Underground anti-blocking filter screen pipe column of oil well electric submersible pump and blocking removal method

Abstract

The invention discloses an oil well electric submersible pump underground anti-blocking filter screen pipe column and a plug removal method.The oil well electric submersible pump underground anti-blocking filter screen pipe column comprises a vertically-arranged inner pipe, a filter screen, an electric submersible pump, an outer pipe and a plurality of plug pieces, the side wall of the top end of the inner pipe is provided with a plurality of flow dividing holes and is provided with a flow stop valve, and the bottom end of the inner pipe is provided with a plurality of liquid drainage holes and is provided with a pressure control valve; a plurality of inner overflowing holes and jet hole arrays are formed in the side wall of the bottom end; the filter screen is arranged in the inner pipe; the electric submersible pump is arranged in the inner pipe, an outlet of the electric submersible pump communicates with the top end of the inner pipe, and an inlet communicates with the filter screen; the inner pipe is coaxially sleeved with the outer pipe so that a flow passing channel can be formed between the outer pipe and the inner pipe, the flow passing channel is communicated with the top end of the inner pipe through the flow dividing holes, and a plurality of outer flow passing holes are formed in the side wall of the bottom end of the outer pipe; the blocking pieces are vertically arranged in the flow passing channel in a sliding mode and correspond to the outer flow passing holes in a one-to-one mode. The problem that oil well production is affected due to the fact that an electric submersible pump and a filter screen cannot be cleaned stably and efficiently can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of unplugging electric submersible pumps in oil wells, and particularly relates to an underground anti-blocking filter pipe string for an electric submersible pump in an oil well and an unplugging method. Background Art

[0002] The efficient operation of electric submersible pump wells has always been a key challenge faced by artificial lift oil wells, especially the problem of electric submersible pump jamming. In formations with complex formation fluid properties, especially formations with sand production and scaling, electric submersible pump wells are extremely prone to frequent jamming. This not only directly affects the oil well production, but also greatly increases the operation cost. At the same time, the frequent start and stop of the electric submersible pump will accelerate the occurrence of equipment failures.

[0003] To address this problem, a filter screen is usually installed at the inlet of the electric submersible pump to prevent impurities such as scale and asphaltene in the wellbore from entering the pump barrel, thereby protecting the impeller and diffuser of the electric submersible pump from jamming. However, with the continuous accumulation of impurities, the filter screen itself will gradually become blocked, thereby affecting the production of the oil well.

[0004] In recent years, some oil wells have tested self-cleaning electric submersible pump technologies. The self-cleaning electric submersible pump forms a jet through the high pressure at the pump outlet to clean the pump inlet or the filter screen. However, this design also has limitations: after the pump inlet and outlet are connected, part of the lifting energy is wasted in the cleaning process, thereby reducing the lifting efficiency of the electric submersible pump. In addition, in oil wells with a high gas content, the jet will exacerbate the formation of bubbles, resulting in an increase in cavitation, and thus affecting the service life of the electric submersible pump. Summary of the Invention

[0005] The purpose of the present invention is to provide an underground anti-blocking filter pipe string for an electric submersible pump in an oil well, so as to solve the problem that the electric submersible pump and the filter screen cannot be cleaned stably and efficiently, thereby affecting the production of the oil well.

[0006] The present invention is achieved through the following technical solutions:

[0007] An underground anti-blocking filter screen string for an electric submersible pump in an oil well, comprising: an inner pipe vertically arranged, with a plurality of diversion holes opened on the side wall at the top end of the inner pipe, and a check valve arranged on the diversion holes; a plurality of liquid discharge holes opened at the bottom end of the inner pipe, and a pressure control valve arranged on the liquid discharge holes; a plurality of inner flow holes opened on the side wall at the bottom end of the inner pipe, and a jet hole array opened on the side wall at the bottom end of the inner pipe, and the jet hole array is located between the diversion holes and the inner flow holes; a filter screen, which is arranged inside the inner pipe and is aligned with the jet hole array; an electric submersible pump, which is arranged inside the inner pipe, and an outlet and an inlet are respectively arranged at the top and bottom of the electric submersible pump, the outlet is communicated with the top end of the inner pipe, and the inlet is communicated with the filter screen; an outer pipe, which is coaxially sleeved outside the inner pipe, and both ends are respectively sealed with the outer wall of the inner pipe to form a flow passage between the outer pipe and the inner pipe, the flow passage is communicated with the top end of the inner pipe through all the diversion holes, and a plurality of outer flow holes are opened on the side wall at the bottom end of the outer pipe, and the outer flow holes are arranged in one-to-one correspondence and alignment with the inner flow holes; a plurality of blocking members, which are vertically slidably arranged in the flow passage and are in one-to-one correspondence with the outer flow holes; when the blocking members are in a natural state, the blocking members can block the corresponding outer flow holes and the corresponding inner flow holes at the same time.

[0008] Optionally, the blocking member comprises a blocking ball and a guiding slide bar; the diameter of the blocking ball matches the width of the flow passage, and is larger than the aperture of the corresponding outer flow hole and the aperture of the corresponding inner flow hole; the guiding slide bar is vertically arranged, the top end of the guiding slide bar is connected with the blocking ball, and the bottom end is slidably matched with the bottom wall of the outer pipe; when the blocking member is in a natural state, the blocking ball is aligned with the corresponding outer flow hole and the corresponding inner flow hole.

[0009] Optionally, a stop step is arranged in the flow passage, and the stop step is located above all the blocking balls for making contact limit on the rising height of the blocking balls.

[0010] Optionally, a nitrogen seal package is arranged at the top end of the flow passage.

[0011] Optionally, the filter screen is in a cylindrical shape with a closed bottom end, the bottom wall and the side wall of the filter screen are both meshed, and the top end of the filter screen is communicated with the inlet of the electric submersible pump; the jet hole array is a circular ring array, the height of the jet hole array matches the height of the side wall of the filter screen, and the jet hole array is aligned with the side wall of the filter screen.

[0012] Optionally, a pipe string joint is coaxially sleeved inside the top end of the inner pipe, the pipe string joint is fixedly connected with the inner pipe, the top end of the pipe string joint extends out of the inner pipe for communicating with an injection pipe; the bottom end of the pipe string joint is connected with the top of the electric submersible pump and is communicated with the outlet.

[0013] Optionally, an injection pump is provided on the liquid injection pipe.

[0014] A method for unblocking a filter screen of an electrical submersible pump in an oil well is carried out by using any one of the above-mentioned downhole anti-blocking filter screen strings for an electrical submersible pump in an oil well, and includes the following steps:

[0015] S1. Shut down the oil well to make the plugging member plug the corresponding outer flow holes and the corresponding inner flow holes;

[0016] S2. Inject a pressurized plugging removal agent into the top end of the inner pipe through the liquid injection pipe, so that the filter screen is immersed in the plugging removal agent, and carry out a positive circulation plugging removal, and repeat the positive circulation plugging removal several times;

[0017] S3. Inject a pressurized plugging removal agent through the top end of the tubing and into the space between the tubing and the outer pipe, so that the plugging removal agent flushes open the plugging member, and sequentially presses into the bottom end of the inner pipe through the outer flow holes and the inner flow holes, passes through the filter screen and the electrical submersible pump, and is discharged from the top end of the inner pipe, and carry out a reverse circulation plugging removal;

[0018] S4. Start the electrical submersible pump with frequency conversion until the plugging is removed.

[0019] Optionally, the positive circulation plugging removal includes the following steps:

[0020] S2.1. Detect the degree of blockage of the electrical submersible pump and the filter screen, and classify it into two degrees: slight and severe;

[0021] S2.2. When it is in the slight degree, inject the plugging removal agent after pressurization through the top end of the inner pipe, so that the original fluid in the inner pipe presses open the pressure control valve and is discharged through the liquid discharge hole, so that the plugging removal agent fills the bottom end of the inner pipe, so that the filter screen is immersed in the plugging removal agent;

[0022] S2.3. When it is in the severe degree, open the stop valve, inject the plugging removal agent after pressurization through the top end of the inner pipe, so that the plugging removal agent is divided into two streams. One stream presses down along the inner pipe to soak the inner side of the filter screen; the other stream presses into the flow channel along the diversion hole and is pressed into the inner pipe through the jet hole array to soak the outer side of the filter screen; the two streams of the plugging removal agent jointly make the original fluid in the inner pipe press open the pressure control valve and be discharged through the liquid discharge hole, so that the filter screen is wrapped and soaked in the plugging removal agent.

[0023] Optionally, repeating the positive circulation plugging removal several times includes the following steps:

[0024] S2.4. Monitor the pump pressure of the injection pump on the liquid injection pipe during the process of the positive circulation plugging removal,

[0025] When the pump pressure of the liquid injection pump remains unchanged, after repeating step 2.4 for a preset number of times, step S3 is implemented;

[0026] When the pump pressure of the liquid injection pump decreases, step S3 is implemented;

[0027] Wherein: the preset number of times > 3 times.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] An underground anti-blocking filter screen string for an oil well electric submersible pump provided by the present invention, by arranging an inner pipe, a filter screen and an electric submersible pump, arranging a liquid discharge hole and an inner flow hole in the inner pipe, arranging the electric submersible pump in the inner pipe, arranging the filter screen at the inlet of the electric submersible pump, and arranging a plugging member at the inner flow hole. When the electric submersible pump and the filter screen are slightly blocked, a pressurized plugging removal agent is introduced into the top end of the inner pipe, and the plugging removal agent presses down along the inner pipe, so that the original liquid at the bottom of the inner pipe presses open the pressure control valve and is discharged from the liquid discharge hole, so that the bottom of the inner pipe is filled with the plugging removal agent, so that the filter screen is immersed in the plugging removal agent, so as to implement plugging removal for the electric submersible pump and the filter screen; by arranging a diversion hole and a jet hole array in the inner pipe, and arranging an outer pipe, an inner flow channel is formed between the outer pipe and the inner pipe, and an outer flow hole is arranged in the outer pipe. When the electric submersible pump and the filter screen are severely blocked, by opening the stop valve, and then introducing a pressurized plugging removal agent into the top end of the inner pipe, the plugging removal agent is divided into two strands, one strand presses down along the inner pipe to discharge the original liquid, so as to immerse the inner side of the filter screen, and the other strand flows into the inner flow channel along the diversion hole, and then is pressed into the inner pipe from the jet hole array, so as to continue to immerse the outer side of the filter screen, so as to implement a wrapped immersion for the filter screen, further improving the plugging removal effect; further, through the above settings, after the above positive circulation plugging removal is completed, a pressurized plugging removal agent can be injected between the bottom end of the oil pipe and the outer appearance of the oil pipe, and the plugging removal agent is used to flush open the plugging member, and is successively pressed into the bottom end of the inner pipe through the outer flow hole and the inner flow hole, and discharged from the top end of the inner pipe after passing through the filter screen and the electric submersible pump, so as to implement reverse circulation plugging removal. By using positive circulation plugging removal and reverse circulation plugging removal, the filter screen and the electric submersible pump are alternately flushed forward and backward, so as to effectively solve the problem that the electric submersible pump and the filter screen cannot be cleaned stably and efficiently, thus affecting the production of the oil well. Brief Description of the Drawings

[0030] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not constitute a limitation to the embodiments of the present invention. In the drawings:

[0031] Figure 1 is a schematic diagram of the underground anti-blocking filter screen string for an oil well electric submersible pump provided by an embodiment of the present invention arranged in an oil pipe;

[0032] Figure 2 is a schematic diagram of the underground anti-blocking filter screen string for an oil well electric submersible pump provided by an embodiment of the present invention during normal operation;

[0033] Figure 3 Schematic diagram when the plugging prevention filter screen string of the downhole electric submersible pump provided by the embodiment of the present invention soaks the filter screen after injecting the plugging removal agent;

[0034] Figure 4 Schematic diagram when the plugging prevention filter screen string of the downhole electric submersible pump provided by the embodiment of the present invention performs normal circulation plugging removal;

[0035] Figure 5 Schematic diagram when the plugging prevention filter screen string of the downhole electric submersible pump provided by the embodiment of the present invention performs reverse circulation plugging removal.

[0036] Marks in the attached drawings and corresponding names of parts:

[0037] 10 - Inner pipe; 11 - Stop valve; 12 - Pressure control valve; 13 - Inner flow - through hole; 14 - Jet hole array; 15 - Liquid injection pipe; 16 - Pipe string joint; 20 - Filter screen; 21 - Electric submersible pump; 30 - Outer pipe; 31 - Flow - through channel; 311 - Stopping step; 312 - Nitrogen seal package; 32 - Outer flow - through hole; 40 - Plugging member; 41 - Plugging ball; 42 - Guide slide bar. Detailed implementation manners

[0038] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in combination with embodiments and the attached drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0039] Please refer to Figures 1 to 5, an embodiment of the present invention provides a downhole anti-blocking filter screen string for an oil well electric submersible pump, comprising: a vertically arranged inner pipe 10, a plurality of diversion holes are formed in the side wall at the top end of the inner pipe 10, and a flow stop valve 11 is arranged in the diversion holes; a plurality of liquid discharge holes are formed at the bottom end of the inner pipe 10, and a pressure control valve 12 is arranged in the liquid discharge holes; a plurality of inner flow holes 13 are formed in the side wall at the bottom end of the inner pipe 10, a jet hole array 14 is formed in the side wall at the bottom end of the inner pipe 10, and the jet hole array 14 is located between the diversion holes and the inner flow holes 13; second, a filter screen 20 is included, the filter screen 20 is arranged inside the inner pipe 10 and is aligned with the jet hole array 14; third, an electric submersible pump 21 is included, the electric submersible pump 21 is arranged inside the inner pipe 10, an outlet and an inlet are respectively arranged at the top and bottom of the electric submersible pump 21, the outlet is communicated with the top end of the inner pipe 10, and the inlet is communicated with the filter screen 20; fourth, an outer pipe 30 is included, the outer pipe 30 is coaxially sleeved outside the inner pipe 10 and is sealed with the outer wall of the inner pipe 10 at both ends to form a flow passage 31 between the outer pipe 30 and the inner pipe 10, the flow passage 31 is communicated with the top end of the inner pipe 10 through all the diversion holes, a plurality of outer flow holes 32 are formed in the side wall at the bottom end of the outer pipe 30, and the outer flow holes 32 are arranged in one-to-one correspondence and alignment with the inner flow holes 13; fifth, a plurality of blocking members 40 are included, the blocking members 40 are vertically slidably arranged in the flow passage 31 and are in one-to-one correspondence with the outer flow holes 32; when the blocking members 40 are in a natural state, the blocking members 40 can block the corresponding outer flow holes 32 and the corresponding inner flow holes 13 at the same time.

[0040] A downhole anti-blocking filter screen 20 string for an oil well electric submersible pump 21 provided by the present invention. By setting an inner pipe 10, a filter screen 20 and an electric submersible pump 21, a liquid discharge hole and an inner flow hole 13 are opened in the inner pipe 10. The electric submersible pump 21 is arranged in the inner pipe 10, the filter screen 20 is arranged at the inlet of the electric submersible pump 21, and a plugging member 40 is arranged at the inner flow hole 13. When the electric submersible pump 21 and the filter screen 20 are slightly blocked, a pressurized deplugging agent is introduced into the top end of the inner pipe 10. The deplugging agent presses down along the inner pipe 10, so that the original liquid at the bottom of the inner pipe 10 presses open the pressure control valve 12 and is discharged from the liquid discharge hole, so that the bottom of the inner pipe 10 is filled with the deplugging agent, so that the filter screen 20 is immersed in the deplugging agent to deplug the electric submersible pump 21 and the filter screen 20; by arranging a diversion hole and a jet hole array 14 in the inner pipe 10 and arranging an outer pipe 30, a flow passage 31 is formed between the outer pipe 30 and the inner pipe 10, and an outer flow hole 32 is opened in the outer pipe 30. When the electric submersible pump 21 and the filter screen 20 are severely blocked, by opening the stop valve 11, and then introducing a pressurized deplugging agent into the top end of the inner pipe 10, the deplugging agent is divided into two streams. One stream presses down along the inner pipe 10 to discharge the original liquid, so as to immerse the inner side of the filter screen 20. The other stream flows into the flow passage 31 along the diversion hole and then is pressed into the inner pipe 10 from the jet hole array 14 to continue to immerse the outer side of the filter screen 20, so as to perform a wrapped immersion on the filter screen 20 and further improve the deplugging effect; further, through the above settings, after the above positive circulation deplugging is completed, a pressurized deplugging agent can be injected between the bottom end of the oil pipe and the outer appearance of the oil pipe, and the deplugging agent is used to wash open the plugging member 40, and is successively pressed into the bottom end of the inner pipe 10 through the outer flow hole 32 and the inner flow hole 13, and is discharged from the top end of the inner pipe 10 after passing through the filter screen 20 and the electric submersible pump 21, so as to perform a reverse circulation deplugging. By using the positive circulation deplugging and the reverse circulation deplugging, the filter screen 20 and the electric submersible pump 21 are alternately washed forward and backward, so as to effectively solve the problem that the electric submersible pump 21 and the filter screen 20 cannot be cleaned stably and efficiently, thus affecting the production of the oil well.

[0041] It should be noted that during normal operation, as Figure 2 shown, the stop valve 11 is closed, the electric submersible pump 21 is started, the pressure above the plugging member 40 is less than the pressure below, so that the plugging member 40 moves upward, so that the outer flow hole 32 and the inner flow hole 13 are opened, and the oil liquid flows upward between the oil pipe and the outer pipe 30, is successively sucked into the inner pipe 10 through the outer flow hole 32 and the inner flow hole 13, and then is discharged from the inner pipe 10 after passing through the filter screen 20 and the electric submersible pump 21.

[0042] To further explain the specific structure and connection method of the plugging member 40, the plugging member 40 includes a plugging ball 41 and a guiding slide bar 42; the diameter of the plugging ball 41 matches the width of the flow passage 31, and is larger than the aperture of the corresponding outer flow hole 32 and the aperture of the corresponding inner flow hole 13; the guiding slide bar 43 is vertically arranged, the top end of the guiding slide bar 43 is connected to the plugging ball 41, and the bottom end is slidably matched with the bottom wall of the outer pipe 30; when the plugging member 40 is in the natural state, the plugging ball 41 is aligned with the corresponding outer flow hole 32 and the corresponding inner flow hole 13.

[0043] It should be noted that the above natural state means that the plugging ball 41 naturally falls under the action of gravity until it is aligned with the corresponding outer flow hole 32 and the corresponding inner flow hole 13.

[0044] To prevent the plugging ball 41 from rising excessively, a stop step 311 is provided in the flow passage 31, and the stop step 311 is located above all the plugging balls 41 to limit the rising height of the plugging ball 41 by contact.

[0045] To improve the sealing performance of the flow passage 31 and ensure the normal operation of the stop valve 11, a nitrogen seal package 312 is provided at the top end of the flow passage 31.

[0046] To specifically explain the specific structure of the filter screen 20 and its cooperation relationship with the jet hole array 14, the filter screen 20 is a cylindrical shape with a closed bottom end, the bottom wall and the side wall of the filter screen 20 are both meshed, and the top end of the filter screen 20 is communicated with the inlet of the electric submersible pump 21; the jet hole array 14 is a circular ring array, the height of the jet hole array 14 matches the side wall height of the filter screen 20, and the jet hole array 14 is aligned with the side wall of the filter screen 20.

[0047] It should be noted that a pipe string joint 16 is coaxially sleeved inside the top end of the inner pipe 10, the pipe string joint 16 is fixedly connected to the inner pipe 10, the top end of the pipe string joint 16 extends out of the inner pipe 10 for communicating with the injection pipe 15; the bottom end of the pipe string joint 16 is connected to the top of the electric submersible pump 21 and is communicated with the outlet.

[0048] By providing the pipe string joint 16, on the one hand, it is used to fix the electric submersible pump 21, and on the other hand, it enables the inner pipe 10 to be hermetically connected to the injection pipe 15.

[0049] Preferably, to monitor the hydraulic pressure of the plugging agent in the injection pipe 15, an injection pump is provided in the injection pipe 15.

[0050] This embodiment also provides a method for unblocking the anti-blocking filter screen of an oil well electric submersible pump, which is carried out by using any one of the above-mentioned downhole anti-blocking filter screen strings for oil well electric submersible pumps, and includes the following steps:

[0051] S1. Close the oil well so that the plugging member 40 plugs the corresponding outer flow holes 32 and the corresponding inner flow holes 13;

[0052] S2. Inject pressurized plugging removal agent into the top end of the inner pipe 10 through the liquid injection pipe, so that the filter screen 20 is immersed in the plugging removal agent, and perform positive circulation plugging removal. Repeat the positive circulation plugging removal several times;

[0053] S3. Inject pressurized plugging removal agent through the top end of the oil pipe and into the space between the oil pipe and the outer pipe 30, so that the plugging removal agent flushes open the plugging member 40, and is successively pressed into the bottom end of the inner pipe 10 through the outer flow holes 32 and the inner flow holes 13, passes through the filter screen 20 and the electric submersible pump 21, and is discharged from the top end of the inner pipe 10 to perform reverse circulation plugging removal;

[0054] S4. Start the electric submersible pump 21 with frequency conversion until the plugging is removed.

[0055] In order to perform adaptive positive circulation plugging removal treatment for different plugging situations, the positive circulation plugging removal includes the following steps:

[0056] S2.1. Detect the blockage degree of the electric submersible pump 21 and the filter screen 20, and classify it into two degrees: slight and severe;

[0057] S2.2. When it is the slight degree, inject the pressurized plugging removal agent through the top end of the inner pipe 10, so that the original fluid in the inner pipe 10 presses open the pressure control valve 12 and is discharged through the drain hole, so that the plugging removal agent fills the bottom end of the inner pipe 10, thereby immersing the filter screen 20 in the plugging removal agent;

[0058] S2.3. When it is the severe degree, open the stop valve 11, inject the pressurized plugging removal agent through the top end of the inner pipe 10, so that the plugging removal agent is divided into two streams. One stream presses down along the inner pipe 10 to immerse the inner side of the filter screen 20; the other stream is pressed into the flow channel 31 through the diversion hole and is pressed into the inner pipe 10 through the jet hole array 14 to immerse the outer side of the filter screen 20; the two streams of plugging removal agent jointly press open the pressure control valve 12 for the original fluid in the inner pipe 10 and are discharged through the drain hole, so that the filter screen 20 is immersed in the plugging removal agent in a wrapped manner.

[0059] It should be noted that the step of repeating the positive circulation plugging removal several times includes the following steps:

[0060] S2.4. During the process of unblocking the positive cycle, monitor the pump pressure of the injection pump on the injection pipe.

[0061] When the pump pressure of the injection pump remains unchanged, after repeating step 2.4 a preset number of times, implement step S3.

[0062] When the pump pressure of the injection pump decreases, implement step S3.

[0063] Wherein: the preset number of times > 3 times.

[0064] Optionally, the detailed implementation method can be implemented according to the following steps:

[0065] Step1: Test the electrical parameters of the electric submersible pump 21 to ensure that the electric submersible pump 21 unit is not damaged. If the electrical parameters determine that the electric submersible pump 21 unit is damaged, the operation needs to be abandoned and the pump needs to be started for maintenance. If the electrical parameters are normal, enter Step2.

[0066] Step2: Try to wash the well in the positive cycle. If the positive cycle washing fluid cannot be injected normally, it means that the electric submersible pump 21 is severely blocked, and enter Step3; if the positive cycle can be directly injected, then perform the positive cycle well washing operation, and then enter Step4.

[0067] Step3: Lower the coiled tubing for flushing and circulation, reduce the blockage in the production inner pipe 10 through flushing, and then continue to try whether the positive cycle can be injected smoothly. If it can be injected, turn to Step4; if it cannot be injected, it means that the electric submersible pump 21 is blocked to death, abandon the operation, and start the pump for maintenance.

[0068] Step4: Squeeze the organic plugging remover in the positive direction and soak for 3 - 6h.

[0069] Step5: Squeeze out the residual liquid with the organic plugging remover in the positive direction and soak for 1 - 3h; during the positive squeezing process, observe the change of the pump pressure of the injection pump. At the same displacement as in Strp4, if the pump pressure decreases, enter Step6; if the pump pressure has no obvious change, repeat Step5. If the pump pressure remains unchanged after repeating Step5 for many times (more than 3 times), enter Step6.

[0070] Step6: Squeeze the inorganic plugging remover in the positive direction and soak for 1 - 2h.

[0071] Step7: Squeeze out the residual liquid with the inorganic plugging remover in the positive direction and soak for 1 - 2h; during the positive squeezing process, observe the change of the pump pressure of the injection pump. At the same displacement as in Strp6, if the pump pressure decreases, enter Step8; if the pump pressure has no obvious change, repeat Step7. If the pump pressure remains unchanged after repeating Step7 for many times (more than 3 times), enter Step8.

[0072] Step8: Wash the well in the reverse cycle and try to start the electric submersible pump 21 with frequency conversion; if the pump is started normally, stop the operation and resume production; if it is not started, enter Step9.

[0073] Step 9: Try to reverse to release the stuck or increase the voltage to rotate forward to resume normal well flushing; if the pump starts normally, stop the operation and resume production; if it fails to start, abandon the operation and repair the pump after starting it.

[0074] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. An oil well electric submersible pump downhole anti-blocking filter string, characterized in that: include: A vertically arranged inner tube (10), wherein the top side wall of the inner tube (10) is provided with a plurality of flow-dividing holes, wherein the flow-dividing holes are provided with a flow-stop valve (11); the bottom side wall of the inner tube (10) is provided with a plurality of liquid discharge holes, wherein the liquid discharge holes are provided with a pressure control valve (12); the bottom side wall of the inner tube (10) is provided with a plurality of inner flow holes (13), and the bottom side wall of the inner tube (10) is provided with an array of jet holes (14), wherein the array of jet holes (14) is located between the flow-dividing holes and the inner flow holes (13); A filter screen (20), the filter screen (20) being arranged in the inner tube (10) and aligned with the jet hole array (14); an electric submersible pump (21), the electric submersible pump (21) being arranged in the inner tube (10), the top and bottom of the electric submersible pump (21) being respectively provided with an outlet and an inlet, the outlet being communicated with the top end of the inner tube (10), and the inlet being communicated with the filter screen (20); An outer tube (30), the outer tube (30) being coaxially sleeved outside the inner tube (10), and having two ends respectively sealed with the outer wall of the inner tube (10), so as to form a flow passage (31) between the outer tube (30) and the inner tube (10), the flow passage (31) being connected with the top end of the inner tube (10) through all the flow diversion holes, and a plurality of external flow holes (32) being formed on the side wall of the bottom end of the outer tube (30), the external flow holes (32) corresponding to the internal flow holes (13) one by one and being aligned; A plurality of blocking members (40), wherein the blocking members (40) are vertically slidably disposed in the flow passage (31) and correspond one-to-one to the external flow holes (32); When the blocking member (40) is in a natural state, the blocking member (40) can simultaneously block the corresponding outer flow hole (32) and the corresponding inner flow hole (13).

2. The oil well electric submersible pump downhole anti-blocking filter string according to claim 1, characterized in that: The blocking member (40) comprises a blocking ball (41) and a guide sliding rod (42); The diameter of the blocking ball (41) matches the width of the flow channel (31), and is larger than the corresponding aperture of the outer flow hole (32) and the corresponding aperture of the inner flow hole (13); The guide slide bar (43) is vertically arranged, the top end of the guide slide bar (43) is connected to the blocking ball (41), and the bottom end is slidably matched with the bottom wall of the outer tube (30); When the blocking member (40) is in a natural state, the blocking ball (41) is aligned with the corresponding outer flow hole (32) and the corresponding inner flow hole (13).

3. The oil well electric submersible pump downhole anti-blocking filter string according to claim 2, characterized in that: A stop step (311) is provided in the flow passage (31), and the stop step (311) is located above all the blocking balls (41) and is used to contact and limit the rising height of the blocking balls (41).

4. The oil well electric submersible pump downhole anti-blocking filter string according to claim 1, characterized in that: A nitrogen gas bag (312) is provided at the top of the flow passage (31).

5. The downhole anti-blocking filter string for oil well electric submersible pump according to claim 1, characterized in that: The filter screen (20) is cylindrical with a closed bottom end, the bottom wall and the side wall of the filter screen (20) are both mesh-shaped, and the top of the filter screen (20) is connected to the inlet of the electric submersible pump (21); The jet hole array (14) is a circular array, the height of the jet hole array (14) matches the height of the side wall of the filter screen (20), and the jet hole array (14) is aligned with the side wall of the filter screen (20).

6. The oil well electric submersible pump downhole anti-blocking filter string according to claim 1, characterized in that: A pipe column joint (16) is coaxially sleeved inside the top end of the inner tube (10), and the pipe column joint (16) is fixedly connected to the inner tube (10). The top end of the pipe column joint (16) extends out of the inner tube (10) and is used to connect to the injection pipe (15); the bottom end of the pipe column joint (16) is connected to the top of the electric submersible pump (21) and is connected to the outlet.

7. The downhole anti-blocking filter string for an oil well electric submersible pump according to claim 6, characterized in that: The liquid injection pipe (15) is provided with an injection pump.

8. A method for removing blockage of an anti-blockage filter screen of an oil well electric submersible pump, characterized in that: The method is carried out using the oil well electric submersible pump downhole anti-blocking filter string according to any one of claims 1 to 7, comprising the following steps: S1, closing the oil well so that the blocking member (40) blocks the corresponding outer flow hole (32) and the corresponding inner flow hole (13); S2, injecting a pressurized unblocking agent into the top of the inner tube (10) through the injection pipe, so that the filter (20) is immersed in the unblocking agent, performing positive cycle unblocking, and repeating the positive cycle unblocking several times; S3, injecting a pressurized unblocking agent through the top of the oil pipe and into the space between the oil pipe and the outer pipe (30), so that the unblocking agent flushes the blocking member (40), and is pressed into the bottom end of the inner pipe (10) through the outer flow hole (32) and the inner flow hole (13) in sequence, and is discharged from the top end of the inner pipe (10) through the filter screen (20) and the electric submersible pump (21), thereby performing reverse circulation unblocking; S4, starting the electric submersible pump (21) by frequency conversion until the blockage is removed.

9. The method for removing blockage of an anti-blockage filter screen for an oil well electric submersible pump according to claim 8, characterized in that: The positive cycle unblocking comprises the following steps: S2.1, detecting the blockage degree of the electric submersible pump (21) and the filter (20), and classifying the blockage degree into two levels: slight and severe; S2.2, when the level is mild, the unblocking agent is pressurized and injected through the top of the inner tube (10), so that the original fluid in the inner tube (10) presses open the pressure control valve (12) and is discharged through the drainage hole, so that the unblocking agent fills the bottom end of the inner tube (10), so that the filter (20) is immersed in the unblocking agent; S2.

3. When the severity is as described above, the stop valve (11) is opened, and the unblocking agent is pressurized and injected through the top of the inner tube (10), so that the unblocking agent is split into two streams, one of which is pressed down along the inner tube (10) to soak the inner side of the filter screen (20); the other stream is pressed into the flow passage (31) along the diversion hole, and is pressed into the inner tube (10) through the jet hole array (14) to soak the outer side of the filter screen (20); the two streams of unblocking agent together cause the original fluid in the inner tube (10) to press open the pressure control valve (12), and are discharged through the drainage hole, so that the filter screen (20) is wrapped and immersed in the unblocking agent.

10. The method for removing blockage of an anti-blockage filter screen for an oil well electric submersible pump according to claim 8, characterized in that: Repeating the positive cycle unblocking several times comprises the following steps: S2.4, during the positive cycle unblocking process, monitor the pump pressure of the injection pump on the injection pipe, When the pump pressure of the injection pump remains unchanged, step 2.4 is repeated for a preset number of times, and then step S3 is implemented; When the pump pressure of the injection pump decreases, step S3 is implemented; Wherein: the preset number of times is greater than 3 times.

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