Underground pulse backflow sand prevention and blockage removal device

Abstract

The invention relates to an underground pulse backflow sand prevention and plug removal device which comprises an energy storage pulse backflow plug removal device and a sand prevention assembly, the energy storage pulse backflow plug removal device comprises a hydraulic cylinder, a central circulation pipe and a high-pressure pulse reverse thrust mechanism, the central circulation pipe penetrates through the two ends of the hydraulic cylinder respectively, and the high-pressure pulse reverse thrust mechanism is arranged at the bottom end of the hydraulic cylinder; the high-pressure pulse reverse thrust mechanism comprises a plurality of nitrogen springs and a reverse thrust mechanism, the plurality of nitrogen springs are annularly arranged in the hydraulic cylinder, each nitrogen spring is connected with the high-pressure pulse reverse thrust mechanism through a hydraulic oil cavity, an end cover plate is exposed at the bottom end of the reverse thrust mechanism, and the central runner pipe is temporarily and fixedly connected with the end cover plate through a shear pin; the central runner pipe and the end cover plate are respectively provided with an oil inlet hole; the sand control assembly comprises a sand control screen pipe and an outer protection sleeve, the inner wall of the top end of the sand control screen pipe is arranged on the outer wall of a hydraulic cylinder of the energy storage pulse backflow plug remover in a sleeving mode, and the sand control assembly is used for being arranged underground; and the outer side of the sand control screen pipe is sleeved with the outer protective sleeve.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a downhole pulse backflow sand prevention and unblocking device. Background Technology

[0002] Sand production, the phenomenon of formation sand particles being transported from the formation to the wellbore along with oil and gas flow during oil and gas extraction, has become a long-standing and increasingly severe bottleneck challenge in global oil and gas field development. This common problem not only directly threatens the economic benefits and operational safety of oil and gas fields, but also has a profound impact on the efficient utilization and long-term sustainable development of oil and gas reservoirs. Sand production accelerates the erosion of downhole equipment and surface pipelines (potentially increasing single-well maintenance costs by more than 45%), leading to high repair and replacement costs. More seriously, long-term sand production will cause damage to the reservoir framework structure and pore collapse in the near-wellbore zone, resulting in irreversible formation damage of up to 70%, severely weakening the ultimate recovery rate of oil and gas reservoirs and the life cycle of oil fields.

[0003] To address blockage, a high-pressure jetting device needs to be connected from the surface to the blockage location via pipeline. High-pressure jetting of unblocking fluid is then used to backflush the sand and gravel clogging the filter holes of the sand control screen, thus clearing the blockage. Alternatively, an ultrasonic transmitter or vibration source can be deployed to break down the sand-laden layer using ultrasonic waves and vibrations. Currently, these methods often require shutting down oil production equipment, severely impacting production efficiency and resulting in a waste of both time and resources. Furthermore, they necessitate deploying unblocking tools downhole, and there is a lack of downhole devices that can achieve sand control and unblocking without requiring the shutdown of oil production equipment. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide an energy storage pulse backflow unblocking device, a downhole pulse backflow sand prevention and unblocking device and method, which solves the current problem of lacking a device that can still achieve sand prevention and unblocking without requiring the shutdown of oil production equipment.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a downhole pulse backflow sand prevention and unblocking device, comprising: An energy storage pulse backflow unblocking device includes a hydraulic cylinder, a central flow pipe, and a high-pressure pulse reverse thrust mechanism. The central flow pipe passes through both ends of the hydraulic cylinder. The high-pressure pulse reverse thrust mechanism is located at the bottom end of the hydraulic cylinder and includes several nitrogen springs and a reverse thrust mechanism. The nitrogen springs are arranged circumferentially inside the hydraulic cylinder, and each nitrogen spring is connected to the high-pressure pulse reverse thrust mechanism through a hydraulic oil chamber. An end cover plate is exposed at the bottom end of the reverse thrust mechanism. The central flow pipe and the end cover plate are temporarily fixedly connected by several shear pins. The central flow pipe and the end cover plate are respectively provided with at least one oil inlet hole. A sand control assembly includes a sand control screen pipe and an outer protective sleeve. The inner wall of the top end of the sand control screen pipe is fitted onto the outer wall of the hydraulic cylinder of the energy storage pulse return unblocking device, for installation downhole. The outer protective sleeve is fitted onto the outside of the sand control screen pipe, and an inner filtration zone is provided on the wall of the sand control screen pipe below the oil inlet of the central flow pipe. The inner filtration zone is densely covered with slotted holes. The outer protective sleeve, corresponding to the inner filtration zone of the sand control screen pipe, is provided with an outer filtration zone, which is densely covered with punched holes. The central flow pipe below the end cap plate of the energy storage pulse return unblocking device passes directly into the inner filtration zone of the central flow pipe.

[0006] When the fluid in the well enters the sand control screen pipe from the outside to the inside through the perforated holes of the outer filter zone and the slotted holes of the inner filter zone, the fluid pressure inside the sand control screen pipe increases, pushing up the end cover plate and preventing the end cover plate from moving downward. At this time, the oil inlet hole of the end cover plate is opposite to the oil inlet hole of the central flow pipe. The inside of the central flow pipe is connected to the outside of the hydraulic cylinder. The fluid inside the sand control screen pipe enters the central flow pipe through several oil inlet holes of the end cover plate and several oil inlet holes of the central flow pipe, and is then transported to the surface through the central flow pipe and its connecting pipe. At this time, it is in normal oil production conditions. If the slit holes in the outer filter area of ​​the outer protective sleeve are gradually blocked by sand and gravel, the fluid entering the sand screen pipe decreases, the fluid pressure inside the sand screen pipe drops, the external force on the end cover plate weakens, each nitrogen spring compresses the hydraulic oil in the hydraulic oil chamber downwards, and the hydraulic oil indirectly pushes the end cover plate of the high-pressure pulse reverse thrust mechanism outwards. The instantaneous pushing force on the end cover plate is much greater than the frictional force of the shear pin, and the shear pin is immediately released. All the elastic potential energy stored in the nitrogen springs is released instantaneously and acts on the end cover plate. The end cover plate is sprayed outwards in the form of an instantaneous, high-pressure pulse. The central flow pipe and the oil inlet of the end cover plate are quickly misaligned, and the inside of the central flow pipe is no longer connected to the outside of the hydraulic cylinder. The normal oil production condition gradually transforms into an abnormal blockage condition. In the instant the abnormal blockage condition is entered, the end cover plate pushes the fluid inside the sand screen pipe to flush the slit holes of the inner filter zone and the punch holes of the outer filter zone in reverse order, thereby discharging the sand and gravel blocking the slit holes of the sand screen pipe, so that the blockage can be cleared without the need for the oil production equipment to be shut down.

[0007] Preferably, a sand-preventing particle layer is pre-filled between the inner and outer filtration zones. Upon entering an abnormal clogging condition, the end cap plate pushes the fluid inside the sand-preventing screen pipe to sequentially and in reverse flush the slit holes of the inner filtration zone, the sand-preventing particle layer, and the flushing holes of the outer filtration zone, discharging the sand and gravel clogging the slit holes of the sand-preventing screen pipe. This unclogging can be achieved without requiring the oil production equipment to be shut down.

[0008] Preferably, the two ends of the outer protective sleeve are fixed to the sand screen pipe by fixing rings; the top and bottom ends of the sand screen pipe are respectively provided with pipe clamp joints and end caps.

[0009] Preferably, a plurality of nitrogen springs are arranged circumferentially inside the hydraulic cylinder; each nitrogen spring includes a cylinder base, a piston rod and a piston, the cylinder base of the plurality of nitrogen springs is fixed to the top of the hydraulic cylinder, the piston rod is movably inserted through the cylinder base and the outer end of the piston rod extends out of the cylinder base, the piston is fixed to the end of the outer end of the piston rod, and the piston of each nitrogen spring is connected to the high-pressure pulse reverse thrust mechanism through a hydraulic oil chamber.

[0010] Preferably, the reverse thrust mechanism further includes an inner push plate, which is concealed inside the hydraulic cylinder, and a hydraulic oil chamber is provided between each inner push plate and the nitrogen spring; the end cover plate is exposed on the outside of the bottom end of the hydraulic cylinder, and the inner push plate and the end cover plate are fixedly connected together; the central flow pipe is temporarily fixedly connected to the end cover plate by a number of shear pins; the central flow pipe and the end cover plate are respectively provided with at least one oil inlet hole; Among them, the pistons of several nitrogen springs correspond to the inner push plate of the high-pressure pulse reverse thrust mechanism, and the space enclosed by the inner push plate, its corresponding hydraulic cylinder, and the inner wall of the hydraulic cylinder between them forms a hydraulic oil chamber for filling hydraulic oil.

[0011] When the external force on the end cover plate weakens, the piston rod of each nitrogen spring simultaneously extends outward, pushing the piston downward to compress the hydraulic oil in the hydraulic oil chamber, and the hydraulic oil pushes the end cover plate outward through the inner push plate.

[0012] Preferably, the reverse thrust mechanism further includes a connecting cylinder, through which the inner push plate and the end cover plate are connected together to achieve a fixed connection between the inner push plate and the end cover plate.

[0013] Preferably, the end cover plate is provided with an inner ring that protrudes outward to form an end cover plate flange. The end cover plate flange is sleeved on the bottom end of the central flow pipe. A plurality of shear pins are arranged circumferentially at the junction of the central flow pipe and the end cover plate flange, thereby realizing a temporary fixed connection between the central flow pipe and the end cover plate. The outer wall of the end cover flange is provided with a plurality of external oil inlets, and the bottom end of the central flow pipe is provided with a plurality of internal oil inlets. When the central flow pipe and the end cover flange are temporarily fixedly connected by a plurality of shear pins, the plurality of external oil inlets of the end cover flange and the plurality of internal oil inlets of the central flow pipe are respectively aligned one-to-one to realize the communication between the inside of the central flow pipe and the outside of the hydraulic cylinder. When the end cover is ejected outward in the form of an instantaneous, high-pressure pulse, the plurality of internal oil inlets of the central flow pipe and the plurality of external oil inlets of the end cover flange are quickly misaligned to realize the separation between the inside of the central flow pipe and the outside of the hydraulic cylinder. When the end cover plate is pressed by an external force and the central flow pipe is temporarily fixed to the end cover plate by a number of shear pins, the number of external oil inlets of the flange of the end cover plate and the number of internal oil inlets of the central flow pipe are respectively opposite to each other, and the interior of the central flow pipe is connected to the exterior of the hydraulic cylinder. This state is recorded as normal oil production condition. When the energy storage pulse return unblocking device is in normal oil production condition, a number of nitrogen springs store elastic potential energy. Once the external force on the end cover plate weakens or disappears, each shear pin is immediately released, and all the elastic potential energy stored in the nitrogen springs is released instantaneously and acts on the end cover plate. The end cover plate sprays outward in the form of an instantaneous, high-pressure pulse. Several inner oil inlets of the central flow pipe and several outer oil inlets of the end cover plate are quickly misaligned, and the inside of the central flow pipe is no longer connected to the outside of the hydraulic cylinder. This state is recorded as the abnormal blockage condition, thereby realizing the transition from normal oil production condition to abnormal blockage condition.

[0014] Preferably, the inner wall of the inner edge of the end cover flange is provided with a plurality of pin grooves circumferentially, and a plurality of shear pins are respectively disposed in the plurality of pin grooves. The central flow pipe is provided with a plurality of pin holes. When the oil inlet hole of the end cover flange and the oil inlet hole of the central flow pipe are respectively aligned, the plurality of pin grooves of the end cover flange and the plurality of pin holes on the central flow pipe are exactly aligned. When hydraulic oil is supplied to the hydraulic oil chamber, it continues until the hydraulic oil at both ends of the hydraulic oil chamber comes into contact with the piston of the nitrogen spring and the inner push plate of the high-pressure pulse reverse thrust mechanism; as hydraulic oil continues to be supplied to the hydraulic oil chamber, the pressure of the hydraulic oil in the hydraulic oil chamber increases until the shear pins in the pin slots of the end cover flange fall into the pin holes of the central flow pipe at the same time. At the same time, the internal energy of the hydraulic oil is converted into the elastic potential energy of the nitrogen spring and stored.

[0015] Preferably, the top and bottom of the hydraulic cylinder are respectively provided with a top cover and a chassis, and the two ends of the central flow pipe pass through the center of the chassis and the top cover respectively, with the exposed ends connected to the outside. The cylinder base of each nitrogen spring is fixed in the inner cavity of the hydraulic cylinder, and the cylinder base pushes upward against the top cover. The chassis is provided with an inner ring, and the connecting cylinder is movably inserted into the inner ring of the chassis. Each nitrogen spring has a hydraulic oil chamber between its piston and its corresponding inner push plate; When the external force on the end cover plate weakens or disappears, the piston rod of each nitrogen spring extends outward simultaneously, pushing the piston to compress the hydraulic oil in the hydraulic oil chamber. The hydraulic oil then pushes several inner push plates to cause the end cover plate to move outward. The instantaneous pushing force on the end cover plate is much greater than the frictional force of the shear pin, and the shear pin is immediately released.

[0016] Preferably, a plurality of shear pins are symmetrically arranged about the centerline of the central flow tube at the connection between the central flow tube and the end cover flange; each shear pin is equipped with a preload spring.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (I) This invention discloses an energy storage pulse backflow unblocking device, belonging to the field of oil extraction technology. It includes a hydraulic cylinder with a central flow pipe passing through its interior, and the central flow pipe passing through both ends of the hydraulic cylinder. The invention is characterized by further including a high-pressure pulse reverse thrust mechanism. The high-pressure pulse reverse thrust mechanism includes several nitrogen springs and a reverse thrust mechanism. The nitrogen springs are arranged circumferentially inside the hydraulic cylinder. The reverse thrust mechanism includes several inner push plates and an end cover plate. Each inner push plate corresponds to one nitrogen spring and is hidden inside the hydraulic cylinder, corresponding to each nitrogen spring. A hydraulic oil chamber is provided between each inner push plate and its corresponding nitrogen spring. The end cover plate is exposed on the outside of the bottom end of the hydraulic cylinder. The several inner push plates and the end cover plate are fixedly connected together. The central flow pipe and the end cover plate are temporarily fixedly connected by several shear pins. The central flow pipe and the end cover plate are respectively provided with... At least one oil inlet hole; wherein, when the end cover plate is pressed by an external force and the central flow pipe is temporarily fixedly connected to the end cover plate by several shear pins, the oil inlet hole of the end cover plate flange and the oil inlet hole of the central flow pipe are respectively opposite, and the interior of the central flow pipe is connected to the exterior of the hydraulic cylinder. This state is recorded as normal oil production condition. When the energy storage pulse return unblocking device is in normal oil production condition, several nitrogen springs store elastic potential energy. Once the external force on the end cover plate weakens or disappears, each shear pin is immediately released, and the elastic potential energy stored in all the nitrogen springs is released instantaneously and acts on the end cover plate. The end cover plate sprays outward in the form of an instantaneous, high-pressure pulse. The oil inlet hole of the central flow pipe and the end cover plate are quickly misaligned, and the interior of the central flow pipe is no longer connected to the exterior of the hydraulic cylinder. This state is recorded as abnormal blockage condition, thereby realizing the transition from normal oil production condition to abnormal blockage condition. The energy storage pulse backflow unblocking device disclosed in this invention can realize the transition from normal oil production conditions to abnormal blockage conditions. It provides a prerequisite for the end cover plate to push the fluid inside the sand screen pipe to flush the slit holes of the inner filter zone, the sand control particle layer and the punch holes of the outer filter zone in reverse order at the moment of entering the abnormal blockage condition, thereby discharging the sand and gravel blocking the slit holes of the sand screen pipe.

[0018] (II) This invention discloses a downhole pulse backflow sand control and unblocking device, belonging to the field of oil extraction technology. It includes the above-mentioned energy storage pulse backflow unblocking device and a sand control component. The sand control component includes a sand control screen pipe and an outer protective sleeve. The inner wall of the top end of the sand control screen pipe is sleeved on the outer wall of the hydraulic cylinder of the energy storage pulse backflow unblocking device for installation downhole. The outer protective sleeve is sleeved on the outside of the sand control screen pipe. An inner filter zone is provided on the pipe wall of the sand control screen pipe below the oil inlet of the central flow pipe. The inner filter zone is densely covered with slotted holes. An outer filter zone is provided on the pipe wall of the outer protective sleeve corresponding to the inner filter zone of the sand control screen pipe. The outer filter zone is densely covered with punched holes. Sand control particles are pre-filled between the inner filter zone and the outer filter zone to form a sand control particle layer. The central flow pipe below the end cap plate of the energy storage pulse backflow unblocking device passes directly into the inner filter zone of the central flow pipe. When the fluid in the well enters the sand control screen pipe from the outside in through the perforated holes of the outer filter zone, the sand control particle layer, and the slotted holes of the inner filter zone, the fluid pressure inside the sand control screen pipe increases, pushing up the end cover plate and preventing the end cover plate from moving downward. At this time, the oil inlet hole of the end cover plate flange is opposite to the oil inlet hole of the central flow pipe. The interior of the central flow pipe is connected to the exterior of the hydraulic cylinder. The fluid inside the sand control screen pipe enters the interior of the central flow pipe through several external oil inlet holes of the end cover plate flange and several internal oil inlet holes of the central flow pipe, and is then transported to the surface through the central flow pipe and its connecting pipe. At this time, it is in normal oil production conditions.

[0019] If the slit holes in the outer filter area of ​​the outer protective sleeve are gradually blocked by sand and gravel, the fluid entering the sand screen pipe decreases, the fluid pressure inside the sand screen pipe drops, the external force on the end cover plate weakens, the piston rod of each nitrogen spring extends outward simultaneously, pushing the piston to compress the hydraulic oil in the hydraulic oil chamber, and the hydraulic oil pushes several inner push plates to cause the end cover plate to move outward. The instantaneous pushing force on the end cover plate is much greater than the frictional force of the shear pin, and the shear pin is immediately released; the elastic potential energy stored in all the nitrogen springs is released instantaneously and acts on the end cover plate, and the end cover plate sprays outward in the form of an instantaneous, high-pressure pulse. The central flow pipe and the oil inlet of the end cover plate are quickly misaligned, and the inside of the central flow pipe is no longer connected to the outside of the hydraulic cylinder. The normal oil production condition gradually transforms into an abnormal blockage condition.

[0020] In the instant the abnormal blockage condition is entered, the end cover plate pushes the fluid inside the sand screen pipe to flush the slit holes of the inner filter zone, the sand control particle layer and the punch holes of the outer filter zone in reverse order, thereby discharging the sand and gravel blocking the slit holes of the sand screen pipe, so that the blockage can be cleared without the need for the oil production equipment to be shut down.

[0021] In addition, the present invention also has the following beneficial effects: 1. The energy storage pulse backflow unblocking device is installed in the blind section of the sand control screen, without affecting the normal sand control and oil production of the sand control screen. This device utilizes the kinetic energy of the fluid itself during oil well production to store energy in situ downhole. When the driving force drops to a preset threshold due to screen blockage, it automatically triggers the release of stored energy, generating a strong reverse pulse flow that instantly impacts and clears the blockage. This constructs a full life cycle adaptive closed-loop cycle of "energy storage → blockage → pulse unblocking → recovery → re-energy storage", completely eliminating the dependence of existing unblocking modes on external operating equipment and production shutdowns.

[0022] 2. The sand control component significantly improves sand control performance, ensuring effective sand control throughout the entire reservoir production cycle. Its sand control precision is higher than conventional screens, with a wide adjustable range (precision up to 50-1000 micrometers), flexibly adapting to different formation sand production conditions. It uses unconsolidated pre-filled sand control particles, possessing self-cleaning capabilities and resisting clogging. Its superior flow characteristics are reflected in the fact that even with a 160-fold increase in fluid viscosity, the flow resistance only increases by 16.76 times, demonstrating excellent flow performance for oil-phase media. The effective flow area is more than 5 times that of ordinary slotted pipes, thereby significantly increasing oil and gas production capacity.

[0023] 3. This invention ingeniously integrates an energy storage pulse backflow unblocking device into the blind section of the sand control component, achieving in-situ, energy-self-sufficient automatic unblocking in the well. This device requires no additional tubing intervention, utilizing the kinetic energy of the oil flow itself during the oil production process to drive the core component—the movable end cap—to compress and store energy in the nitrogen spring and release it instantaneously, thereby forming a reverse high-pressure pulse backflow when blockage occurs. This breakthrough design completely transforms the unblocking mode from passive manual intervention to an active downhole self-healing response, achieving a fully automatic closed-loop feedback cycle of "energy accumulation → blockage formation → pulse backflow release → flow recovery → re-energy storage," ensuring that oil and gas wells maintain high-productivity continuous oil production throughout the entire production cycle, significantly improving operational efficiency and economy.

[0024] 4. This invention innovatively integrates sand control and unblocking functions. Based on the high-precision sand control technology of pre-filled sand control screens, it effectively slows down the clogging speed and degree of pre-filled screens by utilizing the non-consolidated characteristics of sand control particles. Simultaneously, the energy storage pulse reflux unblocking device converts the kinetic energy of the oil into the elastic potential energy of a spring during normal oil production. After the screen becomes clogged, the stored potential energy is rapidly released and converted into mechanical kinetic energy to disperse and unblock the sand and gravel outside the screen. This one-stop solution addresses industry challenges such as insufficient control precision, difficulty in deploying unblocking tools, low unblocking efficiency, and high operating costs, thus achieving a closed-loop function of efficient sand control, coordinated anti-clogging, automatic energy storage, and automatic unblocking. Attached Figure Description

[0025] Figure 1 This is an overall three-dimensional view of the energy storage pulse reflux unblocking device provided in Embodiment 1 of the present invention; Figure 2 yes Figure 1 Front view; Figure 3 yes Figure 2 Top view; Figure 4 yes Figure 3 A sectional view along the AA direction; Figure 5 yes Figure 4 The image shows a magnified view of a section involving shear pins and preload springs. Figure 6 This is a cross-sectional view of the internal structure of the energy storage pulse return unblocking device under normal oil production conditions when the end cover plate is not ejected, as provided in Embodiment 1 of the present invention; at this time, the energy storage pulse return unblocking device stores energy.

[0026] Figure 7 This is a cross-sectional schematic diagram of the internal structure of the energy storage pulse return unblocking device after injection into the end cover plate under abnormal blockage conditions, as provided in Embodiment 1 of the present invention; at this time, the energy storage pulse return unblocking device releases energy. Figure 8 This is a schematic diagram of the external structure of the nitrogen spring provided in Embodiment 1 of the present invention; Figure 9 This is an overall three-dimensional view of the downhole pulse backflow sand prevention and unblocking device provided in Embodiment 2 of the present invention; Figure 10 yes Figure 9 Front view; Figure 11 yes Figure 10 A longitudinal sectional view; Figure 12 yes Figure 9 A schematic diagram of the internal structure after external cross-section; Figure 13 yes Figure 12 A schematic diagram of the structure of the sand-proof component after longitudinal section view.

[0027] Explanation of reference numerals in the attached figures: A-Energy Storage Pulse Backflow Unblocking Device; 1-Hydraulic cylinder, 10-Central flow pipe, 100-Inner oil inlet, 11-Top cover, 12-Chassis, 13-Straightening plate, 14-Isolation frame; 2-Nitrogen spring, 21-Cylinder block base, 22-Piston rod, 23-Piston; 3-Reverse thrust mechanism, 30-Hydraulic oil chamber, 31-Inner push plate, 32-Connecting cylinder, 33-End cover plate, 34-End cover plate flange, 340-Outer oil inlet hole, 35-Shear pin, 36-Preload spring; B-Sand control component; 41-Sand control screen pipe; 410-Slit hole; 411-Pipe clamp joint; 412-End cap; 42-Outer protective sleeve; 420-Punched hole; 421-Outer protective sleeve fixing ring; 43-Sand control particle layer.

[0028] The arrow "→" indicates the direction of fluid flow. Detailed Implementation

[0029] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0030] To address the current lack of a method for sand control and de-clogging without requiring oil production equipment shutdown, it is necessary to develop a downhole pulse backflow sand control and de-clogging device. However, during the development of this device, it was discovered that what is currently lacking in the market is an energy storage pulse backflow de-clogging device. Under normal oil production conditions, when the end cap plate is held in place by external force and the central flow pipe is temporarily fixed to the end cap plate by several shear pins, the oil inlet holes of the end cap plate flange and the central flow pipe are respectively opposite to each other. The interior of the central flow pipe is connected to the... The hydraulic cylinder is externally connected, and several nitrogen springs store elastic potential energy. Once the external force on the end cover plate weakens or disappears, each shear pin is immediately released, and the elastic potential energy stored in all the nitrogen springs is instantaneously released and acts on the end cover plate. The end cover plate sprays outward in the form of an instantaneous, high-pressure pulse. The central flow pipe and the oil inlet of the end cover plate are quickly misaligned, and the interior of the central flow pipe is no longer connected to the exterior of the hydraulic cylinder. This state is recorded as the abnormal blockage condition, thereby realizing the transition from normal oil production conditions to the abnormal blockage condition. The energy storage pulse backflow unblocking device disclosed in this invention can realize the transition from normal oil production conditions to the abnormal blockage condition. It provides the prerequisite that, at the instant of entering the abnormal blockage condition, the end cover plate pushes the fluid inside the sand screen pipe to sequentially and in reverse flush the slit holes of the inner filter zone, the sand control particle layer, and the punch holes of the outer filter zone, discharging the sand and gravel blocking the slit holes of the sand screen pipe. By combining the energy storage pulse backflow unblocking device with the sand control component, a downhole pulse backflow sand control and unblocking device is formed. At the moment of entering the abnormal blockage condition, the end cover plate pushes the fluid inside the sand control screen pipe to flush the slotted holes of the inner filter zone, the sand control particle layer and the punched holes of the outer filter zone in reverse order, thereby discharging the sand and gravel blocking the slotted holes of the sand control screen pipe. This can achieve unblocking without the need for the oil production equipment to be shut down.

[0031] Example 1: An energy storage pulse reflux unblocking device Embodiment 1 of the present invention provides an energy storage pulse reflux unblocking device, the structure of which will be described in detail below with reference to the accompanying drawings.

[0032] refer to Figures 1 to 8 The energy storage pulse backflow unblocking device includes a hydraulic cylinder 1 and a high-pressure pulse reverse thrust mechanism.

[0033] A central flow pipe 10 is provided inside the hydraulic cylinder 1, and the central flow pipe 10 passes through both ends of the hydraulic cylinder 1. The high-pressure pulse reverse thrust mechanism is located at the bottom end of the hydraulic cylinder 1.

[0034] The high-voltage pulse reverse propulsion mechanism includes: Several nitrogen springs 2 are arranged circumferentially inside the hydraulic cylinder 1; A reverse thrust mechanism 3 includes an inner push plate 31 and an end cover plate 33. The inner push plate 31 is concealed inside the hydraulic cylinder 1, and a hydraulic oil chamber 30 is provided between each inner push plate 31 and the corresponding nitrogen spring 2. The end cover plate 33 is exposed on the outside of the bottom end of the hydraulic cylinder 1, and the inner push plate 31 and the end cover plate 33 are fixedly connected together. The central flow pipe 10 is temporarily fixedly connected to the end cover plate 33 by a number of shear pins 35. The central flow pipe 10 and the end cover plate 33 are respectively provided with at least one oil inlet hole. When the end cover plate 33 is pressed by an external force and the central flow pipe 10 is temporarily fixedly connected to the end cover plate 33 by a number of shear pins 35, the oil inlet hole of the end cover plate flange 34 is opposite to the oil inlet hole of the central flow pipe 10, and the interior of the central flow pipe 10 is connected to the exterior of the hydraulic cylinder 1. This state is recorded as normal oil production condition. When the energy storage pulse return unblocking device is in normal oil production condition, a number of nitrogen springs 2 store elastic potential energy. Once the external force on the end cover plate 33 weakens or disappears, each shear pin 35 is immediately released, and the elastic potential energy stored in all nitrogen springs 2 is released instantaneously and acts on the end cover plate 33. The end cover plate 33 is ejected outward in the form of an instantaneous, high-pressure pulse. The central flow pipe 10 and the oil inlet of the end cover plate 33 are quickly misaligned, and the interior of the central flow pipe 10 is no longer connected to the exterior of the hydraulic cylinder 1. This state is recorded as the abnormal blockage condition, thereby realizing the transition from the normal oil production condition to the abnormal blockage condition.

[0035] In a preferred embodiment, the reverse thrust mechanism 3 further includes a connecting cylinder 32, through which the inner push plate 31 and the end cover plate 33 are connected together to achieve a fixed connection between the inner push plate 31 and the end cover plate 33.

[0036] In one specific implementation, the end cover plate 33 is provided with an inner ring that protrudes outward to form an end cover plate flange 34. The end cover plate flange 34 is sleeved on the bottom end of the central flow pipe 10. A plurality of shear pins 35 are arranged circumferentially at the junction of the central flow pipe 10 and the end cover plate flange 34, thereby realizing a temporary fixed connection between the central flow pipe 10 and the end cover plate 33.

[0037] In one specific implementation, the outer wall of the end cover flange 34 is provided with a plurality of external oil inlet holes 340, and the bottom end of the central flow pipe 10 is provided with a plurality of internal oil inlet holes 100. When the central flow pipe 10 and the end cover flange 34 are temporarily fixedly connected by a plurality of shear pins 35, the plurality of external oil inlet holes 340 of the end cover flange 34 and the plurality of internal oil inlet holes 100 of the central flow pipe 10 are respectively aligned one-to-one, so as to realize the internal connection between the central flow pipe 10 and the external connection between the hydraulic cylinder 1. When the end cover 33 is ejected outward in the form of an instantaneous, high-pressure pulse, the plurality of internal oil inlet holes 100 of the central flow pipe 10 and the plurality of external oil inlet holes 340 of the end cover flange 34 are quickly misaligned, so as to realize that the internal connection between the central flow pipe 10 and the external connection between the hydraulic cylinder 1 is no longer established.

[0038] Among them, nitrogen spring 2, full name die nitrogen spring, is a new type of elastic component that uses high-pressure nitrogen as the working medium. It is widely used in the mold industry, such as hardware stamping molds, plastic molds, die casting molds, and other components that play a reset role in other industries. It is an existing technology.

[0039] Specifically, each nitrogen spring 2 includes a cylinder base 21, a piston rod 22, and a piston 23. The cylinder base 21 of several nitrogen springs 2 is fixed to the top of the hydraulic cylinder 1. The piston rod 22 is movably inserted through the cylinder base 21, and the outer end of the piston rod 22 extends out of the cylinder base 21. The piston 23 is fixed to the end of the outer end of the piston rod 22.

[0040] Among them, the pistons 23 of several nitrogen springs 2 correspond to the inner push plate 31 of the high-pressure pulse reverse thrust mechanism 3 respectively, and the space enclosed by the inner push plate 31, its corresponding hydraulic cylinder 1 and the inner wall of the hydraulic cylinder 1 between them forms a hydraulic oil chamber 30 for filling hydraulic oil.

[0041] The inner wall of the inner edge of the end cover flange 34 is provided with a plurality of pin grooves in a circumferential manner, and a plurality of shear pins 35 are respectively disposed in the plurality of pin grooves. The central flow pipe 10 is provided with a plurality of pin holes. When the oil inlet of the end cover flange 34 and the oil inlet of the central flow pipe 10 are respectively opposite, the plurality of pin grooves of the end cover flange 34 and the plurality of pin holes on the central flow pipe 10 are exactly opposite.

[0042] When hydraulic oil is supplied to the hydraulic oil chamber 30, the hydraulic oil at both ends of the hydraulic oil chamber 30 comes into contact with the piston 23 of the nitrogen spring 2 and the inner push plate 31 of the high-pressure pulse reverse thrust mechanism 3; as hydraulic oil continues to be supplied to the hydraulic oil chamber 30, the pressure of the hydraulic oil in the hydraulic oil chamber 30 increases until the shear pins 35 in the pin slots of the end cover flange 34 fall into the pin holes of the central flow pipe 10 at the same time. At the same time, the internal energy of the hydraulic oil is converted into the elastic potential energy of the nitrogen spring 2 and stored.

[0043] Specifically, the top and bottom ends of the hydraulic cylinder 1 are respectively equipped with a top cover 11 and a chassis 12, and the two ends of the central flow pipe 10 pass through the center of the chassis 12 and the top cover 11 and are connected to the outside. The cylinder base 21 of each nitrogen spring 2 is fixed in the inner cavity of the hydraulic cylinder 1, and the cylinder base 21 pushes upward against the top cover 11. The chassis 12 is provided with an inner ring, and the connecting cylinder 32 is movably inserted into the inner ring of the chassis 12. Each nitrogen spring 2 has a hydraulic oil chamber 30 disposed between its piston 23 and its corresponding inner push plate 31; When the external force on the end cover plate 33 weakens or disappears, the piston rod 22 of each nitrogen spring 2 extends outward simultaneously, pushing the piston 23 to compress the hydraulic oil in the hydraulic oil chamber 30. The hydraulic oil then pushes several inner push plates 31 to cause the end cover plate 33 to move outward. The instantaneous pushing force on the end cover plate 33 is much greater than the frictional force of the shear pin 35, and the shear pin 35 is immediately released.

[0044] Specifically, a number of shear pins 35 are symmetrically arranged about the center line of the central flow tube 10 at the connection between the central flow tube 10 and the end cover flange 34; each shear pin 35 is equipped with a preload spring 36.

[0045] More specifically, the inner wall of the inner edge of the end cover flange 34 is provided with a plurality of pin grooves in a circumferential manner. Each pin groove has a preload spring 36 at its inner end and a shear pin 35 at its outer end. One end of each preload spring 36 abuts against the blind end of the pin groove and the other end abuts against the shear pin 35.

[0046] To prevent the nitrogen springs 2 from shifting, a centering plate 13 is provided inside the hydraulic cylinder 1. The centering plate 13 has a central hole, and several nitrogen spring base holes are arranged around the central hole. The centering plate 13 is fixed inside the hydraulic cylinder 1. The central flow pipe 10 passes through the central hole of the centering plate 13, and several nitrogen springs 2 are respectively passed through the several nitrogen spring base holes of the spring centering plate 13.

[0047] Specifically, the top end of the central flow pipe 10 is fixed to the top cover 11, and the bottom end passes through the chassis 12 and is fixed to the end cover plate 33 and its end cover plate flange 34. It passes through the central hole of the straightening plate 13 and the hydraulic oil chamber 30 from top to bottom.

[0048] To increase stability, the hydraulic cylinder 1 is provided with an isolation frame 14. Adjacent hydraulic oil chambers 30 are separated by the isolation frame 14, so that the space enclosed by each inner push plate 31, its corresponding hydraulic cylinder 1, and the inner wall of the hydraulic cylinder 1 and the inner wall of the isolation frame 14 together form a hydraulic oil chamber 30.

[0049] To ensure that the interior of the central flow pipe 10 is no longer connected to the exterior of the hydraulic cylinder 1 after the oil inlet of the end cover plate 33 is misaligned with the oil inlet, as is common practice, the bottom end of the central flow pipe 10 should be set as a blind end. Figure 1 As shown.

[0050] Example 2: A downhole pulse backflow sand prevention and unblocking device Embodiment 2 of the present invention provides a downhole pulse backflow sand prevention and unblocking device, the structure of which will be described in detail below with reference to the accompanying drawings.

[0051] refer to Figures 9 to 13 The downhole pulse backflow sand control and unblocking device includes the energy storage pulse backflow unblocking device A and a sand control component B as described in Example 1.

[0052] The sand-proof component B includes: A sand screen pipe 41, the inner wall of its top end is sleeved on the outer wall of the hydraulic cylinder 1 of the energy storage pulse return unblocking device A, for installation downhole; An outer protective sleeve 42 is fitted over the outside of the sand screen pipe 41, and an inner filtration zone is provided on the pipe wall of the sand screen pipe 41 below the oil inlet of the central flow pipe 10. The inner filtration zone is densely covered with slit holes 410. The outer protective sleeve 42 corresponding to the inner filtration zone of the sand screen pipe 41 is provided on the pipe wall of the outer filtration sleeve 42. The outer filtration zone is densely covered with punch holes 420, and sand-proof particles are pre-filled between the inner filtration zone and the outer filtration zone to form a sand-proof particle layer 43. The central flow pipe 10 below the end cover plate 33 of the energy storage pulse reflux unblocker A is inserted into the inner filter area of ​​the central flow pipe 10. When the fluid in the well enters the sand control screen 41 from the outside in through the perforated holes 420 of the outer filter zone, the sand control particle layer 43, and the slotted holes 410 of the inner filter zone, the fluid pressure inside the sand control screen 41 increases, pushing up the end cover plate 33 and preventing the end cover plate 33 from moving downward. At this time, the oil inlet hole of the end cover plate flange 34 is opposite to the oil inlet hole of the central flow pipe 10. The interior of the central flow pipe 10 is connected to the exterior of the hydraulic cylinder 1. The fluid inside the sand control screen 41 enters the interior of the central flow pipe 10 through several external oil inlet holes 340 of the end cover plate flange 34 and several internal oil inlet holes 100 of the central flow pipe 10, and is then transported to the surface through the central flow pipe 10 and its connecting pipe. At this time, it is in normal oil production conditions. If the punch holes 420 of the outer filter area of ​​the outer protective sleeve 42 are gradually blocked by sand and gravel, the fluid entering the sand screen pipe 41 decreases, the fluid pressure inside the sand screen pipe 41 drops, the external force on the end cover plate 33 weakens, the piston rod 22 of each nitrogen spring 2 extends outward at the same time, pushes the piston 23 to compress the hydraulic oil in the hydraulic oil chamber 30, and the hydraulic oil pushes several inner push plates 31 to cause the end cover plate 33 to move outward. The instantaneous pushing force on the end cover plate 33 is much greater than the frictional force of the shear pin 35, and the shear pin 35 is immediately released; the elastic potential energy stored in all the nitrogen springs 2 is released instantaneously and acts on the end cover plate 33, and the end cover plate 33 is sprayed outward in the form of an instantaneous, high-pressure pulse. The oil inlet of the central flow pipe 10 and the oil inlet of the end cover plate 33 are quickly misaligned, and the interior of the central flow pipe 10 is no longer connected to the exterior of the hydraulic cylinder 1. The normal oil production condition is gradually converted into an abnormal blockage condition. In the instant the abnormal blockage condition is entered, the end cover plate 33 pushes the fluid inside the sand screen pipe 41 to flush the slit holes 410 of the inner filter zone, the sand particle layer 43 and the punch holes 420 of the outer filter zone in reverse order, thereby discharging the sand and gravel blocking the slit holes 410 of the sand screen pipe 41. This can achieve unblocking without the need for the oil production equipment to be shut down.

[0053] As an embodiment for fixing the outer protective sleeve 42 to the sand screen tube 41, both ends of the outer protective sleeve 42 are fixed to the sand screen tube 41 by fixing rings 421.

[0054] To ensure that upon entering a blockage-prone operating condition, the end cap 33 pushes the fluid inside the sand screen pipe 41 to sequentially and in reverse flush the slit holes 410 of the inner filter zone, the sand-preventing particle layer 43, and the perforation holes 420 of the outer filter zone, discharging the sand and gravel blocking the slit holes 410 of the sand screen pipe 41, the fluid must flow from inside the sand screen pipe 41 first into the slit holes 410 of the inner filter zone, through the sand-preventing particle layer 43, and finally out through the perforation holes 420 of the outer filter zone. That is, the fluid cannot flow to the bottom end of the sand screen pipe 41. Therefore, the bottom end of the sand screen pipe 41 is provided with an end cap 412 to form a blind end. Figure 9 As shown.

[0055] To facilitate the upward connection of the sand-proof screen pipe 41 with other screen pipes, a pipe clamp joint 411 is provided at the top of the sand-proof screen pipe 41, and the sand-proof screen pipe 41 is connected to other screen pipes upward through the pipe clamp joint 411.

[0056] Example 3: A downhole pulse backflow unblocking method Embodiment 3 of the present invention provides a downhole pulse backflow unblocking method, which uses the downhole sand control and unblocking device of Embodiment 2. The method includes the following steps: Entering normal oil production conditions: The fluid in the well enters the sand control screen 41 from the outside in through the perforated holes 420 of the outer filter zone, the sand control particle layer 43, and the slotted holes 410 of the inner filter zone. The fluid pressure inside the sand control screen 41 increases, pushing up the end cover plate 33 and preventing the end cover plate 33 from moving downward. At this time, the oil inlet hole of the end cover flange 34 is opposite to the oil inlet hole of the central flow pipe 10. The interior of the central flow pipe 10 is connected to the exterior of the hydraulic cylinder 1. The fluid inside the sand control screen 41 enters the interior of the central flow pipe 10 through several external oil inlet holes 340 of the end cover flange 34 and several internal oil inlet holes 100 of the central flow pipe 10, and is then transported to the surface through the central flow pipe 10 and its connecting pipe. At this time, it is in normal oil production conditions. Switching from normal oil production conditions to abnormal blockage conditions: If the perforated holes 420 of the outer filter zone of the outer protective casing 42 are gradually blocked by sand and gravel, the fluid entering the sand screen pipe 41 decreases, the fluid pressure inside the sand screen pipe 41 drops, the external force on the end cover plate 33 weakens, the piston rod 22 of each nitrogen spring 2 simultaneously extends outward, pushes the piston 23 to compress the hydraulic oil in the hydraulic oil chamber 30, and the hydraulic oil pushes several inner push plates 31 to cause the end cover plate 33 to move outward. The instantaneous pushing force on the end cover plate 33 is much greater than the frictional force of the shear pin 35, and the shear pin 35 is immediately released; all the elastic potential energy stored in the nitrogen spring 2 is released instantaneously and acts on the end cover plate 33, and the end cover plate 33 is ejected outward in the form of an instantaneous, high-pressure pulse. The oil inlet hole of the central flow pipe 10 and the end cover plate 33 are quickly misaligned, and the interior of the central flow pipe 10 is no longer connected to the exterior of the hydraulic cylinder 1. The normal oil production condition is gradually converted into an abnormal blockage condition. In the instant of entering the abnormal blockage condition, the end cover plate 33 pushes the fluid inside the sand screen pipe 41 to flush the slit holes 410 of the inner filter zone, the sand-proof particle layer 43 and the punch holes 420 of the outer filter zone in reverse order, thereby discharging the sand and gravel blocking the slit holes 410 of the sand screen pipe 41, so that the blockage can be cleared without the need for the oil production equipment to be shut down. After unblocking, normal oil production operations resume: After unblocking, the fluid flow rate inside the sand control component is large. As the fluid pressure inside the sand control component increases, it gradually returns to normal oil production conditions.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A downhole pulse backflow sand prevention and unblocking device, characterized in that, include: An energy storage pulse backflow unblocking device (A) includes a hydraulic cylinder (1), a central flow pipe (10), and a high-pressure pulse reverse thrust mechanism. The central flow pipe (10) passes through both ends of the hydraulic cylinder (1). The high-pressure pulse reverse thrust mechanism is located at the bottom end of the hydraulic cylinder (1). The high-pressure pulse reverse thrust mechanism includes several nitrogen springs (2) and a reverse thrust mechanism (3). Several nitrogen springs (2) are arranged circumferentially inside the hydraulic cylinder (1). Each nitrogen spring (2) is connected to the high-pressure pulse reverse thrust mechanism through a hydraulic oil chamber (30). The bottom end of the reverse thrust mechanism (3) exposes an end cover plate (33). The central flow pipe (10) and the end cover plate (33) are temporarily fixedly connected by several shear pins (35). The central flow pipe (10) and the end cover plate (33) are respectively provided with at least one oil inlet hole. A sand control component (B) includes a sand control screen pipe (41) and an outer protective sleeve (42). The inner wall of the top end of the sand control screen pipe (41) is fitted onto the outer wall of the hydraulic cylinder (1) of the energy storage pulse return unblocking device (A) for installation downhole. The outer protective sleeve (42) is fitted onto the outside of the sand control screen pipe (41), and an inner filter zone is provided on the pipe wall of the sand control screen pipe (41) below the oil inlet of the central flow pipe (10). The inner filter zone is densely covered with slotted holes (410). The outer filter zone is provided on the pipe wall of the outer protective sleeve (42) corresponding to the inner filter zone of the sand control screen pipe (41). The outer filter zone is densely covered with punched holes (420). The central flow pipe (10) below the end cap plate (33) of the energy storage pulse return unblocking device (A) is inserted into the inner filter zone of the central flow pipe (10).

2. The downhole pulse backflow sand prevention and unblocking device according to claim 1, characterized in that, The inner filtration zone and the outer filtration zone are pre-filled with sand-proof particles to form a sand-proof particle layer (43).

3. The downhole pulse backflow sand prevention and unblocking device according to claim 2, characterized in that, The two ends of the outer protective sleeve (42) are fixed to the sand screen tube (41) by fixing rings (421); The top and bottom ends of the sand screen pipe (41) are respectively provided with a pipe clamp joint (411) and an end cap (412).

4. The downhole pulse backflow sand prevention and unblocking device according to claim 1, characterized in that, Several nitrogen springs (2) are arranged circumferentially inside the hydraulic cylinder (1); Each nitrogen spring (2) includes a cylinder base (21), a piston rod (22), and a piston (23). The cylinder bases (21) of several nitrogen springs (2) are fixed to the top of the hydraulic cylinder (1). The piston rod (22) is movably mounted on the cylinder base (21), and the outer end of the piston rod (22) extends out of the cylinder base (21). The piston (23) is fixed to the end of the outer end of the piston rod (22), and the piston (23) of each nitrogen spring (2) is connected to the high-pressure pulse reverse thrust mechanism through the hydraulic oil chamber (30).

5. The downhole pulse backflow sand prevention and unblocking device according to claim 4, characterized in that, The reverse thrust mechanism (3) also includes an inner push plate (31), which is hidden inside the hydraulic cylinder (1), and a hydraulic oil chamber (30) is provided between the inner push plate (31) and the nitrogen spring (2); the end cover plate (33) is exposed on the outside of the bottom end of the hydraulic cylinder (1), and the inner push plate (31) and the end cover plate (33) are fixedly connected together; the central flow pipe (10) and the end cover plate (33) are temporarily fixedly connected by several shear pins (35); the central flow pipe (10) and the end cover plate (33) are respectively provided with at least one oil inlet hole; Among them, the pistons (23) of several nitrogen springs (2) correspond to the inner push plate (31) of the high-pressure pulse reverse thrust mechanism (3), and the space enclosed by the inner push plate (31), its corresponding hydraulic cylinder (1), and the inner wall of the hydraulic cylinder (1) between them forms a hydraulic oil chamber (30) for filling hydraulic oil.

6. The downhole pulse backflow sand prevention and unblocking device according to claim 5, characterized in that, The reverse thrust mechanism (3) also includes a connecting cylinder (32), through which the inner push plate (31) and the end cover plate (33) are connected together to achieve a fixed connection between the inner push plate (31) and the end cover plate (33).

7. The downhole pulse backflow sand prevention and unblocking device according to claim 6, characterized in that, The end cover plate (33) is provided with an inner ring and the inner ring protrudes outward to form an end cover plate flange (34). The end cover plate flange (34) is sleeved on the bottom end of the central flow pipe (10). A number of shear pins (35) are arranged circumferentially at the junction of the central flow pipe (10) and the end cover plate flange (34) to achieve a temporary fixed connection between the central flow pipe (10) and the end cover plate (33). The outer wall of the end cap flange (34) is provided with a plurality of external oil inlets (340), and the bottom end of the central flow pipe (10) is provided with a plurality of internal oil inlets (100). When the central flow pipe (10) and the end cap flange (34) are temporarily fixedly connected by a plurality of shear pins (35), the plurality of external oil inlets (340) of the end cap flange (34) and the plurality of internal oil inlets (100) of the central flow pipe (10) are connected in a plurality of shear pins (35). 00) They are respectively aligned one by one to achieve the internal connection between the central flow pipe (10) and the external connection between the hydraulic cylinder (1); when the end cover plate (33) is ejected outward in the form of an instantaneous, high-pressure pulse, the several internal oil inlets (100) of the central flow pipe (10) and the several external oil inlets (340) of the end cover plate flange (34) are quickly misaligned to achieve the separation between the internal connection between the central flow pipe (10) and the external connection between the hydraulic cylinder (1); When the end cover plate (33) is pressed by an external force and the central flow pipe (10) is temporarily fixedly connected to the end cover plate (33) by a number of shear pins (35), a number of external oil inlet holes (340) of the end cover plate flange (34) are opposite to a number of internal oil inlet holes (100) of the central flow pipe (10), and the interior of the central flow pipe (10) is connected to the exterior of the hydraulic cylinder (1). This state is recorded as normal oil production condition. When the energy storage pulse return unblocking device is in normal oil production condition, a number of nitrogen springs (2) store elastic potential energy. Once the external force on the end cover plate (33) weakens or disappears, each shear pin (35) is immediately released, and the elastic potential energy stored in all nitrogen springs (2) is released instantaneously and acts on the end cover plate (33). The end cover plate (33) is ejected outward in the form of an instantaneous, high-pressure pulse. Several inner oil inlet holes (100) of the central flow pipe (10) and several outer oil inlet holes (340) of the end cover plate (33) are quickly misaligned. The interior of the central flow pipe (10) is no longer connected to the exterior of the hydraulic cylinder (1). This state is recorded as a blockage abnormal working condition, thereby realizing the transition from normal oil production working condition to blockage abnormal working condition.

8. The downhole pulse backflow sand prevention and unblocking device according to claim 7, characterized in that, The inner wall of the inner edge of the end cover flange (34) is provided with a plurality of pin grooves in a circumferential manner, and a plurality of shear pins (35) are respectively disposed in the plurality of pin grooves. The central flow pipe (10) is provided with a plurality of pin holes. When the oil inlet of the end cover flange (34) and the oil inlet of the central flow pipe (10) are respectively opposite, the plurality of pin grooves of the end cover flange (34) and the plurality of pin holes on the central flow pipe (10) are exactly opposite to each other. When hydraulic oil is supplied to the hydraulic oil chamber (30), the hydraulic oil at both ends of the hydraulic oil chamber (30) comes into contact with the piston (23) of the nitrogen spring (2) and the inner push plate (31) of the high-pressure pulse reverse thrust mechanism (3); as hydraulic oil continues to be supplied to the hydraulic oil chamber (30), the pressure of the hydraulic oil in the hydraulic oil chamber (30) increases until the shear pins (35) in the pin slots of the end cover flange (34) fall into the pin holes of the central flow pipe (10) at the same time. At the same time, the internal energy of the hydraulic oil is converted into the elastic potential energy of the nitrogen spring (2) and stored.

9. The downhole pulse backflow sand prevention and unblocking device according to claim 8, characterized in that, The top and bottom of the hydraulic cylinder (1) are respectively equipped with a top cover (11) and a chassis (12), and the two ends of the central flow pipe (10) pass through the center of the chassis (12) and the top cover (11) respectively, with the exposed ends connected to the outside. The cylinder base (21) of each nitrogen spring (2) is fixed in the inner cavity of the hydraulic cylinder (1), and the cylinder base (21) pushes against the top cover (11) upward. The chassis (12) is provided with an inner ring, and the connecting cylinder (32) is movably inserted into the inner ring of the chassis (12). Each nitrogen spring (2) has a hydraulic oil chamber (30) between its piston (23) and its corresponding inner push plate (31); When the external force on the end cover plate (33) weakens or disappears, the piston rod (22) of each nitrogen spring (2) extends outward simultaneously, pushing the piston (23) to compress the hydraulic oil in the hydraulic oil chamber (30), and the hydraulic oil pushes the end cover plate (33) outward by pushing several inner push plates (31). The instantaneous pushing force on the end cover plate (33) is much greater than the frictional force of the shear pin (35), and the shear pin (35) is immediately released.

10. The downhole pulse backflow sand prevention and unblocking device according to claim 9, characterized in that, Several shear pins (35) are symmetrically arranged about the center line of the central flow tube (10) at the connection between the central flow tube (10) and the end cover flange (34); each shear pin (35) is equipped with a preload spring (36).

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