Underground sand cleaning system under fluctuating pressure

Abstract

The invention discloses an underground sand cleaning system under fluctuating pressure, and relates to the technical field of underground sand cleaning equipment, in particular to the underground sand cleaning system under fluctuating pressure, which comprises a sand cleaning operation system and a well fluid circulation system, the sand cleaning operation system comprises a plurality of second sleeves and a sand collecting equipment string; the flow adjusting device and the pressurizing device can generate high-frequency fluctuation pressure, the flow adjusting device intermittently blocks flow of sand washing liquid flowing in the flow adjusting device, the pressurizing device pressurizes the sand washing liquid intermittently flowing in the pressurizing device, the sand washing liquid forms pressure flow under intermittent fluctuation, and therefore the pressure flow of the sand washing liquid is increased. And after the sand washing fluid is jetted out through the jet flow device, an inner cavity of the jet flow device is in a high-negative-pressure state, so that the sand-containing fluid in the jet flow device is lifted upwards, and then high-negative-pressure operation of the jet flow device and efficient lifting of the sand-containing fluid are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of downhole sand cleaning systems, and more particularly to a mechanical sand cleaning system during the process of horizontal directional drilling and ramming casing, specifically a downhole sand cleaning system under fluctuating pressure. Background Art

[0002] At present, there are mainly two types of downhole sand cleaning technologies. One is to use a sand washing fluid under high displacement and high pump pressure to wash and carry sand to remove formation sand. The other is mainly a mechanical sand fishing device. Through a sand fishing pump below the casing to the bottom of the well, a negative pressure is generated by lifting and lowering the mechanical device at the bottom of the well, so that the wellbore sand is sucked into the sand fishing barrel, and then the sand fishing pump is lifted to the wellhead to achieve the purpose of fishing out the formation sand.

[0003] Both of these technologies have more or less limitations. The first type of sand fishing method requires ground equipment with high displacement and high pump pressure to pump the sand washing fluid into the well. The implementation of this technology results in higher equipment costs. At the same time, the use of a large displacement and high pump pressure underground may cause the wellbore to collapse, and the performance requirements for the sand washing fluid are also relatively high.

[0004] While using the method of sucking with a sand fishing barrel, although the problem of poor coarse sand carrying can be better avoided, the sand fishing time is long and multiple sand fishing operations are required, which leads to low sand cleaning efficiency. Summary of the Invention

[0005] (I) Technical Problems to be Solved In view of the deficiencies of the prior art, the present invention provides a downhole sand cleaning system under fluctuating pressure, which solves the problems raised in the above background art.

[0006] (II) Technical Solutions To achieve the above object, the present invention is realized through the following technical solutions: A downhole sand cleaning system under fluctuating pressure includes a sand cleaning operation system and a well fluid circulation system. The sand cleaning operation system includes a plurality of second casings and a sand collection equipment string. Each of the second casings is sequentially connected in series and detachably installed. The sand collection equipment string is detachably installed at the lower end of the second casing at the end, and the sand collection equipment string is communicated with the second casing. The sand collection equipment string includes a flow regulating device, a pressurizing device, and a jet device that are sequentially connected in series and communicated with each other. The upper end of the flow regulating device is threadedly connected to the lower end of the second casing at the end. The lower end of the flow regulating device is threadedly connected to the upper end of the pressurizing device. The lower end of the pressurizing device is threadedly connected to the upper end of the jet device. The lower end of the jet device is threadedly connected to the upper end of the first casing. The lower end of the first casing is threadedly connected to the upper end of the sand collection device. The lower end of the sand collection device is threadedly connected to the upper end of the drill collar. During the sand cleaning operation, the sand washing fluid flows through the flow regulating device, the pressurizing device, and the jet device in sequence. The flow regulating device intermittently blocks the sand washing fluid flowing inside it, and the pressurizing device pressurizes the sand washing fluid flowing into it intermittently, so that the sand washing fluid forms a pressure flow under intermittent fluctuations. After the sand washing fluid is ejected by the jet device, the internal cavity of the jet device is in a high negative pressure state, causing the sand-containing fluid in the jet device to lift upward.

[0007] Optionally, the sand collecting equipment string further includes at least one first casing, at least one sand collecting device, and a drill collar. The upper end of the sand collecting device is fixedly installed and communicated with the lower end of the first casing, and the lower end of the sand collecting device is fixedly installed and communicated with the upper end of the drill collar; the lower end of the jet device is threadedly connected and communicated with the upper end of the first casing.

[0008] Optionally, the sand collecting device includes an inner cylinder component and an outer cylinder component. The outer cylinder component includes a fourth cylinder body, and the inner cylinder component includes a fourth inner cylinder body. The fourth inner cylinder body is coaxially and fixedly installed inside the fourth cylinder body, and an annular sand settling chamber is formed between the outer side wall of the fourth inner cylinder body and the inner side wall of the fourth cylinder body; a hollow sand-containing fluid upward channel is longitudinally opened inside the fourth inner cylinder body, and a plurality of upward flow channels are opened on the top side wall of the fourth inner cylinder body, and the upward channel is communicated with the sand settling chamber through the upward flow channels.

[0009] Optionally, the outer cylinder component further includes a sand collecting upper joint and a sand collecting lower joint. The upper end of the fourth cylinder body is fixedly connected to the sand collecting upper joint, and the lower end of the fourth cylinder body is fixedly connected to the sand collecting lower joint; The inner cylinder component further includes an umbrella-shaped cap, an upper adapter joint, and a lower adapter joint. The upper adapter joint is fixedly connected to the inner side wall of the upper part of the fourth cylinder body, the umbrella-shaped cap is fixedly connected to the upper adapter joint, the lower adapter joint is integrally in a cylindrical shape, the lower adapter joint is fixedly installed inside the fourth cylinder body, the upper end of the fourth inner cylinder body is fixedly installed at the bottom of the umbrella-shaped cap, and the lower part of the fourth inner cylinder body passes through and is fixedly connected to the lower adapter joint.

[0010] Optionally, the flow regulating device includes a first cylinder body, a rotating guide member, a fixed guide member, a piston cylinder, and a set of disc springs. The fixed guide member is fixedly installed on the inner side wall of the first cylinder body, the rotating guide member is rotatably installed on the inner side wall of the first cylinder body, and the rotating guide member is located above the fixed guide member; the piston cylinder penetrates through the bottom wall of the first cylinder body and is slidably connected to it, and a spring cavity is formed between the piston cylinder and the first cylinder body, and the set of disc springs is longitudinally placed in the spring cavity; The lower part of the fixed flow guide is in the shape of a cylinder extending downward, and a plurality of flow guide holes are formed in the side wall of the lower part of the fixed flow guide. The outer diameter of the lower cylinder of the fixed flow guide is less than or equal to the inner diameter of the piston cylinder, and the lower cylinder of the fixed flow guide is inserted into the central hole of the piston cylinder; A plurality of longitudinal peripheral rotary flow holes are formed in the rotary flow guide, and a plurality of longitudinal peripheral fixed flow holes are formed in the fixed flow guide; after the rotary flow guide rotates, the peripheral rotary flow holes are longitudinally communicated with or disconnected from the peripheral fixed flow holes on the fixed flow guide; the peripheral fixed flow holes are communicated with the inside of the piston cylinder through the flow guide holes.

[0011] Optionally, an anti-falling assembly is fixedly installed inside the first cylinder. The anti-falling assembly penetrates through the rotary flow guide and the two are rotatably connected, and the lower end of the anti-falling assembly is fixedly installed with the fixed flow guide.

[0012] Optionally, the pressurizing device includes a second cylinder, a second inner cylinder, a valve base, and a drain valve. The valve base is fixedly installed on the inner side wall of the lower part of the second cylinder. The upper part of the valve base is in a convex shape upward. A longitudinal first through hole is formed in the middle of the valve base. The second inner cylinder is fixedly installed on the upper part of the valve base and the two are internally communicated; the drain valve is installed on the valve base; The internal cavity of the second inner cylinder forms a pressurizing cavity, and an annular cavity is formed between the second inner cylinder and the second cylinder; A liquid inlet valve is installed at the inner bottom of the piston cylinder. The lower end of the piston cylinder is inserted into the upper end of the second inner cylinder and the two are slidably connected. A sealing ring is embedded at the sliding connection between the piston cylinder and the second inner cylinder.

[0013] Optionally, the jet device includes a third cylinder, a mounting plate, a nozzle, a third inner cylinder, a throat tube, and a filter cover. The mounting plate is fixedly installed on the inner side wall of the third cylinder. A third through hole is formed in the middle of the mounting plate. The filter cover is fixedly installed above the mounting plate. The nozzle is detachably installed below the mounting plate and is communicated with the third through hole; The third inner cylinder is fixedly installed inside the third cylinder. The throat tube is fixedly installed on the upper inner side wall of the third inner cylinder. The inner flow channel diameter of the throat tube gradually expands from the middle to both ends. Drain ports are formed on the lower side wall of the third cylinder and the lower side wall of the third inner cylinder and the two are communicated.

[0014] Optionally, the well fluid circulation system includes a sleeve, a submersible electric pump, a sand-liquid separator, a first motor, and a sand-liquid separation device. The submersible electric pump is fixedly installed at the lower end of the sleeve, and one medium outflow end of the submersible electric pump communicates with the lower end of the sleeve, and the other medium outflow end of the submersible electric pump communicates with the second casing; the sand-liquid separator is fixedly installed at the medium inflow end of the submersible electric pump and the two are communicated, and the sand-liquid separation device is rotatably installed at the medium inflow end of the sand-liquid separator and the two are communicated.

[0015] Optionally, the sand-liquid separation device includes a first motor, a fifth cylinder, a fifth inner cylinder, a vertical spoiler, and a horizontal spoiler. The middle of the fifth inner cylinder penetrates through the top wall of the fifth cylinder and the two are fixedly connected. A plurality of sand-containing liquid inlets are provided on the outer side wall of the fifth cylinder; the vertical spoiler is fixedly installed on the inner side wall of the lower part of the fifth cylinder, and the horizontal spoiler is fixedly installed above the middle of the vertical spoiler; the upper end of the fifth inner cylinder is rotatably connected to the medium inflow end of the sand-liquid separator, the first motor is fixedly installed on the sand-liquid separator, and the output shaft of the first motor is in transmission connection with the fifth inner cylinder.

[0016] (III) Beneficial effects The present invention provides a downhole sand cleaning system under fluctuating pressure, having the following beneficial effects: 1. The flow regulating device and the pressure boosting device proposed by the present invention can generate high-frequency fluctuating pressure. The flow regulating device intermittently blocks the flow of the sand flushing liquid inside it, and the pressure boosting device boosts the sand flushing liquid flowing into it intermittently, so that the sand flushing liquid forms a pressure flow under intermittent fluctuations, that is, a high-frequency fluctuating pressure flow. After the sand flushing liquid is ejected by the jet device, the internal cavity of the jet device is in a high negative pressure state, causing the sand-containing liquid in the jet device to lift upward, thereby realizing the high negative pressure operation of the jet device and the efficient lifting of the sand-containing liquid. In this way, sand cleaning operations can be carried out without the need for high pump pressure on the ground. Compared with the prior art, the requirements for ground equipment are reduced and costs are saved.

[0017] 2. The jet device proposed by the present invention can make the sand-containing liquid lift fluctuatingly, and can lift the sand-containing liquid to the maximum extent, and is also applicable to well fluids with high sand content. The rotating pipe string can not only ensure the operation of the sand grinding device, but also realize the function of the flow regulating device, thereby realizing the fluctuating flow of the internal sand-containing well fluid to improve the lifting efficiency and finally realize the efficient sand-liquid flow.

[0018] 3. When the present invention is specifically implemented, multi-stage sand settling can be carried out. By using multiple sand collecting devices connected in series longitudinally for sand collection and sand settling, a large amount of sand can be settled in a single time, which not only improves the efficiency of sand cleaning, but also enables the well fluid to be recycled. The time for sand settling during pump shutdown and the operation of surface equipment are reduced, greatly saving the operation cost. Compared with the prior art, the sand cleaning efficiency is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0020] Figure 1 is a schematic diagram of the principle structure of a downhole sand cleaning system under fluctuating pressure of the present invention ( Figure 1 the solid black arrows indicate the flow direction of the sand washing fluid; the hollow arrows indicate the flow direction of the sand-containing fluid or sand grains); Figure 2 is a schematic diagram of the series installation structure of the sand collecting device string in a downhole sand cleaning system under fluctuating pressure of the present invention; Figure 3 is a sectional view structure schematic diagram of a flow regulating device and a pressurizing device in a downhole sand cleaning system under fluctuating pressure of the present invention; Figure 4 is a top view structure schematic diagram of a rotating deflector in a downhole sand cleaning system under fluctuating pressure of the present invention; Figure 5 is a top view structure schematic diagram of a fixed deflector in a downhole sand cleaning system under fluctuating pressure of the present invention; Figure 6 is a sectional view structure schematic diagram of a sand collecting device in a downhole sand cleaning system under fluctuating pressure of the present invention; Figure 7 is a sectional view structure schematic diagram of a jet device in a downhole sand cleaning system under fluctuating pressure of the present invention; Figure 8 is a schematic diagram of the internal three-dimensional structure (partial sectional view) of a sand-liquid separation device in a downhole sand cleaning system under fluctuating pressure of the present invention.

[0021] In the figure: 1, well; 2, abrasive tool; 3, drill collar; 4, sand collecting device; 401, upper sand collecting joint; 402, umbrella-shaped cap; 403, upper adapter joint; 405, fourth inner cylinder; 406, fourth cylinder; 407, lower adapter joint; 410, lower sand collecting joint; 5, first casing; 6. Sand-liquid separation device; 601. Fifth cylinder; 602. Inlet for sand-containing liquid; 604. Fifth inner cylinder; 605. Horizontal flow deflecting plate; 606. Vertical flow deflecting plate; 7. First motor; 9. Sand-liquid separator; 10. Submersible electric pump; 11. Sleeve; 12. Wellhead sealing cover; 13. First one-way valve; 14. Second water pump; 15. Second one-way valve; 17. Second casing; 18. Sand grains; 19. Flow regulating device; 1901. First cylinder; 1902. Anti-falling assembly; 1903. Rotating flow guide; 19033. Peripheral rotating flow holes; 1904. Fixed flow guide; 19042. Peripheral fixed flow holes; 1905. Flow guide hole; 1907. Disc spring group; 1908. Piston cylinder; 1909. Liquid inlet valve; 20. Pressurizing device; 2001. Second cylinder; 2002. Sealing ring; 2003. Pressurizing chamber; 2004. Liquid discharge valve; 2006. Valve base; 2007. Second inner cylinder; 21. Jet device; 2102. Filter cover; 2103. Mounting plate; 2105. Nozzle; 2106. Third cylinder; 2107. Third inner cylinder; 2108. Throat tube; 2109. Diffusion flow channel; 2111. Plug; 22. First infusion tube; 23. Second infusion tube. Detailed implementation manners

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying.

[0023] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0024] Please refer to Figures 1 to 8 , the present invention provides a technical solution: a downhole sand cleaning system under fluctuating pressure, including a sand cleaning operation system, a well fluid circulation system, a wellhead sealing cover 12, and a first infusion pipe 22.

[0025] Among them, the wellhead sealing cover 12 is fixedly installed at the wellhead of well 1, and the wellhead sealing cover 12 is used to seal the wellhead of well 1. The middle part of the first infusion pipe 22 penetrates through the wellhead sealing cover 12, the outflow end of the first infusion pipe 22 is located inside well 1, and the inflow end of the first infusion pipe 22 is located on the ground. The first infusion pipe 22 is used to transport sand washing fluid, etc. into well 1. The sand cleaning operation system is used to clean the inside of well 1. The well fluid circulation system is used to discharge the liquid inside well 1 to ensure the outward discharge of the well fluid.

[0026] The sand cleaning operation system includes a plurality of second casings 17 and a sand collection equipment string. Each of the second casings 17 is connected in series in sequence and is detachably installed, and the sand collection equipment string is detachably installed at the lower end of the second casing 17 at the end, and the sand collection equipment string is communicated with the second casing 17.

[0027] Among them, each of the second casings 17 is longitudinally arranged and lowered into the well, and adjacent second casings 17 are connected by threads, and each of the second casings 17 together forms a pipe structure; among them, one of the second casings 17 located in the upper part penetrates through the wellhead sealing cover 12; the medium inflow end of the second casing 17 located at the uppermost end is communicated with a second water pump 14, and a second one-way valve 15 is fixedly installed at the medium inflow end of the second water pump 14, and the second water pump 14 is used to pump the sand washing fluid into each of the second casings 17 connected in series in sequence.

[0028] The sand collection equipment string includes a flow regulating device 19, a pressurizing device 20, and a jet device 21 that are connected in series and installed in communication with each other. Among them, the sand collection equipment string further includes a grinding device 2. In specific implementation, according to actual implementation needs, the grinding device 2 is selectively installed when necessary, and the grinding device 2 is installed at the lower end of the drill collar 3.

[0029] The upper end of the flow regulating device 19 is threadedly connected to the lower end of the second casing 17 at the end. The lower end of the flow regulating device 19 is threadedly connected to the upper end of the pressurizing device 20, the lower end of the pressurizing device 20 is threadedly connected to the upper end of the jet device 21, the lower end of the jet device 21 is threadedly connected to the upper end of the first casing 5, the lower end of the first casing 5 is threadedly connected to the upper end of the sand collection device 4, and the lower end of the sand collection device 4 is threadedly connected to the upper end of the drill collar 3.

[0030] During the sand flushing operation, the sand flushing fluid flows through the flow regulating device 19, the pressurizing device 20, and the jet device 21 in sequence. The flow regulating device 19 intermittently blocks the sand flushing fluid flowing inside it, and the pressurizing device 20 pressurizes the sand flushing fluid flowing into it intermittently, so that the sand flushing fluid forms a pressure flow under intermittent fluctuations. After the sand flushing fluid is jetted out through the jet device 21, the internal cavity of the jet device 21 is in a high negative pressure state, causing the sand-containing fluid in the jet device 21 to lift upward.

[0031] Among them, the sand flushing fluid flows through each second casing 17, the flow regulating device 19, the pressurizing device 20, and the jet device 21 in sequence. The flow regulating device 19 is used to intermittently block the sand flushing fluid flowing inside it, so that the sand flushing fluid can flow downward intermittently. The pressurizing device 20 is used to pressurize the sand flushing fluid flowing through it. The jet device 21 is used to jet out the sand flushing fluid.

[0032] During the sand flushing operation, the abrasive tool 2 (including but not limited to using a wall scraping tool, etc.) rotates for abrasive grinding under the drive of the drill collar 3. The sand grains 18 enter the abrasive tool 2, and after being ground, they move upward into the upper sand collecting device 4. As the abrasive tool 2 and the like move downward, the sand grains 18 in the sand collecting device 4 gradually increase. The sand grains 18 move upward in the sand collecting device 4 and enter the first casing 5 and the jet device 21; then the well fluid enters the jet device 21. The jet device 21 mainly plays the role of lifting the well fluid. The flow regulating device 19 and the pressurizing device 20 mainly provide a high-frequency fluctuating high water pressure for the jet device 21, thereby generating a pulsating lifting force to effectively lift the well fluid.

[0033] Specifically, the sand collecting equipment string further includes at least one first casing 5, at least one sand collecting device 4, and a drill collar 3. The upper end of the sand collecting device 4 is fixedly installed and communicated with the lower end of the first casing 5, and the lower end of the sand collecting device 4 is fixedly installed and communicated with the upper end of the drill collar 3. The lower end of the jet device 21 is threadedly connected and communicated with the upper end of the first casing 5.

[0034] Among them, the sand flushing fluid flows through each second casing 17, the flow regulating device 19, the pressurizing device 20, the jet device 21, the first casing 5, the sand collecting device 4, and the drill collar 3 in sequence. Refer to Figure 2 , in actual implementation, multiple sand collecting devices 4 and first casings 5 can be used. Each sand collecting device 4 and first casing 5 are installed in series and communicated with each other in sequence, so as to increase and expand the sand collecting capacity, realize a large amount of sand sedimentation in a single time, not only improve the sand flushing efficiency, but also enable the well fluid to be recycled. The upper and lower ends of the first casing 5 are threadedly connected to the adjacent two sand collecting devices 4 respectively; the upper end of the topmost first casing 5 is threadedly connected to the jet device 21; the lower end of the lowermost sand collecting device 4 is threadedly connected to the drill collar 3 (other installation methods can also be used, specifically according to actual implementation needs).

[0035] More specifically, the sand collecting device 4 includes an inner cylinder component and an outer cylinder component. The outer cylinder component includes a fourth cylinder body 406, and the inner cylinder component includes a fourth inner cylinder body 405. The fourth inner cylinder body 405 is coaxially and fixedly installed inside the fourth cylinder body 406. An annular sand settling chamber is formed between the outer side wall of the fourth inner cylinder body 405 and the inner side wall of the fourth cylinder body 406. A hollow upward flow channel for sand-containing liquid is longitudinally formed inside the fourth inner cylinder body 405. A plurality of upward flow channels are formed on the top side wall of the fourth inner cylinder body 405. The upward flow channel communicates with the sand settling chamber through the upward flow channels.

[0036] Among them, the sand-containing liquid (referring to sand grains 18 and a small amount of wellbore liquid) moves upward through the inner cavity of the fourth inner cylinder body 405. The sand-containing liquid flows into the sand settling chamber through each upward flow channel, and the sand settling chamber holds the sand-containing liquid. When the sand settling chamber of the lower-level sand collecting device 4 is full, the sand-containing liquid in the sand settling chamber continues to move upward through the first casing 5 into the sand collecting device 4 of the upper level or the side cavity of the jet device 21.

[0037] Even more specifically, the outer cylinder component further includes a sand collecting upper joint 401 and a sand collecting lower joint 410. The upper end of the fourth cylinder body 406 is fixedly connected to the sand collecting upper joint 401, and the lower end of the fourth cylinder body 406 is fixedly connected to the sand collecting lower joint 410.

[0038] Among them, the lower end of the sand collecting lower joint 410 is threadedly installed with the upper end of the drill collar 3 or the upper end of the first casing 5; the upper end of the sand collecting upper joint 401 is threadedly installed with the lower end of the first casing 5.

[0039] Even more specifically, the inner cylinder component further includes an umbrella cap 402, an upper adapter joint 403, and a lower adapter joint 407. The upper adapter joint 403 is fixedly connected to the inner side wall of the upper part of the fourth cylinder body 406. The umbrella cap 402 is fixedly connected to the upper adapter joint 403. The lower adapter joint 407 is integrally in a cylindrical shape and is fixedly installed inside the fourth cylinder body 406. The upper end of the fourth inner cylinder body 405 is fixedly installed at the bottom of the umbrella cap 402. The lower part of the fourth inner cylinder body 405 penetrates through the lower adapter joint 407 and the two are fixedly connected.

[0040] Among them, the upper adapter joint 403 is used to support and fix the umbrella cap 402. The umbrella cap 402 is used to support and fix the upper end of the fourth inner cylinder body 405. The lower adapter joint 407 is used to support and fix the lower end of the fourth inner cylinder body 405.

[0041] Specifically, the flow regulating device 19 includes a first cylinder body 1901, a rotating flow guide member 1903, a fixed flow guide member 1904, a piston cylinder 1908, and a set of disc springs 1907. The fixed flow guide member 1904 is fixedly installed on the inner side wall of the first cylinder body 1901. The rotating flow guide member 1903 is rotatably installed on the inner side wall of the first cylinder body 1901, and the rotating flow guide member 1903 is located above the fixed flow guide member 1904. The piston cylinder 1908 penetrates through the bottom wall of the first cylinder body 1901 and is slidably connected thereto. A spring chamber is formed between the piston cylinder 1908 and the first cylinder body 1901. The set of disc springs 1907 is longitudinally placed in the spring chamber.

[0042] The lower part of the fixed flow guide member 1904 is in the shape of a cylinder extending downward, and a plurality of flow guide holes 1905 are formed in the side wall of the lower part of the fixed flow guide member 1904. The outer diameter of the lower cylinder of the fixed flow guide member 1904 is less than or equal to the inner diameter of the piston cylinder 1908, and the lower cylinder of the fixed flow guide member 1904 is inserted into the central hole of the piston cylinder 1908.

[0043] A plurality of longitudinal peripheral rotating flow holes 19033 are formed in the rotating flow guide member 1903, and a plurality of longitudinal peripheral fixed flow holes 19042 are formed in the fixed flow guide member 1904. After the rotating flow guide member 1903 rotates, the peripheral rotating flow holes 19033 are longitudinally communicated with or disconnected from the peripheral fixed flow holes 19042 on the fixed flow guide member 1904. The peripheral fixed flow holes 19042 are communicated with the inside of the piston cylinder 1908 through the flow guide holes 1905.

[0044] The upper end of the first cylinder body 1901 is threadedly installed with the lower end port of the lowermost second sleeve 17.

[0045] Among them, the side wall of the rotating flow guide member 1903 located on one side of the peripheral rotating flow hole 19033 is inclined. When the flushing fluid flows inside the first cylinder 1901, the flushing fluid pushes the rotating flow guide member 1903 to rotate. During the rotation of the rotating flow guide member 1903, when the peripheral rotating flow hole 19033 and the peripheral fixed flow hole 19042 are vertically corresponding and connected, the flushing fluid flows through the peripheral rotating flow hole 19033 and the peripheral fixed flow hole 19042 in sequence, and the flushing fluid flows downward; when the peripheral rotating flow hole 19033 and the peripheral fixed flow hole 19042 are not vertically corresponding and not connected, the flushing fluid is blocked and cannot flow downward. As the rotating flow guide member 1903 rotates, the peripheral rotating flow hole 19033 on the rotating flow guide member 1903 will be intermittently connected to the peripheral fixed flow hole 19042. When the flushing fluid flows to the lower part of the fixed flow guide member 1904, the flushing fluid pushes the piston cylinder 1908. Due to the influence of the rotating flow guide member 1903, the intermittently descending flushing fluid repeatedly pushes the piston cylinder 1908, and the piston cylinder 1908 repeatedly compresses the butterfly spring group 1907, and the butterfly spring group 1907 in turn pushes the piston cylinder 1908, so that the piston cylinder 1908 can repeatedly lift and move.

[0046] Further specifically, an anti-falling assembly 1902 is fixedly installed inside the first cylinder 1901. The anti-falling assembly 1902 penetrates through the rotating flow guide member 1903 and the two are rotatably connected. The lower end of the anti-falling assembly 1902 is fixedly installed with the fixed flow guide member 1904.

[0047] Among them, the anti-falling assembly 1902 can adopt a shaft rod. The anti-falling assembly 1902 is used to support the rotating flow guide member 1903. The rotating flow guide member 1903 can rotate on the anti-falling assembly 1902.

[0048] Even more specifically, the pressurizing device 20 includes a second cylinder 2001, a second inner cylinder 2007, a valve base 2006, and a drain valve 2004. The valve base 2006 is fixedly installed on the lower inner side wall of the second cylinder 2001. The upper part of the valve base 2006 is in an upward convex shape. A longitudinal first through hole is provided in the middle of the valve base 2006. The second inner cylinder 2007 is fixedly installed on the upper part of the valve base 2006 and the two are internally connected. The drain valve 2004 is installed on the valve base 2006.

[0049] The internal cavity of the second inner cylinder 2007 forms a pressurizing chamber 2003, and an annular cavity is formed between the second inner cylinder 2007 and the second cylinder 2001.

[0050] An inlet valve 1909 is installed at the inner bottom of the piston cylinder 1908. The lower end of the piston cylinder 1908 is inserted into the upper end of the second inner cylinder 2007 and the two are slidably connected. A sealing ring 2002 is embedded at the sliding connection between the piston cylinder 1908 and the second inner cylinder 2007, and the sealing ring 2002 is used to enhance the sealing effect.

[0051] Among them, the lower end of the first cylinder 1901 is threadedly installed with the lower end of the second cylinder 2001. The generation principle of pulsed high pressure (that is, high-frequency fluctuating pressure flow) is as follows: Refer to Figure 3 , the sand washing liquid sequentially flows through the peripheral rotating flow holes 19033, the peripheral fixed flow holes 19042, and the diversion holes 1905. Then, the sand washing liquid enters the piston cylinder 1908, and the sand washing liquid enters the pressurizing chamber 2003 through the inlet valve 1909, and thus is compressed and pressurized by the reciprocating piston cylinder 1908. The pressurized sand washing liquid in the pressurizing chamber 2003 is discharged through the drain valve 2004. At this time, pulsed high pressure is generated, that is, a fluid with a certain pressure fluctuation. When the piston cylinder 1908 moves upward, the inlet valve 1909 opens and the drain valve 2004 closes. At this time, there is no pulsed high pressure. When the piston cylinder 1908 moves downward, the inlet valve 1909 closes and the drain valve 2004 opens.

[0052] Specifically, the jet device 21 includes a third cylinder 2106, a mounting plate 2103, a nozzle 2105, a third inner cylinder 2107, a throat 2108, and a filter cover 2102. The mounting plate 2103 is fixedly installed on the inner side wall of the third cylinder 2106. A third through hole is provided in the middle of the mounting plate 2103. The filter cover 2102 is fixedly installed above the mounting plate 2103. The nozzle 2105 is detachably installed below the mounting plate 2103, and the nozzle 2105 communicates with the third through hole. A diffusion flow channel 2109 is provided inside the third inner cylinder 2107, and the throat 2108 is fixedly installed in the diffusion flow channel 2109.

[0053] The third inner cylinder 2107 is fixedly installed inside the third cylinder 2106. The throat 2108 is fixedly installed on the upper inner side wall of the third inner cylinder 2107. The inner flow channel diameter of the throat 2108 gradually expands from the middle to both ends. Drain ports are provided on the lower side wall of the third cylinder 2106 and the lower side wall of the third inner cylinder 2107, and the two are communicated.

[0054] Among them, the upper end of the third cylinder 2106 is threadedly installed with the lower end of the second cylinder 2001, and the lower end of the third cylinder 2106 is threadedly installed with the upper end of the first sleeve 5. The filter cover 2102 is used to filter the downward sand washing fluid. The sand washing fluid flows through the filter cover 2102, the third through hole, the nozzle 2105, the throat pipe 2108, the diffusion channel 2109 of the third inner cylinder 2107, and two drainage ports in sequence and then sprays out. A first annular cavity is formed between the third inner cylinder 2107 and the third cylinder 2106; the upper end port of the third inner cylinder 2107 communicates with the first annular cavity. The sand-containing fluid ascending in the first sleeve 5 can ascend into the first annular cavity. After the sand washing fluid is ejected by the jet of the nozzle 2105, the pressure near the nozzle 2105 decreases, and even becomes a negative pressure state. The first annular cavity is in a negative pressure state, thereby accelerating the lifting of the sand-containing fluid and improving the lifting efficiency of the sand-containing fluid. The lower end of the third inner cylinder 2107 is sealed with a plug 2111.

[0055] The jet device 21 selects a structure such as Figure 7 . The structure of the jet device 21 adopts an internal and external double constraint design. The basic equation of the performance characteristics of the jet device 21 is simplified as follows: ; In the formula: H0 and M0 are performance coefficients, related to the area ratio and the density of the suction fluid; φ1 is the velocity coefficient at the nozzle, taking 0.95 - 0.975; H is the pressure ratio, and M is the flow ratio (the ratio of the power fluid flow rate to the suction fluid flow rate).

[0056] ; In the formula: p1 is the power fluid pressure; p2 is the suction fluid pressure; p3 is the discharge fluid pressure.

[0057] The flow ratio M is as follows, ; In the formula: Q1 is the power fluid flow rate; Q2 is the suction fluid flow rate.

[0058] The efficiency η is expressed as follows, ; The throat-nozzle distance Lc of the jet device 21 and the diameter d2 of the throat pipe 2108 satisfy the following relationship, ; The length L2 of the throat pipe 2108 of the jet device 21 and the diameter d2 of the throat pipe 2108 satisfy the following relationship, ; The area ratio of the jet device 21 is as follows, ; Where: d1 is the diameter of the nozzle outlet, and d2 is the diameter of the throat tube. The area ratio range of the jet device is taken as 0.235 - 0.4.

[0059] Among them, the contraction angle range at the nozzle is 8° - 14°, and the bevel angle at the throat inlet is 0° - 60°.

[0060] Based on the above equations, the design optimization of the jet device can be carried out, including the outlet diameter of the nozzle 2105, the diameter of the throat tube, as well as the total length and the outer diameter of the pump body. The optimal values of the throat-nozzle distance and the throat tube length can be obtained through finite element simulation analysis. Through the area ratio, throat-nozzle distance, contraction angle of the nozzle, throat tube length, and bevel angle at the throat inlet of the jet device, an orthogonal experimental design can be carried out.

[0061] Specifically, the well fluid circulation system includes a second infusion pipe 23, a sleeve 11, a submersible electric pump 10, a sand-fluid separator 9, a first motor 7, and a sand-fluid separation device 6. The submersible electric pump 10 is fixedly installed at the lower end of the sleeve 11, and one medium outlet end of the submersible electric pump 10 is communicated with the lower end of the sleeve 11, and the other medium outlet end of the submersible electric pump 10 is communicated with the second casing 17. The sand-fluid separator 9 is fixedly installed at the medium inlet end of the submersible electric pump 10 and the two are communicated, and the sand-fluid separation device 6 is rotatably installed at the medium inlet end of the sand-fluid separator 9 and the two are communicated.

[0062] Among them, the upper end of the sleeve 11 is communicated with one end of the second infusion pipe 23, and a first one-way valve 13 is installed on the second infusion pipe 23. The sand-fluid separator 9 includes but is not limited to a hydrocyclone and a spiral sand-water separator. The submersible electric pump 10 is used to lift the well fluid and discharge the well fluid to the outside of the well. The submersible electric pump 10 pumps the well fluid to make the well fluid go upward. One way of the well fluid flows through the sleeve 11 to the second infusion pipe 23 and then is discharged from the well; the other way of the well fluid flows back into the second casing 17 to compensate for the flushing fluid in the second casing 17. The sand-fluid separator 9 is used to separate sand from the well fluid to prevent sand grains from going upward with the well fluid. The sand-fluid separation device 6 is also used to separate sand from the well fluid.

[0063] More specifically, the sand-fluid separation device 6 includes a first motor 7, a fifth cylinder 601, a fifth inner cylinder 604, a vertical spoiler 606, and a horizontal spoiler 605. The middle part of the fifth inner cylinder 604 penetrates through the top wall of the fifth cylinder 601 and the two are fixedly connected. A plurality of sand-containing fluid inlets 602 are arranged on the outer side wall of the fifth cylinder 601. The vertical spoiler 606 is fixedly installed on the lower inner side wall of the fifth cylinder 601, and the horizontal spoiler 605 is fixedly installed above the middle part of the vertical spoiler 606. The upper end of the fifth inner cylinder 604 is rotatably connected to the medium inlet end of the sand-fluid separator 9. The first motor 7 is fixedly installed on the sand-fluid separator 9, and the output shaft of the first motor 7 is in transmission connection with the fifth inner cylinder 604.

[0064] Among them, under the extraction of the submersible electric pump 10, the well fluid flows through the sand-fluid separation device 6, the sand-fluid separator 9, and the submersible electric pump 10 in sequence. The well fluid enters the fifth cylinder 601 through the sand-containing fluid inlet 602. The first motor 7 drives the fifth inner cylinder 604 to rotate, and the fifth inner cylinder 604 drives the fifth cylinder 601 to rotate. Under the action of centrifugal force, the liquid and sand grains in the fifth cylinder 601 are separated, and the liquid (and a small amount of sand grains) flows upward through the fifth inner cylinder 604.

[0065] The transverse flow spoiler 605 mainly serves to block the rotating well fluid after separation, and the vertical flow spoiler 606 mainly provides a sand settling channel for the sand grains on the inner wall of the fifth cylinder 601, promoting the swirling downward movement of the sand grains.

[0066] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. An under - well sand cleaning system under fluctuating pressure, comprising a sand cleaning operation system and a well fluid circulation system. The sand cleaning operation system includes a plurality of second casings (17) and a sand collection equipment string. Each of the second casings (17) is detachably installed in series in sequence. The sand collection equipment string is detachably installed at the lower end of the second casing (17) at the end, and the sand collection equipment string is communicated with the second casing (17). It is characterized in that: The sand collection equipment string includes a flow regulating device (19), a pressurizing device (20), and a jetting device (21) that are installed in series and communicated with each other in sequence. The upper end of the flow regulating device (19) is threadedly connected to the lower end of the second casing (17) at the end. The lower end of the flow regulating device (19) is threadedly connected to the upper end of the pressurizing device (20). The lower end of the pressurizing device (20) is threadedly connected to the upper end of the jetting device (21). The lower end of the jetting device (21) is threadedly connected to the upper end of the first casing (5). The lower end of the first casing (5) is threadedly connected to the upper end of the sand collection device (4). The lower end of the sand collection device (4) is threadedly connected to the upper end of the drill collar (3). During the sand cleaning operation, the flushing fluid flows through the flow regulating device (19), the pressurizing device (20), and the jetting device (21) in sequence. The flow regulating device (19) intermittently blocks the flushing fluid flowing inside it. The pressurizing device (20) pressurizes the flushing fluid flowing into it intermittently, so that the flushing fluid forms a pressure flow under intermittent fluctuations. After the flushing fluid is jetted out through the jetting device (21), the internal cavity of the jetting device (21) is in a high negative pressure state, causing the sand - containing fluid in the jetting device (21) to lift and flow upward.

2. The downhole sand cleaning system under fluctuating pressure according to claim 1, wherein: The sand collection equipment string further includes at least one first casing (5), at least one sand collection device (4), and a drill collar (3). The upper end of the sand collection device (4) is fixedly installed and communicated with the lower end of the first casing (5). The lower end of the sand collection device (4) is fixedly installed and communicated with the upper end of the drill collar (3). The lower end of the jetting device (21) is threadedly connected and communicated with the upper end of the first casing (5).

3. The downhole sand cleaning system under fluctuating pressure according to claim 2, wherein: The sand collection device (4) includes an inner cylinder component and an outer cylinder component. The outer cylinder component includes a fourth cylinder body (406). The inner cylinder component includes a fourth inner cylinder body (405). The fourth inner cylinder body (405) is coaxially and fixedly installed inside the fourth cylinder body (406). An annular sand - settling chamber is formed between the outer side wall of the fourth inner cylinder body (405) and the inner side wall of the fourth cylinder body (406). A hollow sand - containing fluid upward flow channel is longitudinally opened inside the fourth inner cylinder body (405). A plurality of upward flow channels are opened on the top side wall of the fourth inner cylinder body (405). The upward flow channel is communicated with the sand - settling chamber through the upward flow channels.

4. The downhole sand cleaning system under fluctuating pressure according to claim 3, wherein: The outer cylinder component further includes a sand collection upper joint (401) and a sand collection lower joint (410). The upper end of the fourth cylinder body (406) is fixedly connected to the sand collection upper joint (401). The lower end of the fourth cylinder body (406) is fixedly connected to the sand collection lower joint (410). The inner cylinder component further includes an umbrella-shaped cap (402), an upper adapter joint (403), and a lower adapter joint (407). The upper adapter joint (403) is fixedly connected to the inner side wall of the upper part of the fourth cylinder (406). The umbrella-shaped cap (402) is fixedly connected to the upper adapter joint (403). The lower adapter joint (407) is integrally in the shape of a cylinder and is fixedly installed inside the fourth cylinder (406). The upper end of the fourth inner cylinder (405) is fixedly installed with the bottom of the umbrella-shaped cap (402). The lower part of the fourth inner cylinder (405) penetrates through the lower adapter joint (407) and the two are fixedly connected.

5. The downhole sand cleaning system under fluctuating pressure according to claim 1, wherein: The flow regulating device (19) includes a first cylinder (1901), a rotating flow guide (1903), a fixed flow guide (1904), a piston cylinder (1908), and a set of disc springs (1907). The fixed flow guide (1904) is fixedly installed on the inner side wall of the first cylinder (1901). The rotating flow guide (1903) is rotatably installed on the inner side wall of the first cylinder (1901), and the rotating flow guide (1903) is located above the fixed flow guide (1904). The piston cylinder (1908) penetrates through the bottom wall of the first cylinder (1901) and the two are slidably connected. A spring chamber is formed between the piston cylinder (1908) and the first cylinder (1901). The set of disc springs (1907) is longitudinally placed in the spring chamber. The lower part of the fixed flow guide (1904) is in the shape of a cylinder extending downward, and a plurality of flow guide holes (1905) are formed in the side wall of the lower part of the fixed flow guide (1904). The outer diameter of the lower cylinder of the fixed flow guide (1904) is less than or equal to the inner diameter of the piston cylinder (1908), and the lower cylinder of the fixed flow guide (1904) is inserted into the central hole of the piston cylinder (1908). A plurality of longitudinal peripheral rotating flow holes (19033) are formed in the rotating flow guide (1903), and a plurality of longitudinal peripheral fixed flow holes (19042) are formed in the fixed flow guide (1904). After the rotating flow guide (1903) rotates, the peripheral rotating flow holes (19033) are longitudinally communicated with or disconnected from the peripheral fixed flow holes (19042) on the fixed flow guide (1904). The peripheral fixed flow holes (19042) are communicated with the inside of the piston cylinder (1908) through the flow guide holes (1905).

6. The downhole sand cleaning system under fluctuating pressure according to claim 5, characterized in that: An anti-falling assembly (1902) is fixedly installed inside the first cylinder (1901). The anti-falling assembly (1902) penetrates through the rotating flow guide (1903) and the two are rotatably connected. The lower end of the anti-falling assembly (1902) is fixedly installed with the fixed flow guide (1904).

7. The downhole sand cleaning system under fluctuating pressure according to claim 5, characterized in that: The pressurizing device (20) includes a second cylinder body (2001), a second inner cylinder body (2007), a valve base (2006), and a drain valve (2004). The valve base (2006) is fixedly installed on the inner side wall of the lower part of the second cylinder body (2001). The upper part of the valve base (2006) is in an upward convex shape. A longitudinal first through hole is provided in the middle of the valve base (2006). The second inner cylinder body (2007) is fixedly installed on the upper part of the valve base (2006) and their interiors are communicated; the drain valve (2004) is installed on the valve base (2006). The internal cavity of the second inner cylinder body (2007) forms a pressurizing chamber (2003), and an annular cavity is formed between the second inner cylinder body (2007) and the second cylinder body (2001). A liquid inlet valve (1909) is installed at the inner bottom of the piston cylinder (1908). The lower end of the piston cylinder (1908) is inserted into the upper end of the second inner cylinder body (2007) and they are slidably connected. A sealing ring (2002) is embedded at the sliding connection between the piston cylinder (1908) and the second inner cylinder body (2007).

8. A downhole sand cleaning system under fluctuating pressure according to claim 1, characterized in that: The jet device (21) includes a third cylinder body (2106), a mounting plate (2103), a nozzle (2105), a third inner cylinder body (2107), a throat pipe (2108), and a filter cover (2102). The mounting plate (2103) is fixedly installed on the inner side wall of the third cylinder body (2106). A third through hole is provided in the middle of the mounting plate (2103). The filter cover (2102) is fixedly installed above the mounting plate (2103). The nozzle (2105) is detachably installed below the mounting plate (2103) and the nozzle (2105) is communicated with the third through hole; The third inner cylinder body (2107) is fixedly installed inside the third cylinder body (2106). The throat pipe (2108) is fixedly installed on the upper inner side wall of the third inner cylinder body (2107). The inner flow path diameter of the throat pipe (2108) gradually expands from the middle to both ends. Drain ports are provided on the lower side wall of the third cylinder body (2106) and the lower side wall of the third inner cylinder body (2107) and they are communicated with each other.

9. The downhole sand cleaning system under fluctuating pressure according to claim 1, characterized in that: The well fluid circulation system includes a sleeve (11), a submersible electric pump (10), a sand-liquid separator (9), a first motor (7), and a sand-liquid separation device (6). The submersible electric pump (10) is fixedly installed at the lower end of the sleeve (11), and one medium outlet end of the submersible electric pump (10) is communicated with the lower end of the sleeve (11). The other medium outlet end of the submersible electric pump (10) is communicated with the second casing (17); the sand-liquid separator (9) is fixedly installed at the medium inlet end of the submersible electric pump (10) and they are communicated with each other. The sand-liquid separation device (6) is rotatably installed at the medium inlet end of the sand-liquid separator (9) and they are communicated with each other.

10. A downhole sand cleaning system under fluctuating pressure according to claim 9, characterized in that: The sand-liquid separation device (6) includes a first motor (7), a fifth cylinder (601), a fifth inner cylinder (604), a vertical flow baffle (606), and a horizontal flow baffle (605). The middle part of the fifth inner cylinder (604) penetrates through the top wall of the fifth cylinder (601) and the two are fixedly connected. A plurality of sand-containing liquid inlets (602) are formed on the outer side wall of the fifth cylinder (601); the vertical flow baffle (606) is fixedly installed on the inner side wall of the lower part of the fifth cylinder (601), and the horizontal flow baffle (605) is fixedly installed above the middle part of the vertical flow baffle (606); the upper end of the fifth inner cylinder (604) is rotatably connected to the medium inflow end of the sand-liquid separator (9), the first motor (7) is fixedly installed on the sand-liquid separator (9), and the output shaft of the first motor (7) is in transmission connection with the fifth inner cylinder (604).

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