous operation of oilfield production, so as to achieve stable and standard water quality after filtration.

[0008] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0009] A process for cleaning an oilfield produced water filter, the process comprising the following steps:

[0010] Step S1. Water injection: inject water into the drug buffer tank;

[0011] Step S2. Dissolving the medicine: According to the composition of the filter material scale sample, prepare the descaling agent through experimental debugging, and add the descaling agent into the dissolving medicine buffer tank to dissolve it to obtain the descaling cleaning liquid;

[0012] Step S3. Heating: heating the descaling cleaning liquid by a heating rod;

[0013] Step S4. Soaking: pumping the descaling cleaning liquid into the filter so that the descaling cleaning liquid covers the entire filter and soaks the filter material;

[0014] Step S5. Filtration: The descaling cleaning liquid is discharged from the filter to the filtering device, and the descaling cleaning liquid filtered by the filtering device is returned to the drug buffer tank again to achieve closed cleaning;

[0015] Step S6. Cycle: Repeat steps S3-S6 to perform cyclic cleaning until the cleaning is complete.

[0016] Furthermore, before water injection in step S1, the pipeline is first cleaned with 0.3-0.4 MPa water and a pipeline leak test is performed. Water can be injected for chemical cleaning only after the leak test is qualified.

[0017] Furthermore, the water injected in step S1 is produced water from the front end of the on-site filter or clean water.

[0018] Furthermore, the step S2 specifically includes the following steps:

[0019] Step S201. Collect the scale sample of the filter material, and use the detection instrument to detect and obtain the scale sample components;

[0020] Step S202. According to the composition of the filter material scale sample, the scale sample composition, including the type and content of trace elements, is detected and obtained using an energy spectrum analyzer EDS, a scanning electron microscope and a transmission electron microscope;

[0021] Step S203: Add the descaling agent into the solvent buffer tank and stir to dissolve to obtain a descaling cleaning solution.

[0022] Furthermore, in step S3, the heating temperature of the descaling cleaning liquid is 60°C-80°C.

[0023] Furthermore, in step S3, the descaling cleaning liquid is used to soak the filter material for 6h-8h.

[0024] Furthermore, when implementing steps S4-S5, the scaling of the filter material is observed through the observation hole of the filter:

[0025] If the upper part of the filter material is severely scaled, the descaling cleaning liquid should be introduced from the top and discharged from the bottom; if the lower part of the filter material is severely scaled, the descaling cleaning liquid should be introduced from the bottom and discharged from the top.

[0026] Furthermore, the step S6 specifically includes:

[0027] Check the cleaning status of the filter material through the observation hole of the filter. At the same time, use the online ion detector to detect the content of scale-forming ions such as calcium, magnesium, and silicon in the descaling cleaning liquid returned from the solvent buffer tank:

[0028] When the content of scaling ions in the two consecutive descaling cleaning solutions increases and the increase is ≥5%, the descaling cleaning cycle will continue;

[0029] When the content of scaling ions in the descaling cleaning solution increases between two consecutive times and the increase is less than 5%, the cycle cleaning is stopped.

[0030] Furthermore, in step S3, when the descaling cleaning liquid in the solvent buffer tank is heated, the optimal descaling temperature t0 of the descaling agent is obtained through indoor experiments, and the upper limit of the descaling heating temperature t is set according to the optimal descaling temperature. 0u And descaling heating temperature lower limit t 0m , use the temperature control system to detect and control the heating temperature of the descaling cleaning liquid:

[0031] When the temperature of the descaling cleaning fluid t≤ the lower limit of the degreasing heating temperature t 0m The heating rod is automatically started to heat the descaling cleaning liquid; when the temperature t of the descaling cleaning liquid reaches the upper limit of the descaling heating temperature t 0u When , the heating rod stops heating;

[0032] When the lower limit of descaling heating temperature is t 0m <Temperature of descaling cleaning fluid t<Upper limit of descaling heating temperature t 0u The heating rod does not start heating and directly proceeds to the next process step.

[0033] Furthermore, before step S2 of dissolving the drug, the following oil removal and cleaning steps are also included:

[0034] Add the degreasing agent into the solvent buffer tank and stir to dissolve to obtain the degreasing cleaning solution;

[0035] Heat the degreasing cleaning fluid through a heating rod;

[0036] Pump the degreasing cleaning liquid into the filter so that the degreasing cleaning liquid covers the entire filter and soaks the filter material;

[0037] The degreasing cleaning liquid is discharged from the filter to the filtering device, and then returned to the solvent buffer tank after being filtered by the filtering device.

[0038] Furthermore, in the degreasing and cleaning step, the degreasing and cleaning liquid is heated to 60°C-80°C.

[0039] Furthermore, in the oil removal and cleaning step, the oil removal and cleaning liquid soaks the filter material for 3h-4h.

[0040] Furthermore, in the oil removal and cleaning step, the oil removal and cleaning liquid is discharged from the bottom of the filter, filtered by the filtering device and then returned to the drug dissolving buffer tank. After that, the following detection steps are also included:

[0041] Use an online oil concentration monitor to detect the oil content in the degreasing cleaning fluid returned from the solvent buffer tank:

[0042] When the oil content in the two adjacent degreasing cleaning fluids increases and the increase is ≥5mg / L, the degreasing cleaning cycle will continue;

[0043] When the oil content in two adjacent degreasing cleaning solutions increases and the increase is less than 5 mg / L, proceed to the next process step.

[0044] Furthermore, in the degreasing and cleaning step,

[0045] When heating the degreasing cleaning liquid in the solvent buffer tank, the optimal degreasing temperature T0 of the degreasing agent is obtained through indoor experiments, and the upper limit of the degreasing heating temperature T is set according to the optimal degreasing temperature. 0u and the lower limit of degreasing heating temperature T 0m , use the temperature control system to detect and control the heating temperature of the degreasing cleaning fluid:

[0046] When the temperature of the degreasing cleaning fluid T≤ the lower limit of the degreasing heating temperature T 0m When the temperature T of the degreasing cleaning fluid reaches the upper limit of the degreasing heating temperature T 0u When , the heating rod stops heating;

[0047] When the lower limit of degreasing heating temperature T 0m <Temperature of degreasing cleaning fluid T<Upper limit of degreasing heating temperature T 0u The heating rod does not start heating and directly proceeds to the next process step.

[0048] At the same time, the present invention provides an oilfield produced water filter cleaning device for implementing the cleaning process as described in any one of the above items, wherein the cleaning device comprises a circulating cleaning pump, a solvent buffer tank, a filter to be cleaned and a filtering device;

[0049] The liquid inlet of the filter is connected to the filter liquid inlet pipeline, and the liquid inlet pipeline is provided with a first three-way joint; the liquid outlet of the filter is connected to the filter liquid outlet pipeline, and the filter liquid outlet pipeline is provided with a second three-way joint;

[0050] The first three-way joint is connected to the liquid inlet of the filter device through a filter pipeline; the liquid outlet of the filter device is connected to the liquid inlet of the dissolved drug buffer tank through a return liquid pipeline; the liquid outlet of the dissolved drug buffer tank 1 is connected to the second three-way joint through a dosing pipeline.

[0051] Furthermore, the drug dissolving buffer tank is provided with an automatic stirring device, a heating rod and a temperature transmitter, and the drug dissolving buffer tank is externally connected with an online oil concentration monitor and an online ion detector.

[0052] Furthermore, the filtering device is an online filtering device or a vehicle-mounted filtering device, and the vehicle-mounted filtering device is a skid-mounted device; and the circulating cleaning pump is a centrifugal pump.

[0053] Compared with the prior art, the beneficial effects of the present invention are:

[0054] (1) The cleaning process provided by the present invention first adds a descaling agent to the produced water and mixes it to obtain a descaling cleaning liquid, heats the descaling cleaning liquid and adds it to the filter to soften the scale, and finally dissolves the scale completely, and circulates out of the filter tank together with the descaling cleaning liquid; at the same time, the main components of the descaling agent can be adjusted according to the main components of the scale of the filter material through experimental testing, and the soaking time can be flexibly adjusted according to the dissolution of the scale. If the soaking cleaning is not thorough once, it can be recycled 1-3 times until it is thoroughly cleaned; the entire cleaning process is simple and easy to operate, and is applicable to all types of filter materials. It can avoid the situation where the filter material is fragile and cannot be reused due to external scrubbing, and the problems of long shutdown construction period of traditional cleaning technology and inability to ensure continuous operation of oil field production, so as to achieve stable water quality after filtration;

[0055] (2) The cleaning process of the present invention is an online cleaning process. When conventional backwashing is ineffective, the filter material is directly cleaned thoroughly based on the existing backwashing process to solve the problem of fast scaling rate and difficulty in descaling of produced water treatment filtration equipment. There is no need to clean the filter material, no filter material loss, short cleaning time (the entire cleaning time is about 8 hours), obvious, stable and long-lasting cleaning effect, and basically not affected by season and operating environment;

[0056] (3) The cleaning process provided by the present invention uses a degreasing agent to remove oil before descaling, which can prevent the oil wrapped on the scale from affecting the full reaction of the descaling agent and the scale, thereby improving the descaling effect and descaling speed; at the same time, the oil content in the degreasing cleaning liquid is detected by an online oil concentration monitor to determine whether the degreasing cleaning is terminated, and the scale-forming ion content in the descaling cleaning liquid is detected by an online ion detector to determine whether the descaling cleaning is terminated, thereby avoiding the problem of incomplete circulation cleaning caused by human judgment and the problem of waste of equipment and circulation liquid resources caused by excessive circulation cleaning. The cleaning process is more controllable, the cleaning effect is more reliable, and it is more energy-saving;

[0057] (4) The present invention obtains the optimal heating temperature of the degreasing agent or descaling agent through experimental measurement, and sets the heating temperature threshold range according to the optimal heating temperature. The heating temperature of the degreasing agent or descaling cleaning liquid is controlled by the temperature control system, which can not only avoid the degreasing agent or descaling agent from being too low or overheated to affect the activity and ensure the degreasing or descaling effect of the degreasing agent or descaling agent, but also avoid the waste of electric energy caused by excessive heating and save resources. At the same time, the temperature control system is simple to operate, saves manpower, and has a high degree of automation.

[0058] (5) The equipment used in the cleaning device of the present invention is mature, reliable and easy to obtain; the vehicle-mounted filtering device used is a skid-mounted device, which can be used whenever it is moved; during the inspection and maintenance period of the filter, it is only necessary to install a three-way joint on the filter inlet and outlet water pipelines and connect the pipelines with the solvent buffer tank, the circulating cleaning pump and the filtering device, so as to achieve the purpose of online cleaning of the filter material. Little change is made to the existing pipelines and the installation is convenient. The entire cleaning time is about 8 hours. The operation method is simple, economical and practical, which can effectively ensure that the filter improves work efficiency and greatly improves the economic benefits of production. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A cleaning process flow chart of an embodiment of the present invention;

[0060] Figure 2 Schematic diagram of the structure of a cleaning device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0061] 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.

[0062] Example 1

[0063] Combination Figure 1 As shown, the embodiment of the present invention provides an oilfield produced water filter cleaning process, which mainly includes the following steps:

[0064] Step S1. Water injection: Inject 10m of produced water from the front end of the on-site filter into the drug buffer tank. 3 ;

[0065] Step S2. Dissolving the medicine: According to the scale composition of the filter material, a descaling agent is prepared through experimental debugging, and the descaling agent is added into the dissolving agent buffer tank for dissolution to obtain a descaling cleaning liquid; specifically, the steps include:

[0066] Step S201. Collect the scale sample of the filter material, and use the energy spectrum analyzer EDS, scanning electron microscope and transmission electron microscope to detect and obtain the scale sample components, including the types and contents of trace elements;

[0067] Step S202. Prepare a descaling agent by experimental debugging according to the scale-like components of the filter material, such as: selecting an oilfield polymer descaling agent PR71A, an oilfield high-efficiency plugging remover PR84C or a descaling solubilizer SA73B according to the scale-like components of the filter material;

[0068] Step S203. Add the descaling agent into the solvent buffer tank and stir to dissolve to obtain a descaling cleaning solution;

[0069] Step S3. Heating: heating the descaling cleaning solution to 60°C-80°C through a heating rod;

[0070] Step S4. Soaking: pump the descaling cleaning liquid into the filter through a centrifugal pump so that the descaling cleaning liquid covers the entire filter and the filter material is soaked for 6h-8h;

[0071] Step S5. Filtration: The descaling cleaning liquid is discharged from the filter to the vehicle-mounted filtering device to filter out large particles of impurities, scale, etc. in the descaling cleaning liquid; the descaling cleaning liquid filtered by the vehicle-mounted filtering device is returned to the solvent buffer tank again to achieve the purpose of closed cleaning;

[0072] Step S6. Cycle: Repeat steps S3-S6 to perform cyclic cleaning until the cleaning is complete.

[0073] In addition, before water injection in step S1, the pipeline is first cleaned with 0.3-0.4MPa water and a pipeline leak test is performed. Water can be injected for chemical cleaning only after the leak test is qualified.

[0074] At the same time, when implementing steps S4-S5, the scaling of the filter material is observed through the observation hole of the filter:

[0075] If the upper part of the filter material is severely scaled, the descaling cleaning liquid should be introduced from the top and discharged from the bottom (i.e., it should enter from the upper end of the filter and flow out from the bottom of the filter); if the lower part of the filter material is severely scaled, the descaling cleaning liquid should be introduced from the bottom and discharged from the top to make the cleaning more thorough.

[0076] The cleaning process provided by the embodiment of the present invention first adds a descaling agent to produced water and mixes it to obtain a descaling cleaning liquid, heats the descaling cleaning liquid and adds it to the filter to soften the scale, and finally dissolves the scale completely, and circulates out of the filter tank together with the descaling cleaning liquid; at the same time, the main components of the descaling agent can be adjusted through experimental tests according to the main components of the scaling of the filter material, and the immersion time can be flexibly adjusted according to the dissolution of the scale. If one immersion cleaning is not thorough, the cleaning can be circulated for multiple times until it is thoroughly cleaned; the entire cleaning process is simple and easy to operate, and is applicable to all types of filter materials. It can avoid the situation where the filter material is fragile and cannot be reused due to external rubbing, as well as the long shutdown construction period of traditional cleaning technology and the inability to ensure the continuous operation of oil field production, so as to achieve stable and standard water quality after filtration.

[0077] Example 2

[0078] The embodiment of the present invention provides an oilfield produced water filter cleaning process, which mainly includes the following steps:

[0079] Step S1. Water injection: inject 10m3 of water into the drug buffer tank.3 clean water;

[0080] Step S2. Adding a degreasing agent: adding the degreasing agent into the solvent buffer tank and stirring to dissolve to obtain a degreasing cleaning solution;

[0081] Step S3. Heating: heating the degreasing cleaning liquid to 60°C-80°C through a heating rod;

[0082] Step S4. Soaking: pump the degreasing cleaning liquid into the filter through a centrifugal pump so that the degreasing cleaning liquid covers the entire filter and the filter material is soaked for 3h-4h;

[0083] Step S5. Filtration: The degreasing cleaning liquid is discharged from the filter to the on-site online bag filter device, and then filtered by the online bag filter device and returned to the drug buffer tank;

[0084] Step S6. Detection: Use an online oil concentration monitor to detect the oil content in the deoiling cleaning liquid returned from the solvent buffer tank:

[0085] When the oil content in the two adjacent degreasing cleaning solutions increases and the increase is ≥5 mg / L, steps S3-S6 are repeated to continue degreasing cleaning;

[0086] When the oil content in the two adjacent degreasing cleaning solutions increases and the increase is less than 5 mg / L, the process proceeds to the next step S7;

[0087] Step S7. Dissolving the medicine: According to the scale composition of the filter material, a descaling agent is prepared through experimental debugging, and the descaling agent is added into the dissolving agent buffer tank for dissolution to obtain a descaling cleaning liquid; specifically, the steps include:

[0088] Step S701. Collect the scale sample of the filter material, and use the energy spectrum analyzer EDS, scanning electron microscope and transmission electron microscope to detect and obtain the scale sample components, including the types and contents of trace elements;

[0089] Step S702. According to the scale composition of the filter material, a descaling agent is prepared through experimental debugging;

[0090] Step S703. Add the descaling agent into the solvent buffer tank and stir to dissolve to obtain a descaling cleaning solution;

[0091] Step S8. Heating: heating the descaling cleaning solution to 60°C-80°C through a heating rod;

[0092] Step S9. Soaking: pump the descaling cleaning liquid into the filter through a centrifugal pump so that the descaling cleaning liquid covers the entire filter and the filter material is soaked for 6h-8h;

[0093] Step S10. Filtration: The descaling cleaning liquid is discharged from the bottom of the filter and filtered through the vehicle-mounted filtering device to intercept large particles of impurities, scaling, etc. in the cleaning liquid; the filtered descaling cleaning liquid is returned to the solvent buffer tank again to achieve the purpose of closed cleaning;

[0094] Step S11. Circulation: Check the cleaning status of the filter material through the observation hole of the filter. At the same time, use the online ion detector to detect the content of scale-forming ions such as calcium, magnesium, and silicon in the descaling cleaning liquid returned from the dissolving buffer tank:

[0095] When the content of scale-forming ions in the two adjacent descaling cleaning solutions increases and the increase is ≥5%, steps S8-S11 are repeated to continue descaling cleaning;

[0096] When the content of scaling ions in the descaling cleaning solution increases between two consecutive times and the increase is less than 5%, the cycle cleaning is stopped.

[0097] In addition, before water injection in step S1, the pipeline is first cleaned with 0.3-0.4MPa water and a pipeline leak test is performed. Water can be injected for chemical cleaning only after the leak test is qualified.

[0098] At the same time, when implementing steps S9-S10, the scaling of the filter material is observed through the observation hole of the filter:

[0099] If the scale on the upper part of the filter material is serious, the descaling cleaning liquid should be in from the top and out from the bottom (i.e., it enters from the top of the filter and flows out from the bottom of the filter);

[0100] If the lower part of the filter media is severely scaled, the descaling cleaning liquid should be introduced from the bottom and exited from the top to make the cleaning more thorough.

[0101] The cleaning process provided by the embodiment of the present invention first performs degreasing cleaning with a degreasing agent before descaling, which can prevent the oil wrapped on the scale from affecting the full reaction of the descaling agent with the scale, thereby improving the descaling effect and speed; at the same time, the oil content in the degreasing cleaning liquid is detected by an online oil concentration monitor to determine whether the degreasing cleaning is terminated, and the scale-forming ion content in the descaling cleaning liquid is detected by an online ion detector to determine whether the descaling cleaning is terminated, thereby avoiding the problem of incomplete circulation cleaning caused by human judgment and the problem of waste of equipment and circulation liquid resources caused by excessive circulation cleaning. The cleaning process is more controllable, and the cleaning effect is more reliable and energy-saving.

[0102] Example 3

[0103] The embodiment of the present invention makes the following improvements based on the cleaning process of embodiment 1 or 2:

[0104] When heating the degreasing cleaning liquid in the solvent buffer tank, the optimal degreasing temperature T0 of the degreasing agent is obtained through indoor experiments, and the upper limit of the degreasing heating temperature T is set according to the optimal degreasing temperature.0u and the lower limit of degreasing heating temperature T 0m , use the temperature control system to detect and control the heating temperature of the degreasing cleaning fluid:

[0105] When the temperature of the degreasing cleaning fluid T≤ the lower limit of the degreasing heating temperature T 0m When the temperature of the degreasing cleaning fluid reaches the upper limit of the degreasing heating temperature T, the heating rod is automatically started to heat the degreasing cleaning fluid. 0u When , the heating rod stops heating;

[0106] When the lower limit of degreasing heating temperature T 0m <Temperature of degreasing cleaning fluid T<Upper limit of degreasing heating temperature T 0u The heating rod does not start heating and directly proceeds to the next process step.

[0107] Similarly, when heating the descaling cleaning liquid in the solvent buffer tank, the optimal descaling temperature t0 of the descaling agent is obtained through indoor experiments, and the upper limit of the descaling heating temperature t is set according to the optimal descaling temperature. 0u And descaling heating temperature lower limit t 0m , use the temperature control system to detect and control the heating temperature of the descaling cleaning liquid:

[0108] When the temperature of the descaling cleaning fluid t≤ the lower limit of the degreasing heating temperature t 0m The heating rod is automatically started to heat the descaling cleaning liquid; when the temperature t of the descaling cleaning liquid reaches the upper limit of the descaling heating temperature t 0u When , the heating rod stops heating;

[0109] When the lower limit of descaling heating temperature is t 0m <Temperature of descaling cleaning fluid t<Upper limit of descaling heating temperature t 0u The heating rod does not start heating and directly proceeds to the next process step.

[0110] The embodiment of the present invention obtains the optimal heating temperature of the degreasing agent or descaling agent through experimental measurement, and sets the heating temperature threshold range according to the optimal heating temperature. The heating temperature of the degreasing agent or descaling cleaning liquid is controlled by the temperature control system, which can not only avoid the degreasing agent or descaling agent from being too low or overheated to affect the activity and ensure the degreasing or descaling effect of the degreasing agent or descaling agent, but also avoid the waste of electricity caused by excessive heating and save resources. At the same time, the temperature control system has simple control operation, saves manpower, and has a high degree of automation.

[0111] The above process method is used on site to carry out online cleaning and descaling of filter media. Before cleaning and descaling, the filter pressure difference is 0.3MPa, and the maximum instantaneous processing capacity of a single unit is 75m 3 / h; after cleaning and descaling, the filter pressure difference drops below 0.15MPa, and the maximum instantaneous processing capacity of a single unit is restored to 100m 3 / h, the cleaning effect is obvious.

[0112] Example 4

[0113] An embodiment of the present invention provides an oilfield produced water filter cleaning device, which is used to implement the cleaning process in any of the above embodiments.

[0114] Combination Figure 2 As shown, the cleaning device includes a drug solution buffer tank 1, a circulating cleaning pump 2, a filter to be cleaned 3 and a filtering device 4.

[0115] The liquid inlet of the filter 3 is connected to the filter liquid inlet pipeline 9, and the liquid inlet pipeline 9 is provided with a first three-way joint 10; the liquid outlet of the filter 3 is connected to the filter liquid outlet pipeline 8, and the filter liquid outlet pipeline 8 is provided with a second three-way joint 11;

[0116] The first three-way joint 10 is connected to the liquid inlet of the filter device 4 through the filter pipeline 7; the liquid outlet of the filter device 4 is connected to the liquid inlet of the dissolved drug buffer tank 1 through the return liquid pipeline 6; the liquid outlet of the dissolved drug buffer tank 1 is connected to the second three-way joint 11 through the dosing pipeline 5.

[0117] When injecting water to dissolve medicine, the produced water or engineering water supply enters the liquid inlet of the medicine buffer tank 1 through the filter inlet pipeline 9, the first three-way joint 10, the filter 3, the filter outlet pipeline 8, the second three-way joint 11, the filter pipeline 7, the filter device 4, and the return liquid pipeline 6 in sequence, or directly goes through the backwash pipeline, and the produced water or engineering water supply enters the liquid inlet of the medicine buffer tank 1 through the filter outlet pipeline 8, the second three-way joint 11, the filter pipeline 7, the filter device 4, and the return liquid pipeline 6 in sequence; during the circulating cleaning and descaling process, start the circulating cleaning pump 2, and the cleaning liquid in the medicine buffer tank 1 is injected into the filter 3 through the medicine inlet pipeline 5 and the first three-way joint 10, and after cleaning, it returns to the liquid inlet of the medicine buffer tank 1 through the second three-way joint 11, the filter pipeline 7, the filter device 4, and the return liquid pipeline 6, forming a series closed loop for circulating cleaning.

[0118] The drug dissolving buffer tank 1 is provided with an automatic stirring device, a heating rod and a temperature transmitter. Meanwhile, the drug dissolving buffer tank 1 is externally connected with an online oil concentration monitor and an online ion detector.

[0119] The filtering device is an online filtering device or a vehicle-mounted filtering device, and the vehicle-mounted filtering device is a skid-mounted device;

[0120] The circulating cleaning pump is a centrifugal pump.

[0121] The equipment used in the cleaning device of the embodiment of the present invention is mature, reliable and easy to obtain; the vehicle-mounted filtering device adopted is a skid-mounted equipment, which can be used whenever it is moved; during the inspection and maintenance period of the filter, it is only necessary to install a tee on the inlet and outlet water pipelines of the filter and connect the pipelines with the solvent buffer tank, the circulating cleaning pump and the filtering device, so as to achieve the purpose of online cleaning of the filter material. Little change is made to the existing pipelines and the installation is convenient. The entire cleaning time is about 8 hours. The operation method is simple, economical and practical, which can effectively ensure that the filter improves work efficiency and greatly improves the economic benefits of production.

[0122] It has been verified that the above process method is used on-site for online cleaning and descaling of filter media. Before cleaning and descaling, the filter pressure difference is 0.3MPa, and the maximum instantaneous processing capacity of a single unit is 75m 3 / h; after cleaning and descaling, the filter pressure difference drops below 0.15MPa, and the maximum instantaneous processing capacity of a single unit is restored to 100m 3 / h, the cleaning effect is obvious.

[0123] The above description is only an embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the application scope of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for cleaning an oilfield produced water filter, characterized in that: The process comprises the following steps: Step S1. Water injection: inject water into the drug buffer tank; Step S2. Dissolving the medicine: According to the composition of the filter material scale sample, prepare the descaling agent through experimental debugging, and add the descaling agent into the dissolving medicine buffer tank to dissolve it to obtain the descaling cleaning liquid; Step S3. Heating: heating the descaling cleaning liquid by a heating rod; Step S4. Soaking: pumping the descaling cleaning liquid into the filter so that the descaling cleaning liquid covers the entire filter and soaks the filter material; Step S5. Filtration: The descaling cleaning liquid is discharged from the filter to the filtering device, and the descaling cleaning liquid filtered by the filtering device is returned to the drug buffer tank again to achieve closed cleaning; Step S6. Cycle: Repeat steps S3-S6 to perform cyclic cleaning until the cleaning is complete.

2. The cleaning process according to claim 1, characterized in that: Before water injection in step S1, the pipeline is first cleaned with 0.3-0.4MPa water and tested for pipeline leaks. Water can be injected for chemical cleaning only after the leak test is qualified.

3. The cleaning process according to claim 1, characterized in that: The water injected in step S1 is water produced from the front end of the on-site filter or clean water.

4. The cleaning process according to claim 1, characterized in that: The step S2 specifically includes the following steps: Step S201. Collect the scale sample of the filter material, and use the detection instrument to detect and obtain the scale sample components; Step S202. According to the composition of the filter material scale sample, the scale sample composition, including the type and content of trace elements, is detected and obtained using an energy spectrum analyzer EDS, a scanning electron microscope and a transmission electron microscope; Step S203: Add the descaling agent into the solvent buffer tank and stir to dissolve to obtain a descaling cleaning solution.

5. The cleaning process according to claim 1, characterized in that: In the step S3, the descaling cleaning liquid is heated to a temperature of 60°C-80°C.

6. The cleaning process according to claim 1, characterized in that: In step S3, the descaling cleaning liquid is used to soak the filter material for 6 hours to 8 hours.

7. The cleaning process according to claim 1, characterized in that: When implementing steps S4-S5, observe the scaling of the filter material through the observation hole of the filter: If the upper part of the filter material is severely scaled, the descaling cleaning liquid should be introduced from the top and discharged from the bottom; if the lower part of the filter material is severely scaled, the descaling cleaning liquid should be introduced from the bottom and discharged from the top.

8. The cleaning process according to claim 1, characterized in that: The step S6 specifically includes: Check the cleaning status of the filter material through the observation hole of the filter. At the same time, use the online ion detector to detect the content of scale-forming ions such as calcium, magnesium, and silicon in the descaling cleaning liquid returned from the solvent buffer tank: When the content of scaling ions in the two consecutive descaling cleaning solutions increases and the increase is ≥5%, the descaling cleaning cycle will continue; When the content of scaling ions in the descaling cleaning solution increases between two consecutive times and the increase is less than 5%, the cycle cleaning is stopped.

9. The cleaning process according to claim 1, characterized in that: In step S3, when the descaling cleaning liquid in the solvent buffer tank is heated, the optimal descaling temperature t0 of the descaling agent is obtained through indoor experiments, and the upper limit of the descaling heating temperature t is set according to the optimal descaling temperature. 0u And descaling heating temperature lower limit t 0m , use the temperature control system to detect and control the heating temperature of the descaling cleaning liquid: When the temperature of the descaling cleaning fluid t≤ the lower limit of the degreasing heating temperature t 0m The heating rod is automatically started to heat the descaling cleaning liquid; when the temperature t of the descaling cleaning liquid reaches the upper limit of the descaling heating temperature t 0u When , the heating rod stops heating; When the lower limit of descaling heating temperature is t 0m <Temperature of descaling cleaning fluid t<Upper limit of descaling heating temperature t 0u The heating rod does not start heating and directly proceeds to the next process step.

10. The cleaning process according to any one of claims 1 to 8, characterized in that: Before step S2 of dissolving the drug, the following oil removal and cleaning steps are also included: Add the degreasing agent into the solvent buffer tank and stir to dissolve to obtain the degreasing cleaning solution; Heat the degreasing cleaning fluid through a heating rod; Pump the degreasing cleaning liquid into the filter so that the degreasing cleaning liquid covers the entire filter and soaks the filter material; The degreasing cleaning liquid is discharged from the filter to the filtering device, and then returned to the solvent buffer tank after being filtered by the filtering device.

11. The cleaning process according to claim 9, characterized in that: In the degreasing and cleaning step, the degreasing and cleaning liquid is heated to 60°C-80°C.

12. The cleaning process according to claim 9, characterized in that: In the oil removal and cleaning step, the oil removal and cleaning liquid is used to soak the filter material for 3h-4h.

13. The cleaning process according to claim 9, characterized in that: In the oil removal and cleaning step, the oil removal and cleaning liquid is discharged from the bottom of the filter, filtered by the filtering device and then returned to the drug dissolving buffer tank. After that, the following detection steps are also included: Use an online oil concentration monitor to detect the oil content in the degreasing cleaning fluid returned from the solvent buffer tank: When the oil content in the two adjacent degreasing cleaning fluids increases and the increase is ≥5mg / L, the degreasing cleaning cycle will continue; When the oil content in two adjacent degreasing cleaning solutions increases and the increase is less than 5 mg / L, proceed to the next process step.

14. The cleaning process according to claim 9, characterized in that: In the degreasing and cleaning step, When heating the degreasing cleaning liquid in the solvent buffer tank, the optimal degreasing temperature T0 of the degreasing agent is obtained through indoor experiments, and the upper limit of the degreasing heating temperature T is set according to the optimal degreasing temperature. 0u and the lower limit of degreasing heating temperature T 0m , use the temperature control system to detect and control the heating temperature of the degreasing cleaning fluid: When the temperature of the degreasing cleaning fluid T≤ the lower limit of the degreasing heating temperature T 0m When the temperature T of the degreasing cleaning fluid reaches the upper limit of the degreasing heating temperature T 0u When , the heating rod stops heating; When the lower limit of degreasing heating temperature T 0m <Temperature of degreasing cleaning fluid T<Upper limit of degreasing heating temperature T 0u The heating rod does not start heating and directly proceeds to the next process step.

15. An oilfield produced water filter cleaning device, used for implementing the cleaning process according to any one of claims 1 to 14, characterized in that: The cleaning device comprises a circulating cleaning pump, a drug dissolving buffer tank, a filter to be cleaned and a filtering device; The liquid inlet of the filter is connected to the filter liquid inlet pipeline, and the liquid inlet pipeline is provided with a first three-way joint; the liquid outlet of the filter is connected to the filter liquid outlet pipeline, and the filter liquid outlet pipeline is provided with a second three-way joint; The first three-way joint is connected to the liquid inlet of the filter device through a filter pipeline; the liquid outlet of the filter device is connected to the liquid inlet of the dissolved drug buffer tank through a return liquid pipeline; the liquid outlet of the dissolved drug buffer tank 1 is connected to the second three-way joint through a dosing pipeline.

16. The cleaning device according to claim 15, characterized in that: The drug dissolving buffer tank is provided with an automatic stirring device, a heating rod and a temperature transmitter. Meanwhile, the drug dissolving buffer tank is externally connected with an online oil concentration monitor and an online ion detector.

17. The cleaning device according to claim 15, characterized in that: The filtering device is an online filtering device or a vehicle-mounted filtering device, and the vehicle-mounted filtering device is a skid-mounted device; the circulating cleaning pump is a centrifugal pump.

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