CN113802997A

CN113802997A - Integral elastic centralizer and manufacturing method thereof

Info

Publication number: CN113802997A
Application number: CN202010534779.0A
Authority: CN
Inventors: 王孝刚; 董海峰; 史雪枝; 付先惠; 王毅; 乔智国; 熊昕东; 朱敏; 李友培; 伍强
Original assignee: China Petroleum and Chemical Corp; Sinopec Southwest Oil and Gas Co
Current assignee: China Petroleum and Chemical Corp; Sinopec Southwest Oil and Gas Co
Priority date: 2020-06-12
Filing date: 2020-06-12
Publication date: 2021-12-17

Abstract

The invention relates to an integral elastic centralizer and a manufacturing method thereof. The manufacturing method comprises the following steps: obtaining an elastic cylinder body through casting; forming a plurality of hollowed-out parts in the middle of the barrel, wherein the hollowed-out parts are spaced from each other so as to form a righting strip part between the adjacent hollowed-out parts; and the middle part of the hollowed-out cylinder body is protruded outwards in the radial direction to deform, so that the righting strip part forms an arc-shaped outline; wherein the one-piece resilient centralizer is free of welds or connection structures. The centralizer can smoothly pass through a narrow part and a bent part in a well to smoothly feed the oil pipe into place.

Description

Integral elastic centralizer and manufacturing method thereof

Technical Field

The invention relates to the technical field of well cementation tools, in particular to a manufacturing method of an integral elastic centralizer. The invention also relates to the integral elastic centralizer manufactured by the method.

Background

The centralizer comprises an elastic centralizer, a blade centralizer, a rotary centralizer and the like.

A commonly used elastic centralizer mainly comprises two collars and a plurality of centralizing bars arranged between the two collars. The existing elastic centralizer is generally complex in structure, and a centralizing strip is connected to a coupling through a pin, a bearing and other structures. However, this tends to create stress concentration or stress weakness between the centralizer strips and the collar. Thus, the centralizer strips themselves cannot have a large arcuate profile, nor can they be significantly deformed. Otherwise, the centralizer may be susceptible to breakage, or permanent bulging deformation, resulting in complete failure of the centralizer. As such, the elastic centralizer can only be used for casing run-in because the casing has a larger outer diameter and a smaller distance from the borehole wall, thus eliminating the need for the centralizer strips to have a larger arcuate profile or undergo a larger deformation. However, such elastic centralizers cannot be used as tubing centralizers because the outer diameter of the tubing is small, the distance from the well wall is large, and the tubing itself is less rigid and therefore not easily centered.

Currently, there are also so-called "one-piece" elastic centralizers. However, prior one-piece spring centralizers have been formed by bending a steel plate into a cylinder and welding the plate together, or by splitting the plate into multiple pieces, such as a collar and a centralizer strip, and welding the pieces together. Although the elastic centralizer may be said to be one-piece, it is structurally inevitable that there will be a weld. These welds may also form stress concentration zones or stress weakness zones. Therefore, even in the case of the one-piece elastic centralizer, the centralizing strip portion thereof cannot have a large arcuate profile and cannot be largely deformed. Otherwise, the weld is prone to rupture, resulting in failure of the entire centralizer. Thus, the integrated elastomeric centralizer can also only be used as a casing centralizer, not a tubing centralizer.

Centralizers for oil pipes are typically vane centralizers or rotary centralizers as described above. They are welded to the tubing and are not elastomeric. This allows them to have a large volume to be supported between the tubing and the borehole wall. However, if the well wall is not uniform and there is a narrowing, the passage of such a centralizer becomes difficult, sometimes resulting in a stuck tubing that is difficult to run into the well. This problem may also occur when the centralizer passes through a bend. Currently, if these conditions are encountered, the operator will typically force the tubing harder to help the centralizer pass through the constriction or bend, which sometimes results in premature setting of the packer on the tubing, or other unintended conditions. In particular, such operations are very dangerous for weak formations.

Therefore, there is a need for a centralizer for tubing running that can smoothly pass through a narrowed or curved portion to avoid the above.

Disclosure of Invention

In view of the above problems, the present invention provides a method for manufacturing an integral elastic centralizer, and an integral elastic centralizer especially suitable for oil pipe manufactured by the method, which can smoothly pass through a narrowed part or a bent part in a well to avoid the above situation.

According to a first aspect of the present invention, there is provided a method of manufacturing a unitary resilient centralizer, comprising the steps of: obtaining an elastic cylinder body through casting; forming a plurality of hollowed-out parts in the middle of the barrel, wherein the hollowed-out parts are spaced from each other so as to form a righting strip part between the adjacent hollowed-out parts; and the middle part of the hollowed-out cylinder body is protruded outwards in the radial direction to deform, so that the righting strip part forms an arc-shaped outline; wherein the one-piece resilient centralizer is free of welds or connection structures.

In this way, a one-piece resilient centralizer can be manufactured without welds or separate attachment structures (e.g., pins, rivets, bearings, etc.). Such a resilient centralizer may be free of relatively distinct stress concentrations or stress weaknesses, thus allowing for greater outward bulge dimensions and greater deformation. This enables the manufactured centralizer to be used in the running process of oil pipes. When the centralizer is used for an oil pipe, the centralizer can be effectively deformed to pass through a narrow part or a bent part in a well, so that the centralizer can be prevented from being damaged or stuck in the well.

In one embodiment, the elastic cylinder is made of 140V steel through a hot rolling process, and the cylinder contains chromium, molybdenum, vanadium and nickel so as to improve the structural strength of the cylinder.

In one embodiment, the cut is made on the barrel by a wire saw to form the hollowed-out portion and the centering strip portion.

In one embodiment, the centralizing strip portions are formed with uniform thickness and width.

In one embodiment, the middle part of the hollowed-out cylinder is protruded and deformed outwards in the radial direction by applying pressure to two ends of the hollowed-out cylinder, and the applied pressure is between 50kN and 60 kN.

In one embodiment, the middle part of the hollowed-out cylinder is deformed to bulge outwards in the radial direction by applying pressure on two ends of the hollowed-out cylinder under the condition of heating, and the temperature around the hollowed-out cylinder is between 1100 ℃ and 1300 ℃, preferably 1200 ℃.

In one embodiment, when pressure is applied to two ends of the hollowed-out cylinder, a cylindrical contour limiting mold is sleeved on the outer side of the hollowed-out cylinder, and the arc contour of the righting strip part is limited by the contour limiting mold.

According to a second aspect of the present invention there is provided a one-piece resilient centralizer comprising an annular upper collar, an annular lower collar longitudinally spaced from the annular upper collar, and a longitudinally extending centralizer strip portion connected between the upper and lower collars, the centralizer strip portion having an arcuate profile with a radially outwardly convex central portion, wherein the one-piece resilient centralizer is free of welds or connection formations.

In one embodiment, the ratio of the maximum outside diameter of the centralizer strip portion to the outside diameters of the upper and lower collars is between 1.5-2.2, preferably between 1.64-1.77, without deformation of the unitary resilient centralizer.

In one embodiment, the integrated resilient centralizer has a minimum return force of no less than 15kN and/or a maximum starting force of no more than 600N at a deflection clearance ratio of 67%.

An advantage of the present invention over the prior art is that an integral resilient centralizer can be made by this method without welds or separate attachment structures (e.g., pins, rivets, bearings, etc.). Such a resilient centralizer may be free of relatively distinct stress concentrations or stress weaknesses, thus allowing for greater outward bulge dimensions and greater deformation. This enables the manufactured centralizer to be used in the running process of oil pipes. When the centralizer is used for an oil pipe, the centralizer can be effectively deformed to pass through a narrow part or a bent part in a well, so that the centralizer can be prevented from being damaged or stuck in the well.

Drawings

The invention is described in more detail below with reference to the accompanying drawings. Wherein:

FIG. 1 shows a schematic structural view of one embodiment of a unitary resilient centralizer according to the invention;

FIG. 2 shows a schematic flow chart of one embodiment of a method of manufacturing a unitary resilient centralizer according to the present invention.

In the drawings, like parts are provided with like reference numerals. The figures are not drawn to scale.

Detailed Description

The invention will be further explained with reference to the drawings.

FIG. 1 schematically illustrates one embodiment of a unitary resilient centralizer 10 according to the present invention.

As shown in fig. 1, the centralizer 10 includes an annular upper collar 11 and an annular lower collar 12. The lower collar 12 is aligned with the upper collar 11 in the longitudinal direction and spaced apart from each other. They may be mounted to the tubing so that the entire centralizer 10 is connected to the tubing.

The centralizer 10 further comprises a centralizing band portion 13 extending in the longitudinal direction formed between the upper collar 11 and the lower collar 12. The central portion of the righting strip portion 13 bulges radially outward to form an arcuate profile. In the preferred embodiment shown in fig. 1, the centralizer 10 has 4 centralizer strip portions 13. Which are arranged circumferentially spaced apart from each other with a 90 deg. difference between adjacent righting strip portions 13. The centralizing band section 13 thus arranged provides the maximum lateral force for support against the borehole wall. However, it should be understood that 6 centralizing bar portions 13 may be provided, as desired. Here, the number of the centering bar portions 13 is small, and each centering bar portion 13 can be well stressed to achieve a centering action.

In the present invention, it is important that the centralizer 10 be integrally formed such that no welds or other separate attachment structures, such as pins, rivets, bearings, etc., are present throughout the centralizer 10. This allows the centralizer strip portion 13 to be more resilient, enabling greater deformation, without being damaged thereby, during use of the centralizer 10. Hereinafter, a specific manufacturing method of the centralizer 10 will be described in detail.

In one embodiment, the ratio of the maximum outer diameter of the centralizer strip portion 13 to the outer diameter of the upper and

lower collars

11, 12 is between about 1.5-2.2, preferably between about 1.64-1.77. For example, for a 69mm oil pipe, the above ratio may be approximately between 1.77 and 1.91, preferably 1.77. For example, for an 89mm oil pipe, the above ratio may be approximately 1.64-2.13, preferably 1.64. This allows the overall centralizer 10 to be more "expanded" in shape, in contrast to the "slim" style of prior art centralizers for casing. The combination of integral manufacture and this shape makes centralizer 10 particularly well suited for running smaller sized tubing into larger sized wellbores. In this case, it is possible to ensure effective deformation of the centralizer 10 and thereby allow the centralizer 10 to smoothly pass through a narrowed portion and a curved portion or the like downhole.

The centralizer 10 of the present application may also have a greater extension deformation in the length direction because it may have a greater radial compression deformation when passing through a narrowed or curved portion. This requires the tubing section in which the centralizer 10 is installed to have a relatively long dimension to accommodate deformation of the centralizer 10. To this end, the manufactured centralizer 10, which is not deformed in use, preferably has a small length dimension, for example about 300 mm. This length dimension is much smaller than the length dimension of prior art elastic centralizers, for example about 500 mm. Through the arrangement, the length of an oil pipe for installing the oil pipe is reduced, and the rigidity of the oil pipe is reduced.

To ensure the structural strength of such a smaller length centralizer 10, the centralizer 10 is preferably made entirely of 140V steel through a hot rolling process, which preferably contains chromium, molybdenum, vanadium and nickel. The centralizer 10 made of such material can have better structural strength while having better elasticity.

The elastic material commonly used in the prior art for making the elastic centralizer strips is 65 manganese steel, which has a minimum tensile strength of about 980MPa and a minimum work of shock absorption of about 25J. This makes the yield strength and toughness index of the material unsuitable for the inventive centralizer 10 having a shorter size, a larger ratio of the maximum outer diameter to the collar outer diameter, and a relatively small number of centralizer bar portions, and is prone to fracture during machining. On the contrary, the 140V steel adopted in the invention has the minimum tensile strength of about 1034MPa and the minimum impact absorption work of about 80J-100J, and has very high toughness. Thus, this material can be effectively used in the above-described centralizer 10 so that the centralizer strip portion 13 is not easily broken and can effectively rebound in use.

The advantageous effects of the centralizer 10 of the present invention will be explained by data comparison between examples and comparative examples.

Example 1

In example 1, centralizer 10 is a one-piece elastomeric centralizer that can be used to run tubing of size 89mm into a wellbore of approximately 165.1mm in wellbore size. The centralizer 10 is made entirely of 65Mn steel and has 4 centralizer strip sections 13 with a 90 ° difference between adjacent centralizer strip sections 13. The maximum outer diameter of the centralizer 10 (i.e. the maximum outer diameter of the centralizer strip portion) is about 165 mm. The largest part of the outer diameter of the centralizer strip section 13 is close to the inner wall of the wellbore when the centralizer 10 is undeformed. The outer diameters of the upper and

lower collars

11, 12 are approximately 101 mm. Thus, the ratio of the maximum outside diameter of the centralizer to the collar outside diameter is about 1.64. Through experiments, the maximum starting force of the centralizer 10 is about 528N; the minimum restoring force at a 67% off-gap ratio was about 15466N.

Comparative example 1

In comparative example 1, the existing elastic centralizer is one that can be used to run a 127mm size casing into a borehole having a borehole size of about 165.1 mm. The maximum outer diameter of this prior art elastic centralizer is about 165 mm. The outside diameter of the collar was about 139 mm. Thus, the ratio of the maximum outside diameter of the centralizer to the collar outside diameter is about 1.19. Experiments show that the maximum starting force of the elastic centralizer is about 2313N; the minimum reset force at 67% off gap ratio is about 2758N.

Comparative example 2

In comparative example 2, the existing elastic centralizer is one that can be used to run a casing of 140mm size into a borehole of about 165.1mm in borehole size. The maximum outer diameter of this prior art elastic centralizer is about 165 mm. The outside diameter of the collar is about 152 mm. Thus, the ratio of the maximum outside diameter of the centralizer to the collar outside diameter is about 1.09. Through experiments, the maximum starting force of the elastic centralizer is about 2758N; the minimum reset force at 67% off gap ratio is about 2758N.

As can be seen by comparison, the maximum starting force of the centralizer 10 in example 1 is significantly smaller, and the minimum restoring force at a deviation clearance ratio of 67% is significantly larger, as compared to comparative examples 1 and 2. This demonstrates the more outstanding spring performance and structural strength of the centralizer 10 of the present invention.

In addition, the centralizer 10 of the present invention has also been tested several times for running 89mm size tubing into a 152.4mm size wellbore. The centralizer 10 has 4 centralizer strip sections 13, each centralizer strip section 13 having a width of about 40mm and a height of about 205 mm. The outer diameters of the upper and

lower collars

11, 12 are approximately 97 mm. The maximum outer diameter of the righting strip portion is about 152 mm. In addition, the centralizer 10 of the present invention has also been tested several times for running tubing of 73mm size into a borehole of a directional well of 152.4mm size. The centralizer 10 of the present invention has also been tested several times for running tubing of 88.9mm size into boreholes of 165.1mm size in horizontal and highly deviated wells. In these experiments, tubing was run in place smoothly through the centralizer 10 of the present invention without significant stuck in the process.

In addition, after 200 compression-reduction experiments were performed on the above-described embodiment of the centralizer 10 of the present invention, flaw detection was performed on the portion of the centralizing bar, and no fatigue crack was found.

The method of manufacturing the centralizer 10 of the present invention will be described in detail with reference to fig. 2.

In this method, a cylindrical body having elasticity is obtained first (S1). Here, the cylinder is preferably made by a hot rolling process using 140V steel.

Then, a plurality of hollowed-out portions spaced apart from each other are formed in the middle of the cylinder to form a centering strip portion between the adjacent hollowed-out portions, in which an arc-shaped contour is not yet formed (S2). The centralizing band portions herein may have a uniform width and thickness. The hollowed-out portions and the centering strip portions are preferably formed by wire saw cutting, so that the manufacturing cost of the centralizer 10 can be greatly reduced.

Then, the central portion of the can is bulged radially outwardly, for example, by applying pressure to both ends of the can, so that the righting strip portion forms an outwardly bulged arcuate contour (S3). In this step, the pressure applied at the ends of the cylinder is between about 50kN and 60 kN. When pressure is applied, a corresponding outline limiting mould can be sleeved on the outer side of the cylinder body. When the middle portion of the barrel projects radially outward to some extent, the profile-limiting die is contacted. The portion of the barrel that contacts the mold stops bulging outward. This can guide the degree of deformation of the stabilizer bar portion 13 and avoid excessive deformation thereof. The shape of the inner surface of the profile-limiting mould here preferably matches the profile to be obtained for the righting strip portion 13. The centralizing band portions 13 can be formed into a particular arcuate shape by the cooperation of the degree of applied pressure and the profile limiting die as described above. This shape of the centralizer strip portions 13 is very advantageous for improving the spring properties of the centralizer 10. In addition, a cylindrical limiting block can be sleeved in the barrel to limit the deformation of the righting strip part 13 and avoid inward contraction of the righting strip part. The outer diameter of the cylindrical stopper is preferably about 3mm to 4mm smaller than the inner diameter of the barrel.

In a preferred embodiment, the barrel may also be heated during the application of pressure to a temperature of about 1000 ℃ to 1300 ℃, preferably about 1200 ℃. This further facilitates the deformation and processing of the centralizer strip portions 13. In this case, stress concentration or stress weakness is not easily generated at the portion where the stabilizer bar portion 13 is connected to the upper and

lower collars

11 and 12.

Thereafter, the centralizer 10 may also be subjected to a temper heat treatment (e.g., at a temperature of 640 ℃ -650 ℃) to relieve residual stresses that may be present. A plastic spray may also be applied to the surface of the centralizer 10 to make the centralizer 10 less susceptible to damage.

The integral elastomeric packer 10 of the present invention, which may be used in a tubing string, may be formed by the above-described method of manufacture. The elastic packer 10 has high structural strength and strong elastic restoring force, so that the oil pipe can be smoothly fed in place through a narrow part and a bent part in a well. The packer 10 is well suited for tubing cementing applications.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A method of manufacturing a unitary resilient centralizer, comprising the steps of:

obtaining an elastic cylinder body;

forming a plurality of hollowed-out parts in the middle of the barrel, wherein the hollowed-out parts are spaced from each other so as to form a righting strip part between the adjacent hollowed-out parts; and

the middle part of the hollowed-out cylinder body is protruded outwards in the radial direction to deform, so that the righting strip part forms an arc-shaped outline;

wherein the one-piece resilient centralizer is free of welds or connection structures.

2. The manufacturing method for the integrated elastic centralizer of claim 1, wherein the cylinder with elasticity is made of 140V steel through a hot rolling process, and the cylinder contains chromium, molybdenum, vanadium and nickel to improve the structural strength of the cylinder.

3. The manufacturing method for an integral elastic centralizer according to claim 1 or 2, wherein the cut is made on the cylinder by a wire saw to form the hollowed-out portion and the centralizer strip portion.

4. A method of manufacture for a one-piece resilient centralizer according to any of claims 1 to 3, wherein the formed centralizer strip portion is of uniform thickness and width.

5. The manufacturing method for the integrated elastic centralizer of any one of claims 1 to 4, wherein the middle part of the hollowed-out cylinder is convexly deformed radially outwards by applying pressure at two ends of the hollowed-out cylinder, the applied pressure being between 50kN and 60 kN.

6. A method according to claim 5, wherein the pierced cylinder is heated to a temperature of 1000-1300 ℃, preferably 1200 ℃, by applying pressure to both ends of the pierced cylinder to deform the middle part of the pierced cylinder so as to bulge radially outwards.

7. The manufacturing method for the integrated elastic centralizer of any one of claims 1 to 6, wherein when pressure is applied to two ends of the hollowed-out cylinder, a cylindrical contour limiting mould is sleeved on the outer side of the hollowed-out cylinder, and the arc contour of the centralizing strip part is limited by the contour limiting mould.

8. A one-piece resilient centralizer comprising an annular upper collar, an annular lower collar longitudinally spaced from the annular upper collar, and a longitudinally extending centralizer strip portion connected between the upper and lower collars, the centralizer strip portion having an arcuate profile with a central portion projecting radially outwardly, wherein the one-piece resilient centralizer is free of welds or connection structure.

9. The one-piece elastomeric centralizer of claim 8, wherein a ratio of the maximum outer diameter of the centralizer strip portion to the outer diameter of the upper and lower collars is between 1.5-2.2, preferably between 1.64-1.77, without deformation of the one-piece elastomeric centralizer.

10. The integrated elastic centralizer of claim 8 or 9, wherein the integrated elastic centralizer has a minimum restoring force of not less than 15kN at a deviation clearance ratio of 67%, and/or

The maximum starting force of the integral elastic centralizer is not more than 600N.