Elastic centralizer and variable-diameter elastic centralizing mechanism

Abstract

The invention provides an elastic centralizer which comprises a first connecting cylinder, a second connecting cylinder and a plurality of centralizing ribs, the top ends of the centralizing ribs are connected with the first connecting cylinder, the bottom ends of the centralizing ribs are connected with the second connecting cylinder, the first connecting cylinder and the second connecting cylinder are arranged on the outer wall of a sleeve in a sleeving mode, and the centralizing ribs are made of fiber resin composite materials. And the sleeve extends in an arc form in the direction far away from the sleeve. According to the elastic centralizer, the contact area of the centralizing ribs and the well wall is in a proper range, large supporting force can be provided, stress is not concentrated, meanwhile, the centralizing ribs have good elastic reset capacity, when the centralizing ribs are subjected to local pressure, the centralizing ribs are not prone to plastic deformation, and therefore centering running of a casing cannot be affected.

Description

Technical Field

[0001] The invention relates to the field of oil and gas well cementing tools, and in particular to an elastic centralizer and a variable diameter elastic centralizing mechanism. Background Art

[0002] With the continuous development of drilling technology, deep wells and ultra-deep wells have gradually become the main direction of oil and gas development, and the corresponding cementing operations have become more and more complicated. As a key component of the casing operation in cementing construction, the centralizer can be used to ensure the safe lowering of the casing and tools. Existing centralizers are usually made of metal materials. Although the supporting force applied to the pipe string is large, the metal material also limits its elastic reset ability. Especially when the well diameter is much larger than the casing diameter, the centralizer is prone to plastic deformation once it is subjected to eccentric force. If the centralizer is plastically deformed, the centralizing function will fail, and it will also affect the centering of the subsequent casing. Summary of the invention

[0003] One object of the present invention is to propose an elastic stabilizer and a variable diameter elastic straightening mechanism, so that the contact area between the straightening rib and the well wall is within an appropriate range, which can provide a larger supporting force without concentrated force. At the same time, the straightening rib has better elastic reset ability. When subjected to local pressure, the straightening rib is not prone to plastic deformation, thereby not affecting the centering of the casing.

[0004] According to the present invention, there is provided an elastic straightener, comprising: a first connecting tube, a second connecting tube and a plurality of straightening ribs, wherein the top end of the straightening rib is connected to the first connecting tube, and the bottom end is connected to the second connecting tube, the first connecting tube and the second connecting tube are both sleeved on the outer wall of the casing, the straightening rib is made of a fiber resin composite material, and extends in the form of an arc in a direction away from the casing.

[0005] In a preferred embodiment, a plurality of the straightening ribs are evenly arranged in a circumferential form along the outer wall of the sleeve.

[0006] In a preferred embodiment, the sides of the adjacent righting ribs that are close to each other are both constructed into a streamlined shape, and a flow hole is opened on the main body of the righting rib.

[0007] In a preferred embodiment, the first connecting tube and the second connecting tube are respectively formed integrally with the straightening rib.

[0008] In a preferred embodiment, the first connecting tube and the second connecting tube are both made of fiber-resin composite materials.

[0009] In a preferred embodiment, the elastic centralizer is made by a curing molding process.

[0010] In a preferred embodiment, the curvature of the centralizing rib, the contact area with the wellbore wall, the interval between adjacent centralizing ribs and the specific type of the fiber-resin composite material can all be adjusted according to the wellbore type.

[0011] In a preferred embodiment, the outer surface of the top end of the straightening rib abuts against the well wall.

[0012] The present invention also provides a variable diameter elastic straightening mechanism, comprising: a first inner tube, a first heat expansion part, an elastic straightener, a second heat expansion part and a second inner tube connected to the first inner tube, the first inner tube and the second inner tube are respectively provided with a first step and a second step on the outer surfaces of the ends away from each other, the first connecting tube and the second connecting tube of the elastic straightener are respectively sleeved on the outer surfaces of the first inner tube and the second inner tube, the first heat expansion part abuts between the first step and the first connecting tube, and the second heat expansion part abuts between the second step and the second connecting tube.

[0013] In a preferred embodiment, the first inner tube and the second inner tube are both sleeved on the outer surface of the sleeve.

[0014] The present invention has at least the following technical effects:

[0015] According to the present invention, a first connecting tube, a second connecting tube and a plurality of straightening ribs are provided. The top end of the straightening rib is connected to the first connecting tube, and the bottom end is connected to the second connecting tube. The first connecting tube and the second connecting tube are both sleeved on the outer wall of the casing. Since the straightening rib is made of a fiber resin composite material and extends in an arc form in a direction away from the casing, on the one hand, the contact area between the straightening rib and the well wall is within a suitable range, which can provide a large supporting force without concentrated force. At the same time, the straightening rib has a better elastic reset ability. When subjected to local pressure, the straightening rib is not easy to be plastically deformed, thereby not affecting the central lowering of the casing.

[0016] According to the present invention, the sides of adjacent righting ribs close to each other are streamlined, and the main body of the righting ribs is provided with flow holes. When replacing mud, the mud can form a vortex on the outer wall of the casing after passing through the righting ribs, thereby improving the mud replacement efficiency and cementing quality.

[0017] According to the present invention, the outer surface of the top end of the righting rib abuts against the wellbore wall, thereby increasing the contact area between the righting rib and the wellbore wall at another location, avoiding concentration of the contact location between the righting rib and the wellbore wall, avoiding scraping off mud and sand on the inner wall of the open hole, causing wellbore blockage, and reducing the degree of damage to the wellbore wall by the righting rib.

[0018] According to the present invention, the elastic centralizer adopts a curing molding process, thereby being able to shorten the processing cycle.

[0019] According to the present invention, the first inner tube and the second inner tube are provided with a first step and a second step respectively on the outer surface of the ends away from each other, the first connecting tube and the second connecting tube of the elastic straightener are respectively sleeved on the outer surfaces of the first inner tube and the second inner tube, the first thermal expansion part abuts between the first step and the first connecting tube, and the second thermal expansion part abuts between the second step and the second connecting tube. In the process of the variable diameter elastic straightening mechanism as the casing is continuously lowered, the temperature in the well continues to rise, the first thermal expansion part and the second thermal expansion part respectively expand and squeeze the first connecting tube and the second connecting tube, and the first connecting tube and the second connecting tube can then squeeze the straightening ribs, thereby increasing the outer diameter of the straightener, so as to achieve a better straightening effect for wellbores with different well diameters. In addition, by changing the material and thickness of the first thermal expansion part and the second thermal expansion part, the time of change of the outer diameter of the straightener and the size of the outer diameter after the change can be controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The overall structural diagram of the elastic centralizer according to the present invention is schematically shown;

[0021] Figure 2 The schematic diagram of the structure of the centralizing rib of the elastic centralizer according to the present invention is schematically shown;

[0022] Figure 3 A schematic diagram of a curing process for making an elastic centralizer according to the present invention is shown schematically;

[0023] Figure 4 The structure diagram of the variable diameter elastic righting mechanism according to the present invention is schematically shown;

[0024] Figure 5 Another structural schematic diagram of the variable diameter elastic righting mechanism according to the present invention is schematically shown.

[0025] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "upper", "lower", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the present invention, "multiple" refers to two or more.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] like Figure 1 to Figure 2 As shown, the elastic centralizer 100 of the present invention comprises: a first connecting tube 1, a second connecting tube 2 and a plurality of centralizing ribs 3, the top end of the centralizing rib 3 is connected to the first connecting tube 1, and the bottom end is connected to the second connecting tube 2, and the first connecting tube 1 and the second connecting tube 2 are both sleeved on the outer wall of a casing (not shown in the figure). The centralizing rib 3 is made of a fiber resin composite material and extends in an arc form in a direction away from the outer wall of the casing.

[0030] According to the present invention, a first connecting tube 1, a second connecting tube 2 and a plurality of straightening ribs 3 are provided. The top end of the straightening rib 3 is connected to the first connecting tube 1, and the bottom end is connected to the second connecting tube 2. The first connecting tube 1 and the second connecting tube 2 are both sleeved on the outer wall of the casing. Since the straightening rib 3 is made of a fiber resin composite material and extends in an arc form in a direction away from the casing, on the one hand, the contact area between the straightening rib 3 and the well wall is in a suitable range, which can provide a large supporting force without concentrated force. At the same time, the straightening rib 3 has a better elastic reset ability. When subjected to local pressure, the straightening rib 3 is not easy to be plastically deformed, so as not to affect the centering of the casing.

[0031] In one or more embodiments, a plurality of centralizing ribs 3 are evenly arranged in a circumferential form along the outer wall of the casing.

[0032] like Figure 2 As shown, in one or more embodiments, the sides of adjacent righting ribs 3 that are close to each other are all configured to be streamlined, and a flow hole 31 is provided on the main body of the righting rib 3. Optionally, the flow hole 31 is configured to be elliptical.

[0033] According to the present invention, the sides of adjacent righting ribs 3 that are close to each other are streamlined, and a flow hole 31 is provided on the main body of the righting rib 3. When replacing mud, the mud can form a vortex on the outer wall of the casing after passing through the righting rib 3, thereby improving the mud replacement efficiency and cementing quality.

[0034] In one or more embodiments, the outer surface of the top of the straightening rib 3 abuts against the wellbore wall, thereby increasing the contact area between the straightening rib 3 and the wellbore wall at another location, avoiding concentration of the contact location between the straightening rib 3 and the wellbore wall, avoiding scraping off mud and sand on the inner wall of the open hole, causing blockage of the wellbore, and reducing the degree of damage to the wellbore wall by the straightening rib 3.

[0035] In one or more embodiments, the first connecting tube 1 and the second connecting tube 2 are respectively formed integrally with the straightening rib 3 .

[0036] In one or more embodiments, the first connecting tube 1 and the second connecting tube 2 are both made of a fiber-resin composite material.

[0037] In one or more embodiments, the elastic centralizer 100 of the present invention adopts a curing molding process, so as to reduce the processing cycle. Specifically, the vacuumized fiber resin composite preform is co-cured with the mold. The co-curing process is as follows: Figure 3 As shown, that is: the heating rate and the cooling rate are both 3.5-4.5℃ / min, the temperature is raised from room temperature to 130℃ after 25min, and maintained at this temperature for 30min; then the temperature is raised to 165℃ within 20min, and the pressure is increased to 0.5MPa, and the current temperature and pressure are maintained for 2h; after the end, the pressure is released and the temperature is lowered to room temperature in 40min.

[0038] In one or more embodiments, the curvature of the straightening rib 3, the contact area with the wellbore wall, the spacing between adjacent straightening ribs 3, and the specific type of fiber resin composite material can be adjusted according to the wellbore type, so that an adaptive elastic straightener 100 can be manufactured for different wellbores.

[0039] like Figure 4 and Figure 5As shown, based on the elastic centralizer 100, the present invention further provides a variable diameter elastic centralizer 200, which is used for centralizing the casing, comprising: a first inner tube 4, a first thermal expansion portion 5, an elastic centralizer 100, a second inner tube 6 and a second thermal expansion portion 7, the first inner tube 4 is connected to the second inner tube 6, the first inner tube 4 is provided with a first step 41 on the outer surface of the end away from the second inner tube 6, the second inner tube 6 is provided with a second step 61 on the outer surface of the end away from the first inner tube 4, the first connecting tube 1 and the second connecting tube 2 of the elastic centralizer 100 are respectively sleeved on the outer surfaces of the first inner tube 4 and the second inner tube 6, the first thermal expansion portion 5 abuts between the first step 41 and the first connecting tube 1, and the second thermal expansion portion 7 abuts between the second step 61 and the second connecting tube 2. The first inner tube 4 and the second inner tube 6 are both sleeved on the outer surface of the casing. Optionally, the first thermal expansion portion 5 and the second thermal expansion portion 7 are both made of thermal expansion materials, such as metal composite materials.

[0040] According to the present invention, the first inner tube 4 and the second inner tube 6 are provided with a first step 41 and a second step 61 on the outer surfaces of the ends away from each other, respectively, the first connecting tube 1 and the second connecting tube 2 of the elastic centralizer 100 are respectively sleeved on the outer surfaces of the first inner tube 4 and the second inner tube 6, the first thermal expansion portion 5 abuts between the first step 41 and the first connecting tube 1, and the second thermal expansion portion 7 abuts between the second step 61 and the second connecting tube 2. As the variable diameter elastic centralizing mechanism 200 is continuously lowered into the casing, the temperature in the well continues to rise, the first thermal expansion portion 5 and the second thermal expansion portion 7 respectively expand and squeeze the first connecting tube 1 and the second connecting tube 2, and the first connecting tube 1 and the second connecting tube 2 can then squeeze the centralizing rib 3, thereby increasing the outer diameter of the centralizer 3, so as to achieve a better centralizing effect for wellbores of different diameters.

[0041] Furthermore, by changing the material and thickness of the first heat expansion portion 5 and the second heat expansion portion 7, the time when the outer diameter of the centralizer changes and the size of the outer diameter after the change can be controlled.

[0042] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An elastic centralizer, comprising: A first connecting tube, a second connecting tube and a plurality of straightening ribs, wherein the top end of the straightening rib is connected to the first connecting tube, and the bottom end is connected to the second connecting tube, the first connecting tube and the second connecting tube are both sleeved on the outer wall of the sleeve, and the straightening rib is made of a fiber resin composite material and extends in an arc form in a direction away from the sleeve.

2. The elastic centralizer according to claim 1, characterized in that: The plurality of straightening ribs are evenly arranged in a circumferential form along the outer wall of the casing.

3. The elastic centralizer according to claim 2, characterized in that: The sides of the adjacent righting ribs that are close to each other are all constructed into a streamlined shape, and the main body of the righting rib is provided with a flow hole.

4. The elastic centralizer according to claim 2, characterized in that: The first connecting tube and the second connecting tube are respectively formed integrally with the straightening rib.

5. The elastic centralizer according to claim 4, characterized in that: The first connecting tube and the second connecting tube are both made of fiber-resin composite materials.

6. The elastic centralizer according to claim 5, characterized in that: The elastic centralizer is manufactured by a curing molding process.

7. The elastic centralizer according to claim 6, characterized in that: The curvature of the centralizing rib, the contact area with the wellbore wall, the interval between adjacent centralizing ribs and the specific type of the fiber-resin composite material can all be adjusted according to the wellbore type.

8. The elastic centralizer according to claim 1, characterized in that: The outer surface of the top end of the straightening rib abuts against the well wall.

9. A variable diameter elastic straightening mechanism, characterized in that: include: A first inner tube, a first heat expansion portion, an elastic centralizer, a second heat expansion portion and a second inner tube connected to the first inner tube, the first inner tube and the second inner tube are respectively provided with a first step and a second step on the outer surfaces of one end away from each other, the first connecting tube and the second connecting tube of the elastic centralizer are respectively sleeved on the outer surfaces of the first inner tube and the second inner tube, the first heat expansion portion abuts between the first step and the first connecting tube, and the second heat expansion portion abuts between the second step and the second connecting tube.

10. The variable diameter elastic straightening mechanism according to claim 9, characterized in that: The first inner tube and the second inner tube are both sleeved on the outer surface of the sleeve.

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