Sealing, reinforcing and plugging process for long-well-section large-drift-diameter expansion pipe

Abstract

The invention discloses a sealing, reinforcing and plugging process for a long-well-section large-drift-diameter expansion pipe, and relates to the technical field of oil field well pipe reinforcing and repairing. A plurality of rubber rings are attached to the outer side of the expansion pipe, and the rubber rings are arranged at equal intervals in the axis direction of the expansion pipe; on the outer wall of the expansion pipe, the section between every two adjacent rubber rings is coated with a thermosetting bonding layer; the outer diameter of the thermosetting bonding layer is smaller than that of the rubber ring. The thermosetting bonding layer is creatively arranged on the outer side of the expansion pipe, the structural strength of the expansion pipe is improved through the bonding effect of the bonding layer, the wall thickness of the expansion pipe is reduced, in other words, the inner diameter of the installed expansion pipe is enlarged, and therefore the application range of the expansion pipe plugging technology is expanded. Meanwhile, the technical scheme has the advantages of being long in plugging well section, good in sealing effect and low in single well construction cost.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield well pipe reinforcement and repair, and in particular relates to a sealing reinforcement and plugging process for a long well section large-diameter expansion pipe. Background Art

[0002] In the middle and late stages of oilfield production, the downhole casing will be damaged due to factors such as formation water corrosion, perforating, workover operations, various high-pressure measures, poor cementing quality, long casing service life, and casing quality. This is called casing damage in the industry. Casing damage will have an adverse effect on oilfield production and requires plugging.

[0003] The expansion tube plugging process is one of the processes used to seal and plug the damaged parts of the casing, which has the significant advantages of simple process, short construction period and low cost. The principle is: a section of expansion tube is lowered to the inside of the damaged part of the downhole casing, and then the diameter of the expansion tube is increased by squeezing the inside, and finally it is attached to the inner wall of the downhole casing to achieve sealing and repair of the damaged part of the casing.

[0004] The disadvantages of the above process are:

[0005] In order to ensure the anchoring strength and the ability to withstand downhole pressure on both sides, the wall thickness of the expansion tube is generally 7mm. For the most commonly used casing with an inner diameter of 124mm, such a thick expansion tube is lined inside the casing, which reduces the diameter of the casing to about 110. This size makes it difficult for many standard downhole tools with an outer diameter of 114mm to pass through, limiting the scope of use of the expansion tube plugging process. Therefore, it is necessary to improve the existing expansion tube plugging process. Summary of the invention

[0006] The present invention provides a sealing, reinforcing and plugging process for a long well section large-diameter expansion tube. By optimizing the existing expansion tube plugging process, the restriction on the downhole tool being lowered into the well after the expansion tube plugging process is implemented is eliminated, and the application scope of the expansion tube plugging process is expanded.

[0007] The technical problem solved by the present invention is achieved by adopting the following technical solution: The present invention provides a sealing and reinforcing device for a large-diameter and long-well section expansion pipe, comprising an expansion pipe;

[0008] A plurality of rubber rings are attached to the outside of the expansion tube, and the rubber rings are arranged at equal intervals along the axis direction of the expansion tube;

[0009] On the outer wall of the expansion tube, a section between two adjacent rubber rings is coated with a thermosetting adhesive layer.

[0010] As a preferred solution, the wall thickness of the expansion tube is less than 4 mm.

[0011] As a preferred solution, the rubber ring is vulcanized and connected to the outer wall of the expansion tube.

[0012] As a preferred solution, a spirally wound carbon fiber bundle is arranged in the rubber ring.

[0013] As a preferred embodiment, the thermosetting adhesive layer includes a rubber plate made of epoxy resin AB glue, and a skeleton made of gauze is arranged inside the rubber plate.

[0014] As a preferred solution, the expansion pipe is formed by connecting at least two pipes, and the two pipes are connected by a threaded pair.

[0015] As a preferred solution, the threads constituting the thread pair are rectangular tapered threads.

[0016] As a preferred solution, in the thread pair, upper and lower ends of the external thread and the internal thread are both provided with mutually matching conical surfaces.

[0017] As a preferred solution, the outer side of the section where the thread pair is located corresponds to the thermosetting adhesive layer.

[0018] The present invention also provides an operating method of a large-diameter long-well section expansion pipe sealing reinforcement device, comprising the following steps:

[0019] Step 1: After the two components A and B of the epoxy resin AB glue are evenly mixed, they are fully soaked in gauze. After the epoxy resin AB glue is cooled, its fluidity becomes poor and it forms a plate, thereby making a rubber plate. After the front and back sides of the rubber plate are covered with a protective film, it is placed in a refrigerator for storage;

[0020] Step 2: During well site construction, the expansion pipe not coated with the thermosetting adhesive layer is transported to the well site, and an expansion pipe of appropriate length is selected according to the length of the sealing section. When the length of a single expansion pipe is insufficient, the required length of the expansion pipe is obtained by connecting multiple expansion pipes in series;

[0021] Step 3: Take the rubber sheet, tear off the protective film, and wrap the rubber sheet on the outer wall of the expansion tube;

[0022] Step 4, lowering the expansion pipe to the casing damage location in the well through the pipe string, and expanding the expansion pipe by hydraulic or mechanical means. After expansion, the outer wall of the expansion pipe presses the thermosetting adhesive layer onto the inner wall of the casing in the well;

[0023] Step five, circulate hot water above 80 degrees to the location of the expansion tube for 3 hours. Under the action of high temperature, the epoxy resin AB glue solidifies, and the solidified epoxy resin AB glue bonds the expansion tube to the inner wall of the downhole casing. After bonding, with the surrounding support of the downhole casing, the anchoring strength and the ability to resist internal and external pressures of the expansion tube are enhanced; at the same time, the solidified epoxy resin AB glue fills the space between two adjacent rubber rings, so that the rubber ring loses the space for creeping deformation when under pressure, thereby avoiding failure of the rubber ring seal.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention creatively arranges a thermosetting adhesive layer on the outside of the expansion tube, and the adhesive strength is extremely high after high-temperature curing, which helps to improve the structural strength of the expansion tube and reduce the wall thickness of the expansion tube. The inner diameter of the expansion tube after installation can reach 116mm, which not only effectively expands the flow area in the casing, but also expands the application scope of the expansion tube plugging process.

[0026] 2. In the present invention, the combination of the rubber ring and the cured thermosetting adhesive layer can produce two effects:

[0027] On the one hand, the cured epoxy resin AB glue fills the space between two adjacent rubber rings, so that the rubber ring loses the space for creeping deformation when under pressure, thereby avoiding failure of the rubber ring seal.

[0028] On the other hand, the cured epoxy resin AB glue greatly increases the difficulty for underground gas and liquid substances to reach the sealing ring, and can even completely prevent the rubber ring from contacting the underground gas and liquid, thereby effectively preventing the rubber ring from aging and ensuring that the rubber ring continues to perform its optimal sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0030] Figure 2 This is a partial enlarged view of the threaded connection.

[0031] Figure 1 Middle: 1. Rubber ring; 2. Expansion tube; 3. Thermosetting adhesive layer; 4. Conical surface; 5. Thread. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings.

[0033] As an example:

[0034] like Figure 1 , 2As shown, the sealing and reinforcing device for a large-diameter long-well section expansion pipe of the present invention comprises an expansion pipe 2. When in use, the expansion pipe 2 is lowered to a position in the well that needs to be sealed, and then a force is applied from the inside of the expansion pipe 2 by mechanical or hydraulic means to expand the expansion pipe 2, and finally the expansion pipe 2 is attached to the inner wall of the well casing to repair the casing. The above is conventional technology and will not be repeated here.

[0035] like Figure 1 , 2 As shown, in this embodiment, a plurality of rubber rings 1 are attached to the outside of the expansion tube 2 to seal the gap between the expansion tube 2 and the downhole casing. The rubber rings 1 are arranged at equal intervals along the axis direction of the expansion tube 2, thereby forming multiple seals between the expansion tube 2 and the inner wall of the casing.

[0036] like Figure 1 , 2 As shown, in this embodiment, on the outer wall of the expansion tube 2, the section between two adjacent rubber rings 1 is coated with a thermosetting adhesive layer 3. After the expansion tube 2 is expanded, the thermosetting adhesive layer 3 is clamped between the expansion tube 2 and the casing. In the subsequent process, the thermosetting adhesive layer 3 is solidified by heating, so that the expansion tube 2 and the casing are bonded, and the space surrounded by the expansion tube 2, the casing and the upper and lower rubber rings 1 is filled.

[0037] like Figure 1 , 2 As shown, in this embodiment, the outer diameter of the thermosetting adhesive layer 3 is smaller than the outer diameter of the rubber ring 1. When lowering into the well, the rubber ring 1 can protect the thermosetting adhesive layer 3 to prevent it from being damaged by friction with the well wall.

[0038] In this embodiment, the expansion tube 2 can be made of 316NPT stainless steel seamless pipe, the expansion rate can reach 25%, and it also has high strength plasticity, high work hardening rate and good corrosion resistance, tensile strength and yield strength, and the strength after expansion can be further improved. After field tests, in this embodiment, the size specifications and performance of the expansion tube 2 are shown in the following table.

[0039]

[0040] In this embodiment, the rubber ring 1 is vulcanized and connected to the outer wall of the expansion tube 2 , so as to ensure the adhesion strength of the rubber ring 1 to the outer wall of the expansion tube 2 .

[0041] In this embodiment, in order to improve the structural strength of the rubber ring 1 , a spirally wound carbon fiber bundle is disposed inside the rubber ring 1 .

[0042] In this embodiment, the thermosetting adhesive layer 3 includes a glue plate made of epoxy resin AB glue. Epoxy resin AB glue is a prior art and contains two components, A and B. After the two components are mixed, they undergo a cross-linking reaction when heated and are irreversibly cured.

[0043] In order to facilitate the molding and installation of the thermosetting adhesive layer 3 and improve the structural strength of the thermosetting adhesive layer 3, a skeleton made of gauze is provided in the rubber plate in this embodiment. The material of the gauze can be nylon fiber or carbon fiber.

[0044] like Figure 1 , 2 As shown, in this embodiment, the expansion tube 2 is formed by connecting two pipes, and the two pipes are connected by a pair of threads 5. The threads 5 constituting the pair of threads 5 are rectangular tapered threads 5, which are conducive to ensuring the structural strength of the connection. In the pair of threads 5, the upper and lower ends of the external thread 5 and the internal thread 5 are provided with mutually matching conical surfaces 4. After the expansion tube 2 is expanded, the two mutually matching conical surfaces 4 are squeezed and pressed tightly, thereby achieving the sealing of the connection of the threads 5.

[0045] In this embodiment, the outer side of the section where the thread 5 pair is located corresponds to the thermosetting adhesive layer 3, that is, the outer side of the connection of the thread 5 is provided with a thermosetting adhesive layer 3. Through such a design, the thermosetting adhesive layer 3 can assist in sealing the outer seam of the connection of the thread 5 from the outside, thereby improving the sealing performance of the connection of the thread 5.

[0046] In this embodiment, an operation method of a large-diameter long-well section expansion pipe sealing reinforcement device includes the following steps:

[0047] Step 1: After the two components A and B of the epoxy resin AB glue are evenly mixed, they are fully soaked in gauze. The fluffy multi-layer structure of the gauze can adhere to a sufficient thickness of the epoxy resin AB glue, thereby ensuring the amount of glue attached to the outside of the expansion tube 2. At the same time, the gauze is coated with the epoxy resin AB glue, so that the rubber sheet is adhered to the expansion tube 2. After cooling, the epoxy resin AB glue has poor fluidity and forms a plate, thereby making a rubber sheet. After the front and back sides of the rubber sheet are covered with a protective film, it is stored in a refrigerator.

[0048] Step 2: During well site construction, the expansion tube 2 not coated with the thermosetting adhesive layer 3 is transported to the well site, and an expansion tube 2 of appropriate length is selected according to the length of the sealing section. When the length of a single expansion tube 2 is insufficient, an expansion tube 2 of the required length is obtained by connecting multiple expansion tubes 2 in series.

[0049] Step three, take the rubber sheet, tear off the protective film, and then wrap and fix the rubber sheet on the outer wall of the expansion tube 2.

[0050] Step 4: lower the expansion tube 2 to the casing damage site through the pipe string, and expand the expansion tube 2 by hydraulic or mechanical means. After expansion, the outer wall of the expansion tube 2 presses the thermosetting adhesive layer 3 against the inner wall of the casing in the well.

[0051] Step five, circulate hot water above 80 degrees to the location of the expansion tube 2 for 3 hours. Under the action of high temperature, the epoxy resin AB glue undergoes a cross-linking reaction and solidifies. The solidified epoxy resin AB glue bonds the expansion tube 2 to the inner wall of the downhole casing. After bonding, under the surrounding support of the downhole casing, the anchoring strength and the ability to resist internal and external pressures of the expansion tube 2 are enhanced; at the same time, the solidified epoxy resin AB glue fills the space between two adjacent rubber rings 1, so that the rubber ring 1 loses the space for creeping deformation when under pressure, thereby avoiding sealing failure of the rubber ring 1.

Claims

1. A sealing and reinforcing device for a large-diameter long-well section expandable pipe, comprising an expandable pipe (2), characterized in that: A plurality of rubber rings (1) are attached to the outer side of the expansion tube (2), and the rubber rings (1) are arranged at equal intervals along the axial direction of the expansion tube (2); On the outer wall of the expansion tube (2), the section between two adjacent rubber rings (1) is coated with a thermosetting adhesive layer (3).

2. The sealing and reinforcing device for a large-diameter and long-well section expandable pipe according to claim 1, characterized in that: The wall thickness of the expansion tube (2) is less than 4 mm.

3. The sealing and reinforcing device for a large diameter and long well section expandable pipe according to claim 1, characterized in that: The rubber ring (1) is vulcanized and connected to the outer wall of the expansion tube (2).

4. The sealing and reinforcing device for a large diameter and long well section expandable pipe according to claim 1, characterized in that: A spirally wound carbon fiber harness is arranged inside the rubber ring (1).

5. The sealing and reinforcing device for a large-diameter and long-well section expandable pipe according to claim 1, characterized in that: The thermosetting adhesive layer (3) comprises a rubber plate made of epoxy resin AB glue, and a frame made of gauze is arranged inside the rubber plate.

6. The sealing and reinforcing device for a large-diameter and long-well section expandable pipe according to claim 1, characterized in that: The expansion pipe (2) is formed by connecting at least two pipes, and the two pipes are connected by a threaded pair (5).

7. The large diameter long well section expansion sealing reinforcement device according to claim 6 is characterized by: The threads (5) constituting the thread (5) pair are rectangular tapered threads (5).

8. The sealing and reinforcing device for a large-diameter and long-well section expandable pipe according to claim 7, characterized in that: In the thread (5) pair, the upper and lower ends of the external thread (5) and the internal thread (5) are both provided with mutually matching conical surfaces (4).

9. The sealing and reinforcing device for a large-diameter and long-well section expandable pipe according to claim 6, characterized in that: The outer side of the section where the thread (5) pair is located corresponds to the thermosetting adhesive layer (3).

10. An operating method of a sealing and reinforcing device for a large-diameter long-well section expandable pipe according to any one of claims 1 to 9, characterized in that The steps include: Step 1: After the two components A and B of the epoxy resin AB glue are evenly mixed, they are fully soaked in gauze. After the epoxy resin AB glue is cooled, its fluidity becomes poor and it forms a plate, thereby making a rubber plate. After the front and back sides of the rubber plate are covered with a protective film, it is placed in a refrigerator for storage; Step 2: During well site construction, the expansion pipe (2) not coated with the thermosetting adhesive layer (3) is transported to the well site, and an expansion pipe (2) of appropriate length is selected according to the length of the sealing section. When the length of a single expansion pipe (2) is insufficient, an expansion pipe (2) of the required length is obtained by connecting multiple expansion pipes (2) in series; Step 3, take out the rubber sheet, tear off the protective film, and then wrap the rubber sheet on the outer wall of the expansion tube (2); Step 4: lowering the expansion pipe (2) to the damaged casing in the well through the pipe string, and expanding the expansion pipe (2) by hydraulic or mechanical means. After expansion, the outer wall of the expansion pipe (2) presses the thermosetting adhesive layer (3) against the inner wall of the casing in the well; Step 5: circulate hot water above 80 degrees to the location of the expansion tube (2) for 3 hours. Under the action of high temperature, the epoxy resin AB glue is cured. The cured epoxy resin AB glue bonds the expansion tube (2) to the inner wall of the downhole casing. After bonding, under the surrounding support of the downhole casing, the anchoring strength and the ability to resist internal and external pressures of the expansion tube (2) are enhanced; at the same time, the cured epoxy resin AB glue fills the space between two adjacent rubber rings (1), so that the rubber ring (1) loses the space for creeping deformation when under pressure, thereby avoiding the failure of the rubber ring (1) seal.

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