Hoop rolling friction sucker rod centralizer

Abstract

The invention discloses a clamp rolling friction sucker rod centralizer which is applied to the field of oil exploitation equipment. The centralizer is formed by clamping two single-side spiral three-blade centralizing blocks, a single block is twisted to form a spiral inserting structure, and the centralizer is in a double-side six-blade form after being combined. Different from a traditional straight blade four-blade structure, the double-side spiral six-blade design can improve the well wall supporting effect, the single-side three-blade design increases the blade gap, the middle smooth liquid flow transition zone is matched, and the overflowing efficiency is remarkably optimized. The centralizing blocks adopt rolling friction design, and internal gradient extrusion hemispheres enhance grip strength and structural reliability. Compared with a traditional scheme, fluid resistance and friction force to an oil pipe well wall are effectively reduced, a sucker rod is evenly supported, eccentric wear is reduced, installation is convenient and fast, adaptability is high, the stability of an oil extraction system is improved, and the service life of equipment is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction equipment, and particularly to a clamp rolling friction sucker rod centralizer, which is mainly used for centralizing the sucker rod in a rod pumping system to reduce the friction between the sucker rod and the tubing, improve the oil production efficiency and extend the service life of the equipment. Background Art

[0002] In the common rod pumping operation in oil extraction, the inner wall of the tubing and the sucker rod are easily damaged due to friction. The elasticity of the sucker rod causes it to deform and adhere to the wall when the wellbore is bent or the load is uneven. The complex wellbore shape intensifies the contact, and the fatigue corrosion after long-term use will further deteriorate the friction. Therefore, a centralizer needs to be installed on the sucker rod to improve this problem.

[0003] The currently common four-leaf centralizer has obvious deficiencies. In terms of the flow-through area, its four-leaf structure results in a small gap between the leaves, which hinders the fluid passage during oil production, not only increasing energy consumption and reducing the oil production efficiency. In terms of wellbore support, the four-leaf centralizer has limited support points, and it is difficult to stably support the sucker rod in the face of complex well conditions, easily causing severe eccentric wear between the centralizer and the inner wall of the tubing, thereby shortening the service life of the equipment, increasing the maintenance cost and replacement frequency.

[0004] Currently, in the oilfield construction site, an injection molding machine is used to inject a centralizer with a single-sided three-leaf, double-sided six-leaf structure or a spiral blade onto the sucker rod through an injection molding process. However, this process has problems such as complex construction, large equipment investment, long cycle and inconvenient use. Therefore, a new type of split clamp rolling friction sucker rod centralizer is developed to solve the above problems.

[0005] Currently, the inner diameter bump height of the centralizer is the same. To enhance the grip on the sucker rod, an expanded wedge-shaped insertion wing design is adopted, and its thickness is greater than the width of the insertion groove. Although this structure can improve the grip, it will make the insertion groove of the centralizer face a higher cracking risk in winter. Therefore, it is necessary to optimize from the structural design to balance performance and reliability.

[0006] For the currently applied injection-molded clamp sucker rod centralizer, its friction surface mainly uses an injection-molded body or carbon fiber material, and the friction form with the inner wall of the tubing is sliding friction. This friction method will generate a large amount of friction, which will not only significantly reduce the pump efficiency but also greatly shorten the actual service life of the centralizer. Summary of the Invention

[0007] The present invention aims to provide a clamp rolling friction sucker rod centralizer. Through the structural design of a split clamp three-leaf spiral centralizing block, the flow-through area is increased, the number of wellbore support leaves is increased, the eccentric wear between the centralizer and the tubing is reduced, and at the same time, the installation convenience is improved. The design of the rolling ball sleeve combination reduces friction while avoiding the embedding and detachment of the rolling balls from the centralizing block, reducing the comprehensive cost.

[0008] A kind of clamp rolling friction sucker rod centralizer disclosed by the present invention has the following specific technical solutions: A kind of clamp rolling friction sucker rod centralizer, characterized in that it is formed by clamping two identical centralizing blocks. The centralizing block is a unilateral spiral three-leaf structure, and the whole centralizing block is twisted 45°±2° along the inner circle central axis to form a spiral insertion structure. After the two centralizing blocks are clamped, a spiral six-leaf structure is formed; One end of the centralizing block is provided with an insertion convex part, and the other end is provided with an insertion concave part. The middle part of the centralizing block is designed as a transition semi-ring structure. After the two centralizing blocks are clamped, the transition semi-ring forms a smooth fluid flow transition zone; The insertion concave part is a unilateral spiral three-leaf structure, and the three blades are evenly distributed in the circumferential direction. A ball sleeve is embedded on each blade through a pre-placed and then injection-molded process, and the ball sleeve semi-wraps the rolling ball; Insertion grooves are designed at the inner holes of the lower left blade and the lower right blade, and limit bumps are designed in the insertion grooves; The insertion convex part is designed with two symmetric insertion wings with an included angle of 120°. The insertion wings can be clamped and matched with the insertion grooves. A right-angled triangle limit groove is designed at a position 15 mm away from the end face of the insertion convex part on the insertion wings; 80 - 150 extrusion hemispheres are distributed in a matrix in the inner semi-ring of the centralizing block.

[0009] Compared with the prior art, the present invention has the following remarkable beneficial effects: 1. The flow area is increased Compared with the traditional four-leaf centralizer, the clamp rolling friction sucker rod centralizer of the present invention forms a six-leaf structure after the combination of two centralizing blocks. The gap between the unilateral three blades is significantly increased, thus greatly improving the flow area. During the oil production process, the fluid can pass through the centralizer more smoothly, reducing the fluid flow resistance, reducing the energy loss of the fluid when passing through the centralizer, and helping to improve the overall efficiency of the oil production system. At the same time, the smaller fluid resistance makes the suction pressure of the pump more stable, which can ensure the pump works more stably and reduce the probability of pump failure;

[0010] 2. The wellbore support effect is improved After the two centralizing blocks are clamped, a spiral six-leaf structure is formed. Compared with the traditional four-leaf centralizer, the number of wellbore support leaves increases. More support leaves can be distributed more evenly around the sucker rod, providing more stable and balanced support force. The spiral blades are in more uniform contact with the wellbore, reducing eccentric wear. This centralizer can better keep the sucker rod in the center position of the tubing;

[0011] 3. The structure is stable and reliable The clamp structure of the centralizer block is uniquely designed with a spiral insertion method, ensuring sufficient axial locking force after installation. At the same time, the insertion convex part 2 and the insertion concave part 1 are closely matched. Coupled with the mutual cooperation of the limit convex block 5 and the right triangle limit groove 11, it is ensured that the two centralizer blocks will not separate during operation, guaranteeing the structural stability of the centralizer and enabling it to play a reliable centralizing role in complex downhole environments;

[0012] 4. Split Clamp of Centralizer The present invention uses the clamp installation of two identical centralizer blocks. During the injection molding production in the workshop, the same mold can be used to manufacture these two identical centralizer blocks, greatly reducing production investment. During on-site construction, compared with the on-site injection molding process of the centralizer that requires an expensive vehicle-mounted injection molding machine for on-site construction, the present invention not only has low investment but also avoids complex on-site operations and improves the construction progress;

[0013] 5. Extruded Hemisphere Distribution The protruding height of the extruded hemisphere is designed with the lowest in the middle and gradually increasing towards both sides. When the clamp is installed, the extruded hemisphere can be deformed and extruded. The lowest protruding height in the middle is convenient for clamp installation; the higher protruding heights on both sides are conducive to increasing the gripping force after the centralizer is installed and improving the radial load-bearing capacity. Different from the wedge-shaped insertion wing structure, after installation, the centralizer bears the gripping force through the overall structure, and the insertion wing does not adopt an expanding wedge-shaped structure, which can make the force in the insertion groove uniform and reduce the risk of cracking in the insertion groove from the structure;

[0014] 6. Rolling Ball Sleeve Assembly The design of the rolling ball sleeve assembly significantly reduces the frictional resistance by replacing sliding friction with rolling friction. At the same time, the conical structure at the lower part of the outer side of the ball sleeve is combined with an inverted tooth design, which cleverly restricts the displacement of the ball sleeve, avoiding both the rolling ball from detaching from the assembly and its complete embedding in the centralizer block, thereby effectively improving the reliability and service life of the centralizer; BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is a schematic structural diagram of a clamp rolling friction sucker rod centralizer; Figure 2 It is a schematic structural diagram of a clamp sucker rod centralizer block; Figure 3 It is a schematic diagram after installing the sucker rod on a clamp rolling friction sucker rod centralizer; Figure 4It is the left view after the installation of a clamp rolling friction sucker rod centralizer; Figure 5 It is the front view after the installation of a clamp rolling friction sucker rod centralizer; Figure 6 It is a schematic diagram of the ball sleeve of a clamp rolling friction sucker rod centralizer.

[0017] Explanation of reference numerals: 1. Insertion concave part; 2. Insertion convex part; 3. Insertion wing; 4. Extrusion hemisphere; 5. Limit convex block; 6. Insertion groove; 7. Lower left blade; 8. Lower right blade; 9. Transition half ring; 10. Upper blade; 11. Limit groove; 12. Rolling ball; 13. Ball sleeve. Specific implementation manners

[0018] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be described comprehensively, clearly, and completely. It should be clear that the described embodiments are only a 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 those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0019] In the description of the present invention, it should be particularly noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. These terms are only for the convenience of describing the present invention and simplifying the description, and in no way indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, in practical applications, these terms should not be construed as limiting the present invention.

[0020] Embodiment 1 The following combines the attached Figure 1-2 This embodiment describes a clamp rolling friction sucker rod centralizer, which is formed by clamping two identical centralizing blocks. The centralizing block is a single-sided spiral three-leaf structure, and the whole centralizing block is twisted 45°±2° along the inner circle central axis to form a spiral insertion structure. After clamping the two centralizing blocks, a cross spiral six-leaf structure is formed. This structure can be more evenly distributed around the sucker rod, providing a more stable supporting force and effectively ensuring the central position of the sucker rod on the inner wall of the tubing. At the same time, the cross-sectional spiral three-leaf structure makes the gap between the blades larger, increasing the flow area and facilitating the smoother passage of the fluid, reducing the resistance of the fluid flow; One end of the straightening block is provided with a plugging convex part 2, and the other end is provided with a plugging concave part 1; the middle part of the straightening block is designed as a transition semi-ring 9 structure, and the transition semi-ring 9 forms a smooth fluid flow transition zone after two straightening blocks are clamped. This fluid flow transition zone can enable the fluid to achieve a smooth transition when passing through the centralizer, further reduce the flow resistance of the fluid, and improve the oil production efficiency; The plugging concave part 1 is a unilateral spiral three-leaf structure, namely a lower left blade 7, a lower right blade 8, and an upper blade 10. The three blades are evenly distributed in the circumferential direction, and the two ends of the blades are designed with chamfers of 30°-60°. 9-21 ball sleeves 13 are inlaid on each blade through a pre-placed and injection-molded process. The ball sleeve 13 half-wraps the rolling ball 12. The ball sleeve 13 and the rolling ball 12 are corrosion-resistant metals with a hardness > 280HB. The lower part of the outer side of the ball sleeve 13 is conical. After the rolling ball 12 is sleeved in the middle of the conical shape, the bottom lock core is threadedly locked to avoid detachment and at the same time prevent the rolling ball 12 from being completely embedded in the straightening block.

[0021] Two plugging grooves 6 are designed at the inner holes of the lower left blade 7 and the lower right blade 8. The plugging grooves 6 are rectangular long grooves and are matched with the overall twist of the straightening block to improve the axial locking force between the straightening blocks. A limit convex block 5 is designed at a position 15 mm away from the end face of the plugging concave part of the plugging groove 6; The plugging convex part 2 is designed with two symmetric plugging wings 3 with an included angle of 120°. The plugging wings 3 can be clamped and matched with the plugging groove 6. A right-angled triangle limit groove 11 is designed at a position 15 mm away from the end face of the plugging convex part on the plugging wing 3; 80-150 extrusion hemispheres 4 are distributed in a matrix within the semi-ring inside the straightening block. The protruding height of the extrusion hemispheres 4 is the lowest in the middle and gradually increases towards both sides. The height difference of the unilateral increase is 0.5 mm - 1.5 mm. When the clamp is installed, the extrusion hemispheres 4 can be deformed and extruded. The lowest protruding height in the middle is beneficial to the installation of the clamp, and the higher height on both sides is beneficial to increasing the grip force after the centralizer is installed, reducing the risk of cracking of the plugging groove 6, and improving the radial load-bearing capacity; The material of the straightening block is one of polyether ether ketone and nylon 66.

[0022] Please refer to Figure 1-3 , the specific installation process of this embodiment is as follows: Clamp two manufactured centralizers. First, carefully clean the surfaces of the insertion convex part 2 and the insertion concave part 1 of the centralizer to ensure that there are no substances such as impurities and oil stains that affect the quality of the clamp. Place the two centralizers on the sucker rod with the insertion convex part and the concave part facing each other. Align the insertion convex part 2 of one centralizer with the insertion concave part 1 of the other centralizer, and slowly and steadily apply a certain pressure to gradually insert the spiral insertion wing 3 of the insertion convex part 2 into the insertion groove 6 of the insertion concave part 1. During the clamping process, pay attention to observing whether the limit convex block 5 can accurately cooperate with the right-angled triangle limit groove 11 to ensure that the installation positions of the two centralizers are accurate. When the insertion convex part 2 is completely embedded in the insertion concave part 1 and a certain resistance is felt, it indicates that the clamping is in place. At this time, check whether the connection between the two centralizers is tight and whether there is any looseness or excessive gap.

[0023] Please refer to Figure 6 , the specific processing technology of this embodiment is: The centralizer is manufactured by injection molding. First, according to the design dimensions and shape of the centralizer, process the corresponding mold, and pre-assemble the ball sleeve 13 and the rolling ball 12 and then paste them into the fixed mold. Add the dry raw material particles into the hopper of the injection molding machine, and heat the raw materials through the heating device to make them melt. Extrude the molten plastic through the screw of the injection molding machine and inject it into the mold cavity at high speed to ensure that the plastic can fill every corner of the mold cavity and form a uniform wall thickness. After injection molding, the mold rapidly cools down under the action of the cooling system to make the plastic cool and solidify in the mold.

[0024] Please refer to Figure 4-5 , the specific comparison of wellbore support in this embodiment: When the sucker rod reciprocates in the tubing, the spiral double-sided six-blade structure of the centralizer begins to play a role. Compared with the traditional four-blade clamp rolling friction sucker rod centralizer, this centralizer adopts a double-sided spiral six-blade design, and more cross-section edges are in contact with the inner wall of the tubing. Through the contact angle of the cross-section edge, the contact angle refers to the central angle corresponding to the contact arc length between the blade and the wellbore. The contact angle of the four-blade structure is 170°, the contact angle of the double-sided straight six-blade structure is 255°, and the contact angle of the double-sided spiral six-blade structure is 280°. This enables the sucker rod in this embodiment to be more stable in the central position of the tubing and reduces the eccentric wear between the centralizer and the inner wall of the tubing.

[0025] The specific comparison of the flow area in this embodiment is: Taking the inner diameter of the tubing as 62mm as an example, for the clamp rolling friction sucker rod centralizer with the same outer diameter of 58mm and inner diameter of 22mm, the calculated flow area of the ordinary four-blade clamp rolling friction sucker rod centralizer is 1173mm 2 , the flow area of this embodiment is 1494mm 2, the four-leaf clamp rolling friction sucker rod centralizer increases the flow area by 27%. Due to its large flow area and smooth liquid flow transition zone in the middle, the fluid can pass through the centralizer smoothly without affecting the fluid transmission efficiency during oil production.

[0026] Some exemplary embodiments of the present invention have been described in detail above. For those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A clamp-rolling friction sucker rod centralizer, characterized in that, It is clamped by two identical centering blocks. The centering block is a single-sided spiral three-leaf structure. The whole centering block is twisted 45°±2° along the inner circle central axis to form a spiral plug-in structure. After the two centering blocks are clamped, a cross spiral six-leaf structure is formed, providing a more stable supporting force and increasing the flow-through area; One end of the centering block is provided with a plug-in convex part (2), and the other end is provided with a plug-in concave part (1); The plug-in concave part (1) is a single-sided spiral three-leaf structure, which are respectively a lower left blade (7), a lower right blade (8), and an upper blade (10). The three blades are evenly distributed in the circumferential direction. 9-21 ball sleeves (13) are inlaid on each blade through a pre-placed and then injection molding process; 80-150 extrusion hemispheres (4) are distributed in a matrix in the inner half-ring of the centering block. The protruding height of the extrusion hemispheres (4) is the lowest in the middle and gradually increases towards both sides. The height difference of the single-sided increasing amplitude is 0.5mm-1.5mm. When the clamp is installed, the extrusion hemispheres (4) can be deformed and extruded.

2. The clamping rolling friction sucker rod centralizer according to claim 1, characterized in that, The ball sleeve (13) semi-wraps the rolling ball (12). The ball sleeve (13) and the rolling ball (12) are corrosion-resistant metals with a hardness > 280HB. The lower part of the outer side of the ball sleeve (13) is conical. After the rolling ball (12) is sleeved in the middle of the cone, the bottom lock core is thread-locked to avoid detachment and at the same time prevent the rolling ball (12) from being completely embedded in the centering block.

3. A clamp rolling friction sucker rod centralizer according to claim 1, characterized in that The middle part of the centering block is designed as a transition semi-ring (9) structure. After the two centering blocks are clamped, the transition semi-ring (9) forms a smooth liquid flow transition zone.

4. A clamp rolling friction sucker rod centralizer according to claim 1, characterized in that, Two plug-in grooves (6) are designed at the inner holes of the lower left blade (7) and the lower right blade (8). The plug-in grooves (6) are rectangular long grooves and are matched with the overall twist of the centering block to improve the axial locking force between the centering blocks. A limit convex block (5) is designed at a position 15mm away from the end face of the plug-in concave part of the plug-in groove (6).

5. A clamp rolling friction sucker rod centralizer according to claim 1, characterized in that, The plug-in convex part (2) is designed with two symmetric plug-in wings (3) with an included angle of 120°. The plug-in wings (3) can be clamped and matched with the plug-in groove (6). A right-angled triangle limit groove (11) is designed at a position 15mm away from the end face of the plug-in convex part on the plug-in wing (3).

6. A clamp rolling friction sucker rod centralizer according to claim 1, characterized in that The material of the centering block is one of polyether ether ketone or nylon 66.

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