CN118933592A - An expansion type return plug - Google Patents

Abstract

The present invention belongs to the technical field of oil and gas well development, and specifically, relates to an expansion type tieback plug. The expansion type tieback plug is used to be inserted into a tieback tube, and comprises: a body; and a second sealing component arranged on the outer wall of the body; in an initial state, there is a gap between the outer wall of the second sealing component and the inner wall of the tieback tube; in a sealed state, the outer wall of the second sealing component is sealed and connected to the inner wall of the tieback tube.

Description

Expansion type tieback plug

Technical Field

The invention belongs to the technical field of oil-gas well development, and particularly relates to an expansion type tie-back plug.

Background

In order to reduce the weight of the casing, reduce the length of a single cementing sealing section, reduce the load of a drilling machine and the displacement pressure of well cementation, the liner and tie-back well cementation operation is often required.

In the current tie-back well cementation operation, a tie-back plug is inserted into a tie-back cylinder, so that the seal between the tie-back plug and the tie-back cylinder is realized. Chinese patent document CN203961895U discloses a tailpipe tieback plug, a rectangular groove is designed on the plug body, a sealing ring is accommodated in the rectangular groove, and the tieback plug is inserted into the tieback cylinder to seal. Chinese patent document CN103015912B discloses a tieback plug, which is also inserted into a tieback cylinder to form a seal by a conventional seal ring.

On the one hand, in the process of assembling the tieback plug into the tieback cylinder, the sealing ring can roll and deviate from a preset position, so that the sealing is invalid; on the other hand, along with the oil gas exploitation, the rubber gradually ages, the sealing gradually fails, and long-acting sealing after tail pipe tie-back is difficult to realize, so that the oil gas exploitation period is influenced.

Disclosure of Invention

In view of the above technical problems, the present invention aims to provide an expansion type tieback plug, which can solve the problem of short sealing life between a tieback cylinder and a conventional tieback plug.

According to the present invention there is provided an expandable tieback plug for insertion into a tieback cylinder comprising:

a body; and

A second seal assembly disposed on an outer wall of the body;

In an initial state, a gap exists between the outer wall of the second sealing assembly and the inner wall of the tieback cylinder;

And in a sealing state, the outer wall of the second sealing assembly is in sealing connection with the inner wall of the tieback cylinder.

In a specific embodiment, the lower end of the body is provided with a conical section, the second sealing assembly is arranged on the outer wall of the conical section, the lower end of the tieback cylinder is provided with a downhole tool, and the second sealing assembly is configured such that during the downward insertion of the body into the tieback cylinder, the downhole tool axially abuts against the second sealing assembly, thereby causing the second sealing assembly to move upwards relative to the conical section, and further causing the second sealing assembly to expand into sealing connection with the inner wall of the tieback cylinder.

In a specific embodiment, in the initial state, the second seal assembly is fixedly disposed on the tapered section by a shear pin.

In a specific embodiment, the second seal assembly comprises:

A skeleton coaxially disposed over the tapered section;

an outer seal coaxially disposed on an outer wall of the skeleton; and

And the inner sealing piece is coaxially arranged on the inner wall of the framework.

In a specific embodiment, two outer seals are provided on the outer wall of the skeleton and one inner seal is provided on the inner wall of the skeleton, the inner seal being located between the two outer seals.

In a specific embodiment, a connecting portion is provided at an axial end portion of the backbone, and a pin hole for mounting a shear pin is provided on the connecting portion.

In a specific embodiment, a first sealing assembly is provided on the body for sealing connection with the inner wall of the tieback cylinder.

In a specific embodiment, the body comprises an upper body and a lower body which are sequentially arranged from top to bottom, the first sealing component is arranged on the upper body, a conical section is arranged at the lower end part of the lower body, and the second sealing component is arranged on the conical section.

In a specific embodiment, a centralizing joint is coaxially arranged at the upper end of the body, and a guiding head is coaxially arranged at the lower end of the body.

In a specific embodiment, the inner wall of the lower end of the tieback cylinder is connected to the outer wall of the upper end of the downhole tool, the outer diameter of the lower end of the body being no greater than the inner diameter of the upper end of the downhole tool.

Compared with the prior art, the application has the following advantages.

In the invention, a gap exists between the second sealing component and the inner wall of the cylinder in the initial state, and the second sealing component is in sealing connection with the inner wall of the tieback cylinder in the sealing state.

Under this setting, expansion tieback plug is in the in-process of inserting tieback section of thick bamboo, and second seal assembly is in initial state, can avoid second seal assembly to take place the friction with the inner wall of tieback section of thick bamboo to avoid second seal assembly to take place to roll and deviate from predetermined position and become invalid.

After the expansion type tieback plug is inserted into the tieback cylinder, the second sealing component on the expansion type tieback plug can be axially abutted with the downhole tool, and the second sealing component can move upwards relative to the conical section under the abutting action of the downhole tool after being continuously pressed down, so that the second sealing component expands radially, and the second sealing component seals the expansion type tieback plug and the tieback cylinder with each other.

The second seal assembly of the present invention includes a backbone, an outer seal, and an inner seal. The framework is made of a metal material, the metal material is preferably soft metal, the elongation is high, and the expansion and deformation are easy. The outer sealing element and the inner sealing element are made of rubber materials. And in the process of moving up the second sealing assembly relative to the conical section, the conical section extrudes the metal framework to generate radial deformation. The external diameter of the external sealing ring is larger than the maximum external diameter of the framework, and the external sealing ring can be attached to and tightly pressed with the inner wall of the tieback cylinder in the expansion process of the framework. In the process of continuous expansion, the outer sealing ring is continuously extruded, self-adaptive deformation occurs with the inner wall of the tieback cylinder, then the framework is deformed to be attached to and pressed with the inner wall of the tieback cylinder, and finally the metal-rubber composite seal is formed. And the inner sealing element is similar, and finally, the metal-rubber composite sealing is formed. With the arrangement, the outer sealing element and the inner sealing element which are made of rubber materials are wrapped by the framework made of metal materials, so that the rubber materials are prevented from being damaged, and the sealing life is prolonged.

Drawings

The present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a schematic view of one embodiment of an expansion tieback plug according to the present invention;

FIG. 2 shows a schematic view of an embodiment of a second seal assembly according to the present invention;

FIG. 3 shows a schematic view of an expandable tieback plug according to the present invention as inserted into a tieback cylinder;

fig. 4 shows a schematic view of an expansion tieback plug according to the invention inserted into a tieback cylinder and a second seal assembly completing the seal.

In the figure:

1. Expansion type tie-back plug; 11. centralizing the joint; 111. a limiting piece; 12. a first seal assembly; 13. a body; 131. an upper body; 132. a lower body; 133. a conical section; 15. a second seal assembly; 151. a skeleton; 152. an outer seal; 153. an inner seal; 154. a connection part; 155. a pin hole; 16. a guide head;

2. A tieback cylinder;

3. A downhole tool.

In the present application, all of the figures are schematic drawings which are intended to illustrate the principles of the application only and are not to scale.

Detailed Description

The invention is described below with reference to the accompanying drawings.

The directional terms or qualifiers "upper" and "lower" used in the present application are used with respect to fig. 1 to which reference is made. They are not intended to limit the absolute position of the parts involved, but may vary according to the specific circumstances.

Fig. 1 shows the structure of an expansion type tieback plug 1 according to the present invention. As shown in fig. 1, the expansion type tieback plug 1 includes a body 13 and a second seal assembly 15 provided at an outer wall of the body 13.

The tieback cylinder 2 and the downhole tool 3 are each configured to be substantially cylindrical in shape. The downhole tool 3 is coaxially and sealingly connected to the lower end of the tieback cylinder 2. The downhole tool 3 may be a packer body or a sealed housing body, etc., and the specific structure of the tieback cylinder 2 and the downhole tool 3 and the connection structure between the two are well known to those skilled in the art, and will not be described herein.

In the initial state, a gap exists between the outer wall of the second seal assembly 15 and the inner wall of the tie-back cylinder 2. As shown in fig. 3, after the expansion type tieback plug 1 is inserted into the tieback cylinder 2, in an initial state, the outer diameter of the second seal assembly 15 is smaller than the inner diameter of the tieback cylinder 2, so that a gap exists between the outer wall of the second seal assembly 15 and the inner wall of the tieback cylinder 2. With this arrangement, friction between the second seal assembly 15 and the inner wall of the tie-back tube 2 can be avoided, thereby avoiding failure of the second seal assembly 15 due to rolling away from the predetermined position.

In the sealed state, the outer wall of the second sealing assembly 15 is in sealing connection with the inner wall of the tieback cylinder 2. As shown in fig. 4, after the expansion type tieback plug 1 is inserted into the tieback cylinder 2, the inner wall of the second seal assembly 15 is sealed with the outer wall of the body 13, and the outer wall of the second seal assembly 15 is sealed with the inner wall of the tieback cylinder 2 in a sealed state.

Further, according to the invention, the lower end of the body 13 is provided as a conical section 133. Specifically, the tapered section 133 is configured in a shape in which the outer diameter gradually increases from bottom to top.

The second seal assembly 15 is disposed on the outer wall of the tapered section 133. In the initial state, the second seal assembly 15 is disposed in a position biased toward the lower portion of the tapered section 133. That is, at this time, the second seal assembly 15 is in a state of not being expanded, and there is a margin in a position of the tapered section 133 toward the upper portion, and the second seal assembly 15 can be moved upward along the tapered section 133. As the second seal assembly 15 moves up the tapered section 133, the outer diameter of the tapered section 133 gradually increases, and therefore, the second seal assembly 15 gradually expands radially under the action of the tapered section 133. Finally, as shown in fig. 4, the second sealing member 15 is expanded to seal with the inner wall of the tie-back tube 2, at which time the second sealing member 15 is in a sealed state.

According to the present invention, as shown in fig. 3 and 4, a downhole tool 3 is provided at the lower end of the tieback cylinder 2, and during the downward insertion of the body 13 into the tieback cylinder 2, the downhole tool 3 axially abuts the second seal assembly 15, thereby moving the second seal assembly 15 up relative to the tapered section 133, thereby expanding the second seal assembly 15 into sealing connection with the inner wall of the tieback cylinder 2.

In a specific embodiment, the inner wall of the tieback cylinder 2 is connected to the outer wall of the downhole tool 3. That is, in a length range in which the downhole tool 3 is connected to the tieback cylinder 2, the inside diameter of the downhole tool 3 is smaller than the inside diameter of the tieback cylinder 2, and the downhole tool 3 is inserted into the tieback cylinder 2.

The outer diameter of the conical section 133 is adapted to the inner diameter of the downhole tool 3. That is, the outer diameter of the tapered section 133 is smaller than the inner diameter of the downhole tool 3. As shown in fig. 3 and 4, after the expansion tieback plug 1 is inserted down into the tieback cylinder 2, the tapered section 133 can be inserted down into the interior of the downhole tool 3. At this point, the upper end of the downhole tool 3 will axially abut the second seal assembly 15 upwardly, thereby causing the second seal assembly 15 to move upwardly relative to the tapered section 133 and thereby expand radially.

In a preferred embodiment, in the initial state, the second seal assembly 15 is fixedly disposed on the tapered section 133 by a shear pin, thereby preventing the second seal assembly 15 from moving in advance. During the transition from the initial state to the sealed state, the expandable tieback plug 1 is gradually inserted downwardly into the tieback cylinder 2, the upper end of the downhole tool 3 axially abuts the second seal assembly 15, thereby shearing the shear pin, causing the second seal assembly 15 to move upwardly relative to the tapered section 133, thereby radially expanding the second seal assembly 15 to seal against the inner wall of the tieback cylinder 2.

In one particular embodiment, as shown in FIG. 2, the second seal assembly 15 includes a backbone 151, an outer seal 152, and an inner seal 153.

The skeleton 151 is configured in a ring shape and coaxially sleeved on the conical section 133. In this embodiment, the skeleton 151 is made of a metal material, preferably soft metal, having a high elongation, and being easily expandable and deformable, and capable of radial expansion during movement relative to the tapered segment 133.

Preferably, the inner wall of the skeleton 151 is provided with a tapered surface that is mutually adapted to the tapered surface of the tapered section 133.

Two outer annular grooves are coaxially provided on the outer wall of the skeleton 151 in the axial direction, and two outer seals 152 are provided in the two outer annular grooves, respectively. In the initial state, the outer diameters of the two outer seals 152 are larger than the outer diameter of the backbone 151. In the process of converting the initial state into the sealing state, the conical section 133 of the body 13 descends relative to the descending tieback cylinder 2 and the downhole tool 3, and after the skeleton 151 on the conical section 133 axially abuts against the upper end of the downhole tool 3, the conical section 133 continues to descend, so that the conical section 133 descends relative to the skeleton 151, and the skeleton 151 is radially deformed under the action of the conical surface of the conical section 133. During expansion of the backbone 151, the outer seal 152 is first pressed against the inner wall of the tie-back cylinder 2. In the process of continuing to expand the framework 151, the outer sealing element 152 is continuously extruded and adaptively deforms with the inner wall of the tieback cylinder 2, meanwhile, the framework 151 deforms to be attached to and pressed against the inner wall of the tieback cylinder 2, and finally, a sealing state of metal-rubber composite sealing is formed.

An inner annular groove is coaxially provided on the inner wall of the backbone 151, and an inner seal 153 is provided in the inner annular groove. When the backbone 151 is coaxially sleeved on the tapered section 133, the inner wall of the backbone 151 is sealed with the tapered section 133 by the inner seal 153. In the sealed state, the backbone 151 and the inner seal 153 also form a sealed state of a metal-rubber composite seal with respect to the tapered section 133.

Further, an inner seal 153 is located between the two outer seals 152. Specifically, as shown in fig. 2, one of the outer seals 152 is located axially above the inner seal 153, and the other outer seal 152 is located axially below the inner seal 153. With this arrangement, the sealing effect can be enhanced by the symmetrical structure.

According to the present invention, a connection portion 154 is coaxially provided at the axially lower end portion of the backbone 151, and a pin hole 155 for mounting a shear pin is provided at the connection portion 154. That is, in the initial state, the backbone 151 and the connection part 154 are coaxially sleeved on the tapered section 133, and the shear pin passes through the pin hole 155 to fix the connection part 154 on the tapered section 133.

According to the present invention, when the upper end portion of the downhole tool 3 axially abuts against the second seal assembly 15, the upper end portion of the downhole tool 3 may specifically axially abut against the lower end surface of the connecting portion 154 or may axially abut against the lower end surface of the skeleton 151.

The description will be given taking an example in which the upper end of the downhole tool 3 axially abuts against the lower end surface of the skeleton 151. In the present embodiment, the outer diameter of the connection part 154 is smaller than the outer diameter of the backbone 151, so that the connection part 154 and the backbone 151 form a stepped structure. The downhole tool 3 is configured to be inserted on the steps of the connection 154 and the backbone 151, that is, in an initial state, an upper end portion of the downhole tool 3 can be coaxially sleeved outside the connection 154, that is, an upper end portion of the downhole tool 3 is located between the connection 154 and the tieback cylinder 2, during the insertion of the expansion tieback plug 1 downward into the tieback cylinder 2, so that the upper end portion of the downhole tool 3 finally axially abuts against the lower end surface of the backbone 151. With this arrangement, as the expansion type tieback plug 1 continues to move downwardly, the downhole tool 3 abuts against the backbone 151, causing the tapered section 133 to move downwardly relative to the backbone 151, and both the backbone 151 and the connection 154 expand radially under the influence of the tapered section 133. The radial expansion of the backbone 151 is mainly used to form a seal with the inner wall of the tieback cylinder 2. The connecting portion 154 is also made of the same metal material as the skeleton 151, and the connecting portion 154 can form a seal with the inner wall of the upper end portion of the downhole tool 3 during radial expansion. The junction between the tieback cylinder 2 and the downhole tool 3 is relatively weak, and can be protected from the effects of wellbore internal pressure by way of the connection 154 being sealed to the downhole tool 3.

According to the invention, as shown in fig. 1, a first sealing assembly 12 for sealing connection with the inner wall of the tie-back tube 2 is also provided on the body 13.

Specifically, the body 13 is configured to be substantially cylindrical, and the body 13 includes an upper body 131 and a lower body 132 disposed in order from top to bottom. At least one first sealing member 12 is disposed on the outer wall of the upper body 131, and the plurality of first sealing members 12 can enhance the sealing effect between the outer wall of the upper body 131 and the inner wall of the tieback cylinder 2. A tapered section 133 is provided at the lower end of the lower body 132.

According to the invention, in a particular embodiment, a centralizing joint 11 is coaxially provided at the upper end of the body 13. As shown in fig. 1, the centralizing joint 11 is coaxially fixed to the upper end portion of the upper body 131 of the body 13. The righting joint 11 can play a role in righting.

Further, a radially protruding limiting member 111 is provided on the outer wall of the centralizing joint 11, and the outer diameter of the limiting member 111 is larger than the inner diameter of the tieback cylinder 2. As shown in fig. 2, the stopper 111 can play a role of a stopper after the expansion type tieback plug 1 is inserted into the tieback cylinder 2 in place.

According to the invention, in a particular embodiment, a guide head 16 is coaxially provided at the lower end of the body 13. The guide head 16 is configured in a shape in which the radial dimension gradually decreases from the top to the bottom, thereby facilitating the downward movement of the expansion type tieback plug 1.

In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Finally, it should be noted that the above description is only of a preferred embodiment of the invention and is not to be construed as limiting the invention in any way. Although the invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the techniques described in the foregoing examples, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. An expansion type tieback plug for insertion into a tieback cylinder (2), characterized by comprising:

A body (13); and

A second sealing assembly (15) arranged on the outer wall of the body (13);

In an initial state, a gap exists between the outer wall of the second sealing assembly (15) and the inner wall of the tieback cylinder (2);

In the sealed state, the second sealing assembly (15) radially expands until the outer wall of the second sealing assembly is in sealing connection with the inner wall of the tieback cylinder (2).

2. An expansion type tieback plug according to claim 1, characterized in that the lower end of the body (13) is provided with a conical section (133), the second sealing assembly (15) is provided on the outer wall of the conical section (133), the lower end of the tieback cylinder (2) is provided with a downhole tool (3),

The second seal assembly (15) is configured such that during insertion of the body (13) downwardly into the tieback barrel (2), the downhole tool (3) axially abuts the second seal assembly (15) thereby causing the second seal assembly (15) to move upwardly relative to the tapered section (133) thereby expanding the second seal assembly (15) into sealing engagement with the inner wall of the tieback barrel (2).

3. An expansion-type tieback plug according to claim 2, characterized in that in the initial state the second sealing assembly (15) is fixedly arranged on the conical section (133) by means of shear pins.

4. Expansion tieback plug according to claim 2, characterized in that the second sealing assembly (15) comprises:

A skeleton (151) coaxially disposed on the tapered section (133);

an outer seal (152) coaxially disposed on an outer wall of the skeleton (151); and

And an inner seal (153) coaxially arranged on the inner wall of the skeleton (151).

5. The expansion type tieback plug according to claim 4, characterized in that two outer seals (152) are provided on the outer wall of the skeleton (151), and one inner seal (153) is provided on the inner wall of the skeleton (151), the inner seal (153) being located between the two outer seals (152).

6. The expansion-type tieback plug according to claim 4, characterized in that a connecting portion (154) is provided at an axial end portion of the backbone (151), and a pin hole (155) for mounting a shear pin is provided on the connecting portion (154).

7. An expansion type tieback plug according to any one of claims 1-6, characterized in that a first sealing assembly (12) for sealing connection with the inner wall of the tieback cylinder (2) is provided on the body (13).

8. The expansion type tieback plug according to claim 7, wherein the body (13) comprises an upper body (131) and a lower body (132) which are arranged in sequence from top to bottom, the first sealing assembly (12) is arranged on the upper body (131), a conical section (133) is arranged at the lower end of the lower body (132), and the second sealing assembly (15) is arranged on the conical section (133).

9. Expansion type tieback plug according to any of claims 1-6, characterized in that a centralizing joint (11) is coaxially arranged at the upper end of the body (13), and a guiding head (16) is coaxially arranged at the lower end of the body (13).

10. An expansion type tieback plug according to any of claims 2-6, characterized in that the inner wall of the lower end of the tieback cylinder (2) is connected to the outer wall of the upper end of the downhole tool (3), the outer diameter of the lower end of the body (13) being no larger than the inner diameter of the upper end of the downhole tool (3).