Paraffin removal and scale removal device and method for rodless oil producing well

Abstract

The device comprises a wellhead blowout prevention structure, the wellhead blowout prevention structure comprises a blowout prevention pipe, the top end of the blowout prevention pipe is connected with a blowout prevention cap, and an impact rod capable of ascending and descending is arranged in the blowout prevention cap; the plunger structure comprises a plunger body and a steel ball, a plunger center hole is formed in the plunger body, the impact rod can penetrate through the plunger center hole, and the steel ball can block the bottom end of the plunger center hole under the action of upward axial force or leave under the impact of the impact rod so that the plunger center hole can be communicated; the plunger body is connected with a blade structure, and the blade structure can rotate under the hydraulic action to continuously and automatically remove paraffin and dirt; the underground seating device comprises an adapter connector, a steel ball bearing head is connected to the adapter connector, and a liquid passing channel is formed in the bottom end of the adapter connector. Wax scale on the pipe wall is scraped through up-and-down circulating motion of the plunger structure in the oil pipe, continuous and automatic paraffin removal and scale removal of the whole well section can be achieved, and the plunger can be automatically captured according to the paraffin precipitation and scale removal degree of a shaft.

Description

Technical Field

[0001] The invention relates to the field of oil production engineering in the petroleum industry, and in particular to a device and method for removing wax and scale from a rodless oil production well. Background Art

[0002] During the crude oil production process, changes in temperature, pressure, flow rate and other factors can cause wax and inorganic salts to form deposits in the oil pipe, resulting in wax and scaling in the oil well. Wax and scaling in the oil well will reduce the flow cross-section of the fluid lift, increase the flow resistance of the fluid, affect the normal operation of the oil well equipment, and reduce the oil well production.

[0003] In the prior art, thermal wax removal has potential safety hazards due to the need to heat crude oil, which will cause the water content of the oil well to rise, and even cause the oil well to stop spraying, affecting the oil well production; the commonly used mechanical wax removal is to connect the wax scraper, wax removal drill and other mechanical tools with steel wires and lower them into the wellbore, and manually lift and lower the steel wires repeatedly to remove the wax, which is labor-intensive. The commonly used descaling process is to add anti-scaling agents and corrosion inhibitors to keep the cations that can form scale in the solution to achieve descaling, which is complicated to operate and has high costs.

[0004] Chinese patent (CN206220931U) discloses a rodless oil well mechanical wax cleaning device, which uses well fluid to push the sealing rubber plug and the wax scraper upward to clean the wax. The outer diameter of the oil pipe at the reversing pipe is enlarged, so that the fluid is discharged from the annulus between the reversing pipe, the sealing rubber plug and the wax scraper. The flow area is small, and this device continuously scrapes the wax without stopping the pump. The well fluid always flows upward, and the plunger has no flow passage. There will always be a bottom thrust on the plunger in the oil pipe, and the sealing rubber plug and the wax scraper cannot fall in time, and falling to the baffle will have a large impact on the baffle.

[0005] A Chinese patent (CN218816343U) discloses a rodless oil production machinery anti-scaling and anti-wax device, in which an oil pipe equipped with the anti-scaling and anti-wax device is lowered into a wax-prone position for local anti-scaling and anti-wax prevention. However, the wax-prone position is not easy to accurately determine and find, and at the same time, the fluid keeps rotating in the opposite direction, which reduces the fluid flow rate and affects the lifting effect.

[0006] A Chinese patent (CN103306640A) discloses a hydraulic wax removal device for a rodless pump oil production system, which performs wax removal operations by controlling the start and stop of an electric submersible pump, but cannot achieve continuous automatic wax removal.

[0007] A Chinese patent (CN201386526Y) discloses a plunger capture device for a plunger gas lift wellhead. When the plunger needs to be repaired, the plunger is removed manually, but the timing of the plunger repair cannot be accurately determined manually.

[0008] Therefore, the inventor, relying on many years of experience and practice in related industries, proposes a rodless oil well wax and scale removal device and method to overcome the defects of the prior art. Summary of the invention

[0009] The purpose of the present invention is to provide a rodless oil well wax and scale removal device and method, which can scrape wax scale off the pipe wall through the up and down circular movement of the plunger structure in the oil pipe, overcome the labor cost caused by the increase of water content in the oil well due to hot washing and mechanical wax removal in the prior art, ensure safe and environmentally friendly construction and reduce operating costs, realize continuous and automatic wax and scale removal in the entire well section, and automatically capture the plunger according to the degree of wax and scale formation in the wellbore.

[0010] The object of the present invention is achieved by providing a rodless oil well wax and scale removal device, comprising:

[0011] The wellhead blowout prevention structure comprises a blowout prevention pipe connected to the top of the oil pipe, the top of the blowout prevention pipe is detachably connected to a blowout prevention cap, a lifting and lowering impact rod is arranged inside the blowout prevention cap, and a wellhead flange and a plunger catcher are connected and arranged on the side wall of the blowout prevention pipe;

[0012] The plunger structure comprises a plunger body and a steel ball capable of reciprocating up and down. A plunger center hole is axially penetrated in the plunger body. The outer diameter of the plunger body is smaller than the inner diameter of the oil pipe in a free state, and the outer diameter of the plunger body is larger than the inner diameter of the oil pipe after being expanded under pressure. The impact rod can pass through the plunger center hole. The steel ball can block the bottom end of the plunger center hole under the action of an upward axial force or leave under the impact of the impact rod to make the plunger center hole penetrate. A blade structure is connected to the plunger body, and the blade structure can rotate under the action of hydraulic force to continuously and automatically remove wax and scale.

[0013] The downhole seat comprises a variable buckle joint that can be connected to the oil pipe, the variable buckle joint is connected to a steel ball bearing joint, a joint center hole is axially arranged in the variable buckle joint, and a liquid passage connecting to the joint center hole is arranged at the bottom end of the variable buckle joint.

[0014] In a preferred embodiment of the present invention, a first buffer spring is provided in the spray preventer, and the impact rod can be axially contracted in the first buffer spring, and the first buffer spring is used to mitigate the impact strength of the plunger structure.

[0015] In a preferred embodiment of the present invention, a pressure sensing sheet is provided at the bottom end of the spray cap, and the pressure sensing sheet is used to sense the contact of the plunger structure. When the plunger structure runs and contacts the pressure sensing sheet, the impact rod extends from the first buffer spring and passes through the center hole of the plunger to knock down the steel ball.

[0016] In a preferred embodiment of the present invention, the blade structure comprises an upper blade and a lower blade spaced axially along the plunger body, and the upper blade and the lower blade are rotatably connected to the plunger body via thin-walled ball bearings respectively.

[0017] In a preferred embodiment of the present invention, the bottom end of the plunger body is connected to an anti-steel ball slipping claw, and the steel ball can enter the anti-steel ball slipping claw to block the plunger center hole under the action of an upward axial force or leave the anti-steel ball slipping claw under the pressure of the impact rod.

[0018] In a preferred embodiment of the present invention, the anti-slip claw of the steel ball comprises a claw ring body, and the claw ring body is provided with a claw petal body whose bottom end can be extended and retracted in the radial direction.

[0019] In a preferred embodiment of the present invention, a joint connecting shaft is passed through the variable buckle joint, the top end of the joint connecting shaft is connected to the steel ball bearing joint, and a second buffer spring capable of axially buffering the steel ball bearing joint is sleeved on the joint connecting shaft.

[0020] In a preferred embodiment of the present invention, an inner chamfered groove is provided at the center of the top end of the steel ball bearing joint.

[0021] In a preferred embodiment of the present invention, the liquid passage includes a plurality of oil passage holes arranged at intervals along the circumferential direction at the bottom end of the variable buckle joint.

[0022] The object of the present invention can also be achieved in this way. A method for removing wax and scale from a rodless oil well comprises: preparing the aforementioned rodless oil well cleaning wax and scale removal device, presetting a downhole seat in the wellbore with the oil pipe in advance, lowering a steel ball and a plunger body into the oil pipe through the top of the blowout preventer, the steel ball blocks the plunger body, and the top of the blowout preventer is connected to the blowout cap; the well fluid enters the oil pipe through the liquid passage on the downhole seat, pushing the steel ball and the plunger body to move upward, and the liquid flow acts on the blade structure, and the blade structure rotates to remove wax and scale; the plunger structure moves upward to the wellhead, and the well fluid is discharged through the wellhead flange. When the plunger body contacts the pressure sensing plate, the impact rod extends and knocks down the steel ball, and counts once;

[0023] The plunger body falls, and the steel ball and the plunger body fall onto the downhole seat again. The steel ball blocks the plunger body again, and the liquid is used to lift the plunger body to perform another reciprocating motion for wax and dirt removal, which is counted again. When the plunger body contacts the pressure sensing plate for a set number of times, the impact rod no longer extends, and the plunger catcher captures the plunger structure, the spray preventer is removed, and the plunger structure is taken out.

[0024] In a preferred embodiment of the present invention, the method for removing wax and scale from a rodless oil well comprises the following steps:

[0025] S1: The downhole seat is pre-set in the wellbore with the oil pipe, the blowout preventer is opened, the steel ball and the plunger body are lowered in sequence, the blowout preventer is installed, the steel ball and the plunger body fall to the steel ball bearing joint of the downhole seat by their own gravity, and the steel ball enters the steel ball slip prevention claw of the plunger body under the action of the axial force;

[0026] S2: Well fluid enters the oil pipe through the liquid passage on the downhole seat, pushing the steel ball and the plunger body upward. The liquid flow acts on the spiral grooves of the upper blade and the lower blade, and the upper blade and the lower blade rotate to remove wax and scale;

[0027] S3: The plunger structure moves upward to the wellhead, and the well fluid is discharged through the wellhead flange. When the plunger body contacts the pressure sensing sheet, the impact rod extends from the first buffer spring and hits the steel ball, causing the steel ball to fall. The time t1 when the plunger body first contacts the pressure sensing sheet is recorded and counted once, with the count i=1.

[0028] S4: The steel ball falls, the center hole of the plunger is connected, and the plunger body falls under the action of gravity. The steel ball and the plunger body fall onto the steel ball bearing joint again, and the steel ball enters the steel ball anti-slip claw again, and the liquid is used to lift and perform another reciprocating motion for wax and dirt removal;

[0029] S5: Record the time t2 when the plunger body contacts the pressure sensing sheet for the second time, and count once, count i=2; the speed v of the plunger structure in a reciprocating motion:

[0030]

[0031] Where L is the length of the oil pipe;

[0032] S6: Set the number of times N for the plunger to clean wax and dirt according to the plunger running speed v; when the number of times the plunger body contacts the pressure sensing plate i=N, the impact rod no longer extends, the plunger catcher automatically catches the plunger structure, removes the spray cap, and takes out the plunger structure.

[0033] As described above, the rodless oil well wax and scale removal device and method of the present invention have the following beneficial effects:

[0034] The rodless oil well wax and scale cleaning device of the present invention is easy to install. The plunger structure moves upward by relying on the lifting effect of the well fluid, and does not need its own power. It can be applied to rodless oil wells, gas lift oil wells, self-flowing wells and other oil wells without sucker rods. The plunger structure can automatically fall through the impact rod without affecting the liquid flow area and the lifting effect, thereby realizing continuous and automatic wax and scale cleaning in the entire well section. The downhole seat buffers the plunger structure, and the device has good stability. The wax and scale cleaning method of the present invention is simple and easy to operate. The wax and scale cleaning times are set according to the degree of wax and scale formation in the wellbore, and the plunger is automatically captured, which is convenient for subsequent repair and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0036] in:

[0037] Figure 1 : It is a schematic diagram of a rodless oil well wax and scale removal device of the present invention.

[0038] Figure 2 : is a schematic diagram of the plunger structure of the present invention.

[0039] Figure 3 : It is a top view of the upper blade of the present invention.

[0040] Figure 4 : is a schematic diagram of the anti-slip claw of the steel ball of the present invention.

[0041] Figure 5 : is a schematic diagram of a downhole seat of the present invention.

[0042] Figure 6 :for Figure 5 Middle AA section view.

[0043] Figure 7 : is a flow chart of the rodless oil well dewaxing and descaling method of the present invention.

[0044] In the figure:

[0045] 1. Blowout preventer; 2. First buffer spring; 3. Impact rod; 4. Pressure sensing plate; 5. Wellhead flange; 6. Blowout preventer; 7. Plunger catcher; 8. Plunger body; 9. Steel ball; 10. Downhole seat; 11. Oil pipe; 12. Upper blade; 13. Thin-walled ball bearing; 14. Lower blade; 15. Claw to prevent steel ball from slipping off; 16. Steel ball bearing joint; 17. Second buffer spring; 18. Variable buckle joint; 19. Liquid passage. DETAILED DESCRIPTION

[0046] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0047] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be considered to belong to the scope of the present invention. It should be noted that when an element is referred to as "arranged on" another element, it can be directly on the other element or there can also be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation method.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0049] like Figures 1 to 6 As shown, the present invention provides a rodless oil well wax and scale removal device, comprising:

[0050] The wellhead blowout prevention structure comprises a blowout prevention pipe 6 connected to the top of the oil pipe, the top of the blowout prevention pipe 6 is detachably connected to a blowout prevention cap 1, a lifting and lowering impact rod 3 is arranged in the blowout prevention cap 1, and a wellhead flange 5 and a plunger catcher 7 are connected and arranged on the side wall of the blowout prevention pipe 6;

[0051] The plunger structure comprises a plunger body 8 and a steel ball 9 capable of reciprocating up and down. A plunger center hole is axially penetrated in the plunger body 8. The outer diameter of the plunger body 8 is smaller than the inner diameter of the oil pipe in a free state. The outer diameter of the plunger body 8 is larger than the inner diameter of the oil pipe after being expanded under pressure. The impact rod 3 can pass through the plunger center hole. The steel ball 9 can block the bottom end of the plunger center hole under the action of an upward axial force or leave under the impact of the impact rod 3 to allow the plunger center hole to penetrate. A blade structure is connected to the plunger body 8. The blade structure can rotate under the action of hydraulic force to continuously and automatically remove wax and scale.

[0052] The downhole seat 10 includes a variable buckle joint 18 that can be connected to the oil pipe, and the variable buckle joint 18 is connected to the steel ball bearing joint 16, which cushions the falling plunger structure; the variable buckle joint 18 is provided with a joint center hole axially through, and the bottom end of the variable buckle joint 18 is provided with a liquid passage 19 connected to the joint center hole. The well fluid enters the oil pipe 11 through the liquid passage 19 on the downhole seat 10 to push the steel ball 9 and the plunger body 8 to move upward, forming the power source of the rodless oil well wax and scale removal device of the present invention.

[0053] When the blowout preventer 1 is removed, the plunger structure is put in and taken out from the top of the blowout preventer 6; the wellhead flange 5 is used for drainage; the number of plunger wax and scale cleaning times is set according to the plunger running speed, and when the number of plunger running times reaches the set number of plunger wax and scale cleaning times, the plunger catcher 7 automatically captures the plunger structure; during normal production, the impact rod 3 is installed on the top of the blowout preventer 6. After the plunger body 8 reaches the top, the impact rod 3 can push open the steel ball 9, and the plunger center hole in the plunger body 8 passes liquid. There is a liquid passage inside the plunger body 8, and there is no lifting effect of the well fluid. The plunger body 8 falls under the action of gravity; during maintenance and overhaul, the blowout preventer 1 is opened, and the impact rod 3 is taken out to prevent the steel ball 9 at the bottom of the plunger body 8 from falling to the bottom of the well.

[0054] The steel ball 9 can block the bottom end of the plunger center hole under the action of the upward axial force, and the steel ball 9 and the plunger body 8 move upward under the lifting and pushing action of the liquid flow. The outer diameter of the plunger body 8 is smaller than the inner diameter of the oil pipe in the free state, and the outer diameter of the plunger body 8 is larger than the inner diameter of the oil pipe after being expanded under pressure. The blade structure can rotate under the action of hydraulic force to continuously and automatically remove wax and scale.

[0055] During the upward movement of the plunger structure to remove wax and scale, it is inevitable that the removed wax and scale will adhere to the blades and other parts, so the plunger structure needs to be regularly inspected and maintained. The plunger structure relies on the lifting effect of the well fluid to move upward. The speed of the plunger structure can represent the speed of the well fluid flow rate. The increase in the crude oil flow rate will shorten the flow time of the crude oil in the wellbore, and the wax and scale formation can be alleviated. Then the well fluid flow rate can reflect the degree of wax and scale formation in the wellbore. Therefore, the number of times the plunger removes wax and scale can be set according to the plunger running speed. When the number of times the plunger structure runs reaches the set number of times the plunger removes wax and scale, the plunger structure is automatically captured, and then the spray preventer 1 is opened to remove the plunger body 8.

[0056] The rodless oil well wax and scale cleaning device of the present invention is easy to install. The plunger structure moves upward by relying on the lifting effect of the well fluid, and does not need its own power. It can be applied to rodless oil wells, gas lift oil wells, self-flowing wells and other oil wells without sucker rods. The plunger structure can automatically fall through the impact rod without affecting the liquid flow area and the lifting effect, thereby realizing continuous and automatic wax and scale cleaning in the entire well section. The downhole seat buffers the plunger structure, and the device has good stability. The wax and scale cleaning method of the present invention is simple and easy to operate. The wax and scale cleaning times are set according to the degree of wax and scale formation in the wellbore, and the plunger is automatically captured, which is convenient for subsequent repair and maintenance.

[0057] Further, if Figure 1 As shown, a first buffer spring 2 is provided in the blowout preventer 1, and the impact rod 3 can be axially contracted in the first buffer spring 2. The first buffer spring 2 is used to reduce the impact strength of the plunger structure, protect the wellhead blowout preventer structure, and improve the stability of the device.

[0058] Further, if Figure 1 As shown, a pressure sensing sheet 4 is provided at the bottom end of the spray cap 1, and the pressure sensing sheet 4 is used to sense the contact of the plunger structure. When the plunger structure runs to contact the pressure sensing sheet 4, the impact rod 3 extends from the first buffer spring 2 and passes through the center hole of the plunger to knock down the steel ball 9.

[0059] The impact rod 3 is normally located in the first buffer spring 2. When the plunger body 8 runs to the wellhead and contacts the pressure sensing plate 4, the impact rod 3 extends from the first buffer spring 2 and hits the steel ball 9. The length of the impact rod 3 is greater than the length of the plunger body 8 to meet the impact requirements.

[0060] Further, if Figure 1 , Figure 2 , Figure 3 As shown, the blade structure includes an upper blade 12 and a lower blade 14 spaced apart along the axial direction of the plunger body. The upper blade 12 and the lower blade 14 are rotatably connected to the plunger body 8 through thin-walled ball bearings 13, respectively. The thin-walled ball bearings 13 are used to bear mechanical motion loads. Spiral grooves are provided on the upper blade 12 and the lower blade 14. The liquid flow acts on the spiral grooves, and the blades rotate to remove wax and scale.

[0061] Further, if Figure 1 , Figure 2 , Figure 4 As shown, the bottom end of the plunger body 8 is connected to the anti-slip claw 15, and the steel ball 9 can enter the anti-slip claw 15 to block the plunger center hole under the action of the upward axial force, or leave the anti-slip claw 15 under the top of the impact rod 3. When the steel ball 9 and the plunger body 8 fall onto the downhole seat 10, the steel ball 9 enters the anti-slip claw 15 under the upward supporting force of the downhole seat 10.

[0062] Further, if Figure 4As shown, the anti-slip claw of the steel ball comprises a claw ring body, on which a claw petal body with a bottom end capable of radially extending and retracting is arranged.

[0063] In a specific embodiment of the present invention, the anti-steel ball slip claw adopts an elastic claw structure with six inner mouth bosses. The steel ball 9 can enter the anti-steel ball slip claw under the action of very small force. When there is no external force, the steel ball 9 will not slip from the anti-steel ball slip claw 15. The steel ball 9 is located in the anti-steel ball slip claw 15 during the upward process, playing a single-flow role.

[0064] Further, if Figure 1 , Figure 5 As shown, the variable buckle joint 18 is used to connect the downhole seat 10 and the oil pipe 11; a joint connecting shaft is passed through the variable buckle joint 18, and the top end of the joint connecting shaft is connected to the steel ball bearing joint 16, and a second buffer spring 17 that can axially buffer the steel ball bearing joint is sleeved on the joint connecting shaft. The second buffer spring 17 has a buffering effect on the falling plunger body 8 and the steel ball 9, thereby improving the stability of the device.

[0065] Further, if Figure 1 , Figure 5 As shown, an inner chamfered groove is provided at the center of the top of the steel ball bearing joint 16 to facilitate the centering of the steel ball 9.

[0066] Further, if Figure 1 , Figure 6 As shown, the liquid passage 19 includes a plurality of oil holes arranged at intervals along the circumferential direction at the bottom end of the variable buckle joint, and the well fluid flows upward through the oil holes. In a specific embodiment of the present invention, the number of the oil holes is 8, and the diameter is 12 mm.

[0067] The present invention also provides a method for removing wax and scale from a rodless oil well, comprising: preparing the aforementioned rodless oil well removing wax and scale device, presetting a downhole seat 10 in the wellbore with an oil pipe 11 in advance, lowering a steel ball 9 and a plunger body 8 into the oil pipe through the top of a blowout preventer 6, the steel ball 9 blocking the plunger body 8, and the top of the blowout preventer 6 connected to a blowout cap 1; well fluid enters the oil pipe 11 through a liquid passage 19 on the downhole seat 10, pushing the steel ball 9 and the plunger body 8 to move upward, and the liquid flow acts on a blade structure, and the blade structure rotates to remove wax and scale; the plunger structure moves upward to the wellhead, and the well fluid is discharged through the wellhead flange 5, and when the plunger body contacts the pressure sensing sheet, the impact rod 3 extends and knocks down the steel ball 9, and counts once;

[0068] The plunger body 8 falls, and the steel ball 9 and the plunger body 8 fall onto the downhole seat 10 again. The steel ball 9 blocks the plunger body 8 again, and uses liquid lifting to perform another reciprocating motion for wax and dirt removal, and counts again; when the plunger body 8 contacts the pressure sensing plate 4 for a set number of times, the impact rod 3 no longer extends, and the plunger catcher 7 captures the plunger structure, the spray preventer 1 is disassembled, and the plunger structure is taken out.

[0069] The rodless oil well wax and scale removal method of the present invention sets the wax and scale removal times of the plunger structure according to the wax and scale degree, and automatically captures the plunger structure when the plunger structure runs the set times. The wax and scale removal method specifically includes the following steps (flow chart as shown in FIG. Figure 7 shown):

[0070] S1: The downhole seat 10 is pre-installed in the wellbore along with the oil pipe 11, the blowout preventer 1 is opened, the steel ball 9 and the plunger body 8 are lowered in sequence, the blowout preventer 1 is installed, the steel ball 9 and the plunger body 8 fall to the steel ball bearing joint 16 on the downhole seat 10 by their own gravity, and the steel ball 9 enters the steel ball anti-slip claw 15 of the plunger body 8 under the action of the axial force, and the second buffer spring 17 plays a buffering role on the falling plunger body 8 and steel ball 9.

[0071] S2: The well fluid enters the oil pipe 11 through the liquid passage 19 on the downhole seat 10, pushing the steel ball 9 to move upward. The steel ball 9 is in close contact with the anti-steel ball slip claw 15 of the plunger body 8, pushing the plunger body 8 to move upward. The liquid flow acts on the spiral grooves of the upper blade 12 and the lower blade 14, and the upper blade 12 and the lower blade 14 rotate to remove wax and scale.

[0072] S3: The plunger structure moves upward to the wellhead, and the well fluid is discharged through the wellhead flange 5. When the plunger body 8 contacts the pressure sensing plate 4, the impact rod 3 extends from the first buffer spring 2 and hits the steel ball 9. The first buffer spring 2 has a buffering effect on the plunger body 8, and the steel ball 9 falls. The time t1 when the plunger body 8 first contacts the pressure sensing plate 4 is recorded and counted once, and the count i=1.

[0073] S4: The steel ball 9 with a single-flow function falls, and the center hole of the plunger is connected, so that there is a liquid passage inside the plunger body 8, and there is no lifting effect of the well fluid. The plunger body 8 falls under the action of gravity, and the steel ball 9 and the plunger body 8 fall onto the steel ball bearing joint 16 again. The steel ball 9 enters the anti-steel ball slip claw 15 again, and uses the liquid lifting to perform another reciprocating motion for wax and dirt removal.

[0074] S5: Record the time t2 when the plunger body 8 contacts the pressure sensing sheet 4 for the second time, and count once, i=2. The speed v of the plunger structure in a reciprocating motion:

[0075]

[0076] Where L is the length of the oil pipe.

[0077] S6: The number of times N of the plunger wax and scale removal is set according to the plunger running speed v. The greater the plunger running speed v, the smaller the number of times N of the plunger wax and scale removal is set. When the number of times the plunger body 8 contacts the pressure sensing sheet 4 i=N, the impact rod 3 no longer extends, and the plunger structure is captured by the plunger catcher 7, the spray-proof cap 1 is disassembled, and the plunger structure is taken out.

[0078] As described above, the rodless oil well wax and scale removal device and method of the present invention have the following beneficial effects:

[0079] The rodless oil well wax and scale cleaning device of the present invention is easy to install. The plunger structure moves upward by relying on the lifting effect of the well fluid, and does not need its own power. It can be applied to rodless oil wells, gas lift oil wells, self-flowing wells and other oil wells without sucker rods. The plunger structure can automatically fall through the impact rod without affecting the liquid flow area and the lifting effect, thereby realizing continuous and automatic wax and scale cleaning in the entire well section. The downhole seat buffers the plunger structure, and the device has good stability. The wax and scale cleaning method of the present invention is simple and easy to operate. The wax and scale cleaning times are set according to the degree of wax and scale formation in the wellbore, and the plunger is automatically captured, which is convenient for subsequent repair and maintenance.

[0080] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A rodless oil well wax and scale removal device, characterized in that: include, The wellhead blowout prevention structure comprises a blowout prevention pipe connected to the top of the oil pipe, the top of the blowout prevention pipe is detachably connected to a blowout prevention cap, a lifting and lowering impact rod is arranged inside the blowout prevention cap, and a wellhead flange and a plunger catcher are connected and arranged on the side wall of the blowout prevention pipe; The plunger structure comprises a plunger body and a steel ball capable of reciprocating up and down. A plunger center hole is axially penetrated in the plunger body. The outer diameter of the plunger body is smaller than the inner diameter of the oil pipe in a free state, and the outer diameter of the plunger body is larger than the inner diameter of the oil pipe after being expanded under pressure. The impact rod can pass through the plunger center hole. The steel ball can block the bottom end of the plunger center hole under the action of an upward axial force or leave under the impact of the impact rod to make the plunger center hole penetrate. A blade structure is connected to the plunger body, and the blade structure can rotate under the action of hydraulic force to continuously and automatically remove wax and scale. The downhole seat comprises a variable buckle joint that can be connected to the oil pipe, the variable buckle joint is connected to a steel ball bearing joint, a joint center hole is axially arranged in the variable buckle joint, and a liquid passage connecting to the joint center hole is arranged at the bottom end of the variable buckle joint.

2. The rodless oil well wax and scale removal device according to claim 1, characterized in that: A first buffer spring is arranged in the spray-proof cap, and the impact rod can be axially contracted in the first buffer spring, and the first buffer spring is used to mitigate the impact strength of the plunger structure.

3. The rodless oil well wax and scale removal device according to claim 2, characterized in that: A pressure sensing sheet is provided at the bottom end of the spray cap, and the pressure sensing sheet is used to sense the contact of the plunger structure. When the plunger structure runs and contacts the pressure sensing sheet, the impact rod extends from the first buffer spring and passes through the center hole of the plunger to knock down the steel ball.

4. The rodless oil well wax and scale removal device according to claim 1, characterized in that: The blade structure comprises an upper blade and a lower blade spaced axially along the plunger body, and the upper blade and the lower blade are rotatably connected to the plunger body via thin-walled ball bearings respectively.

5. The rodless oil well wax and scale removal device according to claim 1, characterized in that: The bottom end of the plunger body is connected to the anti-slip claw. The steel ball can enter the anti-slip claw to block the plunger center hole under the action of the upward axial force or leave the anti-slip claw under the top of the impact rod.

6. The rodless oil well wax and scale removal device according to claim 5, characterized in that: The anti-slip claw of the steel ball comprises a claw ring body, and the claw ring body is provided with a claw petal body whose bottom end can be extended and retracted in radial direction.

7. The rodless oil well wax and scale removal device according to claim 1, characterized in that: A joint connecting shaft is passed through the variable buckle joint, the top end of the joint connecting shaft is connected to the steel ball bearing joint, and a second buffer spring capable of axially buffering the steel ball bearing joint is sleeved on the joint connecting shaft.

8. The rodless oil well wax and scale removal device according to claim 7, characterized in that: An inner chamfered groove is arranged at the center of the top end of the steel ball bearing joint.

9. The rodless oil well wax and scale removal device according to claim 7, characterized in that: The liquid passage includes a plurality of oil holes arranged at intervals along the circumferential direction at the bottom end of the variable buckle joint.

10. A method for removing wax and scale from a rodless oil well, characterized in that: The device comprises: preparing a rodless oil well wax and scale removal device as claimed in any one of claims 1 to 9; a downhole seat is pre-set in the wellbore along with the oil pipe; a steel ball and a plunger body are lowered into the oil pipe through the top of the blowout preventer; the steel ball blocks the plunger body; the top of the blowout preventer is connected to the blowout cap; the well fluid enters the oil pipe through the liquid passage on the downhole seat, pushing the steel ball and the plunger body to move upward, and the liquid flow acts on the blade structure, and the blade structure rotates to remove wax and scale; The plunger structure moves upward to the wellhead, and the well fluid is discharged through the wellhead flange. When the plunger body contacts the pressure sensing sheet, the impact rod extends and knocks down the steel ball, which counts once. The plunger body falls, and the steel ball and the plunger body fall onto the downhole seat again. The steel ball blocks the plunger body again, and the liquid is used to lift the plunger body to perform another reciprocating motion for wax and dirt removal, which is counted again. When the plunger body contacts the pressure sensing plate for a set number of times, the impact rod no longer extends, and the plunger catcher captures the plunger structure, the spray preventer is removed, and the plunger structure is taken out.

11. The rodless oil well dewaxing and descaling method according to claim 10, characterized in that: The following steps are involved: S1: The downhole seat is pre-set in the wellbore with the oil pipe, the blowout preventer is opened, the steel ball and the plunger body are lowered in sequence, the blowout preventer is installed, the steel ball and the plunger body fall to the steel ball bearing joint of the downhole seat by their own gravity, and the steel ball enters the steel ball slip prevention claw of the plunger body under the action of the axial force; S2: Well fluid enters the oil pipe through the liquid passage on the downhole seat, pushing the steel ball and the plunger body upward. The liquid flow acts on the spiral grooves of the upper blade and the lower blade, and the upper blade and the lower blade rotate to remove wax and scale; S3: The plunger structure moves upward to the wellhead, and the well fluid is discharged through the wellhead flange. When the plunger body contacts the pressure sensing sheet, the impact rod extends from the first buffer spring and hits the steel ball, causing the steel ball to fall. The time t1 when the plunger body first contacts the pressure sensing sheet is recorded and counted once, with the count i=1. S4: The steel ball falls, the center hole of the plunger is connected, and the plunger body falls under the action of gravity. The steel ball and the plunger body fall onto the steel ball bearing joint again, and the steel ball enters the steel ball anti-slip claw again, and the liquid is used to lift and perform another reciprocating motion for wax and dirt removal; S5: Record the time t2 when the plunger body contacts the pressure sensing sheet for the second time, and count once, count i=2; the speed v of the plunger structure in a reciprocating motion: Where L is the length of the oil pipe; S6: Set the number of times N for the plunger to clean wax and dirt according to the plunger running speed v; when the number of times the plunger body contacts the pressure sensing plate i=N, the impact rod no longer extends, the plunger catcher automatically catches the plunger structure, removes the spray cap, and takes out the plunger structure.

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