Negative-pressure variable-diameter centralizer

Abstract

The utility model relates to the technical field of centralizers, and discloses a negative-pressure variable-diameter centralizer which comprises a base tube which is a machining main body and used for component supporting, a centralizing component which is arranged on the outer wall of the base tube and used for centralizing the base tube, and a driving component which is arranged on the outer wall of the base tube and used for driving the centralizing component to rotate. The driving assembly is used for providing power for the righting assembly for accurate righting, the driving assembly comprises a hydraulic cylinder and a pin, the hydraulic cylinder is arranged on the outer wall of the base pipe, and the pin is arranged in the hydraulic cylinder. According to the centralizer, the casing pipe is tripped, pressure difference is formed on the two sides, the pin is cut off, the hydraulic cylinder moves leftwards to push the centralizing rib to support the well wall to achieve centralizing, the centralizer is opened through the hydraulic cylinder and controlled to be started through the pin, the connecting ring and the hydraulic cylinder can assist in centralizing protection, and the centralizer is connected to an upper base pipe and a lower base pipe of the packer and can centralize the packer. The problems of casing centralizing opportunity control and packer centralizing are solved, and operation safety and packing effectiveness are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a centralizer technical field especially relates to a variable-diameter centralizer under negative pressure. BACKGROUND

[0002] In oil and gas exploitation operations, the accurate centralization of casing is crucial for ensuring wellbore stability, improving cementing quality, and the smooth progress of subsequent exploitation operations. With the increasing depth of exploitation and the increasing complexity of well conditions, the performance requirements of casing centralization devices are becoming increasingly stringent. In various complex formation conditions, such as irregular lithology changes, natural fractures, or solution cavities, traditional fixed-size centralizers are difficult to adapt to the changes in well diameter at different well sections, resulting in the casing being unable to maintain an ideal central state in the well. Therefore, developing a centralizer that can automatically adjust the outer diameter according to the actual situation in the well and accurately control the centralization timing has become an urgent problem in the industry, and a variable-diameter centralizer under negative pressure has emerged to meet the high-precision requirements of casing centralization in complex exploitation environments.

[0003] Currently, the casing centralization devices in the prior art mostly use relatively simple mechanical structures. Commonly seen are rigid centralizers, which achieve centralization by fixedly installing a certain number and shape of centralizing arms on the outer wall of the casing. These centralizing arms are usually made of rigid materials and are directly welded or bolted to the casing. The technical principle is to use the contact between the centralizing arms and the well wall to push the casing to the center of the wellbore. Some elastic centralizers mainly rely on elastic elements such as springs to allow the centralizing components to deform when they are pressed by the well wall, thereby adapting to changes in well diameter within a certain range. However, these traditional centralizers often lack precise control over the timing of activation in actual application.

[0004] However, the existing technology has a significant problem, which is the difficulty in accurately controlling the timing of casing centralization. Whether rigid or elastic, once installed on the casing, the centralizing components of traditional centralizers are always in a working state. During the casing running-in process, the centralizing components are in constant contact with the well wall, which can easily increase the resistance to casing running-in, and even cause sticking while drilling, seriously affecting the progress and safety of the operation. Moreover, when the centralizer needs to be activated, the traditional centralizer cannot accurately activate the centralization function at a specific location, making it difficult for the packer to be accurately positioned at the center of the wellbore, thereby affecting the sealing effect and reducing the overall efficiency and quality of the exploitation operation. This contradicts the requirements of oil and gas exploitation operations for high efficiency, safety, and precision, and there is an urgent need for a new technical solution to solve this problem, and therefore a variable-diameter centralizer under negative pressure is proposed to solve the above problems. SUMMARY

[0005] In order to make up for the above shortcomings, the utility model provides a negative pressure variable diameter centralizer, aims at improving the casing centralizing timing control and packer centralizing problems in the prior art.

[0006] In order to achieve the above object, the utility model adopts the following technical scheme:

[0007] A negative pressure variable diameter centralizer, including base pipe, base pipe is processing main part, is used for component support, centralizing assembly, centralizing assembly sets up in base pipe outer wall, is used for centralizing and centering to base pipe, drive assembly, drive assembly sets up in base pipe outer wall, is used for providing power to centralizing assembly accurately centralizing;

[0008] Drive assembly includes liquid cylinder and pin, liquid cylinder sets up in base pipe outer wall, pin sets up in liquid cylinder inside, is used for connecting and fixing liquid cylinder with base pipe.

[0009] As further description of the above technical scheme:

[0010] Centralizing assembly includes centralizing rib, and both ends of centralizing rib are provided with pin shaft.

[0011] As further description of the above technical scheme:

[0012] One side pin shaft sets up in liquid cylinder inside, is used for connecting and fixing liquid cylinder with centralizing rib.

[0013] As further description of the above technical scheme:

[0014] The other side pin shaft outer wall is provided with connecting ring, and the connecting ring is arranged on the outer wall of the base pipe.

[0015] As further description of the above technical scheme:

[0016] The pin shaft is used to connect the other side of the centralizing rib with the connecting ring, and the connecting ring is used to connect the centralizing rib to the outer wall of the base pipe.

[0017] As further description of the above technical scheme:

[0018] The connecting ring is provided with a clamping ring inside, and the clamping ring is arranged on the outer wall of the base pipe.

[0019] As further description of the above technical scheme:

[0020] The clamping ring is used to limit the connecting ring, so that the centralizing rib can be guided.

[0021] The utility model has the advantages of:

[0022] The utility model discloses a casing string, the outer diameter of the centralizer is less than the inner diameter of the upper casing when running in, the casing is run in, and the annular liquid column pressure forms the pressure difference on both sides of the hydraulic cylinder, and the pin is sheared, and the hydraulic cylinder moves left to push the centralizer to support the well wall and realize the centralization, and the utility model discloses a hydraulic cylinder as the opening device, and the starting pressure is controlled by the pin, and the connecting ring and the hydraulic cylinder can assist the centralization protection, the device is connected on the base pipe of packer, can centralize the packer, solves the casing centralization timing control and the problem of packer centralization, improves the operation safety and the sealing effectiveness. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 A negative pressure variable diameter centralizer is provided in the utility model, and a three-dimensional schematic view is shown in the utility model.

[0024] Fig. 2 A base pipe structure of a negative pressure variable diameter centralizer is provided in the utility model.

[0025] Fig. 3 A centralizer structure of a negative pressure variable diameter centralizer is provided in the utility model.

[0026] LEGEND:

[0027] 1, base pipe, 2, snap ring, 3, connecting ring, 4, centralizer, 5, pin shaft, 6, hydraulic cylinder, 7, pin. DETAILED DESCRIPTION

[0028] The technical scheme in the utility model embodiments will be described clearly and completely below with reference to the drawings in the utility model embodiments. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0029] REFERENCE Figs. 1-3The utility model provides a variable diameter centralizer of negative pressure, including base pipe 1, base pipe 1 adopts high strength alloy steel material and is carefully processed, has outstanding compression and tensile property, can provide solid reliable support for other components in complex downhole environment, base pipe 1 is the processing main part, is used for component support, righting assembly, righting assembly sets up in the outer wall of base pipe 1, is used for righting the center of base pipe 1, drive assembly, drive assembly sets up in the outer wall of base pipe 1, is used for providing power to righting assembly and accurately righting, drive assembly includes liquid cylinder 6 and pin 7, liquid cylinder 6 sets up in the outer wall of base pipe 1, pin 7 sets up in the inside of liquid cylinder 6, is used for connecting and fixing liquid cylinder 6 with base pipe 1, righting assembly includes righting rib 4, righting rib 4 usually is made of special elastic alloy, this alloy not only has good flexibility, can flexibly bend when being stressed, also has higher strength, is enough to bear the lateral pressure in the well, and both ends of righting rib 4 are provided with pin shaft 5, and one side pin shaft 5 sets up in the inside of liquid cylinder 6, is used for connecting and fixing liquid cylinder 6 with righting rib 4, and the other side pin shaft 5 outer wall is provided with connecting ring 3, and connecting ring 3 sets up in the outer wall of base pipe 1, and this pin shaft 5 is used for connecting the other side of righting rib 4 with connecting ring 3, and connecting ring 3 is used for connecting righting rib 4 in the outer wall of base pipe 1, and connecting ring 3 is provided with snap ring 2 in the inside, and snap ring 2 sets up in the outer wall of base pipe 1, and snap ring 2 is used for the location of connecting ring 3, can further guide righting rib 4, in the action process of righting rib 4, can guide connecting ring 3 to move according to predetermined trajectory, and further accurately guide the movement direction of righting rib 4, ensure the stability and high efficiency of whole righting process.

[0030] Specifically, in the use of negative pressure variable diameter centralizer, the device is connected on the casing through the threads on both ends of the base pipe 1, and then the two ends of the centralizer rib 4 are connected through the pin shaft 5, so that the centralizer rib 4 can rotate freely with one side of the pin shaft 5 as the center, then the centralizer rib 4 is evenly distributed and fixed between the snap ring 2 and the connecting ring 3, so the assembly preparation work before the use of the device is completed, at this time the device can be lowered into the well with the casing string, when the lowering operation is successfully completed, the device reaches the specified depth, and the annular liquid column pressure begins to play a role, at this time a pressure difference will be formed on both sides of the liquid cylinder 6, and the right side pressure is greater than the left side. The force generated by this pressure difference will directly act on the pin 7 until the pin 7 is sheared off. In this process, due to the continuous existence of the pressure difference, the liquid cylinder 6 will continue to move to the left, and the movement of the liquid cylinder 6 will push the centralizer rib 4 through the pin shaft 5, so that it gradually bends outward. With multiple centralizer ribs 4 bending outward and contacting the well wall at the same time, they work together to stabilize the casing to the center of the wellbore, achieving good centralizing effect. It is worth mentioning that the outer diameter of the connecting ring 3 and the liquid cylinder 6 itself is greater than the base pipe 1, which can play a certain role in centralizing and protecting during the lowering process, reducing the collision and friction between the casing and the well wall. Moreover, the device can also be connected to the specific packer to lower the two base pipes 1, and when the centralizer rib 4 is opened, it can centralize the packer, thereby greatly improving the sealing effect. This device solves the problems of difficult precise control of casing centralizing time and poor centralizing effect of packer, significantly improving the safety and effectiveness of the operation.

[0031] Working principle: when in use, the device is connected on the casing through the threads on both ends of the base pipe 1, and the two ends of the centralizer rib 4 are connected through the pin shaft 5, and then the centralizer rib 4 is evenly distributed between the snap ring 2 and the connecting ring 3 with one side of the pin shaft 5 as the center, so that it can be used. When the lowering is completed, under the action of the annular liquid column pressure, the liquid cylinder 6 forms a left-right pressure difference when it reaches the specified depth, so as not to hinder the lowering of the base pipe 1. When the right side pressure is greater than the left side, the force acts on the pin 7, shearing off the pin 7. Under the action of the pressure difference, the liquid cylinder 6 continuously moves to the left, and then the centralizer rib 4 is bent through the pushing of the pin shaft 5, thereby supporting the well wall. The action of multiple centralizer ribs 4 realizes centralizing, and the outer diameter of the connecting ring 3 and the liquid cylinder 6 is greater than the base pipe 1, which plays a certain role in centralizing and protecting during the lowering process, and can be connected to the specific packer to lower the two base pipes 1, thereby playing a better sealing role.

[0032] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and is not intended to limit the present application, although the foregoing embodiments of the present application has been described in detail, for the skilled in the art, it still can be modified, or for part of the technical features of the equivalent replacement, the spirit and principles of the present application, made any modification, equivalent replacement, improvement, etc., should be included within the scope of the present application.

Claims

1. A variable-gauge centralizer for use in a wellbore under negative pressure, the centralizer comprising: Include: Base pipe (1), the base pipe (1) is the processing main body, for assembly support; The righting assembly is arranged on the outer wall of the base pipe (1), which is used for righting and centering the base pipe (1); Driving assembly, the driving assembly is arranged on the outer wall of the base pipe (1), which is used for providing power for the righting assembly to accurately right; The driving assembly includes a liquid cylinder (6) and a pin (7), the liquid cylinder (6) is arranged on the outer wall of the base pipe (1), the pin (7) is arranged in the liquid cylinder (6), which is used for connecting and fixing the liquid cylinder (6) and the base pipe (1); The righting assembly includes a righting rib (4), and the righting rib (4) is provided with a pin shaft (5) at both ends; One side of the pin shaft (5) is arranged in the liquid cylinder (6), which is used for connecting and fixing the liquid cylinder (6) and the righting rib (4); The other side of the pin shaft (5) is provided with a connecting ring (3) on the outer wall, and the connecting ring (3) is arranged on the outer wall of the base pipe (1).

2. The variable diameter centralizer of claim 1, wherein: The pin shaft (5) is used for connecting the other side of the righting rib (4) and the connecting ring (3), and the connecting ring (3) is used for connecting the righting rib (4) on the outer wall of the base pipe (1).

3. The variable diameter centralizer of claim 2, wherein: The connecting ring (3) is provided with a snap ring (2) inside, and the snap ring (2) is arranged on the outer wall of the base pipe (1).

4. The variable diameter centralizer of claim 3, wherein: The snap ring (2) is used for limiting the connecting ring (3), so that the righting rib (4) can be guided.

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