Offshore polymer flooding blocked well pretreatment device and using method thereof

Abstract

The invention discloses an offshore polymer flooding blocked well pretreatment device and a using method thereof. The offshore polymer flooding blocked well pretreatment device comprises a first connecting pipe and a second connecting pipe. The device further comprises a filtering device; the filtering device is arranged between the first connecting pipe and the second connecting pipe, and the first connecting pipe is communicated with the second connecting pipe; a first medicament inlet and a first pressure gauge are arranged on the side wall of the first connecting pipe; a first valve is arranged between the first connecting pipe and the filtering device; a second medicament inlet and a second pressure gauge are arranged on the side wall of the second connecting pipe; and a second valve is arranged between the second connecting pipe and the filtering device. The filtering device is used for filtering possible blockages in advance, normal injection of the offshore polymer is guaranteed, and meanwhile unblocking construction is simplified.

Description

Technical Field

[0001] The invention relates to the technical field of polymer injection and plugging removal in oil production, in particular to an offshore polymer drive plugged well pretreatment device and a use method thereof. Background Art

[0002] During the water flooding development of oil fields, the heterogeneity of the reservoir and the unfavorable mobility ratio lead to low water drive sweep efficiency. Polymer flooding is a commonly used technology to improve the recovery rate in the secondary oil recovery process of oil fields. The polymers used in polymer flooding are mostly high molecular weight polyacrylamide (molecular weight of about 15 million). Its oil displacement mechanism is: adding polyacrylamide to water flooding is conducive to expanding the swept surface of the oil layer. When the oil layer is a high permeability layer, the polymer solution first enters the high permeability layer, and the subsequent injected water changes the flow direction around the polymer and enters the low permeability layer, thereby increasing the sweep coefficient and achieving the purpose of improving crude oil recovery.

[0003] However, polymer injection wells often experience blockage. This is because under the formation temperature and pressure, partially hydrolyzed polyacrylamide is catalyzed by clay minerals, and the carboxyl and amide groups on the linear macromolecular chain segments are prone to intramolecular crosslinking or crosslinking reactions with other active functional groups to generate crosslinked polymers with low solubility. These crosslinked polymers are adsorbed on the surface of clay minerals, sand particles, and inorganic substances to form colloid nuclei, and further form polymer micelles that precipitate from the solution and remain in the formation. In addition, the carboxyl and amide groups in the molecular structure of partially hydrolyzed polyacrylamide are easily adsorbed, captured, or retained on the surface of the formation rock, reducing the porosity and permeability of the oil layer, and reacting with Ca2+ and Mg2+ in the formation water to produce flocculent precipitates that separate from the solution and block the pores. The above reasons cause some polymer injection wells to have varying degrees of blockage problems, resulting in an increase in injection pressure (even reaching the fracture pressure), an increase in injection resistance, and an inability to complete the injection according to the ratio. Some wells have stopped injection, which seriously affects the economic benefits. How to solve the blockage problem of polymer injection wells is crucial to ensure normal polymer injection and to increase the oil production of polymer injection wells.

[0004] Publication (Announcement) No.: CN105443104A, discloses a method for removing blockage in a polymer flooding plugged well after acidification, the method is carried out according to the following steps: a. injecting an oil washing agent into the acidified polymer flooding plugged well, pre-treating the formation around the wellbore, and removing the water-insoluble crude oil on the surface of the plug, so as to facilitate the water-soluble treatment agent in the subsequent steps to react with the plug; the oil washing agent is a composite system composed of multiple surfactants, the weight concentration is generally 0.1-0.5%, the usage is 20-30m 3; b. Inject a 5-10% cross-linked gel degradation agent aqueous solution equal to the acid injected during the previous acidification into the blocked well. After the injection is completed, the well is closed for one day and then reopened; c. Inject a 6-10% composite depolymerization agent aqueous solution into the blocked well. The blockage is highly efficient and completely unblocked, solving the problem of other unblocking methods being ineffective. Various chemical solutions are easy to prepare on site, and the implementation is safe, reliable and convenient.

[0005] Publication (Announcement) No.: CN112342004B, discloses a hydrophobic modifier and polymer flooding method for improving the unblocking effect of polymer injection plugged wells. The hydrophobic modifier is composed of an organic silane coupling agent, an activator, a mutual solvent and water; the activator is an organic acid with a carbon number of 1-3; the mutual solvent is selected from an organic alcohol with a carbon number of 1-3; the mass ratio of the organic silane coupling agent, the activator and the mutual solvent is (0.5-1.0): (0.01-0.03): (4-10). The hydrophobic modifier of the present invention utilizes an organic silane coupling agent to hydrophobically modify the surface of sandstone in the presence of an activator. During the hydrophobic modification process, the hydrolysis product of the organic silane coupling agent reacts with the formation. After the reaction, the surface of the sandstone changes to a hydrophobic state, and the wettability is reversed, thereby significantly reducing the adsorption amount of the polymer.

[0006] Publication (Announcement) No.: CN112662385A, discloses a polymer micelle depolymerizer for oilfield injection wells and a preparation method thereof, and relates to the field of injection and unblocking in oil production. The polymer micelle depolymerizer for oilfield injection wells comprises the following components by weight: 12-16 parts of sodium α-olefin sulfonate, 10-20 parts of polysorbate, 0.5-1 part of activated carbon, 4-8 parts of polyaluminium chloride, 1-3 parts of depolymerization aid, 2-8 parts of protective agent, 40-55 parts of solvent, wherein the activated carbon is a fruit shell particle, the depolymerization aid is a mixture of one or more of calcium peroxide, sodium hypochlorite, and potassium hydrogen sulfate, and the solvent is a mixture of one or more of methanol, ethanol, and citric acid and phosphoric acid. The prior art has a higher efficiency when depolymerizing the polymer by mixing polysorbate, polyaluminium chloride and other raw materials, can greatly reduce the viscosity of the polymer, and make it fully dissolved, thereby achieving the effect of unblocking.

[0007] The above-mentioned prior art has achieved certain effects in field applications, but there are also problems of pipeline corrosion and safety of oxidants.

[0008] In summary, the technical solutions of the above-disclosed technologies, the technical problems to be solved, and the beneficial effects produced are all different from the present invention. Regarding more technical features, technical problems to be solved, and beneficial effects of the present invention, the above-disclosed technical documents do not provide any technical inspiration. Summary of the invention

[0009] In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide an offshore polymer flooding plugging well pretreatment device and a method of using the same, which can reduce construction costs, prolong the effective period of flooding and plugging, and prevent chemicals from corroding the pipe column.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] An offshore polymer flooding plugged well pretreatment device and a method of using the same include a first connecting pipe, a second connecting pipe, and a filtering device;

[0012] The filtering device is disposed between the first connecting pipe and the second connecting pipe to connect the first connecting pipe with the second connecting pipe;

[0013] The first connecting pipe side wall is provided with a first medicine inlet and a first pressure gauge; a first valve is provided between the first connecting pipe and the filter device;

[0014] A second medicine inlet and a second pressure gauge are arranged on the side wall of the second connecting pipe; and a second valve is arranged between the second connecting pipe and the filtering device.

[0015] The upper opening of the first connecting pipe is provided with a first conversion joint, and the upper opening of the second connecting pipe is provided with a second conversion joint.

[0016] The filtering device comprises a casing, a screen tube, a precision woven mesh, and a sealing sleeve;

[0017] The casing is connected to the axial rear end of the screen tube via a sealing sleeve, so that the right end of the first annulus between the casing and the screen tube is sealed;

[0018] The axial front and rear ends of the precision woven net are a front steel ring and a rear steel ring, a woven net is arranged between the front steel ring and the rear steel ring, and the precision woven net is welded to the screen tube through the front steel ring and the rear steel ring.

[0019] The sieve tube is provided with sieve holes in the area covered by the woven mesh; the pore size of the woven mesh is 48-110 μm.

[0020] The filter device is provided with a first flow guide joint at the axial front end, and a convex ring is provided in the middle of the first flow guide joint;

[0021] The first flow-guiding joint is provided with a countersunk hole at the axial front end and a flow-guiding hole communicating with the countersunk hole is provided on the side wall of the axial rear end;

[0022] The outer wall of the convex ring of the first flow guide joint is connected to the axial front end of the casing, the axial rear end of the first flow guide joint is connected to the axial front end of the screen tube and closes the axial front end of the screen tube, and the flow guide hole connects the first annulus with the countersunk hole.

[0023] The filter device is provided with a second flow guiding joint at the axial rear end, the second flow guiding joint is provided with an axial through hole, and the axial front end of the second flow guiding joint is connected to the axial rear end of the screen tube.

[0024] The first valve is connected to the first flow guiding joint, and the second valve is connected to the second flow guiding joint, or the first valve is connected to the second flow guiding joint, and the second valve is connected to the first flow guiding joint.

[0025] Two of each of the first valve, the filter device and the second valve are provided.

[0026] The filter device is made by integral welding, and is electroplated with phosphorus nickel after welding. The filtering accuracy of the precision woven mesh is higher than that of the bottom well sand filter mesh.

[0027] The method for using the offshore polymer flooding plugged well pretreatment device comprises the following steps:

[0028] S1. Select the filtration accuracy and choose the precision woven mesh according to the actual situation of the oil well; weld the filtration device;

[0029] S2, installing a filter device between the first connecting pipe and the second connecting pipe;

[0030] S3, connecting pipelines, the first conversion joint is connected to the plunger pump; the second conversion joint is connected to the wellhead, the first reagent inlet is connected to the oxidant injection pump, and the second reagent inlet is connected to the reducing agent injection pump;

[0031] S4, injecting the polymer, opening the valve, and using a plunger pump to pump in water containing the polymer; using a first pressure gauge and a second pressure gauge to measure the pressure difference between the first connecting pipe and the second connecting pipe, which is the basic pressure;

[0032] S5, unblocking construction, when the pressure difference reaches the blocking pressure, unblocking construction is carried out, the first agent is injected into the unblocking agent, and the unblocking agent and remover are injected from the second agent until the pressure difference drops below the unblocking pressure, the injection of the unblocking agent is stopped, and then the injection of the unblocking agent and remover is stopped after X hours, and the construction is completed.

[0033] S6. Scrap and replace. When the pressure difference cannot be reduced below the unobstructed pressure, stop the injection, close the first valve and the second valve, and replace the filter device.

[0034] In one embodiment of the present invention, adjustments are made to the following steps:

[0035] S2, installing a filtering device, installing two filtering devices between the first connecting pipe and the second connecting pipe, one for standby and one for working;

[0036] S4, injecting polymer, opening the valve of the working path, using a plunger pump to pump water containing polymer; using a first pressure gauge and a second pressure gauge to measure the pressure difference between the first connecting pipe and the second connecting pipe, which is the basic pressure;

[0037] S6. Scrap and replace. When the pressure difference cannot be reduced below the unobstructed pressure, stop the injection, close the working valve, replace the working filter device, open the valve in the spare line, and resume the injection.

[0038] The components of the blocking remover are 20% by weight of oxidant, 2% of corrosion inhibitor, 2% of iron ion stabilizer, 1% of drainage aid, and the balance of water;

[0039] The components of the declogging agent and remover are 30% by weight of reducing agent, 5% of corrosion and scale inhibitor, and the balance is water.

[0040] The filtration accuracy of the precision woven mesh is 48-110μm; the water injection volume is 200-240m 3 / day; the polymer is an acrylamide polymer; the polymer concentration in the water is 2000-2500 mg / L; the base pressure is 0.3-0.6 MPa; the blocking pressure is 4-6 MPa higher than the base pressure; the injection volume of the blocking agent is 8-10m 3 / day; the injection amount of the plugging remover is 8-10m 3 / day; the unobstructed pressure is 0.5-1Mpa; the X hours is 1-2 hours.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The filtering device is used to filter possible blockages in advance, which simplifies the unblocking construction while ensuring the normal injection of offshore polymer. At the same time, the blockage is handled in the pipeline without external discharge, which reduces environmental pollution. The reducing agent of the unblocking agent reduces the corrosion of the unblocking agent on the tubing in the well, ensuring normal polymer injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the offshore polymer flooding plugged well pretreatment device of the present invention;

[0044] Figure 2 It is a schematic structural diagram of a filtering device of an offshore polymer flooding plugged well pretreatment device of the present invention;

[0045] In the figure: 1. first pressure gauge; 2. first medicine inlet; 3. first conversion joint; 4. first connecting pipe; 5. first valve; 6. filtering device; 7. second valve; 8. second conversion joint; 9. second medicine inlet; 10. second pressure gauge; 11. second connecting pipe; 61. first flow guide joint; 62. casing; 63. screen tube; 64. precision woven mesh; 65. sealing sleeve; 66. second flow guide joint. DETAILED DESCRIPTION

[0046] 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.

[0047] See also Figure 1 to Figure 2 The offshore polymer flooding plugged well pretreatment device and the use method thereof provided by the present invention include a first connecting pipe 4, a filtering device 6, and a second connecting pipe 11;

[0048] A filter device 6 is provided between the first connecting pipe 4 and the second connecting pipe 11 to connect the first connecting pipe 4 and the second connecting pipe 11;

[0049] The first connecting pipe 4 is provided with a first conversion joint 3 at the upper end opening, and a first medicine inlet 2 and a first pressure gauge 1 are provided on the side wall of the first connecting pipe 4. The first pressure gauge 1 detects the liquid pressure in the first connecting pipe 4; a first valve 5 is provided between the first connecting pipe 4 and the filter device 6;

[0050] A second conversion joint 8 is provided at the upper opening of the second connecting pipe 11, and a second medicine inlet 9 and a second pressure gauge 10 are provided on the side wall of the second connecting pipe 11. The second pressure gauge 9 detects the liquid pressure in the second connecting pipe 11; a second valve 7 is provided between the second connecting pipe 4 and the filtering device 6.

[0051] The filtering device 6 comprises a first flow guide joint 61, a sleeve 62, a screen tube 63, a precision braided mesh 64, a sealing sleeve 65, and a second flow guide joint 66; the sleeve 62 and the screen tube 63 are connected at the axial rear end through a sealing sleeve, so that the right end of the first annulus between the sleeve 62 and the screen tube 63 is sealed, the axial front and rear ends of the precision braided mesh 64 are a front steel ring and a rear steel ring, a braided mesh is arranged between the front steel ring and the rear steel ring, the aperture of the braided mesh is 48-110 μm, the precision braided mesh 64 is welded to the screen tube 63 through the front steel ring and the rear steel ring, and the screen tube 63 is provided with a sieve hole in the area covered by the braided mesh;

[0052] A convex ring is provided in the middle of the first flow guiding joint 61, a countersunk hole is provided at the axial front end of the first flow guiding joint 61, and a flow guiding hole connected to the countersunk hole is provided on the side wall of the axial rear end. The outer wall of the convex ring of the first flow guiding joint 61 is connected to the axial front end of the casing 62, and the axial rear end of the first flow guiding joint 61 is connected to the axial front end of the screen tube 63 and closes the axial front end of the screen tube 63. The flow guiding hole connects the first annulus with the countersunk hole.

[0053] The second flow guiding joint 66 is provided with an axial through hole, and the axial front end of the second flow guiding joint 66 is connected to the axial rear end of the screen tube 63 .

[0054] The first valve 5 is connected to the first flow guiding joint 61 , and the second valve 7 is connected to the second flow guiding joint 66 , or the first valve 5 is connected to the second flow guiding joint 66 , and the second valve 7 is connected to the first flow guiding joint 61 .

[0055] The first valve 5, the filtering device 6 and the second valve 7 are all provided in pairs, and two filtering pipelines are provided, one for working and the other for standby.

[0056] The filter device 6 is made of integral welding and can be replaced as a whole when there is a problem. The filter device is made of 316 steel. The filter device 6 is electroplated with phosphorus nickel after welding to increase the corrosion resistance. The filter device 6 filters and retains insoluble polyacrylamide. The filtering accuracy of the filter device 6 is higher than or equal to the bottom well filter.

[0057] The length of the filtering device is determined according to the specific offshore conditions and the allowable size of the offshore platform, and is made as long as possible under the conditions allowed by the platform to ensure that the flow is not affected.

[0058] The filtering accuracy of the precision woven mesh 64 is higher than that of the bottom well sand filter.

[0059] The substances that may cause blockage are filtered and removed at the wellhead through the filter device 6. When the pressure difference between the inlet and outlet of the filter device 6 becomes larger and blockage is formed, a plunger pump is used to inject a designed amount of unblocking agent from the inlet, and a designed amount of unblocking agent remover is injected at the outlet at the same time to eliminate the adverse effects of the depolymerizing agent, ensure the injection effect, reduce construction, reduce the corrosion of the unblocking agent to the tubing in the well, and ensure normal injection.

[0060] Embodiment 1:

[0061] Method for using the offshore polymer flooding plugged well pretreatment device:

[0062] S1. Select the filtration accuracy. According to the actual situation of the oil well, select a precision woven mesh with a filtration accuracy of 110 μm; and weld the first flow guide joint 61, the casing 62, the screen tube 63, the precision woven mesh 64, the sealing sleeve 65, and the second flow guide joint 66 into a filter device 6;

[0063] S2, installing the filter device 6, installing a filter device 6 between the first connecting pipe 4 and the second connecting pipe 11;

[0064] S3, connecting pipeline, the first conversion joint 3 is connected to the plunger pump; the second conversion joint 8 is connected to the wellhead, the first reagent inlet 2 is connected to the oxidant injection pump, and the second reagent inlet 9 is connected to the reducing agent injection pump;

[0065] S4, inject polymer, open the first valve 5 and the second valve 7, and use the plunger pump to pump 200m per day 3 Water, the polymer in the water is acrylamide polymer, and its concentration is 2000 mg / L; the pressure difference between the first connecting pipe 4 and the second connecting pipe 11 is measured using the first pressure gauge 1 and the second pressure gauge 10; at this time, the basic pressure is 0.3 MPa

[0066] S5, unblocking construction, as the injection time increases, the pressure difference gradually increases. When the pressure difference is higher than the base pressure by 6MPa, unblocking construction is carried out. The displacement of the injected polymer remains unchanged. The first reagent inlet 2 is 8m 3 / day discharge rate to inject unblocking agent, from the second agent inlet 9 at 8m 3 / day of injection of plugging remover, until the pressure difference drops below 0.5MPa, stop injecting plugging remover, then stop injecting plugging remover after 1 hour, and the construction is completed;

[0067] S6, scrap and replace. When the pressure difference cannot be reduced below 0.5 MPa, stop the injection, close the first valve 5 and the second valve 7, and replace the filter device 6.

[0068] Embodiment 2:

[0069] S1. Select the filtration accuracy. According to the actual situation of the oil well, select a precision woven mesh with a filtration accuracy of 48 μm; and weld the first flow guide joint 61, the casing 62, the screen tube 63, the precision woven mesh 64, the sealing sleeve 65, and the second flow guide joint 66 into a filter device 6;

[0070] S2, installing the filter device 6, installing two filter devices 6 between the first connecting pipe 4 and the second connecting pipe 11, one for standby and one for working;

[0071] S3, connecting pipeline, the first conversion joint 3 is connected to the plunger pump; the second conversion joint 8 is connected to the wellhead, the first reagent inlet 2 is connected to the oxidant injection pump, and the second reagent inlet 9 is connected to the reducing agent injection pump;

[0072] S4, inject polymer, open the first valve 5 and the second valve 7 of the working path, and use the plunger pump to pump 240m per day 3Water, the polymer in the water is acrylamide polymer, and its concentration is 2500 mg / L; the pressure difference between the first connecting pipe 4 and the second connecting pipe 11 is measured using the first pressure gauge 1 and the second pressure gauge 10; at this time, the basic pressure is 0.6 MPa

[0073] S5, unblocking construction, as the injection time increases, the pressure difference gradually increases. When the pressure difference is higher than the base pressure by 4MPa, unblocking construction is carried out. The displacement of the injected polymer remains unchanged. The first reagent inlet 2 is set at 10m 3 / day discharge rate to inject unblocking agent, from the second agent inlet 9 at 10m 3 / day of injection of plugging remover, until the pressure difference drops below 1MPa, stop injecting plugging remover, then stop injecting plugging remover after 2 hours, and the construction is completed;

[0074] S6, scrap and replace. When the pressure difference cannot be reduced below 1 MPa, stop the polymer injection, close the first valve 5 and the second valve 7 of the working path, replace the working filter device 6, open the valve in the spare path, and resume the polymer injection.

[0075] Embodiment 3;

[0076] In Example 1 and Example 2, a blocking agent and a blocking agent reducing agent are used. The blocking agent has a weight ratio of 20% oxidant, 2% corrosion inhibitor, 2% iron ion stabilizer, 1% drainage agent, and the balance is water;

[0077] The components of the declogging agent and remover are 30% by weight of reducing agent, 5% of corrosion and scale inhibitor, and the balance is water.

[0078] The corrosion inhibitor can be selected from existing oil well corrosion inhibitors, or from acidizing corrosion inhibitors disclosed in publication number CN104109529A. The iron ion stabilizer can be selected from iron ion stabilizers for acidification disclosed in publication number CN104109530A. The oxidant, corrosion inhibitor, drainage aid, and reducing agent are all prior art, and those skilled in the art are aware of this.

[0079] All components and connection methods of components not discussed in this application belong to the known technologies in this technical field and can be directly applied without further explanation.

[0080] In the present invention, the term "plurality" refers to two or more than two, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0081] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front” and “back” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation on the present invention.

[0082] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An offshore polymer flooding plugged well pretreatment device, comprising a first connecting pipe and a second connecting pipe; characterized in that: Also includes a filtering device; The filtering device is disposed between the first connecting pipe and the second connecting pipe to connect the first connecting pipe with the second connecting pipe; The first connecting pipe side wall is provided with a first medicine inlet and a first pressure gauge; The side wall of the second connecting pipe is provided with a second medicine inlet and a second pressure gauge.

2. The offshore polymer flooding plugged well pretreatment device according to claim 1 is characterized in that: The upper opening of the first connecting pipe is provided with a first conversion joint, and the upper opening of the second connecting pipe is provided with a second conversion joint.

3. The offshore polymer flooding plugged well pretreatment device according to claim 1 is characterized in that: The filtering device comprises a casing, a screen tube, a precision woven mesh, and a sealing sleeve; The casing is connected to the axial rear end of the screen tube via a sealing sleeve, so that the right end of the first annulus between the casing and the screen tube is sealed; The axial front and rear ends of the precision woven net are a front steel ring and a rear steel ring, a woven net is arranged between the front steel ring and the rear steel ring, and the precision woven net is welded to the screen tube through the front steel ring and the rear steel ring.

4. The offshore polymer flooding plugged well pretreatment device according to claim 3 is characterized in that: The sieve tube is provided with sieve holes in the area covered by the woven mesh; the pore size of the woven mesh is 48-110 μm.

5. The offshore polymer flooding plugged well pretreatment device according to claim 3 is characterized in that: The filter device is provided with a first flow guide joint at the axial front end, and a convex ring is provided in the middle of the first flow guide joint; The first flow-guiding joint is provided with a countersunk hole at the axial front end and a flow-guiding hole communicating with the countersunk hole is provided on the side wall of the axial rear end; The outer wall of the convex ring of the first flow guide joint is connected to the axial front end of the casing, the axial rear end of the first flow guide joint is connected to the axial front end of the screen tube and closes the axial front end of the screen tube, and the flow guide hole connects the first annulus with the countersunk hole.

6. The offshore polymer flooding plugged well pretreatment device according to claim 5 is characterized in that: The filter device is provided with a second flow guiding joint at the axial rear end, the second flow guiding joint is provided with an axial through hole, and the axial front end of the second flow guiding joint is connected to the axial rear end of the screen tube.

7. The offshore polymer flooding plugged well pretreatment device according to claim 6 is characterized in that: A first valve is provided between the first connecting pipe and the filter device; a second valve is provided between the second connecting pipe and the filter device; The first valve is connected to the first flow guiding joint, and the second valve is connected to the second flow guiding joint, or the first valve is connected to the second flow guiding joint, and the second valve is connected to the first flow guiding joint.

8. The offshore polymer flooding plugged well pretreatment device according to claim 7, characterized in that: Two of each of the first valve, the filter device and the second valve are provided.

9. The offshore polymer flooding plugged well pretreatment device according to claim 6, characterized in that: The filter device is made by integral welding, and is electroplated with phosphorus nickel after welding. The filtering accuracy of the precision woven mesh is higher than that of the bottom well sand filter mesh.

10. A method for using an offshore polymer flooding plugged well pretreatment device, characterized in that: The following steps are involved: S1. Select the filtration accuracy and choose the precision woven mesh according to the actual situation of the oil well; weld the filtration device; S2, installing a filter device between the first connecting pipe and the second connecting pipe; S3, connecting pipelines, the first conversion joint is connected to the plunger pump; the second conversion joint is connected to the wellhead, the first reagent inlet is connected to the oxidant injection pump, and the second reagent inlet is connected to the reducing agent injection pump; S4, injecting the polymer, opening the valve, and using a plunger pump to pump in water containing the polymer; using a first pressure gauge and a second pressure gauge to measure the pressure difference between the first connecting pipe and the second connecting pipe, which is the basic pressure; S5, unblocking construction, when the pressure difference reaches the blocking pressure, unblocking construction is carried out, the first agent is injected into the unblocking agent, and the unblocking agent and remover are injected from the second agent until the pressure difference drops below the unblocking pressure, the injection of the unblocking agent is stopped, and then the injection of the unblocking agent and remover is stopped after X hours, and the construction is completed.

11. The method for using the offshore polymer flooding plugging well pretreatment device according to claim 10, characterized in that: The following steps are also included: S6. Scrap and replace. When the pressure difference cannot be reduced below the unobstructed pressure, stop the injection, close the first valve and the second valve, and replace the filter device.

12. The method for using the offshore polymer flooding plugging well pretreatment device according to claim 11, characterized in that: Make adjustments to the following steps: S2, installing a filtering device, installing two filtering devices between the first connecting pipe and the second connecting pipe, one for standby and one for working; S4, injecting polymer, opening the valve of the working path, using a plunger pump to pump water containing polymer; using a first pressure gauge and a second pressure gauge to measure the pressure difference between the first connecting pipe and the second connecting pipe, which is the basic pressure; S6. Scrap and replace. When the pressure difference cannot be reduced below the unobstructed pressure, stop the injection, close the working valve, replace the working filter, open the valve in the spare line, and resume the injection.

13. The method for using the offshore polymer flooding plugging well pretreatment device according to claim 10, characterized in that: The components of the blocking remover are 20% by weight of oxidant, 2% of corrosion inhibitor, 2% of iron ion stabilizer, 1% of drainage aid, and the balance of water; The components of the blockage remover and eliminater are 30% by weight of reducing agent, 5% of corrosion and scale inhibitor, and the balance is water.

14. The method for using the offshore polymer flooding plugging well pretreatment device according to claim 10, characterized in that: The filtration accuracy of the precision woven mesh is 48-110μm; the water injection volume is 200-240m 3 / day; the polymer is an acrylamide polymer; the polymer concentration in the water is 2000-2500 mg / L; the base pressure is 0.3-0.6 MPa; the blocking pressure is 4-6 MPa higher than the base pressure; the injection volume of the blocking agent is 8-10m 3 / day; the injection amount of the plugging remover is 8-10m 3 / day; the unobstructed pressure is 0.5-1Mpa; the X hours is 1-2 hours.

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