Delay reducing casing centralizer

Abstract

The invention belongs to the field of petroleum and natural gas engineering, particularly relates to a delayed variable-diameter casing centralizer, and aims to solve the problems that in the prior art, the requirements for the large well diameter expansion rate, the irregular well hole and the centering of a while-drilling reaming well section pipe string cannot be met. The device comprises an upper inner shaft, bow pieces, a body, a lower inner shaft and a sliding mechanism, an upper inner shaft and a lower inner shaft are mounted in the body, and the upper inner shaft and the lower inner shaft are clamped with each other; the body is in sliding connection with the sliding mechanism, the sliding mechanism is fixed with one end of the bow piece, and the other end of the bow piece is fixed with the body. In the initial state, the maximum outer diameter is equal to the outer diameter of the casing coupling, and it can be ensured that a casing can be smoothly put in. During construction operation, the centralizer descends to a designed position along with a sleeve, after the centralizer descends in place, the positioning bolt is gradually dissolved, the spring piece is unlocked, and the bow piece shrinks under the action of restoring force of the spring, so that the outer diameter of the whole centralizer is increased, and the sleeve is centered.

Description

Technical Field

[0001] The invention belongs to the field of petroleum and natural gas engineering, and in particular relates to a delayed variable diameter casing centralizer. Background Art

[0002] Wellbore conditions are affected by many factors during the drilling process, including irregular elliptical or "sugar gourd" profiles, sawtooth-shaped longitudinal profiles, and even "big belly". The cementing of irregular wellbore wells is prone to channeling, unclean displacement of drilling fluid, low displacement efficiency, and inability to form effective cementation at the interface due to the irregular geometric curve of the wellbore annulus and large annular gaps. On the other hand, there is no suitable casing centralizer for such irregular, reaming while drilling, or large wellbore expansion rates. The casing centering is low, which ultimately seriously affects the cementing quality. Conventional centralizers cannot effectively center wells with large wellbore expansion rates, irregular wells, and reaming while drilling.

[0003] At present, short-section hydraulic centralizers and other types of variable diameter centralizers are commonly used. Although they can solve the problems of large well diameter expansion rate, irregular wellbore, and casing centering in the well section of drilling expansion, due to their high rigidity, if a large number of pipes are lowered, it is impossible to ensure that the pipe string is smoothly lowered to the bottom of the well; secondly, there are internal fluid inlet holes in the structure itself. If the seal fails in the later stage, the integrity of the pipe string cannot be guaranteed; in addition, its processing cost is high, and large-scale use will increase the drilling cost. In addition, once the wellbore pressure reaches the starting pressure of the hydraulic centralizer, the hydraulic centralizer will change its diameter. If the diameter is changed, it will be impossible to pull the casing.

[0004] Other types of variable diameter casing centralizers, one type relies on the contraction of the support spring to change the outer diameter of the centralizer. Even if it can ensure the smooth running of the casing, the reset force is low and cannot achieve effective straightening effect. In addition, during the running process, the straightening blades always rub against the casing or the well wall and are easily damaged. The other type relies on rotating the casing to unlock the blades through the friction between the straightening blades and the well wall. This form has the risk of being unable to unlock or unlocking in advance, and the reset force is not high, and it cannot achieve a good casing straightening effect.

[0005] Based on this, the present invention proposes a delayed reducing casing centralizer. Summary of the invention

[0006] In order to solve the above problems in the prior art, that is, the prior art cannot meet the problems of large well diameter expansion rate, irregular wellbore, and centering of the pipe string in the well section of the hole expansion while drilling, the present invention provides a delayed variable diameter casing centralizer, including an upper inner shaft, a bow piece, a body, a lower inner shaft, and a sliding mechanism;

[0007] An upper inner shaft and a lower inner shaft are installed inside the body, and the upper inner shaft and the lower inner shaft are clamped with each other;

[0008] The body is slidably connected to the sliding mechanism, the sliding mechanism is fixed to one end of the bow piece, and the other end of the bow piece is fixed to the body.

[0009] In some preferred embodiments, the sliding mechanism includes a spring, a nut, a sliding shaft, a limiting bolt, a first hollow groove, a second hollow groove and a guide groove;

[0010] The first hollow groove and the second hollow groove are formed on the outer circumferential surface of the body along the axial direction thereof, and the angle between the first hollow groove and the second hollow groove is a first preset angle;

[0011] Penetrating guide grooves are provided on both end surfaces of the main body and on the main body adjacent to the first hollow groove and the second hollow groove;

[0012] A bow piece is disposed in each of the first hollow groove and the second hollow groove, one end of the bow piece is fixed to the sliding shaft, one end of the sliding shaft passes through the guide groove and is fixed to the body via a nut, and the other end of the sliding shaft is disposed in the guide groove and is fixed to the body via a limiting bolt;

[0013] Both ends of the sliding shaft are fixed to one end of the spring, and the other end of the spring is fixed to the body;

[0014] The spring, the nut, the sliding shaft, the limiting bolt, the first hollow groove, the second hollow groove and the guide groove are evenly arranged in multiple groups along the outer circumferential surface of the body.

[0015] In some preferred embodiments, the clamping ends of the upper inner shaft and the lower inner shaft are flap-tooth structures, and the upper inner shaft and the lower inner shaft are fixed to the body by positioning screws.

[0016] In some preferred embodiments, one-way saw teeth are provided in the guide groove, and the portion of the sliding shaft disposed in the guide groove is provided with axial teeth that cooperate with the one-way saw teeth in the guide groove.

[0017] In some preferred embodiments, one end of the bow piece is fixed to the sliding shaft in the following manner: one end of the bow piece is wrapped around the sliding shaft and fixed by a rivet.

[0018] In some preferred embodiments, the material of the limiting bolt includes a soluble material.

[0019] In some preferred embodiments, the bow piece is an arc-shaped structure, and the material of the bow piece is an elastic material.

[0020] In some preferred embodiments, the guide groove is arc-shaped, and the center of the guide groove and the center of the body are on the same axis.

[0021] Beneficial effects of the present invention:

[0022] The invention provides a time-delayed variable diameter casing centralizer, the maximum outer diameter before the diameter change is equal to the outer diameter of the casing coupling, which can smoothly pass through the upper casing to ensure the safe lowering of the casing. After lowering to the designed position, the positioning bolt gradually dissolves to achieve unlocking, and under the action of the spring restoring force, the bow piece contracts, so that the outer diameter of the entire centralizer increases, which plays a role in centralizing the casing in the well section with a large well diameter expansion rate, an irregular wellbore, and while drilling expansion, thereby improving the cementing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0024] Figure 1 It is a structural schematic diagram of an initial state of a delayed variable diameter casing centralizer of the present invention;

[0025] Figure 2 It is a structural schematic diagram of a body of a delayed variable diameter casing centralizer of the present invention;

[0026] Figure 3 It is a structural schematic diagram of a lower inner shaft of a delayed variable diameter casing centralizer of the present invention;

[0027] Figure 4 It is a structural schematic diagram of a fin of a delayed reducer casing centralizer of the present invention;

[0028] Figure 5 It is a structural schematic diagram of a sliding shaft of a delayed variable diameter casing centralizer of the present invention;

[0029] Figure 6 It is a structural schematic diagram of an expanded state of a delayed reducer casing centralizer of the present invention;

[0030] Figure 7 It is a schematic diagram comparing the initial state and the expanded state of a delayed variable diameter casing centralizer of the present invention. DETAILED DESCRIPTION

[0031] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0032] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0033] like Figure 1-7 As shown, see Figure 1 , Figure 3 , Figure 4 , Figure 6 The present invention provides a delayed variable diameter casing centralizer, comprising an upper inner shaft 1, a bow piece 3, a body 4, a lower inner shaft 6, and a sliding mechanism;

[0034] An upper inner shaft 1 and a lower inner shaft 6 are installed inside the body 4, and the upper inner shaft 1 and the lower inner shaft 6 are mutually clamped;

[0035] The body 4 is slidably connected to a sliding mechanism, the sliding mechanism is fixed to one end of the bow piece 3 , and the other end of the bow piece 3 is fixed to the body 4 .

[0036] For further explanation of the present invention, see Figure 1 , Figure 2 , Figure 5 , Figure 6 The sliding mechanism includes a spring 2, a nut 7, a sliding shaft 8, a limiting bolt 9, a first hollow groove 10, a second hollow groove 11 and a guide groove 12;

[0037] The first hollow groove 10 and the second hollow groove 11 are formed on the outer circumferential surface of the body 4 along the axial direction thereof, and the angle between the first hollow groove 10 and the second hollow groove 11 is a first preset angle;

[0038] A penetrating guide groove 12 is provided on both end surfaces of the main body 4 and on the main body 4 adjacent to the first hollow groove 10 and the second hollow groove 11;

[0039] A bow piece 3 is disposed in each of the first hollow groove 10 and the second hollow groove 11, one end of the bow piece 3 is fixed to the sliding shaft 8, one end of the sliding shaft 8 passes through the guide groove 12 and is fixed to the body 4 through a nut 7, and the other end of the sliding shaft 8 is disposed in the guide groove 12 and is fixed to the body 4 through a limiting bolt 9;

[0040] Both ends of the sliding shaft 8 are fixed to one end of the spring 2, and the other end of the spring 2 is fixed to the body 4;

[0041] The spring 2 , the nut 7 , the sliding shaft 8 , the limiting bolt 9 , the first hollow groove 10 , the second hollow groove 11 and the guide groove 12 are evenly arranged in multiple groups along the outer circumferential surface of the body 4 .

[0042] Among them, the upper inner shaft 1 and the lower inner shaft 6 in the present invention, on the one hand, play the role of supporting the spring 2 and the bow piece 3, otherwise after assembly, the spring 2 will be in a straight line, resulting in the inner cavity not being circular and unable to be installed on the casing on site; on the other hand, protect the main body 4 to prevent friction with the casing wall or the well wall during the lowering process.

[0043] Among them, see Figure 2 The first preset angle θ is the angle between the line between point a and point b and the first center line m. The first preset angle is preferably 60° in this embodiment. The first center line m is the center line of the first hollow groove 10. Point a is the midpoint of the outer edge of the right end surface of the first hollow groove 10. Point b is the midpoint of the outer edge of the left end surface of the second hollow groove 11.

[0044] Among them, in this embodiment, the spring 2, the nut 7, the sliding shaft 8, the limiting bolt 9, the first hollow groove 10, the second hollow groove 11 and the guide groove 12 are evenly arranged in three groups along the outer circumferential surface of the body 4.

[0045] For further explanation of the present invention, see Figure 3 The clamping ends of the upper inner shaft 1 and the lower inner shaft 6 are flap-tooth structures, and the upper inner shaft 1 and the lower inner shaft 6 are fixed to the body 4 by positioning screws 5.

[0046] The upper inner shaft 1 and the lower inner shaft 6 are mutually engaged to achieve the function of preventing rotation.

[0047] In this embodiment, the number of teeth of the flap tooth structure is 3.

[0048] As a further explanation of the present invention, the guide groove 12 is provided with one-way saw teeth, and the portion of the sliding shaft 8 disposed in the guide groove 12 is provided with axial teeth that cooperate with the one-way saw teeth in the guide groove 12 .

[0049] For further explanation of the present invention, see Figure 4 One end of the bow piece 3 is fixed to the sliding shaft 8 in the following manner: one end of the bow piece 3 is wrapped around the sliding shaft 8 and fixed by rivets.

[0050] For further explanation of the present invention, see Figure 1 The material of the limiting bolt 9 includes a soluble material.

[0051] For further explanation of the present invention, see Figure 4 The bow piece 3 is an arc-shaped structure, and the material of the bow piece 3 is an elastic material.

[0052] The material of the bow piece 3 includes 65Mn spring steel in addition to the elastic material.

[0053] For further explanation of the present invention, see Figure 2 The guide groove 12 is arc-shaped, and the center of the guide groove 12 and the center of the body 4 are on the same axis.

[0054] During the use of the present invention, when it is implemented on site, the delayed variable diameter straightener is inserted into the designed position of the casing, and the positioning screw 5 is tightened with a hexagonal wrench to complete the installation; in the initial state, due to the limiting action of the limit bolt 9, the sliding shaft 8 cannot move, the spring 2 is in a tensile state, the bow piece 3 will not be compressed, and the outer diameter of the bow piece 3 is smaller than the outer diameter of the body 4. The limit bolt 9 is made of a soluble material, and it gradually dissolves when it encounters an aqueous solution at the bottom of the well. After dissolution, the sliding shaft 8 moves to the other end under the action of the restoring force of the spring 2, and at the same time compresses the bow piece 3. The outer diameter of the bow piece 3 gradually increases until it reaches the maximum outer diameter. See the comparison diagram after expansion. Figure 7 .

[0055] The terms "first", "second", etc. are used to distinguish similar objects rather than to describe or indicate a particular order or sequence.

[0056] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus / device.

[0057] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A delayed reducer casing centralizer, characterized in that: It comprises an upper inner shaft (1), a bow piece (3), a body (4), a lower inner shaft (6), and a sliding mechanism; An upper inner shaft (1) and a lower inner shaft (6) are installed inside the body (4), and the upper inner shaft (1) and the lower inner shaft (6) are mutually clamped; The main body (4) is slidably connected to the sliding mechanism, the sliding mechanism is fixed to one end of the bow piece (3), and the other end of the bow piece (3) is fixed to the main body (4).

2. A delayed reducer casing centralizer according to claim 1, characterized in that: The sliding mechanism comprises a spring (2), a nut (7), a sliding shaft (8), a limiting bolt (9), a first hollow groove (10), a second hollow groove (11) and a guide groove (12); The first hollow groove (10) and the second hollow groove (11) are formed on the outer circumferential surface of the body (4) along the axial direction thereof, and the angle between the first hollow groove (10) and the second hollow groove (11) is a first preset angle; Penetrating guide grooves (12) are provided on both end surfaces of the main body (4) and on the main body (4) adjacent to the first hollow groove (10) and the second hollow groove (11); A bow piece (3) is disposed in each of the first hollow groove (10) and the second hollow groove (11); one end of the bow piece (3) is fixed to the sliding shaft (8); one end of the sliding shaft (8) passes through the guide groove (12) and is fixed to the body (4) via a nut (7); the other end of the sliding shaft (8) is disposed in the guide groove (12) and is fixed to the body (4) via a limiting bolt (9); Both ends of the sliding shaft (8) are fixed to one end of the spring (2), and the other end of the spring (2) is fixed to the body (4); The spring (2), the nut (7), the sliding shaft (8), the limiting bolt (9), the first hollow groove (10), the second hollow groove (11) and the guide groove (12) are evenly arranged in multiple groups along the outer circumferential surface of the body (4).

3. A delayed reducer casing centralizer according to claim 2, characterized in that: The clamping ends of the upper inner shaft (1) and the lower inner shaft (6) are flap-tooth structures, and the upper inner shaft (1) and the lower inner shaft (6) are fixed to the body (4) by means of positioning screws (5).

4. A delayed reducer casing centralizer according to claim 3, characterized in that: The guide groove (12) is provided with one-way saw teeth, and the portion of the sliding shaft (8) disposed in the guide groove (12) is provided with axial teeth that cooperate with the one-way saw teeth in the guide groove (12).

5. The delayed reducer casing centralizer according to claim 4, characterized in that: One end of the bow piece (3) is fixed to the sliding shaft (8) in the following manner: One end of the bow piece (3) is wrapped around the sliding shaft (8) and fixed by a rivet.

6. A delayed reducer casing centralizer according to claim 5, characterized in that: The material of the limiting bolt (9) includes a soluble material.

7. A delayed reducer casing centralizer according to claim 6, characterized in that: The bow piece (3) is an arc-shaped structure, and the material of the bow piece (3) is an elastic material.

8. The delayed reducer casing centralizer according to claim 7, characterized in that: The guide groove (12) is arc-shaped, and the center of the guide groove (12) and the center of the body (4) are on the same axis.

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