Special-shaped expandable corrugated screen pipe for deep well and ultra-deep well and forming method

Abstract

The invention belongs to the technical field of petroleum and natural gas, and discloses a special-shaped expandable corrugated screen pipe for a deep well and an ultra-deep well and a forming method.The special-shaped expandable corrugated screen pipe comprises a filtering assembly, and the outer wall of the filtering assembly is attached to the well wall; the filtering assembly comprises an 8-shaped base pipe, the base pipe is connected with the exploitation pipe through a transition connector, a plurality of filtering gaps arranged in an array mode are formed in the side wall of the base pipe in a penetrating mode, oil gas is allowed to enter an inner cavity of the base pipe, and mud and sand in a reservoir are stopped from entering a well. Before the base pipe is tripped into a mining well, the base pipe is machined through a cold press forming technology, and a contraction section of an 8-shaped corrugated structure is formed; after the contraction section is placed in a set position of the mining well, the contraction section is mechanically expanded through a mechanical shaping tool to be expanded and unfolded into a circular base pipe to be tightly attached to the well wall. The sand prevention function of the screen pipe and the well wall supporting function of the expansion corrugated pipe are organically combined, on the premise that the size of a well hole is not reduced, sand prevention and control and well wall stability are achieved at the same time, and the expansion corrugated pipe is suitable for high-temperature and high-pressure and complex geological conditions of deep wells and ultra-deep wells.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and natural gas extraction, and in particular to a special-shaped expandable corrugated screen pipe for deep wells and ultra-deep wells and a forming method thereof. Background Art

[0002] Wellbore stability and sand control are two key technical challenges in deep and ultra-deep well oil and gas production. These challenges are particularly acute in deep and ultra-deep wells, where high formation pressures, temperatures, and complex geological conditions are present. Uncontrolled sand can enter the wellbore, causing wear and tear on downhole equipment, clogging the wellbore, and potentially even causing wellbore collapse, severely impacting normal oil and gas production.

[0003] Traditional screens are prefabricated with narrow slits or other forms of filtration channels in the base pipe to prevent sand from entering the wellbore while allowing oil and gas fluids to pass through. Their advantages include excellent sand control and filtration, and a large fluid flow area. However, in deep and ultra-deep wells, the wellbore structure is complex, and the deployment of conventional screens significantly reduces the wellbore size, impacting oil and gas production efficiency. As oil and gas exploration and development progresses toward deep and ultra-deep wells, the downhole environment becomes increasingly complex. Existing conventional screen technology is no longer able to meet the dual requirements of sand control and wellbore protection while maintaining oil and gas production efficiency.

[0004] Therefore, there is an urgent need to develop a special-shaped expandable corrugated screen pipe and a forming method for deep and ultra-deep wells to meet engineering applications in complex environments of deep and ultra-deep wells. Summary of the Invention

[0005] The present invention aims to provide a special-shaped expandable corrugated screen for deep and ultra-deep wells and its forming method to address the technical problem of conventional screens reducing wellbore diameter after deployment, thereby affecting oil and gas production efficiency. The filter assembly comprises a filter assembly connected to a production pipe in a production well, the outer wall of which is in contact with the production well wall;

[0006] The filter assembly includes an 8-shaped base pipe, which is connected to the production pipe through a transition joint. The side wall of the base pipe is provided with a plurality of filter slots arranged in an array, allowing oil and gas to enter the base pipe cavity and preventing mud and sand in the production well from entering;

[0007] Before the base pipe is lowered into the mining well, it is processed by cold pressing and extrusion forming to form a contraction section with an 8-shaped corrugated structure;

[0008] After the contraction section is placed in a set position in the mining well, it is expanded by a mechanical shaping tool so that the contraction section is expanded and unfolded into the base pipe.

[0009] Preferably, the outer diameter of the base pipe is larger than the outer diameter of the production pipe, and both ends of the base pipe are fixedly connected and communicated with the production pipe through the transition joint.

[0010] Preferably, the plurality of filtering slits are distributed axially or spirally along the surface of the base pipe.

[0011] Preferably, after the filter gap is extruded and then expanded, the width of the filter gap is no greater than the diameter of the mud and sand.

[0012] Preferably, an expansion section corresponding to the base pipe is provided on the production well, the diameter of the expansion section is larger than the diameter of the production pipe, and the outer wall of the base pipe is supported in contact with the side wall of the expansion section.

[0013] The present invention also discloses a method for forming a special-shaped expandable corrugated screen pipe for deep wells and ultra-deep wells, comprising the following steps:

[0014] High-strength alloy pipes are used as base pipes, and arrayed filter slits are machined on the surface to form a filter component with sand control function;

[0015] Pre-treat the processed filter components to ensure they have good plastic deformation ability and strength characteristics;

[0016] Using precision cold pressing technology, the filter component is pressed into a contraction section with an 8-shaped corrugated structure under low temperature environment;

[0017] Perform stress relief treatment on the shrinkage section after molding to eliminate the internal stress generated during the molding process;

[0018] Use non-destructive testing technology to conduct comprehensive testing on the corrugated screen to ensure that the product quality meets the use requirements;

[0019] Under simulated underground mining environment conditions, the expansion performance, filtration effect and mechanical strength comprehensive performance tests of the contraction section were carried out.

[0020] Preferably, the pretreatment process of the substrate tube includes ultrasonic cleaning, surface electrochemical treatment and solution heat treatment, and the solution treatment is carried out in a nitrogen protection environment at a temperature of 920° C.±0° C. and a holding time of 2.5-5 hours.

[0021] Preferably, the cold pressing of the filter assembly requires extrusion molding using a mold through multiple steps.

[0022] Preferably, the cold pressing process of the filter assembly is completed in no less than six times, and the compression rate of each time is controlled below 3%.

[0023] Preferably, the performance test of the contraction section includes an expansion capacity test, a sand control efficiency test, a cyclic load test and a corrosion resistance test under temperature conditions of not less than 80° C. and pressure conditions of not less than 50 MPa.

[0024] Compared with the prior art, the special-shaped expandable corrugated screen for deep and ultra-deep wells disclosed in the present invention has the following advantages and technical effects:

[0025] 1. Functional integration: The filter assembly organically combines the sand control and filtration function of the screen with the function of post-deployment compensation to reduce the wellbore diameter, realizing an integrated solution, effectively maintaining bottomhole stability without affecting oil and gas production efficiency.

[0026] 2. No reduction in wellbore size: After the production well is in place, the base pipe is mechanically expanded and shaped by a mechanical shaping tool. After expansion, it clings to the wellbore wall of the production well. Compared with the disadvantage of traditional screen pipes that permanently reduce the effective diameter of the production section wellbore, the special-shaped expandable corrugated screen pipe for deep wells and ultra-deep wells of the present invention does not affect oil production efficiency.

[0027] 3. Excellent sand control effect: The prefabricated filter gaps on the base pipe are reasonably designed, which can effectively prevent sand particles in the mining well from entering the wellbore, and at the same time prevent sand particles from clogging the filter gaps, ensuring sufficient flow capacity for fluids such as oil and gas, and the flow capacity is better than that of conventional screen pipes.

[0028] 4. Strong well wall support: The expanded base pipe can fit closely to the well wall of the production well, providing effective support for unstable well sections, preventing collapse and improving the safety of oil and gas production.

[0029] 5. Good adaptability: The 8-shaped corrugated design of the contraction section gives the product good deformation ability, can adapt to various irregular well walls, and improve the compensation effect.

[0030] 6. Easy installation: The shrinking section after diameter reduction has low resistance when lowered into the mining well, and can smoothly reach the target position of deep wells and ultra-deep wells, reducing the difficulty and risk of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0032] Figure 1 This is an axial view of the filter assembly of the present invention;

[0033] Figure 2 This is a schematic diagram of the structure of the filter assembly of the present invention;

[0034] Figure 3 This is an axial view of the contraction section of the present invention;

[0035] Figure 4 Schematic diagram showing cross-section comparison of the base pipe and the contraction section of the present invention;

[0036] Figure 5 This is a schematic diagram of the cold pressing process of the substrate tube of the present invention;

[0037] Figure 6 This is a schematic diagram of the contraction section expansion step of the present invention;

[0038] In the figure: 1. Production well; 2. Production pipe; 3. Base pipe; 4. Filter gap; 5. Contraction section; 6. Mechanical shaping tool; 7. Transition joint; 8. Expansion section; 9. Cold pressing mold. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Reference Figures 1-6 As shown, this example provides a special-shaped expandable corrugated screen for deep and ultra-deep wells, comprising a filter assembly connected to a production pipe 2 in a production well 1, wherein the outer wall of the filter assembly is attached to the wall of the production well 1 after mechanical expansion;

[0042] The filter assembly includes an 8-shaped base pipe 3, which is connected to the production pipe 2 via a transition joint 7. The side wall of the base pipe 3 is penetrated by a plurality of filter slits 4 arranged in an array, allowing oil and gas to enter the inner cavity of the base pipe 3 while preventing mud and sand in the reservoir from entering.

[0043] Before the base pipe 3 is lowered into the mining well 1, it is processed by cold pressing to form a contraction section 5 with an 8-shaped corrugated structure;

[0044] After the contraction section 5 is placed in a set position under the mining well 1 , it is expanded by a mechanical shaping tool 6 so that the contraction section 5 is expanded and unfolded into a base pipe 3 .

[0045] The present invention discloses a special-shaped expandable corrugated screen pipe for deep wells and ultra-deep wells and a forming method thereof. The screen pipe is mainly composed of a filter assembly connected to a production pipe 2 in a production well 1. The outer wall of the filter assembly can abut against the wall of the production well 1, playing a supporting and filtering role, thereby enhancing the stability of the screen pipe and preventing it from collapsing during the production process; the filter assembly includes a circular base pipe 3 connected to the production pipe 2, and a plurality of filter slots 4 arranged in an array are provided on the side wall of the base pipe 3. These slots allow oil and gas to enter the inner cavity of the base pipe 3, and can effectively block impurities such as mud and sand from entering the production pipe 2, preventing gravel from clogging the wellbore or damaging the wellbore Lower the instrument and equipment; before the base pipe 3 is lowered into the mining well 1, the base pipe 3 is processed into a contraction section 5 with an 8-shaped corrugated structure through a cold pressing process to reduce the diameter of the screen pipe, so that the base pipe 3 can maintain a smaller diameter when placed in the mining well 1, which is convenient for lowering; after the contraction section 5 is placed in the set position of the mining well 1, the contraction section 5 is mechanically expanded using a mechanical shaping tool 6 to expand it into the original shape of the base pipe 3, so that the base pipe 3 is close to the wall of the mining well 1, playing an effective sand prevention role. The special-shaped expandable design can adapt to the complex environment of deep wells and ultra-deep wells, and improve mining efficiency without reducing the diameter of the production section wellbore. The present invention organically combines the sand prevention function of the screen pipe with the wellbore support function of the expansion bellows. Without reducing the wellbore size, it solves the problems of sand prevention and control and wellbore stability at the same time. It is suitable for deep wells and ultra-deep wells with high temperature, high pressure and complex geological conditions.

[0046] In one embodiment of the present invention, the base pipe 3 is made of Ni-Cr-Mo-V high-strength alloy material with a wall thickness of 8-10 mm. It has excellent high temperature resistance, corrosion resistance and high strength properties and is suitable for underground high temperature and high pressure environments.

[0047] In one embodiment of the present invention, the base tube 3 is cold pressed from four mutually perpendicular directions of the outer wall using cold pressing dies 9. The cold pressing dies 9 on opposite sides are symmetrically arranged, so that the outer diameter thereof is reduced by 15%-25% compared with the original size.

[0048] In one embodiment of the present invention, the corrugation height of the 8-shaped corrugated structure of the contraction section 5 is 10-15 mm, and the wave pitch is 35-45 mm.

[0049] In a further optimized solution, the outer diameter of base pipe 3 is larger than that of production pipe 2, and both ends of base pipe 3 are fixedly connected to and communicate with production pipe 2 via transition joints 7. Production well 1 is provided with an expansion section 8 corresponding to base pipe 3. The diameter of expansion section 8 is larger than that of production pipe 2, and the outer wall of base pipe 3 is mechanically expanded to fit against the sidewall of expansion section 8. The outer diameter of base pipe 3 is larger than that of production pipe 2, and the transition connection of transition joint 7 ensures the coaxiality of base pipe 3 and production pipe 2, avoids fluid turbulence, and improves the connection strength. At the same time, the outer diameter of base pipe 3 is larger than that of production pipe 2, and the outer diameter of base pipe 3 is adapted to expansion section 8, so that the expanded base pipe 3 can be precisely positioned on the wellbore expansion section 8, preventing axial movement, enhancing the isolation effect, providing effective support for unstable well sections, and preventing collapse. This improves the safety of oil and gas production, avoids reducing the effective diameter of the production wellbore, and ensures oil and gas production efficiency.

[0050] In one embodiment of the present invention, the transition joint 7 is a specially processed reducer transition head, which is convenient for connection with the conventional mining pipe 2. The circular end of the joint is connected to the running tool through a thread, and the end with a special cross-section is connected to the base pipe 3 by welding.

[0051] A further optimization scheme features multiple filtration slots 4 distributed axially or helically along the surface of the base tube 3. The filtration slots 4 of this invention have a rectangular cross-section and are distributed axially or helically along the base tube 3, with a helical angle of 20°-45° to avoid localized concentration. After cold pressing, the slot integrity retention rate exceeds 98%. Furthermore, the helically distributed filtration slots 4 reduce fluid resistance, create a turbulent effect, and reduce the probability of sand deposition, thereby enhancing self-cleaning capabilities and increasing filtration efficiency by 15%.

[0052] In one embodiment of the present invention, the filter gap 4 has a width of 50-200 μm and a length of 15-50 mm.

[0053] In one embodiment of the present invention, the number density of the filtering gaps 4 is 500-700 per square decimeter, and the distance between the gaps is 4-6 mm.

[0054] In one embodiment of the present invention, the edge of the filter slot 4 is chamfered, and the edge fillet radius is controlled within the range of 20-30 μm to reduce stress concentration.

[0055] A further optimization scheme ensures that the width of the filter slot 4, after extrusion and expansion, is no larger than the diameter of the sand. Because the base pipe 3 behind the filter slot 4 is cold-formed and then expanded and reset, this can cause the slot 4 to deform. Controlling the width of the filter slot 4 during the cold-pressing deformation and expansion process ensures effective interception of target sand particles, achieving a sand control efficiency of 97%.

[0056] The present invention also discloses a method for forming a special-shaped expandable corrugated screen pipe for deep wells and ultra-deep wells, comprising the following steps:

[0057] A high-strength alloy tube is used as the base tube 3, and an array of filter slots 4 are machined on the surface to form a filter assembly with sand control function. The filter slots are machined using precision CNC laser cutting technology, and the slot edges are chamfered after cutting.

[0058] The processed filter assembly is pretreated to ensure that it has good plastic deformation ability and strength characteristics. The pretreatment process of the base tube 3 includes ultrasonic cleaning, surface electrochemical treatment and solution heat treatment. The solution treatment is carried out in a nitrogen atmosphere at a temperature of 920°C ± 10°C for 2.5-5 hours.

[0059] Using precision cold pressing technology, the filter assembly is pressed into a contraction section 5 having an 8-shaped corrugated structure in a low-temperature environment. The cold pressing of the filter assembly is carried out at a temperature of -40°C to 30°C, with a pressure controlled at 800-1000 MPa. The cold pressing process of the filter assembly is completed in no less than six steps, with the compression rate of each step controlled at less than 3%.

[0060] The shrinkage section 5 after molding is subjected to stress relief treatment to eliminate the internal stress generated during the molding process; the stress relief is carried out under the protection of inert gas, the temperature is controlled at 280℃±10℃, the holding time is 5 hours, and the cooling rate is 40℃ per hour;

[0061] The corrugated screens are fully inspected using non-destructive testing technology to ensure that product quality meets the requirements. Quality testing includes phased array ultrasonic testing, industrial CT scanning testing, and pressure testing. The pressure test pressure is 1.5 times the design working pressure, and the pressure holding time is not less than 30 minutes.

[0062] Under the environmental conditions simulated in the mining well 1, the contraction section 5 is subjected to comprehensive performance tests of expansion performance, filtration effect and mechanical strength; the performance tests of the contraction section 5 include expansion capacity test, sand control efficiency test, cyclic load test and corrosion resistance test under the conditions of temperature not less than 180°C and pressure of 50MPa.

[0063] Example 1:

[0064] like Figures 1 to 5 As shown, the present invention provides a special-shaped expandable corrugated screen pipe for deep wells and ultra-deep wells, comprising a base pipe 3 and a filtering gap 4 arranged on the surface of the base pipe 3. The base pipe 3 is cold-pressed into a special-shaped corrugated screen pipe with an 8-shaped corrugated structure.

[0065] The base pipe 3 is made of a high-strength Ni-Cr-Mo-V alloy with a wall thickness of 8-10 mm. It exhibits excellent heat and corrosion resistance, as well as high strength, making it suitable for use in high-temperature, high-pressure downhole environments. Narrow filter slits 4, 30 mm long and 100 μm wide, are prefabricated on the surface of the base pipe 3. These slits are evenly distributed along the axial direction, with a spacing of 5 mm between them. There are approximately 600 filter slits 4 per square decimeter of surface, effectively preventing reservoir sand from entering the wellbore.

[0066] The figure-eight corrugated structure is formed by pressing it through a dedicated cold-pressing die 9, reducing the outer diameter by approximately 20% compared to the original size. The cold-pressing process is gradual, with each step containing less than 3% compression to prevent deformation or damage to the filter gap 4. After cold-pressing, a special heat treatment process eliminates internal stresses, ensuring product stability and reliability.

[0067] like Figure 6 As shown, after the corrugated screen is lowered into the target wellbore, the mechanical shaping tool 6 causes the contracted section 5 of the figure-eight corrugated structure to gradually return to a circular shape, forming the base pipe 3 and fitting tightly against the inner wall of the expanded section 8. During the expansion process, the filter gap 4 expands slightly, but remains within the design allowable range of 120-150μm, ensuring the proper function of the sand control function.

[0068] like Figure 6 As shown, after expansion, there is no gap between the expanded base pipe 3 and the wellbore wall. This not only supports the wellbore wall in the production section and prevents collapse, but also provides sand control through the retained filter slits 4. Oil and gas can enter the wellbore through the filter slits 4, forming a flow path for oil and gas, while sand particles are blocked by the filter slits 4. This overcomes the shortcomings of traditional screens (which reduce wellbore size) and conventional expansion bellows (which lack sand control), achieving an organic combination of functions.

[0069] Example 2:

[0070] The forming method of the special-shaped expandable corrugated screen pipe of the present invention comprises the following specific steps:

[0071] 1. Preparation of filter components:

[0072] The base tube 3 is made of a high-strength Ni-Cr-Mo-V alloy with a yield strength of no less than 800 MPa, a tensile strength of no less than 1000 MPa, and an elongation of no less than 15%. Precision CNC laser cutting technology is used to create filtration slits 4 measuring 30 mm x 100 μm on the tube surface. The slits are arranged in a spiral pattern along the tube surface at a 30° angle to enhance filtration efficiency and structural strength. After cutting, the slits are chamfered to a radius of no more than 20 μm to prevent stress concentration and sharp edges in the filtration slits 4.

[0073] 2. Pretreatment process:

[0074] The processed filter components are ultrasonically cleaned to remove surface impurities and oil, followed by surface electrochemical treatment to form a uniform protective film. Solution treatment is then performed in a nitrogen atmosphere at 920°C ± 10°C for two hours, followed by rapid cooling to room temperature to achieve optimal plastic deformation, laying the foundation for subsequent cold forming.

[0075] 3. Corrugated forming:

[0076] A dedicated cold-pressing mold 9 is used to form the pre-treated filter assembly into an 8-shaped corrugation. The cold-pressing process is controlled within the temperature range of -35°C ± 5°C, and a liquid nitrogen spray system is used for cooling to ensure that the material undergoes plastic deformation at low temperatures. The cold-pressing pressure is controlled at approximately 900 MPa, and the compression process is completed in six steps, with the compression rate of each step controlled below 3% to avoid gap deformation or cracking. Intermediate inspections are performed after each compression step to ensure that the filter gap 4 is intact. The final outer diameter of the corrugated screen tube is approximately 20% smaller than the original size, with a corrugation height of 12 mm and a wave pitch of 40 mm.

[0077] 4. Stress relief:

[0078] The formed compressed section is placed in a dedicated stress relief device 11 and subjected to low-temperature stress relief treatment under inert gas protection. The temperature is controlled at 280°C ± 10°C for 5 hours, and then slowly cooled to room temperature at a rate of 40°C per hour. This effectively eliminates the internal stress generated during the cold forming process and improves the dimensional stability and reliability of the product.

[0079] 5.Quality inspection:

[0080] Phased array ultrasonic testing technology is used to conduct a 100% comprehensive inspection of the product, focusing on the integrity of the filter gap 4 and the consistency of the corrugated structure. Industrial CT scanning technology is also used for non-destructive testing of key product areas to ensure the absence of cracks, deformation, and other defects. Pressure testing is conducted in accordance with API standards at 1.5 times the design working pressure, with a holding time of at least 30 minutes, to verify the product's sealing and strength.

[0081] 6. Performance testing:

[0082] In a high-temperature, high-pressure test facility, the compression section of the corrugated screen was subjected to comprehensive performance tests, simulating downhole environmental conditions at 180°C and 50 MPa. These tests included: expansion capacity testing, using the same mechanical shaping tool used in actual operations (6), to measure the expansion ratio and force; sand control efficiency testing, using standard sand samples with a particle size of 50-300 μm to perform filtration tests, recording filtration efficiency and fluid flow rate; cyclic load testing, subjecting the product to 100,000 axial and radial cyclic loads to simulate downhole conditions to verify fatigue performance; and corrosion resistance testing, immersing the product in an environment with a 2000 ppm H2S content and a 10% CO2 content for 500 hours, measuring corrosion rate and strength changes. Test results showed that the corrugated screen retained over 98% of its original design strength after expansion, with a sand control efficiency exceeding 95%. The system is expected to have a service life of 3 to 5 years in a high-temperature environment of 180°C.

[0083] Example 3:

[0084] The present invention's special-shaped expandable corrugated screen was successfully used in a high-temperature, high-pressure gas well at a depth of 6,500 meters. The well is located in a complex geological area with a downhole temperature of approximately 170°C and a pressure of approximately 48 MPa. The target formation is low-permeability sandstone, which is subject to severe sand production and localized formation instability.

[0085] Based on the specific conditions of this well, a custom-designed expandable corrugated screen system was developed, consisting of multiple sections of corrugated screens and a dedicated expansion tool. The screen design parameters are as follows: the base pipe (3) is made of a special Ni-Cr-Mo-V-Ti alloy; the filter slots (4) are 80 μm wide and 25 mm long, distributed in a spiral pattern; the corrugations are 14 mm high, 35 mm pitch, and a 22% reduction ratio.

[0086] During construction, multiple sections of corrugated screen pipe are first connected on the surface using welding equipment. A special sealing welding process is used to ensure that the weld strength is at least 95% of the parent material strength. After each section is welded, the weld quality is rigorously inspected using X-ray nondestructive testing equipment. Only qualified welds can be lowered into the well.

[0087] After the corrugated screen is lowered into the target well section, a hydraulically driven mechanical shaping tool 6 is used to expand the screen. The expansion process is carried out in stages, with an expansion pressure of 35-40 MPa and an expansion rate of approximately 2-3 meters per hour. During the expansion process, a downhole monitoring system monitors expansion parameters in real time to ensure expansion quality.

[0088] After the well was completed, production testing and downhole inspections revealed that the corrugated screen successfully resolved the existing sand production and wellbore instability issues, reducing the sand content in the produced fluid by 97% and significantly enhancing wellbore stability, with no collapse observed. Furthermore, the use of the corrugated screen technology maintained the original wellbore diameter, resulting in no loss of production capacity and an actual gas production rate approximately 25% higher than that of a traditional screen completion solution.

[0089] After 18 months of continuous production monitoring, the well maintained stable production without issues such as sand plugging, screen deformation, or corrosion perforation, fully demonstrating the applicability and reliability of the proposed special-shaped expandable corrugated screen. This technology has since been applied in several other deep wells with similar conditions, achieving excellent results, providing a new technical solution for the completion of deep and ultra-deep wells in complex formations.

[0090] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0091] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A special-shaped expandable corrugated screen for deep and ultra-deep wells, characterized by: It comprises a filter assembly connected to a production pipe (2) in a production well (1), wherein the outer wall of the filter assembly is attached to the wall of the production well (1) after mechanical expansion; The filter assembly comprises an 8-shaped base pipe (3), the base pipe (3) being connected to the production pipe (2) via a transition joint (7), and a plurality of filter slits (4) arranged in an array are provided through the side wall of the base pipe (3), allowing oil and gas to enter the inner cavity of the base pipe (3) and preventing mud and sand in the reservoir from entering; Before the base pipe (3) is lowered into the mining well (1), it is processed by a cold pressing process to form a contraction section (5) with an 8-shaped corrugated structure; After the contraction section (5) is placed in a set position below the mining well (1), it is expanded by a mechanical shaping tool (6) so that the contraction section (5) is expanded and unfolded into the base pipe (3).

2. The special-shaped expandable corrugated screen for deep and ultra-deep wells according to claim 1, characterized in that: The outer diameter of the base pipe (3) is greater than the outer diameter of the production pipe (2), and both ends of the base pipe (3) are fixedly connected and communicated with the production pipe (2) via the transition joint (7).

3. The special-shaped expandable corrugated screen for deep and ultra-deep wells according to claim 1 is characterized by: The plurality of filtering slits (4) are distributed axially or spirally along the surface of the base pipe (3).

4. The special-shaped expandable corrugated screen for deep and ultra-deep wells according to claim 1, characterized in that: After the filtering gap (4) is extruded and then expanded, the width of the filtering gap (4) is no greater than the diameter of the mud and sand.

5. The special-shaped expandable corrugated screen for deep and ultra-deep wells according to claim 2, characterized in that: An expansion section (8) corresponding to the base pipe (3) is provided on the production well (1); the diameter of the expansion section (8) is larger than the diameter of the production pipe (2); and the outer wall of the base pipe (3) is supported against the side wall of the expansion section (8).

6. A method for forming a special-shaped expandable corrugated screen pipe for deep and ultra-deep wells, used for producing the special-shaped expandable corrugated screen pipe for deep and ultra-deep wells according to any one of claims 1 to 5, characterized in that The following steps are involved: A high-strength alloy pipe is selected as a base pipe (3), and array-arranged filter slits (4) are machined on the surface to form a filter assembly with a sand control function; Pre-treat the processed filter components to ensure they have good plastic deformation ability and strength characteristics; Using precision cold pressing technology, the filter component is pressed into a contraction section (5) having an 8-shaped corrugated structure under a low temperature environment; Performing stress relief treatment on the contraction section (5) after forming to eliminate the internal stress generated during the forming process; Use non-destructive testing technology to conduct comprehensive testing on the corrugated screen to ensure that the product quality meets the use requirements; Under the environmental conditions of a simulated mining well (1), the contraction section (5) is tested for its expansion performance, filtering effect and mechanical strength.

7. The method for forming a special-shaped expandable corrugated screen pipe for deep and ultra-deep wells according to claim 6, characterized in that: The pretreatment process of the substrate tube (3) includes ultrasonic cleaning, surface electrochemical treatment and solution heat treatment. The solution heat treatment is carried out in a nitrogen protection environment at a temperature of 920°C±10°C and a holding time of 1.5-2.5 hours.

8. The method for forming a special-shaped expandable corrugated screen for deep and ultra-deep wells according to claim 6, characterized in that: The cold pressing of the filter assembly requires multiple extrusion steps.

9. The method for forming a special-shaped expandable corrugated screen pipe for deep and ultra-deep wells according to claim 8, characterized in that: The cold pressing process of the filter assembly is completed in no less than six times, and the compression rate of each time is controlled below 3%.

10. The method for forming a special-shaped expandable corrugated screen pipe for deep and ultra-deep wells according to claim 6, characterized in that: The performance tests on the contraction section (5) include expansion capacity test, sand control efficiency test, cyclic load test and corrosion resistance test under temperature conditions of not less than 180° C. and pressure conditions of not less than 50 MPa.

Images