Downhole pulse backflow sand prevention and blockage removal method

Abstract

The invention relates to an underground pulse backflow sand prevention and plug removal method. The method comprises the steps that firstly, an energy storage pulse backflow plug remover is arranged; the method comprises the steps that firstly, a sand prevention assembly is combined with an energy storage pulse backflow unblocking device, and an underground pulse backflow unblocking device is formed; thirdly, an underground pulse backflow unblocking device is used for operation, and a normal oil extraction working condition is started; 4, switching from a normal oil extraction working condition to a blockage abnormal working condition; wherein at the moment of entering the abnormal blocking working condition, the end cover plate pushes fluid in the sand control screen pipe to sequentially and reversely wash the slotted holes of the inner-layer filtering area, the sand control particle layer and the punched holes of the outer-layer filtering area, and gravel blocked on the slotted holes of the sand control screen pipe is discharged; blockage removal can be realized under the condition that oil extraction equipment does not need to be shut down; and 5, after plug removal is completed, normal oil extraction operation is carried out again.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a downhole pulse backflow method for sand prevention and unblocking. 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 purpose of this invention is to provide a downhole pulse backflow sand prevention and unblocking method, which solves the current lack of devices that can 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 method for sand prevention and unclogging, including... Step 1: Install an energy storage pulse backflow unblocking device. The 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. 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. 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.

[0006] Step 2: Combine the sand control component with the energy storage pulse backflow unblocking device to form a downhole pulse backflow unblocking device; The 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 of the energy storage pulse return unblocking device passes directly into the inner filtration zone of the central flow pipe.

[0007] Step 3: Use the downhole pulse backflow unblocking device to enter normal oil production conditions, including the following steps: The fluid in the well enters the sand control screen pipe from the outside in 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 it from moving downward. At this time, the oil inlet of the end cover plate is opposite to the oil inlet 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 the oil inlet of the end cover plate and the oil inlet 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. Step 4: Switching from normal oil production conditions to abnormal blockage conditions, including the following steps: 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 simultaneously extends outward and compresses the hydraulic oil in the hydraulic oil chamber, and the hydraulic oil pushes several high-pressure pulse reverse thrust mechanisms 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 is sprayed outward in the form of instantaneous, high-pressure pulses. 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 that the blockage occurs, 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. This can achieve unblocking without the need for the oil production equipment to be shut down. Step 5: After unblocking, resume normal oil production operations, including the following steps: As the fluid pressure inside the sand control component increases, the flow rate of the fluid gathered inside the sand control component after unblocking gradually increases until it re-enters normal oil production conditions.

[0008] Preferably, each nitrogen spring includes a cylinder base, a piston rod, and a piston. The cylinder bases of several nitrogen springs are 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 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.

[0009] 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 corresponding nitrogen spring; the end cover plate is exposed on the outside of the bottom end of the hydraulic cylinder, and several inner push plates and the end cover plate are fixedly connected together; the central flow pipe is temporarily fixedly connected to the end cover plate by several 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. 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 several shear pins, the oil inlet hole of the end cover plate flange is opposite to the oil inlet hole of the central flow pipe, 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 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. 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. This state is recorded as the abnormal blockage condition, thereby realizing the transition from normal oil production condition to abnormal blockage condition.

[0010] 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.

[0011] 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.

[0012] 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 and are 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.

[0013] 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.

[0014] Preferably, the downhole pulse backflow unblocking device includes an energy storage pulse backflow unblocker and a sand control assembly. The sand control assembly includes a sand control screen and an outer protective sleeve. The inner wall of the top end of the sand control screen is fitted onto the outer wall of the hydraulic cylinder of the energy storage pulse backflow unblocker for installation downhole. The outer protective sleeve is fitted onto the outside of the sand control screen. An inner filtration zone is provided on the wall of the sand control screen below the oil inlet of the central flow pipe. The inner filtration zone is densely covered with slotted holes. An outer filtration zone is provided on the wall of the outer protective sleeve corresponding to the inner filtration zone of the sand control screen. The outer filtration zone is densely covered with punched holes. The central flow pipe below the end cap of the energy storage pulse backflow unblocker passes directly into the inner filtration zone of the central flow pipe.

[0015] Preferably, a sand-preventing particle layer is pre-filled between the inner and outer filtration zones to form a sand-preventing particle layer. 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.

[0016] 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.

[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 unblocking device, belonging to the field of oil extraction technology, including 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, and 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. The outer protective sleeve corresponding to the inner filter zone of the sand control screen pipe is provided with an outer filter zone, which 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] (III) This invention discloses a downhole pulse backflow sand control and unblocking method, belonging to the field of oil extraction technology, including the following steps: Entering normal oil production conditions: 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, 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 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 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. Switching from normal oil production conditions to abnormal blockage conditions: If the slit holes in the outer filter zone of the outer protective casing 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 simultaneously extends outward, 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 instantaneously released and acts on the end cover plate, and the end cover plate sprays outward in the form of instantaneous, high-pressure pulses. 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 conditions gradually switch to abnormal blockage conditions. In the instant that the blockage occurs, 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. This can achieve unblocking 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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

[0026] 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.

[0027] 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 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.

[0028] 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.

[0029] The arrow "→" indicates the direction of fluid flow. Detailed Implementation

[0030] 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.

[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.

[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 contacts the nitrogen spring 2. 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. 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 plurality 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 unblocking device Embodiment 2 of the present invention provides a downhole pulse backflow 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 unblocking device includes the energy storage pulse backflow unblocking device A of Example 1 and a sand control component B.

[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 method for sand prevention and unclogging Embodiment 3 of the present invention provides a downhole pulse backflow sand prevention and unblocking method, which includes the following steps: Step 1: Set up the energy storage pulse backflow unblocking device A in Example 1; Step 2: Combine the sand control component B with the energy storage pulse backflow unblocking device A to form the downhole pulse backflow unblocking device of Example 2; Step 3: Use the downhole pulse backflow unblocking device to enter normal oil production conditions, including the following steps: 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 slit 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. Step 4: Switching from normal oil production conditions to abnormal blockage conditions, including the following steps: 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 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. Step 5: After unblocking, resume normal oil production operations, including the following steps: As the fluid pressure inside the sand control component increases, the flow rate of the fluid gathered inside the sand control component after unblocking gradually increases until it re-enters 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 control and plug removal method, characterized in that, Comprising Step one: set up the energy storage pulse backflow plugging remover (A); Step two: combine the sand control assembly (B) with the energy storage pulse backflow plugging remover (A) to form the downhole pulse backflow plugging device; Step three: use the downhole pulse backflow plugging device for operation, enter the normal oil production condition, including the following steps: The fluid in the well passes through the slit hole (420) of the outer filter area and the slit hole (410) of the inner filter area in turn from outside to inside, enters the inside of the sand control screen pipe (41), the fluid pressure in the inside of the sand control screen pipe (41) increases, lifts the end cover plate (33), blocks the downward movement of the end cover plate (33), at this time the oil inlet hole of the end cover plate (33) and the oil inlet hole of the center flow pipe (10) are opposite respectively, the inside of the center flow pipe (10) is in communication with the outside of the hydraulic cylinder (1), the fluid in the inside of the sand control screen pipe (41) enters the inside of the center flow pipe (10) through the oil inlet hole of the end cover plate (33) and the oil inlet hole of the center flow pipe (10), and then is transported to the ground through the center flow pipe (10) and the connecting pipe, at this time the normal oil production condition is achieved; Step four: switch from the normal oil production condition to the plugging abnormal condition, including the following steps: If the slit hole (420) of the outer filter area of the outer protective sleeve (42) is gradually blocked by sand, the fluid entering the inside of the sand control screen pipe (41) decreases, the fluid pressure in the inside of the sand control screen pipe (41) decreases, the external force acting on the end cover plate (33) decreases, each nitrogen gas spring (2) simultaneously extends outward, compresses the hydraulic oil in the hydraulic oil cavity (30), and the hydraulic oil promotes the end cover plate (33) to move outward by pushing a plurality of high-pressure pulse back-pushing mechanisms, the instantaneous pushing force acting on the end cover plate (33) is much greater than the friction force of the shear pin (35), and the shear pin (35) is immediately released; the elastic potential energy stored in all nitrogen gas 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 instantaneous and high-pressure pulse, the center flow pipe (10) and the oil inlet hole of the end cover plate (33) are quickly misaligned, the inside of the center flow pipe (10) is no longer in communication with the outside of the hydraulic cylinder (1), and the normal oil production condition is gradually converted into the plugging abnormal condition; At the moment of entering the plugging abnormal condition, the end cover plate (33) pushes the fluid in the inside of the sand control screen pipe (41) to backwash the slit hole (410) of the inner filter area and the slit hole (420) of the outer filter area in turn, and the sand blocked in the slit hole (410) of the sand control screen pipe (41) is discharged, so that the plugging can be solved without stopping the production of the oil production equipment; Step five: return to the normal oil production operation after the plugging is completed.

2. The downhole pulse backflow sand control and plugging method according to claim 1, characterized in that, The energy storage pulse backflow plug remover (A) comprises a hydraulic cylinder (1), a central flow pipe (10) and a high-pressure pulse back-pushing mechanism, the central flow pipe (10) passes through the two ends of the hydraulic cylinder (1) respectively, the high-pressure pulse back-pushing mechanism is arranged at the bottom end of the hydraulic cylinder (1), the high-pressure pulse back-pushing mechanism comprises a plurality of nitrogen gas springs (2) and a back-pushing mechanism (3), the plurality of nitrogen gas springs (2) are arranged in the circumferential direction in the interior of the hydraulic cylinder (1), each nitrogen gas spring (2) is connected with the high-pressure pulse back-pushing mechanism through a hydraulic oil cavity (30), the bottom end of the back-pushing mechanism (3) is exposed to an end cover plate (33), the central flow pipe (10) and the end cover plate (33) are temporarily fixed and connected through a plurality of shear pins (35), and the central flow pipe (10) and the end cover plate (33) are respectively provided with at least one oil inlet hole.

3. The downhole pulse backflow sand prevention and plug removal method according to claim 2, characterized in that, each nitrogen gas spring (2) comprises a cylinder base (21), a piston rod (22) and a piston (23), the cylinder bases (21) of the plurality of nitrogen gas springs (2) are fixed on the top of the hydraulic cylinder (1), the piston rod (22) is movably arranged on the cylinder base (21), the outer end of the piston rod (22) extends out of the cylinder base (21), the piston (23) is fixed on the end of the outer end of the piston rod (22), and the piston (23) of each nitrogen gas spring (2) is connected with the high-pressure pulse back-pushing mechanism through a hydraulic oil cavity (30).

4. The downhole pulse backflow sand prevention and plug removal method according to claim 3, characterized in that, the back-pushing mechanism (3) further comprises an inner pushing plate (31), the inner pushing plate (31) is arranged in the interior of the hydraulic cylinder (1) in a hidden manner, and a hydraulic oil cavity (30) is arranged between the inner pushing plate (31) and the corresponding nitrogen gas spring (2); the end cover plate (33) is exposed to the outside of the bottom end of the hydraulic cylinder (1), the inner pushing 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 fixed and connected through a plurality of shear pins (35), and the central flow pipe (10) and the end cover plate (33) are respectively provided with at least one oil inlet hole; wherein the pistons (23) of the plurality of nitrogen gas springs (2) and the inner pushing plate (31) of the high-pressure pulse back-pushing mechanism (3) correspond to each other respectively, and a space formed by the inner pushing plate (31), the corresponding hydraulic cylinder (1) and the inner wall of the hydraulic cylinder (1) between them forms a hydraulic oil cavity (30) for filling hydraulic oil. When the end cover plate (33) is pressed by external force and the center flow pipe (10) is temporarily fixed and connected with the end cover plate (33) through the shear pins (35), the oil inlet holes of the end cover plate flange (34) and the oil inlet holes of the center flow pipe (10) are opposite to each other, the inside of the center flow pipe (10) is in communication with the outside of the hydraulic cylinder (1), and the state is recorded as the normal oil production condition. When the energy storage pulse backflow plug remover is in the normal oil production condition, the elastic potential energy of the nitrogen gas springs (2) is stored; Once the external force applied to the end cover plate (33) is weakened or disappears, each shear pin (35) is immediately released, the elastic potential energy stored in all the nitrogen gas 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 instantaneous high-pressure pulse, the oil inlet holes of the center flow pipe (10) and the end cover plate flange (34) are quickly misaligned, the inside of the center flow pipe (10) is no longer in communication with the outside of the hydraulic cylinder (1), and the state is recorded as the abnormal plugging condition, so that the conversion from the normal oil production condition to the abnormal plugging condition is realized.

5. The downhole pulse backflow sand prevention and plug removal method according to claim 4, characterized in that the end cover plate (33) is provided with an inner ring, and the inner ring is outwardly convex to form an end cover plate flange (34), the end cover plate flange (34) is sleeved on the bottom end of the center flow pipe (10), and a plurality of shear pins (35) are arranged around the joint of the center flow pipe (10) and the end cover plate flange (34), so that the center flow pipe (10) and the end cover plate (33) are temporarily fixed and connected; a plurality of outer oil inlet holes (340) are arranged around the outer wall of the end cover plate flange (34), a plurality of inner oil inlet holes (100) are arranged around the bottom end of the center flow pipe (10), and when the center flow pipe (10) is temporarily fixed and connected with the end cover plate flange (34) through the shear pins (35), the plurality of outer oil inlet holes (340) of the end cover plate flange (34) and the plurality of inner oil inlet holes (100) of the center flow pipe (10) are opposite to each other one by one, so that the inside of the center flow pipe (10) is in communication with the outside of the hydraulic cylinder (1); when the end cover plate (33) is ejected outward in the form of instantaneous high-pressure pulse, the plurality of inner oil inlet holes (100) of the center flow pipe (10) and the plurality of outer oil inlet holes (340) of the end cover plate flange (34) are quickly misaligned, so that the inside of the center flow pipe (10) is no longer in communication with the outside of the hydraulic cylinder (1). When the end cover plate (33) is pressed by external force and the center flow tube (10) is temporarily fixed and connected with the end cover plate (33) through a plurality of shear pins (35), a plurality of outer oil inlet holes (340) of the end cover plate flange (34) are respectively opposite to a plurality of inner oil inlet holes (100) of the center flow tube (10), the inside of the center flow tube (10) is in communication with the outside of the hydraulic cylinder (1), and the state at this time is recorded as a normal oil production condition, and when the energy storage pulse backflow plugging remover is in the normal oil production condition, a plurality of nitrogen gas springs (2) store elastic potential energy. Once the external force applied to the end cover plate (33) is weakened or disappears, each shear pin (35) is immediately released, the elastic potential energy stored in all the nitrogen gas springs (2) is instantaneously released and acts on the end cover plate (33), the end cover plate (33) is ejected outward in the form of a transient and high-pressure pulse, the plurality of inner oil inlet holes (100) of the center flow tube (10) are quickly misaligned with the plurality of outer oil inlet holes (340) of the end cover plate (33), the inside of the center flow tube (10) is no longer in communication with the outside of the hydraulic cylinder (1), and the state at this time is recorded as a plugging abnormal condition, thereby realizing the conversion from the normal oil production condition to the plugging abnormal condition.

6. The downhole pulse backflow sand prevention and plugging removal method according to claim 5, characterized in that, the inner wall of the inner edge of the end cover plate flange (34) is circumferentially provided with a plurality of pin grooves, a plurality of shear pins (35) are respectively arranged in the plurality of pin grooves, and the center flow tube (10) is provided with a plurality of pin holes, the oil inlet holes of the end cover plate flange (34) are respectively opposite to the oil inlet holes of the center flow tube (10), and the plurality of pin grooves of the end cover plate flange (34) are respectively opposite to the plurality of pin holes of the center flow tube (10): when hydraulic oil is delivered into the hydraulic oil cavity (30), the hydraulic oil at both ends in the hydraulic oil cavity (30) abuts against the piston (23) of the nitrogen gas spring (2) and the inner push plate (31) of the high-pressure pulse counter-acting mechanism (3); the delivery of the hydraulic oil into the hydraulic oil cavity (30) is continued, the pressure of the hydraulic oil in the hydraulic oil cavity (30) is increased, and the shear pins (35) in the plurality of pin grooves of the end cover plate flange (34) are respectively and simultaneously dropped into the plurality of pin holes of the center flow tube (10), and at the same time, the internal energy of the hydraulic oil is converted into the elastic potential energy stored in the nitrogen gas spring (2).

7. The downhole pulse backflow sand prevention and plugging removal method according to claim 6, characterized in that, the plurality of shear pins (35) are symmetrically arranged about the center line of the center flow tube (10) at the connection between the center flow tube (10) and the end cover plate flange (34); and each shear pin (35) is provided with a preloaded spring (36).

8. The downhole pulse backflow sand control cleanup method of claim 1, wherein, The downhole pulse backflow plugging removal device comprises an energy storage pulse backflow plugging remover (A) and a sand prevention assembly (B), The sand control assembly (B) comprises a sand control screen pipe (41) and an outer protective sleeve (42), an inner wall of a top end of the sand control screen pipe (41) is sleeved on an outer wall of a hydraulic cylinder (1) of the energy storage pulse backflow plug remover (A) for being arranged downhole, the outer protective sleeve (42) is sleeved on an outer side of the sand control screen pipe (41), and an inner layer filtering area is arranged on a pipe wall of the sand control screen pipe (41) below an oil inlet hole of the center flow pipe (10), the inner layer filtering area is densely provided with slit holes (410), an outer layer filtering area is arranged on the pipe wall of the outer protective sleeve (42) corresponding to the inner layer filtering area of the sand control screen pipe (41), and the outer layer filtering area is densely provided with flush holes (420); the center flow pipe (10) below the end cover plate (33) of the energy storage pulse backflow plug remover (A) is just penetrated into the inner layer filtering area of the center flow pipe (10).

9. The downhole pulse backflow plug removing device according to claim 8, characterized in that, the inner layer filtering area and the outer layer filtering area are pre-filled with sand control particles to form a sand control particle layer (43); at the moment of entering the abnormal plugging condition, the end cover plate (33) pushes the fluid inside the sand control screen pipe (41) to reversely flush the slit holes (410) of the inner layer filtering area, the sand control particle layer (43) and the flush holes (420) of the outer layer filtering area in sequence, and the sand and stones plugged on the slit holes (410) of the sand control screen pipe (41) are discharged, so that the plugging can be removed without stopping the production of the oil extraction equipment.

10. The downhole pulse backflow plug removing device according to claim 8, characterized in that, both ends of the outer protective sleeve (42) are fixed on the sand control screen pipe (41) through fixing rings (421); the top end and the bottom end of the sand control screen pipe (41) are respectively provided with a pipe clamp joint (411) and an end cover (412).

Images