Offshore polymer-flooded well pretreatment device and method of using same

Abstract

The application discloses a sea polymer plugging well pretreatment device and a use method thereof, and belongs to the technical field of oil exploitation. The sea polymer plugging well pretreatment device comprises a first connecting pipe, a second connecting pipe and a filter device. The first connecting pipe is communicated with the second connecting pipe through the filter device. The first connecting pipe is provided with a first medicament inlet and a first pressure gauge on the side wall. The first connecting pipe is provided with a first valve between the first connecting pipe and the filter device. The second connecting pipe is provided with a second medicament inlet and a second pressure gauge on the side wall. The second connecting pipe is provided with a second valve between the second connecting pipe and the filter device. The filter device is used for filtering possible plugging materials in advance, so that the normal injection of the sea polymer is ensured, and the plugging operation is simplified.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer injection and plugging removal in oil exploitation, in particular to a pretreatment device for offshore polymer flooding plugged wells and a use method thereof. BACKGROUND

[0002] In the process of water injection development in oil fields, the heterogeneity of the reservoir and the unfavorable mobility ratio result in low water flooding sweep efficiency. Polymer flooding is a commonly used technology to improve recovery in the process of secondary oil recovery in oil fields. The polymer used in polymer flooding is mostly high molecular weight polyacrylamide (molecular weight of about 15 million), and the oil displacement mechanism is as follows: the addition of polyacrylamide in water flooding is beneficial to the expansion of the swept area 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 improving the sweep efficiency and achieving the purpose of improving the recovery of crude oil.

[0003] However, plugging often occurs in polymer injection wells, which is due to the catalytic action of clay minerals on partially hydrolyzed polyacrylamide at the temperature and pressure of the formation. The carboxyl and amide groups on the linear macromolecular chain segment are prone to intramolecular crosslinking or crosslinking reaction with other active functional groups to form crosslinked polymers with low solubility. These crosslinked polymers are adsorbed on the surface of clay minerals, sand particles and inorganic substances to form a glue core, and further form polymer micelles to precipitate out of the solution and stay in the formation. In addition, the carboxyl and amide groups in the molecular structure of partially hydrolyzed polyacrylamide are prone to adsorption, capture or retention on the surface of formation rocks, which reduces the porosity and permeability of the oil layer, and reacts with Ca2+ and Mg2+ in the formation water to produce flocculent precipitates that separate out of the solution and block the pore channels. The above reasons cause different degrees of plugging problems in some polymer flooding oil wells, resulting in an increase in injection pressure (even reaching the fracture pressure), an increase in injection resistance, an inability to complete the injection according to the ratio, a stoppage of injection in some wells, and a serious impact on economic benefits. How to solve the plugging problem of polymer injection wells is crucial to ensure normal polymer injection and improve the oil production of polymer injection wells.

[0004] Publication (announcement) No. CN105443104A discloses a method for removing the plugging of polymer flooding wells after acidification, which is performed according to the following steps: a. injecting a oil washing agent into the polymer flooding well after acidification to pretreat the formation around the wellbore and remove the water-insoluble crude oil on the surface of the plugging material, so as to facilitate the reaction between the water-soluble treatment agent and the plugging material in the subsequent step; the oil washing agent is a complex system composed of multiple surfactants, and the weight concentration is generally 0.1-0.5%, and the usage amount is 20-30m 3b. Injecting into the plugged well a crosslinked gel degrading agent aqueous solution with a weight concentration of 5-10% in an amount equivalent to the acid injected in the previous acidizing, and after the injection is completed, shutting down the well for one day and then opening the well; c. Injecting into the plugged well a composite depolymerization agent aqueous solution with a weight concentration of 6-10%, the plugging removal efficiency is high, the plugging removal is complete, and the problem that other plugging removal methods are ineffective is solved, the various chemical agent solutions are easy to prepare in the field, and the implementation is safe and reliable.

[0005] Publication (announcement) No. CN112342004B discloses a hydrophobic modifier for improving the plugging removal effect of polymer injection plugging wells and a polymer flooding method. The hydrophobic modifier is composed of an organic silane coupling agent, an activator, a mutual solvent and water; the activator is selected from organic acids with 1-3 carbon atoms; the mutual solvent is selected from organic alcohols with 1-3 carbon atoms; 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 application uses the organic silane coupling agent to modify the surface of sandstone in the presence of the activator, and the hydrolysis product of the organic silane coupling agent reacts with the formation during the hydrophobic modification process. After the reaction, the surface of the sandstone changes to a hydrophobic state, the wettability is reversed, and then the adsorption amount of the polymer can be significantly reduced.

[0006] Publication (announcement) No. CN112662385A discloses an oilfield polymer injection well polymer micellar deaggregating agent and a preparation method thereof, and relates to the field of polymer injection and plugging removal in oil exploitation. The oilfield polymer injection well polymer micellar deaggregating agent comprises the following components in parts by weight: 12-16 parts of sodium alpha-olefin sulfonate, 10-20 parts of polysorbate, 0.5-1 part of activated carbon, 4-8 parts of polyaluminum chloride, 1-3 parts of deaggregation aid, 2-8 parts of protective agent, and 40-55 parts of solvent. The activated carbon is a nutshell particle, the deaggregation aid is a mixture of one or more of calcium peroxide, sodium hypochlorite and potassium bisulfate, and the solvent is a mixture of one or more of methanol, ethanol and citric acid phosphoric acid. The prior art has high efficiency in polymer deaggregation by mixing polysorbate, polyaluminum chloride and other raw materials, can greatly reduce the viscosity of the polymer, and make it fully dissolved, thereby achieving the effect of plugging removal.

[0007] The above prior art has achieved certain effect in field application, but there are problems of pipeline corrosion and safety of oxidizing agents.

[0008] In summary, the technical solutions, the technical problems to be solved and the beneficial effects of the above disclosed technologies are different from those of the present application. The above disclosed technology documents do not have technical inspiration for more technical features and technical problems to be solved and beneficial effects of the present application. SUMMARY

[0009] In view of the above defects existing in the prior art, the purpose of the present application is to provide offshore polymer flooding well plugging pretreatment device and its using method, which reduces construction cost, has long effective period of flooding and prevents corrosion of the pipe string by the agent.

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

[0011] The offshore polymer flooding well plugging pretreatment device and its using method comprise a first connecting pipe and a second connecting pipe, further comprise a filtering device;

[0012] The filtering device is arranged between the first connecting pipe and the second connecting pipe, and the first connecting pipe and the second connecting pipe are communicated;

[0013] The side wall of the first connecting pipe is provided with a first agent inlet and a first pressure gauge, and a first valve is arranged between the first connecting pipe and the filtering device;

[0014] The side wall of the second connecting pipe is provided with a second agent inlet and a second pressure gauge, and a second valve is arranged between the second connecting pipe and the filtering device.

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

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

[0017] The sleeve pipe and the screen pipe are connected through the sealing sleeve at the axial rear end, so that the right end of the first annulus between the sleeve pipe and the screen pipe is sealed;

[0018] The axial front end and the axial rear end of the precision woven mesh are a front steel ring and a rear steel ring, a woven mesh is arranged between the front steel ring and the rear steel ring, and the precision woven mesh is welded on the screen pipe through the front steel ring and the rear steel ring.

[0019] The screen pipe is provided with screen holes in the area covered by the woven mesh, and the aperture of the woven mesh is 48-110 mu m.

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

[0021] The axial front end of the first flow guide joint is provided with a counterbore, and the side wall of the axial rear end is provided with a flow guide hole communicating with the counterbore;

[0022] The outer wall of the convex ring of the first flow guide joint is connected with the axial front end of the sleeve pipe, the axial rear end of the first flow guide joint is connected with the axial front end of the screen pipe and seals the axial front end of the screen pipe, and the flow guide hole communicates the first annulus with the counterbore.

[0023] The second flow guide joint is provided with an axial through hole, and an axial front end of the second flow guide joint is connected with an axial rear end of the screen pipe.

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

[0025] The first valve, the filter device and the second valve are all provided with two.

[0026] The filter device is integrally welded, the filter device is welded, and then phosphorus nickel is electroplated, and the filtering precision of the precision woven mesh is higher than that of the sand filter mesh at the well bottom.

[0027] The use method of the offshore polymer plugging well pretreatment device comprises the following steps:

[0028] S1, selecting filtering precision, selecting precision woven mesh according to the actual situation of the oil well; welding the filter device;

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

[0030] S3, connecting the pipeline, the first conversion joint is communicated with the plunger pump; the second conversion joint is communicated with the wellhead, the first medicament inlet is communicated with the oxidizing agent injection pump, and the second medicament inlet is communicated with the reducing agent injection pump;

[0031] S4, injecting polymer, opening the valve, pumping water using the plunger pump, and the water contains polymer; the first pressure gauge and the second pressure gauge are used to measure the pressure difference between the first connecting pipe and the second connecting pipe, which is the basic pressure at this time;

[0032] S5, plugging removal construction, when the pressure difference reaches the plugging pressure, the plugging removal construction is carried out, the first medicament is injected into the plugging removal agent, and the second medicament is injected into the plugging removal agent eliminating agent, until the pressure difference is reduced to below the unobstructed pressure, the injection of the plugging removal agent is stopped, and then the injection of the plugging removal agent eliminating agent is stopped after X hours, and the construction is completed.

[0033] S6, scrap replacement, when the pressure difference cannot be reduced to below the unobstructed pressure, stop injecting polymer, close the first valve and the second valve, and replace the filter device.

[0034] In an embodiment of the present application, the following steps are adjusted:

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

[0036] S4, inject the polymer, open the valve of the working path, use the plunger pump to inject the water containing the polymer, use the first pressure gauge and the second pressure gauge to measure the pressure difference between the first connecting pipe and the second connecting pipe, at this time, the base pressure is obtained;

[0037] S6, scrap replacement, when the pressure difference cannot be reduced below the unobstructed pressure, stop injecting the polymer, close the valve of the working path, replace the working filter device, open the valve in the standby path, and resume the polymer injection.

[0038] The proportion of each component of the plugging remover is 20% of the oxidizing agent, 2% of the corrosion inhibitor, 2% of the iron ion stabilizer, 1% of the cleanup agent, and the balance is water;

[0039] The proportion of each component of the plugging remover is 30% of the reducing agent, 5% of the corrosion and scale inhibitor, and the balance is water.

[0040] The precision woven mesh has a filtering precision of 48-110 mu m; the water injection amount is 200-240 m 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 plugging pressure is higher than the base pressure by 4-6 MPa; the plugging remover injection amount is 8-10 m 3 / day; the plugging remover elimination agent injection amount is 8-10 m 3 / day; the unobstructed pressure is 0.5-1 Mpa; and the X hours are 1-2 hours.

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

[0042] The filter device can filter the possible blockage in advance, ensure normal injection of the polymer at sea, simplify the plugging removal construction, and reduce environmental pollution by not discharging the blockage in the pipeline; and the plugging remover reducing agent reduces the corrosion of the plugging remover to the pipe column in the well, and ensures normal polymer injection. BRIEF DESCRIPTION OF DRAWINGS

[0043] Fig. 1 is a structural schematic view of the offshore polymer flooding well plugging pretreatment device of the present application;

[0044] Fig. 2 is a structural schematic view of the filter device of the offshore polymer flooding well plugging pretreatment device of the present application;

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

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0047] Please refer to Figs. 1-2 The offshore polymer flooding well pretreatment device provided by the present application comprises a first connecting pipe 4, a filtering device 6 and a second connecting pipe 11.

[0048] The filtering device 6 is arranged between the first connecting pipe 4 and the second connecting pipe 11 to communicate the first connecting pipe 4 and the second connecting pipe 11.

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

[0050] The second conversion joint 8 is arranged at the upper end opening of the second connecting pipe 11, the second medicament inlet 9 and the second pressure gauge 10 are arranged on the side wall of the second connecting pipe 11, and the second pressure gauge 9 detects the liquid pressure in the second connecting pipe 11; and the second valve 7 is arranged 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 pipe 63, a precision woven mesh 64, a sealing sleeve 65 and a second flow guide joint 66; the sleeve 62 and the screen pipe 63 are connected through the sealing sleeve at the axial rear end, so that the first annular space between the sleeve 62 and the screen pipe 63 is sealed at the right end, the axial front end and the rear end of the precision woven mesh 64 are front and rear steel rings, a woven mesh is arranged between the front and rear steel rings, the aperture of the woven mesh is 48-110 μm, the precision woven mesh 64 is welded on the screen pipe 63 through the front and rear steel rings, and the screen pipe 63 is provided with screen holes in the area covered by the woven mesh.

[0052] The first flow guide joint 61 is provided with a convex ring in the middle, the first flow guide joint 61 is provided with a counterbore at the axial front end and a flow guide hole communicating with the counterbore at the side wall of the axial rear end, the outer wall of the convex ring of the first flow guide joint 61 is connected with the axial front end of the sleeve 62, the axial rear end of the first flow guide joint 61 is connected with the axial front end of the screen pipe 63 and seals the axial front end of the screen pipe 63, and the flow guide hole communicates the first annulus with the counterbore.

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

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

[0055] The first valve 5, the filtering device 6 and the second valve 7 are all provided with two filtering pipelines, one of which is working and the other is standby.

[0056] The filtering device 6 is integrally welded and is replaced as a whole when there is a problem, the filtering device is made of 316 steel, the filtering device 6 is electroplated with phosphorus nickel after being welded to increase the corrosion resistance, the filtering device 6 filters and retains insoluble polyacrylamide, and the filtering precision of the filtering device 6 is higher than or equal to the filtering precision of the well bottom filter screen.

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

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

[0059] The substances that may cause plugging are removed by the filtering device 6 at the wellhead, when the pressure difference between the inlet and the outlet of the filtering device 6 becomes large and plugging is formed, a designed amount of plugging removal agent is injected from the inlet by the plunger pump, and a designed amount of plugging removal elimination agent is injected at the outlet to eliminate the adverse effects of the plugging removal agent, ensure the effect of polymer injection, reduce construction, reduce the corrosion of the plugging removal agent to the pipe column in the well, and ensure normal polymer injection.

[0060] Example 1:

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

[0062] S1, select the filtering precision, select the precision woven screen with a filtering precision of 110 μm according to the actual situation of the oil well; and weld the first flow guide joint 61, the sleeve 62, the screen pipe 63, the precision woven screen 64, the sealing sleeve 65 and the second flow guide joint 66 into the filtering device 6;

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

[0064] S3, connect the pipeline, the first conversion joint 3 communicates with the plunger pump; the second conversion joint 8 communicates with the wellhead, the first medicament inlet 2 communicates with the oxidizing agent injection pump, and the second medicament inlet 9 communicates with the reducing agent injection pump;

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

[0066] S5, plug removal construction, as the injection time is prolonged, the pressure difference gradually increases, when the pressure difference is higher than the basic pressure 6MPa, plug removal construction is carried out, the displacement of the polymer injection is unchanged, the first medicament inlet 2 injects the plug removal agent at the displacement of 8m 3 / day, the second medicament inlet 9 injects the plug removal agent eliminating agent at the displacement of 8m 3 / day, until the pressure difference is reduced to 0.5MPa or less, stop injecting the plug removal agent, and then stop injecting the plug removal agent eliminating agent after 1 hour, the construction is completed;

[0067] S6, scrap replacement, when the pressure difference cannot be reduced to 0.5MPa or less, stop injecting the polymer, close the first valve 5 and the second valve 7, and replace the filtering device 6.

[0068] Example 2:

[0069] S1, select the filtering precision, select the precision woven mesh with the filtering precision of 48μm according to the actual situation of the oil well; and weld the first flow guide joint 61, the sleeve 62, the screen pipe 63, the precision woven mesh 64, the sealing sleeve 65, and the second flow guide joint 66 into the filtering device 6;

[0070] S2, install the filtering device 6, install two filtering devices 6 between the first connecting pipe 4 and the second connecting pipe 11, one of which is standby and the other of which is working;

[0071] S3, connect the pipeline, the first conversion joint 3 communicates with the plunger pump; the second conversion joint 8 communicates with the wellhead, the first medicament inlet 2 communicates with the oxidizing agent injection pump, and the second medicament inlet 9 communicates with the reducing agent injection pump;

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

[0073] S5, plugging construction, as the injection time is prolonged, the pressure difference is gradually increased, when the pressure difference is higher than the basic pressure 4 MPa, the plugging construction is carried out, the displacement of the injection polymer is unchanged, the first medicament inlet 2 injects the plugging agent at the displacement of 10 m 3 / day, the second medicament inlet 9 injects the plugging agent eliminating agent at the displacement of 10 m 3 / day, until the pressure difference is reduced to below 1 MPa, stop injecting the plugging agent, and then stop injecting the plugging agent eliminating agent after 2 hours, the construction is completed;

[0074] S6, scrap replacement, when the pressure difference cannot be reduced to below 1 MPa, stop injecting the polymer, close the first valve 5 and the second valve 7 of the working road, replace the filter device 6, open the valve in the standby road, and restore the injection of the polymer.

[0075] Example 3;

[0076] The plugging agent and the plugging agent eliminating agent used in examples 1 and 2 are as follows: the proportion of each component by weight of the plugging agent is as follows: oxidizing agent 20%, corrosion inhibitor 2%, iron ion stabilizer 2%, and the balance is water;

[0077] The proportion of each component by weight of the plugging agent eliminating agent is as follows: reducing agent 30%, corrosion and scale inhibitor 5%, and the balance is water.

[0078] The corrosion inhibitor can be an existing corrosion inhibitor for oil wells, or an acidizing corrosion inhibitor disclosed in CN104109529A. The iron ion stabilizer can be an acidizing iron ion stabilizer disclosed in CN104109530A. The oxidizing agent, the corrosion inhibitor, the cleanup agent, and the reducing agent are all prior art, and those skilled in the art are clear about them.

[0079] In the present application, the parts that are not discussed in detail, and the connection modes of the parts in the present application all belong to the known technology in the technical field. Direct application can be used, and no further description is given.

[0080] In the present application, the term "a plurality of" refers to two or more, unless otherwise explicitly limited. The terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, "connecting" can be fixed connection, or detachable connection, or integrally connected; "connecting" can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0081] In the description of the application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the application and simplify the description, and do not indicate or imply that the device or unit referred to must have a particular direction, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0082] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "a specific embodiment" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description 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 only describes the preferred embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of using a pre-treatment device for offshore polymer-flooded plugged wells, c h a r a c t e r i s e d in that, The offshore polymer flooding well plugging pretreatment device comprises a first connecting pipe, a second connecting pipe and a filtering device; The filtering device is arranged between the first connecting pipe and the second connecting pipe and communicates the first connecting pipe 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; and a second medicament inlet and a second pressure gauge are arranged on the side wall of the second connecting pipe; A first conversion joint is arranged on the upper end opening of the first connecting pipe, and a second conversion joint is arranged on the upper end opening of the second connecting pipe; The filtering device comprises a sleeve pipe, a screen pipe, a precision woven mesh and a sealing sleeve; the sleeve pipe and the screen pipe are connected through the sealing sleeve at the axial rear end, so that the first annular space between the sleeve pipe and the screen pipe is sealed at the right end; The axial front end and the axial rear end of the precision woven mesh are a front steel ring and a rear steel ring, a woven mesh is arranged between the front steel ring and the rear steel ring, and the precision woven mesh is welded to the screen pipe through the front steel ring and the rear steel ring; the screen pipe is provided with screen holes in the area covered by the woven mesh; The filtering device is provided with a first flow guide joint at the axial front end, and a convex ring is arranged in the middle of the first flow guide joint; a counterbore is arranged at the axial front end of the first flow guide joint, and a flow guide hole communicating with the counterbore is arranged on the side wall at the axial rear end of the first flow guide joint; the outer wall of the convex ring of the first flow guide joint is connected with the axial front end of the sleeve pipe, the axial rear end of the first flow guide joint is connected with the axial front end of the screen pipe, and the axial front end of the screen pipe is closed, and the flow guide hole communicates the first annular space with the counterbore; The filtering device is provided with a second flow guide joint at the axial rear end, and the second flow guide joint is provided with an axial through hole; the axial front end of the second flow guide joint is connected with the axial rear end of the screen pipe; A first valve is arranged between the first connecting pipe and the filtering device; and a second valve is arranged between the second connecting pipe and the filtering device; The first valve is connected with the first flow guide joint, the second valve is connected with the second flow guide joint or the first valve is connected with the second flow guide joint, and the second valve is connected with the first flow guide joint; the first valve, the filtering device and the second valve are each provided with two; The filtering device is integrally welded, the filtering device is electroplated with phosphorus nickel after being welded, and the filtering precision of the precision woven mesh is higher than that of the sand filter screen at the bottom of the well; The method for using the pretreatment device comprises the following steps: S1. Selecting filtering precision, selecting the precision woven mesh according to the actual situation of the oil well; and welding the filtering device; S2. Installing the filtering device, installing the filtering device between the first connecting pipe and the second connecting pipe; S3. Connecting the pipeline, connecting the first conversion joint with the plunger pump; connecting the second conversion joint with the wellhead; connecting the first medicament inlet with the oxidizing agent injection pump; and connecting the second medicament inlet with the reducing agent injection pump; S4. Injecting polymer, opening the valve, pumping water containing polymer by using the plunger pump; and measuring the pressure difference between the first connecting pipe and the second connecting pipe by using the first pressure gauge and the second pressure gauge, which is the basic pressure at this time; S5. Plugging removal construction, when the pressure difference reaches the plugging pressure, the plugging removal construction is performed, the plugging removal agent is injected through the first medicament inlet, the plugging removal agent eliminating agent is injected through the second medicament inlet, until the pressure difference is reduced to below the unobstructed pressure, the injection of the plugging removal agent is stopped, and then the injection of the plugging removal agent eliminating agent is stopped after X hours, and the construction is completed; The plugging remover comprises 20% of oxidizing agent, 2% of corrosion inhibitor, 2% of iron ion stabilizer, 1% of cleanup agent, and the rest is water. The plugging remover comprises 30% of reducing agent, 5% of corrosion and scale inhibitor, and the rest is water.

2. A method of using a subsea polymer plug removal pre-treatment device according to claim 1, wherein, The method further comprises the following steps: S6. Scrap replacement, when the pressure difference cannot be reduced to below the unobstructed pressure, stop the polymer injection, close the first valve and the second valve, and replace the filter device.

3. A method of using a subsea polymer plug removal pre-treatment device according to claim 1, wherein, The two filter devices are installed between the first connecting pipe and the second connecting pipe, one of which is standby and the other is working.

4. A method of using a subsea polymer plug removal pre-treatment device according to claim 1, wherein, The precision woven mesh filter precision is 48-110 pm; the water injection amount is 200-240 m 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 plugging pressure is higher than the base pressure by 4-6 MPa; the amount of the plugging agent injected is 8-10 m 3 / day; the amount of the plugging agent removal agent injected is 8-10 m 3 / day; the unobstructed pressure is 0.5-1 MPa; the X hours are 1-2 hours.

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