Sand control and anti-plugging pipe string

Abstract

The application discloses a sand-prevention and blockage-prevention pipe string, which comprises a pipe string body, a vibrating screen pipe structure is arranged in the pipe string body, the vibrating screen pipe structure comprises a central cylinder which is coaxially arranged in the pipe string body, a micro wave structure is formed on the outer wall of the central cylinder, an external screen pipe is arranged on the outer wall of the central cylinder, and a gravel filling cavity is formed between the central cylinder and the external screen pipe; a sliding vibrating assembly and a self-powered vibrating driving mechanism are arranged on the cylinder wall of the central cylinder; five groups of bypass flow channels are axially arranged in the inner wall of the side wall of the central cylinder, a flow channel switch assembly is arranged at the flow channel entrance of each group of bypass flow channels, and the flow channel switch assembly is connected with a driving and adjusting unit. The sand-prevention and blockage-prevention pipe string has the functions of bypass blockage prevention, vibration compaction and wave turbulence sand carrying, can highly simulate real downhole working conditions, is suitable for various types of easy-sand reservoirs such as loose sandstone, argillaceous siltstone and natural gas hydrate, and can significantly improve the sand-prevention and blockage-prevention efficiency and long-term stability.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field and natural gas hydrate reservoir development technology, and particularly to a filling anti-sand and anti-blocking tubing string. Background Technology

[0002] As global oil and gas resource development continues to advance into deeper, low-permeability, loose, and unconventional reservoirs, formation sand production has become one of the core issues restricting oil and gas well productivity, equipment lifespan, and production safety. In loose sandstone, silty mudstone, and natural gas hydrate reservoirs, the rocks have low cementation strength and loose structure, making them highly susceptible to particle shedding, migration, and accumulation under drilling, perforation, production pressure differentials, and fluid scouring. This leads to a series of problems such as wellbore sand blockage, screen blockage, pump barrel and rod wear, reservoir sand burial, and narrowing of production channels. In severe cases, this can cause oil and gas well shutdowns and even abandonment, resulting in huge economic losses. According to incomplete statistics, in loose sandstone oilfields, the operation and maintenance costs caused by sand production and sand blockage can account for more than 30% of the total production costs, and the production efficiency of some severely sand-producing well sections is only about 60% of that of normal well sections.

[0003] Currently, gravel packing is the most widely used and technologically mature sand control completion method both domestically and internationally. Its basic principle is to fill the annular space between the downhole screen and the wellbore or casing with gravel or ceramsite particles of a certain size, forming a highly permeable and stable filter barrier that prevents formation sand from entering the production channel while allowing oil and gas fluids to pass smoothly. However, in long-term field application, traditional gravel packing strings have revealed several insurmountable technical defects.

[0004] First, traditional tubing strings are prone to sand bridging, sand shedding, and localized accumulation in horizontal wells, highly deviated wells, and long well sections, leading to premature blockage of the filling channel. This prevents subsequent gravel from advancing smoothly, resulting in problems such as filling blind spots, insufficient compaction, and failure of the sand control layer. Second, traditional tubing strings are mostly passive filtration structures, lacking active anti-blocking and deblocking mechanisms. Once sand blockage occurs, it can only be addressed through backwashing and well workover, which are complex, costly, and impact production efficiency. Third, the gravel filling process relies on construction experience and lacks real-time monitoring methods for downhole filling compaction and uniformity. It is impossible to dynamically adjust pumping parameters, sand volume, and discharge rate based on the actual downhole conditions, easily leading to overfilling, underfilling, or uneven filling. Fourth, the sand-carrying fluid in the annulus is mostly in a laminar or weakly turbulent state, with rapid particle settling velocity, easily accumulating at the bottom or in localized areas, further exacerbating the risk of sand blockage. Fifth, conventional vibration sand control devices mostly rely on ground power or complex downhole motors, which are bulky in structure, have a high failure rate, consume a lot of energy, and are difficult to operate stably for a long time.

[0005] In recent years, technicians in this field have proposed various improved sand control tools and tubing structures, some of which have incorporated vibration, bypass, and monitoring concepts. However, significant shortcomings remain: some structures only achieve a single vibration function without combining it with bypass unblocking and turbulent sand carrying; some bypass structures are single-channel designs, unable to achieve graded and segmented control; most structures do not improve particle transport from a flow field optimization perspective; and there are almost no integrated tubing strings that highly integrate the four core functions of vibration compaction, graded bypass, wave turbulence, and density monitoring. Therefore, developing a new type of filling sand control and anti-blocking tubing string with a simplified structure, reliable operation, active anti-blocking, turbulent flow aid, and real-time control has become an urgent need in the field of sand control for oil and gas well completion. Summary of the Invention

[0006] To address the problems of sand blockage, uneven compaction, lack of active control, poor flow field, and insufficient monitoring methods in traditional filling tubing, this invention provides a filling sand-prevention and anti-blockage tubing string that highly integrates four functions: vibration compaction, staged bypass, wave turbulence, and real-time monitoring. This achieves the effects of active anti-blockage, uniform compaction, smooth movement, and dynamic control, significantly improving the effectiveness, continuity, and long-term effectiveness of sand prevention, and adapting to various sand-producing reservoirs and complex well types.

[0007] The present invention is achieved by the following technical solution.

[0008] A filling and anti-sanding pipe string includes a main body of the pipe string, and a vibrating screen pipe structure is provided inside the main body of the pipe string. The vibrating screen pipe structure includes a central cylinder coaxially installed inside the main body of the pipe string. The outer wall of the central cylinder forms a micro-wave structure. An outer screen pipe is installed outside the central cylinder, and a gravel filling cavity is formed between the central cylinder and the outer screen pipe. A sliding vibration component and a self-powered vibration drive mechanism are provided on the cylinder wall of the central cylinder. Five sets of bypass channels are opened axially inside the side wall of the central cylinder. The bypass channels connect the gravel filling cavity and the central cylinder. A channel switch component is provided at the inlet of each set of bypass channels. The channel switch component is connected to a drive adjustment unit.

[0009] By adopting the above technical solutions, this invention simplifies the vibration drive structure, enhances the graded bypass anti-blocking function, adds a micro-wave turbulence structure, and combines a high-density distributed density monitoring component to achieve the synergistic operation of "vibration compaction + bypass unblocking + wave turbulence + intelligent control," fundamentally improving the gravel filling quality and long-term sand control capability. It has broad application prospects in the development of horizontal wells in offshore oilfields.

[0010] Furthermore, the wall surface of the central cylinder is uniformly provided with multiple rows of oil inlet holes along the circumference.

[0011] Furthermore, the sliding vibration assembly includes axial vibration vertical grooves symmetrically opened on the inner wall of the central cylinder, a sliding block is slidably connected in the vibration vertical groove, a receiving groove is opened at the bottom of the sliding block, a vibration block is provided in the receiving groove, and a fault-tolerant spring is installed below the vibration block.

[0012] Furthermore, the micro-wave structure is a continuous smooth wave surface on the outer wall of the central cylinder, covering the entire length of the gravel-filled cavity.

[0013] Furthermore, the flow channel switch assembly includes a valve seat mounted on the inner wall of the flow channel, a valve core slidably disposed within the valve seat, the valve core being connected to the drive adjustment unit via a transmission column, and an elastic reset member sleeved on the transmission column.

[0014] Furthermore, the drive adjustment unit includes a guide cylinder that is rotatably mounted outside the external screen tube. A drive gear is provided on the outer wall of the guide cylinder, and an annular groove is formed on the inner wall of the guide cylinder in the circumferential direction. A guide ring is embedded in the annular groove, and the guide ring is connected to the transmission column of the flow channel switch assembly.

[0015] Furthermore, the bottom of the annular groove is a cam surface with gradually changing depths along the circumference. When the guide tube rotates, it drives the guide ring to move radially through the curved surface at the bottom of the annular groove, thereby causing the valve core to open and close the bypass flow channel.

[0016] Furthermore, multiple density sensors are embedded in the inner wall of the external sieve tube. The density sensors are connected to the data transmission module via cables, and the data transmission module uploads the signals to the ground terminal via wired or wireless means.

[0017] Furthermore, an injection pipe interface is provided at the top of the external screen tube.

[0018] This application has the following beneficial effects: 1. The vibration mechanism is highly simplified, and its reliability is greatly improved. This invention significantly simplifies the vibration structure, eliminates complex transmission components, adopts a self-driven mode, and relies on fluid kinetic energy to achieve vibration. It has no motor, no cable, no complex gearbox, fewer moving parts, low failure rate, and long service life. It can operate stably for a long time in high temperature, high sand content, and high corrosion downhole environments, and significantly reduces maintenance costs.

[0019] 2. The tiered bypass system actively prevents blockages, significantly improving operational continuity. The system features five independent axial bypass channels, enabling segmented, graded, and precise blockage control. The corresponding channels can be flexibly opened according to the location and severity of the blockage, allowing for proactive blockage avoidance and rapid unblocking without the need for well repair or backwashing. This significantly improves the continuity of construction and production and reduces downtime.

[0020] 3. Micro-wave turbulence aids drainage, suppressing sand blockage at its source. This invention is the first to set a continuous micro-wave structure on the outer wall of the central cylinder, which passively enhances the turbulence of the flow field, improves the sand carrying capacity, delays particle settling, and makes the particle movement smoother and the distribution more uniform. It reduces the probability of sand blockage from the flow mechanism. Combined with vibration and bypass, it forms a triple anti-blockage system, which reduces the sand blockage rate by more than 80%.

[0021] 4. Distributed density monitoring enables intelligent control throughout the entire process. This invention employs high-density distributed density sensors to monitor filling density in real time across the entire area. The ground terminal automatically analyzes, issues warnings, and adjusts pumping parameters, vibration intensity, and bypass status to achieve closed-loop intelligent control, avoiding human experience errors and resulting in more stable and uniform filling quality.

[0022] 5. Highly integrated functions and extremely adaptable. This invention highly integrates four major functions: vibration compaction, graded bypass, wave turbulence, and density monitoring. It has a compact structure, consistent outer diameter, and smooth lowering. It can be widely used in various sand-producing formations such as loose sandstone, silty mudstone, heavy oil reservoirs, and natural gas hydrate reservoirs. It is compatible with various well types such as vertical wells, deviated wells, horizontal wells, and long well sections, and has a very wide range of applications.

[0023] 6. It has a prominent long-lasting sand control effect and significant economic benefits. This invention achieves a more stable sand-proof layer structure and a longer lifespan through uniform and dense filling, active anti-blocking and de-blocking, flow field optimization, and intelligent control. The effective period of sand prevention is extended by more than 30% compared with traditional tubing, equipment erosion and wear are reduced, maintenance costs are reduced, and the overall economic benefits and safety are greatly improved.

[0024] This invention is applicable to sand control wells in loose sandstone, silty mudstone, and natural gas hydrate reservoirs in offshore oilfields. It has broad application prospects in loose sandstone reservoirs such as Caofeidian 11-1, Suizhong 36-1, and Enping 18-1 in the eastern South China Sea. It is also adaptable to the development of natural gas hydrates. Once the technology matures, it can be implemented as a single-well operation with material delivery service, opening up new markets. It is expected to achieve no less than 20 applications per year, with an estimated direct economic benefit of 60 million yuan per year. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a partially enlarged view of the present invention; Figure 3 yes Figure 2 Enlarged view of section A.

[0026] Figure 4 This is a schematic diagram of the self-powered vibration drive mechanism and sliding vibration assembly in this invention.

[0027] Among them, 1. Tube column body; 2. Vibrating screen tube structure; 21. Central cylinder; 211. Oil inlet; 212. Vibrating vertical groove; 22. External screen tube; 23. Gravel filling cavity; 24. Injection pipe interface; 25. Support base; 26. Sliding block; 261. Receiving groove; 27. Vibrating block; 28. Fault-tolerant spring; 29. ​​Impeller; 291. Reciprocating screw; 292. Screw nut; 293. Connecting rod; 3. Bypass anti-blocking structure; 31. Bypass flow channel; 32. Flow channel switch assembly; 321. Valve seat; 322. Valve core; 323. Elastic reset element; 324. Transmission column; 33. Drive adjustment unit; 331. Flow guide tube; 333. Drive gear; 334. Annular groove; 336. Guide ring; 4. Filling density monitoring component; 41. Density sensor; 5. Micro-wave structure. Detailed Implementation

[0028] The present patent application will be further described below with reference to the embodiments. Unless otherwise specified, the materials used in the preparation process in the following embodiments have not undergone further processing and have been commercially available.

[0029] like Figure 1-4 As shown, a filling sand-proof and anti-clogging tubing string includes a tubing body 1, a vibrating screen pipe structure 2, a bypass anti-clogging structure 3, a micro-wave structure 5, and a filling density monitoring component 4. Each module works independently and collaboratively, without motion interference or flow channel disturbance. The overall structure is compact with a consistent outer diameter, ensuring smooth running. It can adapt to different sizes of casing and wellbore, and is suitable for various working conditions such as vertical wells, deviated wells, horizontal wells, and long well sections in reservoirs.

[0030] The tubing string body 1 is a hollow tubular structure, with its lower end connected to the reservoir and its upper end extending to the surface wellhead, providing overall support and a central production channel. The vibrating screen structure 2, bypass anti-clogging structure 3, micro-wave structure 5, and filling density monitoring component 4 are all integrated inside the tubing string body 1, working together to achieve sand prevention, anti-clogging, turbulent sand carrying, and dynamic adjustment functions. From the inside to the outside along the radial direction of the tubing string are the central cylinder 21, the micro-wave structure 5 formed on the outer wall of the central cylinder 21, the gravel filling cavity 23, the external screen pipe 22, the guide tube 331, and the tubing string body 1. All of the above cylinders are coaxially arranged with the tubing string body 1. The bypass flow channel 31 and the flow channel switch component 32 are built into the side wall of the central cylinder 21. The density sensor 41 of the filling density monitoring component 4 is embedded in the inner wall of the external screen pipe 22. The guide tube 331 of the drive adjustment unit 33 is located in the annular space between the external screen pipe 22 and the tubing string body 1.

[0031] The vibrating screen tube structure 2 is the core actuator for achieving efficient and dense gravel compaction. This invention significantly simplifies the traditional complex vibration mechanism, retaining the core vibration function while eliminating redundant transmission structures, thereby improving reliability and reducing the failure rate. Specifically, the vibrating screen tube structure 2 includes a central cylinder 21, an external screen tube 22, a sliding vibration assembly, and a self-powered vibration drive mechanism. The central cylinder 21 is an integral hollow tubular structure, coaxially located inside the main body 1 of the tube column. Multiple rows of oil inlet holes 211 are evenly opened along its circumference on its wall surface for oil and gas fluids to enter the central cylinder 21 and be transported upwards. The external screen tube 22 adopts a high-strength wedge-shaped mesh screen tube, which is fitted outside the central cylinder 21, forming an annular closed space between the two, namely the gravel filling cavity 23, for accommodating gravel and sand-carrying fluid, forming a sand barrier. The top of the external screen tube 22 is provided with an injection pipe interface 24 for connecting to the ground pumping pipeline to realize the injection of gravel and sand-carrying fluid.

[0032] The sliding vibration assembly includes two axial vibration vertical grooves 212 symmetrically opened on the inner wall of the central cylinder 21, and sliding blocks 26 that slide freely up and down are slidably connected in the grooves; a receiving groove 261 is opened at the bottom of the sliding block 26, and a vibration block 27 is installed in the receiving groove 261. A fault-tolerant spring 28 is installed below the vibration block 27. The elastic coefficient of the fault-tolerant spring 28 is 15-25 N / mm, which can ensure sufficient impact force and buffer rigid impact to avoid structural fatigue damage.

[0033] The sliding block 26 is equipped with a self-powered vibration drive mechanism on its outer side. This mechanism relies entirely on the kinetic energy of the sand-carrying fluid itself, requiring no surface power, cable power supply, or downhole motor. Specifically, the self-powered vibration drive mechanism is installed inside the central cylinder 21, above the vibration vertical groove 212. It includes a support fixed to the inner wall of the central cylinder 21, an impeller rotatably supported on the support, a reciprocating screw fixedly connected coaxially to the impeller, and a screw nut fitted onto the reciprocating screw. The screw nut is circumferentially limited by the guide surface on the support and cannot rotate with the reciprocating screw; it can only reciprocate axially along the reciprocating screw. The screw nut is fixedly connected to the upper end of the sliding block 26 via a connecting rod (i.e.,...). Figure 1 The rod-shaped component located above the sliding block 26 and extending axially. Specifically, its internal structure and mating relationships are as follows: Figure 4As shown, the support base 25 is fixed on the inner wall of the central cylinder 21. The impeller 29, reciprocating screw 291, screw nut 292, and connecting rod 293 are arranged sequentially along the axis of the central cylinder 21. The support base 25 provides rotational support for the impeller 29 and the reciprocating screw 291, and restricts the circumferential rotation of the screw nut 292 through the guide surface. When the sand-carrying liquid flows upward, it drives the internal rotating component, drives the reciprocating screw to move, and then drives the sliding block 26 and the vibrating block 27 to move up and down reciprocally. This causes the vibrating block 27 to strike the bottom of the vibrating vertical groove 212 at high frequency, generating stable and continuous vibration waves, which are transmitted to the entire gravel filling cavity 23 through the central cylinder wall. This causes the gravel particles to rearrange, fill the gaps, and eliminate loose areas, achieving uniform compaction throughout the entire area.

[0034] This invention simplifies the structure by eliminating traditional complex gearboxes, multi-section connecting rods, eccentric wheels and other easily damaged components. It has fewer moving parts, lower sealing requirements and lower operating resistance. It can still maintain long-term stable operation in high temperature, high sand content and high corrosion downhole environments, significantly improving the overall life and reliability of the tubing string.

[0035] The micro-wave structure 5 is a passive, optimized structure specifically added to this invention to improve the flow field, enhance sand-carrying capacity, and suppress rapid particle settling. It requires no drive, control, or energy consumption throughout its operation, relying solely on its external structure to achieve flow field disturbance and turbulence enhancement. Specifically, the micro-wave structure 5 is integrally machined onto the outer wall of the central cylinder 21, extending continuously along the axial direction and completely covering the entire length range corresponding to the gravel-filled cavity 23. The wave structure adopts a continuous, smooth sinusoidal curved surface, composed of alternating crests and troughs, with smooth transitions and no sharp corners or sand-trapping areas. The crest height, trough depth, and wave period have been optimized through fluid dynamics simulation, maximizing turbulence intensity without significantly increasing flow resistance.

[0036] When the sand-carrying fluid carrying gravel particles flows within the annular gravel filling cavity 23, the smooth, wavy walls continuously disturb the fluid, transforming the originally stable laminar or weakly turbulent flow into a strongly turbulent state. Strong turbulence significantly increases the radial and circumferential pulsating velocities of the fluid, enhancing its particle-carrying capacity, reducing the effective settling velocity of the particles, and preventing rapid particle accumulation in localized areas. Simultaneously, the turbulent state allows for a more uniform distribution of gravel during filling, reducing bottom sedimentation and top looseness issues, and, combined with vibration, further improves overall density and structural stability.

[0037] The micro-wave structure 5 of this invention has the following significant advantages: no moving parts, never wears out; no drive required, zero energy consumption; does not change the external dimensions of the tubing, unobstructed insertion; can work in conjunction with vibration and bypass functions; suppresses sand blockage from the flow source, significantly reducing the probability of blockage. In field tests, the amount of particle deposition in the tubing equipped with the micro-wave structure was reduced by approximately 40%, and the risk of sand blockage was significantly reduced.

[0038] The bypass anti-blocking structure 3 of this invention is the core module for achieving active anti-blocking, rapid unblocking, and ensuring continuous operation. It adopts an integrated design of 5 independent axial bypass channels, graded switch control, and rotating guide tube linkage, which can achieve precise, graded, and segmented control according to the location and degree of blockage in the well.

[0039] Specifically, the bypass anti-blocking structure 3 includes a bypass channel 31, a channel switch assembly 32, and a drive adjustment unit 33. The bypass channel 31 is built into the side wall of the central cylinder 21. The bypass channel 31 is an axially elongated hole opened within the thickness of the side wall of the central cylinder 21, and its extension direction is parallel to the axis of the central cylinder 21, and it does not penetrate the side wall of the central cylinder 21 radially. Figure 2 The central channel is located inside the side wall of the central cylinder 21, parallel to the cylinder axis, and marked with arrows indicating the upward and downward flow directions. Five sets of bypass channels 31 are evenly arranged along the axial direction of the central cylinder 21, each independent of the others. Each set of channels has a short radial through-hole at each end serving as the channel inlet and outlet. The channel inlet connects to the lower part of the gravel filling cavity 23 via the channel switch assembly 32, and the channel outlet connects to the internal production channel of the central cylinder 21, forming an independent bypass return channel. Except for the two short through-holes mentioned above, the bypass channels 31 are not connected to the inner or outer surfaces of the central cylinder 21. The five sets of channels are arranged in segments along the height direction, corresponding to different filling states in different downhole sections, enabling segmented unblocking and segmented anti-blocking.

[0040] A flow channel switch assembly 32 is installed at the inlet of each group of bypass flow channels 31. Each group of bypass flow channels 31 is equipped with a corresponding flow channel switch assembly 32. The flow channel outlet is normally open to the inner cavity of the central cylinder 21. The flow channel switch assembly 32 includes a valve seat 321, a valve core 322, and a resilient reset member 323. The valve seat 321 is fixedly and sealed on the inner wall of the flow channel, and the valve core 322 can slide within the valve seat 321 to open and close the flow channel. The resilient reset member 323 provides a reset force to ensure that the valve remains closed in the non-controlled state to prevent leakage. In addition to the valve seat 321, valve core 322, and elastic reset member 323, the flow channel switch assembly 32 also includes: a transmission column 324 fixedly connected to the end of the valve core 322 facing away from the flow channel and extending radially outward, passing through the gravel filling cavity 23 and the external screen tube 22, and then extending into the annular space outside the external screen tube 22; a sealing ring disposed between the mating surfaces of the valve seat 321 and the valve core 322; and an end cap that seals the outer port of the valve seat 321 and provides axial support and limiting for the elastic reset member 323. The elastic reset member 323 is a helical spring fitted onto the transmission column 324 of the valve core 322, with both ends abutting against the shoulders of the end cap and the valve core 322, respectively. The head of the valve core 322 is a conical sealing head that mates with the inner sealing surface of the valve seat 321. Figure 3As shown. All switching components operate synchronously or independently to achieve hierarchical control of single, multiple, and full flow channels. The linkage between valve core 322 and drive adjustment unit 33 is as follows: a transmission column 324 extending radially outward is fixedly connected to one end of valve core 322 away from the flow channel. The transmission column 324 passes through the through hole on the gravel filling cavity 23 and the external screen tube 22 and extends to the outside of the external screen tube 22. A guide ring 336 is fixedly installed at its outer end. The guide ring 336 is embedded in the annular groove 334 opened circumferentially on the inner wall of the guide tube 331 and can slide relative to the annular groove 334 circumferentially. The bottom of the annular groove 334 is a cam surface with gradually changing depth along the circumferential direction, which includes a deep groove section, a transition slope section and a shallow groove section in sequence along the circumferential direction. When the drive gear 333 drives the guide tube 331 to rotate around the axis of the tube column, the guide ring 336 slides along the bottom curved surface of the annular groove 334 and is forced to generate radial displacement, which in turn pushes or releases the valve core 322 through the transmission column 324, thereby converting the circumferential rotation of the guide tube 331 into the radial linear motion of the valve core 322: when the guide ring 336 is in the deep groove section, the valve core 322 is reset inward under the action of the elastic reset member 323, and its conical sealing head is pressed against the sealing surface of the valve seat 321, and the flow inlet of the bypass flow channel 31 is closed; when the guide ring 336 is lifted by the transition inclined section and enters the shallow groove section, the valve core 322 overcomes the elastic force of the elastic reset member 323 and moves radially outward, disengaging from the sealing surface of the valve seat 321, and the flow inlet of the bypass flow channel 31 is opened. Since the guide rings 336 corresponding to the five sets of flow channel switch assemblies 32 are respectively matched with the five annular grooves 334 at different axial positions on the flow guide tube 331, and the deep groove section and the shallow groove section of each annular groove 334 are different in phase in the circumferential direction, when the flow guide tube 331 rotates through different angles, it can open a single set, multiple adjacent sets or all five sets of bypass flow channels 31 respectively, thereby realizing graded control.

[0041] The drive adjustment unit 33 adopts an external rotating guide tube mode. The guide tube 331 is rotatably fitted outside the external screen tube 22 and inside the tubing body 1, that is, located in the annular space between the external screen tube 22 and the tubing body 1. This annular space is not filled with gravel, thereby ensuring that the guide tube 331 can rotate flexibly downhole for a long time. It can rotate around the axis of the tubing at a certain angle. The rotation refers to the guide tube 331 rotating in the same direction around the axis of the tubing in the forward and reverse directions. During the rotation, the guide tube 331 does not move axially, nor does it produce radial sway or overturning. Its single rotation angle is 15° to 30°. The circumferential guidance and axial limit of this rotation are achieved by the cooperation of the annular groove 334 on the inner wall of the guide tube 331 and the guide ring 336 embedded in the annular groove 334. The outer wall of the guide tube 331 is provided with a drive gear 333, which can be driven by a small downhole actuator or surface hydraulic control. The drive adjustment unit 33 also includes a locking mechanism. The locking mechanism is a worm gear transmission structure with reverse self-locking function, which is set between the drive gear 333 and its matching actuator. Alternatively, a ratchet and pawl type circumferential positioning structure can be adopted. After the actuator stops driving, the locking mechanism will reliably lock the guide tube 331 and keep it at the current angle position to prevent it from rotating on its own under the action of downhole vibration, fluid scouring and pressure difference.

[0042] The inner wall of the flow guide tube 331 is provided with annular grooves 334 along the circumference. Five annular grooves 334 are arranged at intervals along the axial direction of the flow guide tube 331, and their axial positions correspond one-to-one with the five sets of flow channel switch assemblies 32. Each annular groove 334 is fitted with a guide ring 336. The inner hole of the guide ring 336 is fixedly connected to the transmission column 324 at the outer end of the valve core 322 in the corresponding flow channel switch assembly 32. The outer ring of the guide ring 336 is embedded in the annular groove 334 and can slide along the circumference of the annular groove 334. The annular groove 334 and the guide ring 336 serve two purposes: First, they form a circumferential guiding and axial limiting pair, rotatably constraining the guide tube 331 between the external screen pipe 22 and the main body of the tubing string 1, so that the guide tube 331 retains only the degree of freedom to rotate around the axis of the tubing string, avoiding axial movement and radial sway under the action of downhole vibration and fluid scouring, ensuring the coaxiality of the guide tube 331 and the external screen pipe 22, as well as the alignment accuracy of the guide ring 336 and the transmission column 324; Second, the bottom of the annular groove 334 is a cam surface with gradually changing depth along the circumferential direction. When the guide tube 331 rotates, the guide ring 336 slides along the bottom surface of the groove and is forced to generate radial displacement, thereby converting the circumferential rotation of the guide tube 331 into the radial linear motion of the valve core 322, realizing the linkage between the guide tube 331 and the flow channel switch assembly 32. After the guide tube 331 rotates at a certain angle, the valve core 322 of each flow channel switch assembly 32 is driven to move radially through the annular groove 334 opened along the circumference of its inner wall and the guide ring 336 embedded in the annular groove 334, thereby controlling the operation of the flow channel switch assembly 32 and controlling the opening and closing of the bypass flow channel 31 at different heights to adapt to the blockage conditions of different sections.

[0043] When the tubing is in normal filling or production mode, the guide tube 331 is in its initial position. The valve cores 322 of each group of flow channel switch assemblies 32 are pressed against the sealing surface of the valve seat 321 under the action of the elastic reset member 323, and the bypass flow channel 31 is completely closed. The fluid normally enters the central cylinder 21 through the oil inlet 211. When the monitoring system detects sand blockage, abnormal increase in density, or abnormal increase in pressure in a certain section, the control system drives the guide tube 331 to rotate a certain angle. Through the annular groove 334 on its inner wall and the guide ring 336 embedded in the annular groove 334, the valve core 322 is driven to move radially, so that the bypass flow channel switch at the corresponding height is opened. The sand-carrying fluid enters the central cylinder 21 directly through the bypass flow channel 31, bypassing the blocked section, and achieving active blockage avoidance.

[0044] Based on the degree of blockage, a three-level control mode can be implemented: For minor blockage, a single flow channel at the corresponding height is opened to achieve local diversion and flushing; for moderate blockage, 2-3 adjacent flow channels are opened to expand the diversion range and accelerate the loosening of accumulated particles; for severe blockage, all 5 flow channels are opened to form a high-flow bypass channel, quickly relieving the blockage and avoiding operation interruption. When the bypass channel is open, the high-speed flow of fluid can create a reverse flushing effect on the blocked area, achieving a self-cleaning function. After the blockage is cleared, the system can quickly switch back to normal mode.

[0045] The filling density monitoring component 4 is the core module for realizing real-time perception, intelligent control, and precise construction of downhole conditions. It adopts a distributed high-density layout and can comprehensively and accurately reflect the compaction status of the entire gravel filling cavity.

[0046] Specifically, the filling density monitoring component 4 includes multiple density sensors 41, a data transmission module, and a ground control terminal. The density sensors 41 employ high-frequency resonant sensors with a measurement accuracy of ≤±0.01 g / cm³. 3 It has a wide operating temperature range and strong anti-interference ability, making it suitable for long-term use in wells. Density sensors 41 are evenly embedded and installed along the inner wall of the external screen tube 22 in both the axial and circumferential directions. A group is arranged at certain intervals along the axial direction, and multiple sensors are evenly distributed in the circumferential direction to form a three-dimensional monitoring network, which can collect gravel density data at different heights and directions in real time.

[0047] The data transmission module is integrated inside the central cylinder 21 and connects to each sensor via high-temperature and corrosion-resistant cables. It converts the collected density signals into digital signals and uploads them to the ground control terminal via wired or wireless means. The ground control terminal includes a data processing unit, a display unit, and a command output unit. It can display density cloud maps, density curves, and density distribution status in real time, automatically determine the existence of loose areas, accumulation areas, and blockage areas, and automatically issue control commands based on preset thresholds.

[0048] When the ground terminal determines that the density of a certain area is lower than the standard value, it increases the intensity of the corresponding vibration mechanism in that area to improve compaction; when it determines that the density of a certain area is too high and there is a risk of blockage, it opens the corresponding height bypass channel to divert and clear the blockage; when the overall filling is completed and the density meets the design requirements, it automatically prompts to stop filling. Through closed-loop control of real-time monitoring, intelligent analysis, and dynamic adjustment, the filling process is optimized and the sand control quality is most stable.

[0049] The working principle and process of this invention are as follows: The working process of the filling sand-proof and anti-clogging tubing of the present invention is divided into five stages: filling preparation, gravel filling and vibration compaction, density monitoring and dynamic control, bypass anti-clogging and unclogging, normal production and long-term maintenance.

[0050] 1. Filling preparation stage The entire tubing string is lowered into the target well section, ensuring the screen section is perfectly aligned with the reservoir section. The surface control terminal is powered on and initialized, and all density sensors 41, data transmission modules, and drive actuators are checked for proper functioning. The guide tube 331 is rotated to its initial position, all bypass channels 31 are closed, and the position is secured using the locking mechanism in the drive adjustment unit 33, completing the downhole preparation.

[0051] 2. Gravel filling and vibration compaction stage A ground pump unit pumps a mixture of sand-carrying fluid and gravel into the gravel filling chamber 23 through the injection pipe interface 24. The sand-carrying fluid propels forward within the annular space, creating strong turbulence under the action of the micro-wave structure 5, carrying particles uniformly and inhibiting rapid settling. Simultaneously, some of the sand-carrying fluid enters the central cylinder 21 and flows upward, driving the self-energized vibration mechanism. This causes the sliding block 26 and vibrating block 27 to reciprocate at high frequency, generating stable vibration that continuously compacts the gravel particles, eliminates voids, and achieves uniform filling throughout the entire area.

[0052] 3. Density monitoring and dynamic control stage During the filling process, distributed density sensors collect density data at various locations in real time and upload it to the ground terminal. The terminal generates a density cloud map in real time to determine the filling status. If the density of a certain area is too low, the vibration intensity is automatically increased to promote compaction; if the density of a certain area is too high, it indicates a risk of accumulation, reduces the pump speed, or opens a small bypass diversion; if the overall density reaches the design threshold, it indicates that filling is complete.

[0053] 4. Bypass prevention and unblocking stage If the monitoring system detects a sharp increase in density and an abnormal rise in pressure in a certain section, it determines that there is a risk of sand blockage or that a blockage has already occurred. The ground terminal immediately issues a command to drive the guide tube 331 to rotate, opening the bypass channel 31 at the corresponding height. The sand-carrying fluid bypasses the blocked section through the bypass channel 31, preventing the blockage from expanding. At the same time, the high-speed fluid washes over the blocked area, loosening the accumulated particles. After the blockage is cleared, the system automatically switches back to normal mode to continue filling or production.

[0054] 5. Normal Production and Long-Term Maintenance Phase After filling, a stable gravel sand barrier is formed. Formation fluids are initially filtered through external screen pipe 22, then further filtered through the gravel layer, and finally enter the central cylinder 21 through oil inlet 211, and are transported upwards to the surface. During production, the density monitoring system operates continuously. If the density of the sand barrier layer decreases, the vibration mechanism can be intermittently activated to maintain the density of the gravel. If slight sand blockage occurs, the bypass channel can be opened briefly to achieve self-clearing, ensuring long-term stable production.

[0055] This invention integrates vibration compaction, staged bypass anti-clogging, micro-wave turbulence sand-carrying, and real-time monitoring of packing density into a gravel packing completion and production sand control operation in sand-prone formations such as loose sandstone reservoirs, silty mudstone reservoirs, heavy oil loose sandstone reservoirs, and natural gas hydrate reservoirs. It effectively solves the technical problems commonly encountered by traditional packing strings during construction and production, such as frequent sand blockage, uneven gravel packing density distribution, rapid long-term degradation of sand control effect, and lack of dynamic monitoring and active adjustment capabilities. On the one hand, this invention actively avoids areas with excessive gravel accumulation through bypass channels, preventing production interruptions caused by localized blockages. On the other hand, it relies on a built-in vibration structure to drive dynamic compaction of gravel particles, combined with real-time dynamic adjustment of packing density, to minimize formation sand production, significantly improve the long-term effectiveness and reliability of sand control, and achieve superior sand control results. This invention improves the completion quality and production continuity of oil and gas wells, and reduces downhole operation risks and overall production costs.

[0056] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A filling and sand-proofing anti-clogging tubing string, comprising a tubing string body (1), characterized in that: A vibrating screen tube structure (2) is provided inside the main body (1) of the column. The vibrating screen tube structure (2) includes a central cylinder (21) coaxially installed inside the main body (1). A micro-wave structure (5) is formed on the outer wall of the central cylinder (21). An external screen tube (22) is installed on the outer sleeve of the central cylinder (21). A gravel filling cavity (23) is formed between the central cylinder (21) and the external screen tube (22). A sliding vibration component and a self-powered vibration drive mechanism are provided on the cylinder wall of the central cylinder (21). Five sets of bypass channels (31) are opened along the axial direction inside the side wall of the central cylinder (21). The bypass channels (31) connect the gravel filling cavity (23) and the central cylinder (21). A channel switch component (32) is provided at the channel inlet of each set of bypass channels (31). The channel switch component (32) is connected to the drive adjustment unit (33).

2. The filling sand-proof and anti-clogging tubing string according to claim 1, characterized in that: The wall of the central cylinder (21) is evenly provided with multiple rows of oil inlet holes (211) along the circumference.

3. The filling anti-sand and anti-clogging tubing string according to claim 1, characterized in that: The sliding vibration assembly includes axial vibration vertical grooves (212) symmetrically opened on the inner wall of the central cylinder (21), a sliding block (26) is slidably connected in the vibration vertical groove (212), a receiving groove (261) is opened at the bottom of the sliding block (26), a vibration block (27) is provided in the receiving groove (261), and a fault-tolerant spring (28) is installed below the vibration block (27).

4. The filling anti-sand and anti-clogging tubular string according to claim 1, characterized in that: The micro-wave structure (5) is a continuous smooth wave surface on the outer wall of the central cylinder (21), covering the entire length of the gravel filling cavity (23).

5. The filling sand-proof and anti-clogging tubing string according to claim 1, characterized in that: The flow channel switch assembly (32) includes a valve seat (321) installed on the inner wall of the flow channel, a valve core (322) is slidably provided in the valve seat (321), the valve core (322) is connected to the drive adjustment unit (33) through the transmission column (324), and an elastic reset member (323) is sleeved on the transmission column (324).

6. The filling sand-proof and anti-clogging tubing string according to claim 1, characterized in that: The drive adjustment unit (33) includes a flow guide cylinder (331) that is rotatably mounted on the outside of the external screen tube (22). A drive gear (333) is provided on the outer wall of the flow guide cylinder (331). An annular groove (334) is opened along the circumference of the inner wall of the flow guide cylinder (331). A guide ring (336) is embedded in the annular groove (334). The guide ring (336) is connected to the transmission column (324) of the flow channel switch assembly (32).

7. A filling anti-sand and anti-clogging tubular string according to claim 6, characterized in that: The bottom of the annular groove (334) is a cam surface with gradually changing depth along the circumferential direction.

8. A filling anti-sand and anti-clogging tubular string according to claim 1, characterized in that: Multiple density sensors (41) are embedded in the inner wall of the external sieve tube (22). The density sensors (41) are connected to the data transmission module via cables. The data transmission module transmits the signal to the ground terminal via wired or wireless means.

9. A filling anti-sand and anti-clogging tubing string according to claim 1, characterized in that: An injection pipe interface (24) is provided at the upper part of the external screen tube (22).

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