A clamp rolling friction sucker rod centralizer

Abstract

The present invention discloses a clamp rolling friction sucker rod straightener, which is used in the field of oil extraction equipment. It is composed of two single-sided spiral three-leaf straightening block clamps. The single block is twisted to form a spiral plug-in structure, and after being combined, it presents a double-sided six-leaf shape. Different from the traditional straight-leaf four-leaf structure, the double-sided spiral six-leaf design can improve the well wall support effect, and the single-sided three-leaf increases the blade gap, and cooperates with the smooth liquid flow transition zone in the middle to significantly optimize the flow efficiency. The straightening block adopts a rolling friction design, and the internal gradient extrusion hemisphere enhances the grip and structural reliability. Compared with traditional solutions, this device effectively reduces fluid resistance and friction against the oil pipe well wall, evenly supports the sucker rod to reduce eccentric wear, and is easy to install and has strong adaptability, thereby improving the stability of the oil production system and the life of the equipment.

Description

Technical Field

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

[0002] In rod pumping operations, which are commonly used in oil production, the sucker rod and the inner wall of the tubing are susceptible to frictional damage. The elasticity of the sucker rod causes it to deform and adhere to the wall when the wellbore is curved or unevenly loaded. Complex wellbore geometries exacerbate contact, and fatigue corrosion after long-term use further exacerbates friction. Therefore, installing a centralizer on the sucker rod is necessary to alleviate this problem.

[0003] Currently common four-blade centralizers have significant shortcomings. Their four-blade structure results in a small gap between the blades in terms of flow area, which hinders fluid flow during oil production, increasing energy loss and reducing oil production efficiency. In terms of wellbore support, four-blade centralizers have limited support points, making it difficult to stably support the sucker rod in complex well conditions. This can easily cause severe eccentric wear between the centralizer and the inner wall of the tubing, shortening the equipment's service life and increasing maintenance costs and replacement frequency.

[0004] At present, injection molding machines are used at oil field construction sites to inject single-sided three-blade, double-sided six-blade structures, or stabilizers with spiral blades onto sucker rods through the injection molding process. However, this process has problems such as complex construction, large equipment investment, long cycle, and inconvenience in use. A new split clamp rolling friction sucker rod centralizer has been developed to solve the above problems.

[0005] Currently, centralizers feature a uniform inner diameter bump height. To enhance grip on the sucker rod, they employ an expanded wedge-shaped fin design whose thickness is greater than the slot width. While this design improves grip, it also increases the risk of cracking in the centralizer slot during winter. Therefore, structural design optimization is needed to balance performance and reliability.

[0006] The friction surfaces of currently used injection-molded clamp sucker rod centralizers are primarily made of injection-molded plastic or carbon fiber, resulting in sliding friction against the inner wall of the tubing. This creates significant friction, significantly reducing pump efficiency and shortening the centralizer's useful life. Summary of the Invention

[0007] The present invention aims to provide a clamp rolling friction sucker rod centralizer. Through the split clamp three-leaf spiral centralizer block structure design, the flow area is increased, the number of well wall support leaves is increased, the eccentric wear between the centralizer and the oil pipe is reduced, and the installation convenience is improved. The design of the rolling ball sleeve combination reduces friction while preventing the rolling ball from being embedded in and detached from the centralizer block, thereby reducing the overall cost.

[0008] The present invention discloses a clamp rolling friction sucker rod centralizer, and the specific technical solution is as follows:

[0009] A clamp rolling friction sucker rod centralizer, characterized in that it is composed of two identical centralizing blocks clamped together, the centralizing blocks having a single-sided spiral three-lobed structure, the centralizing blocks being twisted 45°±2° along the inner circle center axis to form a spiral plug-in structure, and the two centralizing blocks being clamped together to form a spiral six-lobed structure;

[0010] One end of the straightening block is provided with a plug-in convex portion, and the other end is provided with a plug-in concave portion. The middle part of the straightening block is designed as a transition semi-ring structure. The transition semi-ring behind the two straightening block clamps forms a smooth liquid flow transition zone;

[0011] The plug-in recess is a single-sided spiral three-leaf structure, with the three leaves evenly distributed in the circumferential direction. A ball sleeve is embedded on each leaf through a pre-placed post-injection molding process, and the ball sleeve half-wraps the rolling ball;

[0012] The inner holes of the lower left blade and the lower right blade are designed with plug-in slots, and limiting protrusions are designed in the plug-in slots;

[0013] The plug-in protrusion is designed with two symmetrical plug-in wings with an angle of 120 degrees. The plug-in wings can cooperate with the plug-in slot clamp. A right-angled triangular limiting groove is designed on the plug-in wings 15 mm away from the end face of the plug-in protrusion;

[0014] 80-150 extruded hemispheres are distributed in a matrix within the inner semi-ring of the straightening block.

[0015] Compared with the prior art, the present invention has the following significant beneficial effects:

[0016] 1. Increased flow area

[0017] Compared to traditional four-blade centralizers, the clamp-type rolling friction sucker rod centralizer of the present invention combines two centralizing block clamps to form a six-blade structure. The gaps between the three blades on one side are significantly increased, significantly increasing the flow area. During the oil production process, fluid can flow more smoothly through the centralizer, reducing fluid flow resistance and energy loss during passage, thus helping to improve the overall efficiency of the oil production system. Furthermore, the reduced fluid resistance stabilizes the pump's suction pressure, ensuring more stable operation and reducing the probability of pump failure.

[0018] 2. Improved well wall support effect

[0019] The two centralizing blocks are clamped together to form a spiral six-blade structure. Compared with the traditional four-blade centralizer, the number of wellbore support blades has increased. More support blades can be more evenly distributed around the sucker rod, providing more stable and balanced support force. The spiral blades have more uniform contact with the wellbore wall, reducing eccentric wear. This centralizer can better keep the sucker rod in the center of the tubing.

[0020] 3.Stable and reliable structure

[0021] The centralizing block's unique clamp structure and spiral plug-in method ensure sufficient axial locking force after installation. At the same time, the plug-in protrusion 2 and the plug-in recess 1 fit tightly together. In addition, the mutual cooperation between the limiting protrusion 5 and the right-angled triangular limiting groove 11 ensures that the two centralizing blocks will not separate during operation, ensuring the stability of the centralizer structure and enabling it to reliably perform its centralizing function in complex underground environments.

[0022] 4. Centralizer split clamp

[0023] This invention uses two identical centralizing blocks mounted with clamps. During injection molding in the workshop, the same mold can be used to create these two identical blocks, significantly reducing production investment. During on-site construction, compared to the traditional on-site injection molding process for centralizers that requires expensive vehicle-mounted injection molding machines, this invention not only reduces investment but also avoids complex on-site operations, accelerating construction progress.

[0024] 5. Squeezed hemispherical distribution

[0025] The extrusion hemisphere's protrusion height is designed to be lowest in the middle and gradually increase toward the sides. During clamp installation, the extrusion hemisphere deforms and squeezes, with the lowest protrusion height in the middle facilitating clamp installation. The higher protrusion heights on both sides increase the grip of the centralizer after installation, improving radial load bearing capacity. Unlike a wedge-shaped plug-in wing structure, where the centralizer bears the gripping force through the entire structure after installation, the plug-in wing does not adopt an expanded wedge-shaped structure, which allows for uniform force distribution within the slot and structurally reduces the risk of slot cracking.

[0026] 6. Rolling ball sleeve combination

[0027] The rolling ball-and-sleeve design significantly reduces frictional resistance by replacing sliding friction with rolling friction. Furthermore, the conical structure on the lower outer side of the sleeve, combined with the inverted teeth, cleverly limits the sleeve's displacement, preventing the rolling ball from disengaging and completely embedding in the centralizer block, effectively increasing the centralizer's reliability and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0029] Figure 1 This is a structural diagram of a clamp rolling friction sucker rod centralizer;

[0030] Figure 2 This is a schematic diagram of the structure of a clamp sucker rod straightening block;

[0031] Figure 3 This is a schematic diagram of a clamp rolling friction sucker rod centralizer after the sucker rod is installed;

[0032] Figure 4 This is the left side view of a clamp rolling friction sucker rod centralizer after installation;

[0033] Figure 5 This is a front view of a clamp rolling friction sucker rod centralizer after installation;

[0034] Figure 6 This is a schematic diagram of a ball sleeve for a clamp rolling friction sucker rod centralizer.

[0035] Description of reference numerals:

[0036] 1. Insertion concave part; 2. Insertion convex part; 3. Insertion wing; 4. Extrusion hemisphere; 5. Limiting protrusion; 6. Insertion groove; 7. Lower left blade; 8. Lower right blade; 9. Transition semi-ring; 10. Upper blade; 11. Limiting groove; 12. Rolling ball; 13. Ball sleeve. DETAILED DESCRIPTION

[0037] The following will be closely combined with the embodiments of the present invention to provide a comprehensive, clear, and complete description of the technical solutions in the embodiments of the present invention. It should be understood that the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are included in the scope of protection of the present invention.

[0038] In describing the present invention, it is important to note that terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate positions or locations based on the positions or locations shown in the accompanying drawings. These terms are used solely to facilitate the description of the present invention and simplify the description. They in no way indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific manner. Therefore, in actual application, these terms should not be construed as limiting the present invention.

[0039] Example 1

[0040] The following is combined with Figure 1-2 This embodiment describes a clamped rolling friction sucker rod centralizer, comprising two identical clamped straightening blocks. The straightening blocks are single-sided spiral three-lobed structures, twisted 45°±2° along the inner central axis to form a spiral splice. The two straightening blocks are clamped together to form a cross-spiral six-lobed structure. This structure distributes support more evenly around the sucker rod, providing more stable support and effectively securing the rod's center position on the inner wall of the tubing. Furthermore, the cross-sectional spiral three-lobed structure increases the gaps between the blades, increasing the flow area, facilitating smoother fluid flow and reducing resistance to fluid flow.

[0041] The centralizing block is provided with a protruding portion 2 at one end and a recessed portion 1 at the other. The central portion of the centralizing block is designed as a transition semi-ring 9. The transition semi-ring 9 forms a smooth fluid transition zone after the two centralizing block clamps. This transition zone allows for a smooth transition of fluid through the centralizer, further reducing fluid flow resistance and improving oil recovery efficiency.

[0042] The plug-in recess 1 is a single-sided spiral three-leaf structure, which includes 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 30°-60° chamfers. Each blade is inlaid with 9-21 ball sleeves 13 through a pre-placement and post-injection molding 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 of >280HB. The lower outer part of the ball sleeve 13 is conical. After the rolling ball 12 is inserted into the middle of the cone, the bottom lock core thread is locked to prevent detachment while lowering the rolling ball 12 to fully embed into the straightening block.

[0043] Two insertion slots 6 are designed at the inner holes of the lower left blade 7 and the lower right blade 8. The insertion slots 6 are rectangular long slots and are twisted to match the overall straightening block to improve the axial locking force between the straightening blocks. A limiting protrusion 5 is designed at a distance of 15 mm from the end surface of the insertion recess of the insertion slot 6.

[0044] The plug-in protrusion 2 is designed with two symmetrical plug-in wings 3 with an angle of 120 degrees. The plug-in wings 3 can cooperate with the plug-in slot 6 clamp. A right-angled triangular limiting groove 11 is designed on the plug-in wing 3 at a distance of 15 mm from the end face of the plug-in protrusion;

[0045] 80-150 extruded hemispheres 4 are distributed in a matrix within the inner semi-ring of the centralizing block. The protruding height of the extruded hemispheres 4 is lowest in the middle and increases step by step toward both sides, with a height difference of 0.5mm-1.5mm on one side. The extruded hemispheres 4 can be deformed and extruded during the installation of the clamp. The lowest protruding height in the middle facilitates the installation of the clamp, while the higher height on both sides increases the gripping force after the centralizer is installed, reduces the risk of cracking of the socket 6, and improves the radial load bearing capacity.

[0046] The material of the righting block is one of polyetheretherketone and nylon 66.

[0047] See Figure 1-3 The specific installation process of this embodiment is as follows:

[0048] Clamp the two manufactured straightening blocks. First, carefully clean the surface of the plug-in protrusion 2 and the plug-in recess 1 of the straightening block to ensure that there are no impurities, oil stains, or other substances that affect the quality of the clamp. Place the two straightening blocks on the sucker rod in a manner that the plug-in protrusion and the recess are opposite to each other, align the plug-in protrusion 2 of one straightening block with the plug-in recess 1 of the other straightening block, and slowly and steadily apply a certain amount of pressure so that the spiral plug-in wing 3 of the plug-in protrusion 2 is gradually inserted into the plug-in groove 6 of the plug-in recess 1. During the clamping process, pay attention to whether the limiting protrusion 5 and the right-angled triangle limiting groove 11 can be accurately matched to ensure that the installation position of the two straightening blocks is accurate. When the plug-in protrusion 2 is completely embedded in the plug-in recess 1 and a certain amount of resistance is felt, it indicates that the clamp is in place. At this time, check whether the connection between the two straightening blocks is tight and whether there is any looseness or excessive gap.

[0049] See Figure 6 , the specific processing technology of this embodiment is:

[0050] The righting block is manufactured using an injection molding process. First, a mold is fabricated according to the block's designed dimensions and shape. The ball sleeve 13 and rolling ball 12 are preassembled and then affixed to the interior of a fixed mold. Dry raw material granules are added to the injection molding machine's hopper and melted by a heating device. The molten plastic is extruded through the machine's screw and injected into the mold cavity at high speed, ensuring that the plastic fills every corner of the mold cavity and forms a uniform wall thickness. After injection molding is complete, the mold is rapidly cooled by a cooling system, allowing the plastic to cool and set within the mold.

[0051] See Figure 4-5 , the specific well wall support comparison of this embodiment:

[0052] As the sucker rod reciprocates within the tubing, the stabilizer's double-sided, six-blade spiral structure comes into play. Compared to conventional four-blade, clamp-type rolling friction sucker rod stabilizers, this stabilizer utilizes a double-sided, six-blade design, allowing more cross-sectional edges to contact the tubing's inner wall. The cross-sectional edge contact angle, which refers to the central angle corresponding to the arc length of contact between the blades and the wellbore wall, is 170° for a four-blade structure, 255° for a double-sided, straight six-blade structure, and 280° for a double-sided, spiral six-blade structure. This allows the sucker rod in this embodiment to remain more stably in the center of the tubing, reducing eccentric wear between the stabilizer and the tubing's inner wall.

[0053] The specific flow area comparison of this embodiment is:

[0054] For example, the inner diameter of the oil pipe is 62mm. For the same clamp rolling friction sucker rod centralizer with an outer diameter of 58mm and an inner diameter of 22mm, the calculated flow area of ​​the ordinary four-leaf clamp rolling friction sucker rod centralizer is 1173mm. 2 , the flow area of ​​this embodiment is 1494mm 2 Compared with the four-leaf clamp rolling friction sucker rod centralizer, the flow area is increased by 27%. Due to its larger flow area and the smooth liquid transition zone in the middle, the fluid can pass through the centralizer smoothly without affecting the fluid transmission efficiency during the oil production process.

[0055] The above detailed descriptions of certain exemplary embodiments of the present invention are provided. Those skilled in the art will appreciate that the described embodiments may be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and description are illustrative in nature and should not be construed as limiting the scope of the claims.

Claims

1. A clamp rolling friction sucker rod centralizer, characterized in that: It is composed of two identical centralizing block clamps. The centralizing block has a single-sided spiral three-leaf structure. The centralizing block is twisted 45°±2° along the inner circle center axis to form a spiral plug-in structure. After the two centralizing blocks are clamped, a cross-spiral six-leaf structure is formed, providing more stable support force and increasing the flow area. One end of the straightening block is provided with a plug-in convex portion (2), and the other end is provided with a plug-in concave portion (1); The plug-in recess (1) is a single-sided spiral three-leaf structure, comprising a lower left leaf (7), a lower right leaf (8), and an upper leaf (10). The three leaves are evenly distributed in the circumferential direction, and each leaf is inlaid with 9-21 ball sleeves (13) by a pre-placed post-injection molding process. 80-150 extruded hemispheres (4) are distributed in a matrix within the inner semi-ring of the straightening block. The protruding height of the extruded hemispheres (4) is the lowest in the middle and increases step by step toward both sides. The height difference of the single-side increasing height is 0.5mm-1.5mm. The extruded hemispheres (4) can be deformed and extruded when the clamp is installed.

2. The clamp rolling friction sucker rod centralizer according to claim 1, characterized in that: The ball sleeve (13) half-wraps the rolling ball (12). The ball sleeve (13) and the rolling ball (12) are made of corrosion-resistant metal with a hardness greater than 280HB. The lower outer portion of the ball sleeve (13) is conical. After the rolling ball (12) is inserted into the middle of the cone, the bottom lock core thread is locked to prevent it from being disengaged while lowering the rolling ball (12) to be completely embedded in the straightening block.

3. The clamp rolling friction sucker rod centralizer according to claim 1, characterized in that: The middle portion of the straightening block is designed as a transition semi-ring (9) structure, and the transition semi-rings (9) behind the two straightening block clamps form a smooth liquid flow transition zone.

4. The clamp rolling friction sucker rod centralizer according to claim 1, characterized in that: Two plug-in slots (6) are designed at the inner holes of the lower left blade (7) and the lower right blade (8). The plug-in slots (6) are rectangular long slots and are twisted in conjunction with the overall straightening block to improve the axial locking force between the straightening blocks. A limiting protrusion (5) is designed at a distance of 15 mm from the end face of the plug-in recess of the plug-in slot (6).

5. The clamp rolling friction sucker rod centralizer according to claim 1, characterized in that: The plug-in protrusion (2) is designed with two symmetrical plug-in wings (3) with an included angle of 120 degrees. The plug-in wings (3) can cooperate with the plug-in groove (6) clamp. A right-angled triangular limiting groove (11) is designed on the plug-in wing (3) at a distance of 15 mm from the end face of the plug-in protrusion.

6. The clamp rolling friction sucker rod centralizer according to claim 1, characterized in that: The material of the centralizing block is one of polyetheretherketone or nylon 66.

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