Pull-in rotatable elastic casing centralizer and centralizing method therefor

Abstract

Disclosed in the present invention is a pull-in rotatable elastic casing centralizer, comprising an upper end ring. A plurality of working rib plates are connected to the bottom of the upper end ring.

Description

The present invention relates to the technical field of oil drilling, production and well cementing, and in particular, to a pull-in type rotatable casing elastic centralizer and a centralizing method using the pull-in type rotatable casing elastic centralizer. Background A casing centralizer is a device used for centralization of a casing in an oilfield wellbore, and is mainly used in well cementing operations, especially during the process of running the casing into the well. According to the well conditions in practical applications, and the structural characteristics, manufacturing processes, and materials of casing centralizers, casing centralizers are classified into different types; and according to the classification standards of the petroleum industry, casing centralizers are typically classified into elastic centralizers and rigid centralizers. The elastic centralizer is the earliest and most widely used type of centralizer. The elastic centralizer has a relatively low manufacturing cost, a wide variety of types, and also has the characteristics of significant deformation and restoring force. The centralizer not only ensures the centralization of the casing, but also has good passability in well sections with large diameter variations, reducing the frictional resistance during casing running, and improving the uniformity of the annular cement bonding between the casing and the well wall. A casing centralizer is a device mounted on a casing string so as to centralize the casing string in a wellbore. The centralization of the casing in the wellbore is one of the key factors determining the quality of well cementing in oil and gas wells, and the proper placement of the centralizer is fundamental to ensuring the centralization of the casing. A centralizer is a component used for centralizing a casing and ensuring the concentricity of the casing in a wellbore. The main functions of a casing centralizer are as follows: 1. the casing centralizer reduces the eccentricity of the casing, and improves the displacement efficiency of well cementing, effectively preventing cement slurry channeling, and ensuring the quality of well cementing, thereby achieving a good sealing effect; 2. the casing centralizer supports the casing to reduce the contact area between the casing and the well wall, thereby decreasing the friction between the casing and the well wall, and facilitating the casing running into the wellbore and the movement of the casing during well cementing; 3. the casing centralizer reduces the risk of casing sticking during casing running, and lowering the risks associated with casing running; the casing centralizer ensures that the casing is centralized, preventing it from being in close contact with the well wall; and even in well sections with good permeability, the casing is less likely to be stuck by mud cake formed due to differential pressure, thus avoiding the risk of casing sticking; and 4. the casing centralizer can reduce the bending of the casing in the well, thereby minimizing the wear on the casing caused by drilling tools or other downhole tools during the drilling process after casing running, thus serving to protect the casing. In conclusion, there are various types of casing centralizers, and as drilling increasingly progresses toward ultra-deep wells, high-displacement wells, horizontal wells, and other complex well types, conventional casing centralizers are no longer sufficient to meet the needs of downhole operations. At present, most of the elastic centralizers on the market are mounted between two stopper rings, but this mounting method has the following problems: (1) the mounting efficiency on-site is low, as it requires the separate fitting of two stopper rings and a centralizer; (2) it is a push-in type, which has greater resistance compared to the pull-in type when entering a wellbore, it is more difficult to enter, and in some cases, for smaller wellbores, it may not be able to pass through, leading to damage to the centralizer; and (3) if the elastic centralizer encounters resistance in the well, the push-in type is also more likely to cause destructive compression of the rib plates of the centralizer. Summary The first objective of the present invention is to provide a pull-in type rotatable casing elastic centralizer, solving the problem existing in the art known to inventors where there is greater resistance when entering a wellbore, leading to damage to the centralizer. The second objective of the present invention is to provide a centralizing method for the pull-in type rotatable casing elastic centralizer. The first technical solution adopted by the present invention is a pull-in type rotatable casing elastic centralizer, including an upper end ring; the plurality of working rib plates are connected with a bottom of the upper end ring, the plurality of working rib plates are collectively connected with a lower end ring on a side away from the upper end ring, and the stopper ring is sleeved on an outer wall of the lower end ring. The first technical solution of the present invention is further characterized in that, an outer wall of the stopper ring is provided with several set screws. The upper end ring and the lower end ring have a same inner diameter, and the lower end ring is evenly provided with a plurality of pin mounting holes. The plurality of working rib plates are evenly distributed around the upper end ring and the lower end ring; the plurality of pins are welded into the plurality of pin mounting holes; and the lower end ring is connected with the stopper ring through the plurality of pins. An inner wall of the stopper ring is provided with a plurality of pin slots; the plurality of pins are provided in the plurality of pin slots; the lower end ring is connected with the stopper ring through the pins; and the lower end ring can freely rotate 360° relative to the stopper ring. The upper end ring and the lower end ring have a same inner diameter, and a lower end ring is evenly provided with a plurality of stopper block mounting holes. The working rib plates are evenly distributed around the upper end ring and the lower end ring; stopper blocks are welded into the plurality of stopper block mounting holes; and the lower end ring is connected with the stopper ring through the plurality of stopper blocks. An inner wall of the stopper ring is provided with a plurality of stopper block slots; the plurality of stopper blocks are provided in the plurality of stopper block slots; the lower end ring is connected with the stopper ring through the plurality of stopper blocks; and the lower end ring can freely rotate 360° relative to the stopper ring. Another technical solution adopted by the present invention is a centralizing method for the pull-in type rotatable casing elastic centralizer, and the method includes the following steps: before entering a wellbore, the centralizer is sleeved on the outer side of a casing; the lower end ring is mounted in a direction of entering the wellhead; the set screws distributed on the outer side of the stopper ring are tightened; and the entire centralizer is then fixed to the casing, completing the centralization. Compared with the art known to inventors, the beneficial effects of the present invention are: the pull-in type rotatable casing elastic centralizer of the present invention is easy and quick to mount on-site; it requires only one fitting to mount both the stopper ring and the centralizer; and by fixing only one stopper ring, the stopper ring on the outer side of the lower end ring, the relative position of the centralizer on the casing can be fixed, while still allowing the centralizer to rotate freely. After the mounting is completed, the stopper ring of the centralizer is relatively fixed to the casing through the set screws, and then the lower end ring is pulled through pins or stopper blocks, allowing the entire centralizer to be pulled into the wellbore along with the casing; the entry resistance is relatively low, preventing any destructive impact on the rib plates of the centralizer due to difficulties during entry; in addition, even if the centralizer encounters resistance in the wellbore, the pull-in type will not cause destructive compression of the rib plates of the centralizer, and make the centralizer easier to pass through. Brief Description of the Drawings Fig. 1 is a schematic diagram of the structure of a pull-in type rotatable casing elastic centralizer of the present invention; Fig. 2 is a partial enlarged view of the area marked as A in Fig. 1; Fig. 3 is a schematic diagram of the structure of a pull-in type rotatable casing elastic centralizer using working rib plates which is made of a spring steel material according to embodiment 4 of the present invention; Fig. 4 is a partial enlarged view of the area marked as B in Fig. 3. In the figures, 1. upper end ring; 2. lower end ring; 3. working rib plate; 4. stopper ring; 5. set screw; 6. pin slot; 7. pin; 8. pin mounting hole; 9. stopper block mounting hole; 10. stopper block; 11. stopper block slot. Detailed Description of the Embodiments The present invention is hereinafter described in detail with reference to the accompanying drawings and embodiments. Some embodiments of the present invention provide a pull-in type rotatable casing elastic centralizer. As shown in Fig. 1, the centralizer includes an upper end ring 1; a plurality of working rib plates 3 the plurality of are connected with a bottom of the upper end ring 1, the plurality of working rib plates 3 are collectively connected with the lower end ring 2 on a side away from the upper end ring 1, and the stopper ring 4 is sleeved on an outer wall of the lower end ring 2; the upper end ring 1 and the lower end ring 2 have the same inner diameter; and the plurality of working rib plates 3 are evenly distributed around the circumferential direction of the upper end ring 1 or the lower end ring 2. As shown in Fig. 2, the lower ring 2 is evenly provided with a plurality of pin mounting holes 8 in the circumferential direction of 360°; a pin 7 is welded into each pin mounting hole 8; the stopper ring 4 is sleeved on the outer side of the lower end ring 2; the inner side of the stopper ring 4 is provided with pin slots 6; the pins 7 are provided in the pin slots 6; the stopper ring 4 is connected with the lower end ring 2 through the pins 7; the lower end ring 2 can freely rotate 360° relative to the stopper ring 4; and the stopper ring 4 is provided with a plurality of set screws 5 which is evenly distributed in the circumferential direction of 360°. As shown in Figs. 3 and 4, the lower end ring 2 is evenly provided with stopper block mounting holes 9 in the circumferential direction of 360°; a stopper block 10 is welded into each stopper block mounting hole 9; the stopper ring 4 is sleeved on the outer side of the lower end ring 2; the inner side of the stopper ring 4 are provided with stopper block slots 11; the stopper blocks 10 are provided in the stopper block slots 11; the stopper ring 4 is connected with the lower end ring 2 through the stopper blocks 10; the lower end ring 2 can freely rotate 360° relative to the stopper ring 4; and the stopper ring 4 is provided with a plurality of set screws 5 which is evenly distributed in the circumferential direction of 360°. Some embodiments of the present invention also provide a centralizing method using the pull-in type rotatable casing elastic centralizer. The method includes the following specific steps: before entering a wellbore, the centralizer is sleeved on the outer side of a casing; the lower end ring is mounted in a direction of entering the wellhead; the set screws 5 distributed on the outer side of the stopper ring 4 are tightened; and the entire centralizer is then fixed to the casing, completing the centralization. The relative position of the centralizer on the casing is fixed, and the centralizer is pulled into the wellbore along with the casing; the entry resistance is relatively small, and there is no destructive impact on the rib plates of the centralizer due to difficulties during entry; in addition, even if the centralizer encounters resistance in the wellbore, the pull-in type will not cause destructive compression of the rib plates of the centralizer, and make the centralizer easier to pass through. Embodiment 1 The present embodiment provides a pull-in type rotatable casing elastic centralizer. As shown in Fig. 1, the centralizer includes an upper end ring 1; a plurality of working rib plates 3 are connected with the bottom of the upper end ring 1; the plurality of working rib plates 3 are collectively connected with a lower end ring 2 on the side away from the upper end ring 1; and a stopper ring 4 is sleeved on the outer wall of the lower end ring 2. Embodiment 2 The present embodiment provides a pull-in type rotatable casing elastic centralizer. As shown in Figs. 1 and 2, the centralizer includes an upper end ring 1; a plurality of working rib plates 3 are connected with the bottom of the upper end ring 1; the plurality of working rib plates 3 are collectively connected with a lower end ring 2 on the side away from the upper end ring 1; a stopper ring 4 is sleeved on the outer wall of the lower end ring 2; the outer wall of the stopper ring 4 is provided with a plurality of set screws 5; the upper end ring 1 and the lower end ring 2 have the same inner diameter; the lower end ring 2 is evenly provided with a plurality of pin mounting holes 8; the working rib plates 3 are evenly distributed around the upper end ring 1 and the lower end ring 2; pins 7 are welded into the plurality of pin mounting holes 8; the lower end ring 2 is connected with the stopper ring 4 through the pins 7; the inner wall of the stopper ring 4 is provided with pin slots 6; the pins 7 are provided in the pin slots 6; the lower end ring 2 is connected with the stopper ring 4 through the pins 7; and the lower end ring 2 can freely rotate 360° relative to the stopper ring 4. Embodiment 3 The present embodiment provides a pull-in type rotatable casing elastic centralizer. As shown in Fig. 3, the centralizer includes an upper end ring 1; a plurality of working rib plates 3 are connected with the bottom of the upper end ring 1; the working rib plates 3 are made of a spring steel material; the plurality of working rib plates 3 are connected with a lower end ring 2 on the side away from the upper end ring 1; and a stopper ring 4 is sleeved on the outer wall of the lower end ring 2. Embodiment 4 The present embodiment provides a pull-in type rotatable casing elastic centralizer. As shown in Figs. 3 and 4, the centralizer includes an upper end ring 1; a plurality of working rib plates 3 are connected with the bottom of the upper end ring 1; the working rib plates 3 are made of a spring steel material; the plurality of working rib plates 3 are connected with a lower end ring 2 on the side away from the upper end ring 1; a stopper ring 4 is sleeved on the outer wall of the lower end ring 2; the outer wall of the stopper ring 4 is provided with a plurality of set screws 5; the upper end ring 1 and the lower end ring 2 have the same inner diameter; the lower end ring 2 is evenly provided with a plurality of stopper block mounting holes 9; the working rib plates 3 are evenly distributed around the upper end ring 1 and the lower end ring 2; stopper blocks 10 are welded into the plurality of stopper block mounting holes 9; the lower end ring 2 is connected with the stopper ring 4 through the stopper blocks 10; the inner wall of the stopper ring 4 is provided with stopper block slots 11; the stopper blocks 10 are provided in the stopper block slots 11; the lower end ring 2 is connected with the stopper ring 4 through the stopper blocks 10; and the lower end ring 2 can freely rotate 360° relative to the stopper ring 4. The pull-in type rotatable casing elastic centralizer of the present invention is easy and quick to mount on-site; it requires only one fitting to mount both the stopper ring 4 and the centralizer; and by fixing only one stopper ring 4, the stopper ring 4 on the outer side of the lower end ring 2, the relative position of the centralizer on the casing can be fixed, while still allowing the centralizer to rotate freely. After the mounting is completed, the stopper ring 4 of the centralizer is relatively fixed to the casing, and the centralizer is pulled into the wellbore along with the casing; the entry resistance is relatively low, preventing any destructive impact on the rib plates of the centralizer due to difficulties during entry; in addition, even if the centralizer encounters resistance in the wellbore, the pull-in manner of the pull-in type rotatable casing elastic centralizer will not cause destructive compression of the rib plates of the centralizer, and make the centralizer easier to pass through.

Claims

1. A pull-in type rotatable casing elastic centralizer, comprising an upper end ring (1); a plurality of working rib plates (3) are connected with a bottom of the upper end ring (1), the plurality of working rib plates (3) are collectively connected with the lower end ring (2) on a side away from the upper end ring (1), and the stopper ring (4) is sleeved on an outer wall of the lower end ring (2).

2. The pull-in type rotatable casing elastic centralizer according to claim 1, wherein an outer wall of the stopper ring (4) is provided with several set screws (5).

3. The pull-in type rotatable casing elastic centralizer according to claim 1, wherein the upper end ring (1) and the lower end ring (2) have a same inner diameter, and the lower end ring (2) is evenly provided with a plurality of pin mounting holes (8).

4. The pull-in type rotatable casing elastic centralizer according to claim 3, wherein the plurality of working rib plates (3) are evenly distributed around the upper end ring (1) and the lower end ring (2); pins (7) are welded into the plurality of pin mounting holes (8); and the lower end ring (2) is connected with the stopper ring (4) through the plurality of pins (7).

5. The pull-in type rotatable casing elastic centralizer according to claim 4, wherein an inner wall of the stopper ring (4) is provided with a plurality of pin slots (6); the plurality of pins (7) are provided in the plurality of pin slots (6); the lower end ring (2) is connected with the stopper ring (4) through the pins (7); and the lower end ring (2) can freely rotate 360° relative to the stopper ring (4).

6. The pull-in type rotatable casing elastic centralizer according to claim 1, wherein the upper end ring (1) and the lower end ring (2) have a same inner diameter, and a lower end ring (2) is evenly provided with a plurality of stopper block mounting holes (9).

7. The pull-in type rotatable casing elastic centralizer according to claim 6, wherein the working plate ribs (3) are evenly distributed around the upper end ring (1) and the lower end ring (2); stopper blocks (10) are welded into the plurality of stopper block mounting holes (9); and the lower end ring (2) is connected with the stopper ring (4) through the plurality of stopper blocks (10).

8. The pull-in type rotatable casing elastic centralizer according to claim 7, wherein an inner wall of the stopper ring (4) is provided with a plurality of stopper block slots (11); the plurality of stopper blocks (10) are provided in the plurality of stopper block slots (11); the lower end ring (2) is connected with the stopper ring (4) through the plurality of stopper blocks (10); and the lower end ring (2) can freely rotate 360° relative to the stopper ring (4).

9. A pull-in type rotatable casing elastic centralizer, comprising:an upper end ring (1);a lower end ring (2);a plurality of working rib plates (3), two ends of each of the plurality of working rib plates (3) being respectively connected with the upper end ring (1) and the lower end ring (2); anda stopper ring (4), sleeved on the lower end ring (2), wherein the lower end ring (2) is rotatably disposed relative to the stopper ring (4).

10. The pull-in type rotatable casing elastic centralizer according to claim 9, whereinthe plurality of working rib plates (3) are disposed at intervals in a circumferential direction of the upper end ring (1) and / or the lower end ring (2).

11. The pull-in type rotatable casing elastic centralizer according to claim 9, wherein the lower end ring (2) is provided with a plurality of mounting portions, and the plurality of mounting portions are evenly spaced apart in a circumferential direction of the lower end ring (2); anda connector is provided in each of the mounting portions, and the lower end ring (2) is connected with the stopper ring (4) through the plurality of connectors.

12. The pull-in type rotatable casing elastic centralizer according to claim 11, wherein the plurality of mounting portions are pin mounting holes (8); the plurality of connectors are pins (7); and the pins (7) are welded into the pin mounting holes (8) and are connected with the stopper ring (4).

13. The pull-in type rotatable casing elastic centralizer according to claim 11, wherein the plurality of mounting portions are stopper block mounting holes (9); the plurality of connectors are stopper blocks (10); and the stopper blocks (10) are welded into the stopper block mounting holes (9) and are connected with the stopper ring (4).

14. A centralizing method using the pull-in type rotatable casing elastic centralizer according to any one of claims 1-13, wherein the specific steps are as follows: before entering a wellbore, the centralizer is sleeved on the outer side of a casing; the lower end ring (2) is mounted in a direction of entering the wellhead; and the set screws (5) distributed on the outer side of the stopper ring (4) are tightened; and the entire centralizer is then fixed to the casing, completing the centralization.

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