Optical fiber sealing device used in high-temperature and high-pressure environment

Abstract

The utility model discloses an optical fiber sealing device used in a high-temperature and high-pressure environment, which relates to the technical field of optical fiber petroleum logging and comprises a main body shell and an auxiliary main body shell, the main body shell is provided with a sealing cavity for fixing an optical fiber, and a cavity for accommodating the main body shell is arranged in the auxiliary main body shell. The auxiliary main body shell is further provided with a first variable-diameter part which is variable in diameter towards the middle of the auxiliary main body shell, the main body shell is provided with a second variable-diameter part matched with the first variable-diameter part, the first variable-diameter part and the second variable-diameter part are mutually limited at the variable-diameter position, and the inner sealing main body is prevented from displacing from the high-pressure direction to the low-pressure direction through the limiting structure and the sealing cavity. Therefore, optical fiber sensing signals are not affected, and penetration sealing of the optical fiber can be completed at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fiber petroleum well logging, in particular to an optical fiber sealing device used in a high-temperature and high-pressure environment. Background Art

[0002] With the development of distributed fiber optic logging technology in the field of geophysical well detection in oil wells, the optical cable leakage plugging after the failure of the outer cable to avoid radiation, the wellhead pressure relief device, the spiral optical cable in the ultra-deep well casing, etc. all require a fiber optic sealing device under high temperature and high pressure environment.

[0003] Due to the technical characteristics of distributed optical fiber sensing technology, when the optical fiber seal in the well is subjected to additional stress, noise signals will be generated at that point and all optical fibers below it; and the outer diameter of the optical fiber itself is about 0.25mm;

[0004] Currently, conventional sealing methods such as fluororubber, ferrules or combined extrusion sealing methods cannot meet the requirements of optical fiber sealing under high temperature and high pressure. In order to ensure the normal transmission of optical fiber sensor signals while isolating downhole pressure, a high temperature and high pressure optical fiber sealing device is required. Utility Model Content

[0005] In order to ensure the normal transmission of optical fiber sensing signals and isolate the downhole pressure at the same time, the utility model provides an optical fiber sealing device for use in high temperature and high pressure environments. The device uses a composite structure with variable diameter to prevent the internal sealing body from shifting from the high pressure direction to the low pressure direction, thereby completing the penetration seal of the optical fiber without affecting the optical fiber sensing signal.

[0006] The utility model is realized by the following technical solutions:

[0007] An optical fiber sealing device for use in a high temperature and high pressure environment, comprising:

[0008] A main body shell, wherein the main body shell is provided with a sealed cavity for fixing the optical fiber;

[0009] A secondary main body shell is provided with a cavity for accommodating the main body shell inside, the secondary main body shell is also provided with a first diameter-changing portion which changes diameter toward the middle part thereof, and the main body shell is provided with a second diameter-changing portion matching the first diameter-changing portion.

[0010] In the present solution, one end of the sub-main shell is in a high temperature and high pressure environment. In order to prevent the main shell in the sub-main shell from shifting from the high pressure direction to the low pressure direction, thereby causing the sealing failure of the sealing cavity in which the main shell fixes the optical fiber, a first diameter-changing portion that changes diameter toward the middle part of the sub-main shell is provided in the sub-main shell, and the main shell is provided with a second diameter-changing portion that matches the first diameter-changing portion, so that the first diameter-changing portion and the second diameter-changing portion limit each other. Through the limiting structure and the sealing cavity, the optical fiber is neither subjected to force nor deformed when the overall structure is subjected to lateral bending force and longitudinal pressure, thereby completing the penetration sealing of the optical fiber without affecting the optical fiber sensing signal.

[0011] As a further technical solution of the optical fiber sealing device, the ends of the main body shell and the auxiliary main body shell are lap welded to make the connection between the main body shell and the auxiliary main body shell more reliable.

[0012] As a further technical solution to the optical fiber sealing device, in order to allow the main shell to have sufficient space for movement inside the sub-main shell, a gap is provided between the outer wall surface of the main shell and the inner wall surface of the sub-main shell. In specific use, the value of the gap depends on the difference in inner diameters of different tubes that can be overlapped and welded.

[0013] As a further technical solution to the optical fiber sealing device, the inner wall surfaces of the main shell and the sub-main shell are surface treated by sand blasting to remove attachments and loose oxides on the inner surface and increase the roughness of the inner surface, thereby improving the bonding ability of the high-temperature sealing colloid with the main shell and the sub-main shell.

[0014] As a further technical solution of the optical fiber sealing device, the sealing cavity is filled with high-temperature sealant, and the pressure of the high-pressure space and the low-pressure space are isolated by filling with the high-temperature sealant.

[0015] As a further technical solution of the optical fiber sealing device, the space between the main body shell and the auxiliary main body shell is filled with high-temperature sealant to further isolate the pressure of the high-pressure space from the low-pressure space.

[0016] As a further technical solution of the optical fiber sealing device, the high temperature sealant is epoxy type A sealant or epoxy type B sealant.

[0017] In this solution, an epoxy type A glue is used in the sealed cavity or the space between the main body shell and the sub-main body shell. It is liquid at room temperature and is cured by baking at high temperature. Or an epoxy type B glue is a two-component glue. The pressure of the high-pressure and low-pressure spaces is isolated by filling with high-temperature sealant.

[0018] As a further technical solution of the optical fiber sealing device, the inner wall surfaces of the main body shell and the auxiliary main body shell are coated with high-temperature resistant optical fiber coatings to ensure the high-temperature performance and mechanical properties of the overall structure.

[0019] As a further technical solution of the optical fiber sealing device, the first diameter-changing portion is formed by connecting rectangular or circular tubes of different diameters. This sealing method is not prone to causing noise signals from the sealing point to the tail end due to pressure.

[0020] As a further technical solution of the optical fiber sealing device, the axial cross-section of the first diameter-reducing portion is a trumpet-shaped portion with a diameter gradually changing toward the middle, thereby further improving the sealing ability by increasing the limiting contact area.

[0021] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0022] The utility model provides an optical fiber sealing device for use in a high-temperature and high-pressure environment, the device comprises a main body shell and a sub-main body shell, wherein the main body shell is provided with a sealing cavity for fixing the optical fiber, the sub-main body shell is provided with a cavity for accommodating the main body shell, the sub-main body shell is further provided with a first diameter-changing portion which changes diameter toward the middle part thereof, the main body shell is provided with a second diameter-changing portion which matches the first diameter-changing portion, the first diameter-changing portion and the second diameter-changing portion limit each other at the diameter-changing position, and the internal sealing body is prevented from shifting from the high-pressure direction to the low-pressure direction through the limiting structure and the sealing cavity, thereby completing the through-sealing of the optical fiber without affecting the optical fiber sensing signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the embodiments of the present utility model, constitute a part of this application, and do not constitute a limitation of the embodiments of the present utility model. In the drawings:

[0024] Figure 1 It is a structural schematic diagram of the utility model.

[0025] Marks and corresponding parts names in the attached drawings:

[0026] 1-optical fiber, 2-sub-main body shell, 3-main body shell, 4-sealed cavity, 5-first diameter-changing portion, 6-second diameter-changing portion. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the utility model more clearly understood, the utility model is further described in detail below in conjunction with embodiments and drawings. The schematic implementation manner of the utility model and its description are only used to explain the utility model and are not intended to limit the utility model.

[0028] Example 1

[0029] This embodiment 1 provides an optical fiber sealing device for use in a high temperature and high pressure environment, such as Figure 1 As shown, the device includes a main body shell 3 and a sub-main body shell 2, wherein the main body shell 3 is provided with a sealed cavity 4 for fixing the optical fiber 1, and the sub-main body shell 2 is provided with a cavity for accommodating the main body shell 3. A first diameter reducing portion 5 that changes diameter toward the middle part of the sub-main body shell 2 is also provided on one side of the sub-main body shell 2, and the main body shell is provided with a second diameter reducing portion 6 that matches the first diameter reducing portion 5. The first diameter reducing portion 5 is formed by connecting rectangular or circular tubes with different diameters. This sealing method is not easy to cause noise signals from the sealing point to the tail end due to the pressure, and one end of the sub-main body shell 2 on the same side as the first diameter reducing portion 5 and away from the first diameter reducing portion 5 is connected to a high temperature and high pressure environment, and the first diameter reducing portion 5 and the second diameter reducing portion 6 are mutually limited at the diameter reducing position to avoid displacement of the internal sealing body from the high pressure direction to the low pressure direction, so that the optical fiber can be sealed through without affecting the optical fiber sensing signal.

[0030] Among them, the ends of the main shell 3 and the sub-main shell 2 are lap welded to make the connection between the main shell 3 and the sub-main shell 2 more reliable. At the same time, in order to allow the main shell 3 to have sufficient activity space inside the sub-main shell 2, there is a gap between the outer wall surface of the main shell 3 and the inner wall surface of the sub-main shell 2. In specific use, the value of the gap depends on the difference in inner diameters that can be lap welded between different tubes. For example, the commonly used small tube has an outer diameter of 2.45, and the gap value is 0.3-0.5mm.

[0031] At the same time, the inner wall surfaces of the main shell 3 and the sub-main shell 2 are surface treated by sandblasting to remove attachments and loose oxides on the inner surface, and at the same time increase the roughness of the inner surface, thereby improving the bonding ability of the high-temperature sealing colloid with the main shell and the sub-main shell. After the sandblasting operation, two ultrasonic cleanings should be performed to ensure that there is no residual oil stains on the inner surface and do not affect the bonding performance of the sealing body.

[0032] In this embodiment, in order to isolate the pressure of the high-pressure and low-pressure spaces within the main body shell 3 and the sub-body shell 2, the sealing cavity 4 is filled with high-temperature sealant, and the space between the main body shell 2 and the sub-body shell 3 is filled with high-temperature sealant. The above-mentioned high-temperature sealant is epoxy A glue or epoxy B glue, and in order to ensure the high temperature performance and mechanical properties of the overall structure, the inner wall surfaces of the main body shell 3 and the sub-body shell 2 are coated with high-temperature resistant optical fiber coating.

[0033] Example 2

[0034] This embodiment 2 provides an optical fiber sealing device for use in a high temperature and high pressure environment, such as Figure 1As shown, the device includes a main body shell 3 and a sub-main body shell 2, wherein the main body shell 3 is provided with a sealed cavity 4 for fixing the optical fiber 1, and the sub-main body shell 2 is provided with a cavity for accommodating the main body shell 3, and both sides of the sub-main body shell 2 are provided with a first diameter-reducing portion 5 that changes diameter toward the middle part thereof, and the main body shell is provided with a second diameter-reducing portion 6 that matches the above-mentioned first diameter-reducing portion 5, and the first diameter-reducing portion 5 is formed by connecting rectangular or circular tubes with different diameters, and an end of the sub-main body shell 2 away from the first diameter-reducing portion 5 is connected to a high temperature and high pressure environment, and the first diameter-reducing portion 5 and the second diameter-reducing portion 6 are mutually limited at the diameter-reducing position to reduce the axial deformation of the main body shell 3, and avoid displacement of the internal sealing body from the high-pressure direction to the low-pressure direction, so that the optical fiber can be sealed through without affecting the optical fiber sensing signal.

[0035] Among them, the ends of the main shell 3 and the sub-main shell 2 are lap welded to make the connection between the main shell 3 and the sub-main shell 2 more reliable. At the same time, in order to allow the main shell 3 to have sufficient activity space inside the sub-main shell 2, there is a gap between the outer wall surface of the main shell 3 and the inner wall surface of the sub-main shell 2. In specific use, the value of the gap depends on the difference in inner diameters that can be lap welded between different pipes.

[0036] At the same time, the inner wall surfaces of the main shell 3 and the sub-main shell 2 are surface treated by sandblasting to remove attachments and loose oxides on the inner surface, and at the same time increase the roughness of the inner surface, thereby improving the bonding ability of the high-temperature sealing colloid with the main shell and the sub-main shell. After the sandblasting operation, two ultrasonic cleanings should be performed to ensure that there is no residual oil stains on the inner surface and do not affect the bonding performance of the sealing body.

[0037] In this embodiment, in order to isolate the pressure of the high-pressure and low-pressure spaces in the main body shell 3 and the sub-body shell 2, the sealing cavity 4 is filled with high-temperature sealant, and the space between the main body shell 2 and the sub-body shell 3 is filled with high-temperature sealant. The above-mentioned high-temperature sealant is epoxy type A glue or epoxy type B glue. The pouring process should use matching special tools to ensure that no cavities or bubbles are generated in the sealing cavity 4 during the pouring process, and to reduce the sealing failure caused by the pouring process; and in order to ensure the high temperature performance and mechanical properties of the overall structure, the inner wall surfaces of the main body shell 3 and the sub-body shell 2 are coated with high-temperature resistant optical fiber coatings.

[0038] Example 3

[0039] This embodiment 2 provides an optical fiber sealing device for use in a high temperature and high pressure environment, such as Figure 1As shown, the device includes a main body shell 3 and a sub-main body shell 2, wherein the main body shell 3 is provided with a sealed cavity 4 for fixing the optical fiber 1, the sub-main body shell 2 is provided with a cavity for accommodating the main body shell 3, and both sides of the sub-main body shell 2 are provided with a first diameter-reducing portion 5 that changes diameter toward the middle part thereof, and the main body shell is provided with a second diameter-reducing portion 6 that matches the above-mentioned first diameter-reducing portion 5, and the axial cross-section of the first diameter-reducing portion 5 is a trumpet shape with a diameter gradually changing toward the middle, and the end of the sub-main body shell 2 away from the first diameter-reducing portion 5 is connected to a high temperature and high pressure environment, and the first diameter-reducing portion 5 and the second diameter-reducing portion 6 are mutually limited at the diameter-reducing position to reduce the axial deformation of the main body shell 3, and avoid displacement of the internal sealing body from the high pressure direction to the low pressure direction, so that the optical fiber can be sealed through without affecting the optical fiber sensing signal.

[0040] Among them, the ends of the main shell 3 and the sub-main shell 2 are lap welded to make the connection between the main shell 3 and the sub-main shell 2 more reliable. At the same time, in order to allow the main shell 3 to have sufficient activity space inside the sub-main shell 2, there is a gap between the outer wall surface of the main shell 3 and the inner wall surface of the sub-main shell 2. In specific use, the value of the gap depends on the difference in inner diameters that can be lap welded between different pipes.

[0041] At the same time, the inner wall surfaces of the main shell 3 and the sub-main shell 2 are surface treated by sandblasting to remove attachments and loose oxides on the inner surface, and at the same time increase the roughness of the inner surface, thereby improving the bonding ability of the high-temperature sealing colloid with the main shell and the sub-main shell. After the sandblasting operation, two ultrasonic cleanings should be performed to ensure that there is no residual oil stains on the inner surface and do not affect the bonding performance of the sealing body.

[0042] In this embodiment, in order to isolate the pressure of the high-pressure and low-pressure spaces in the main body shell 3 and the sub-body shell 2, the sealing cavity 4 is filled with high-temperature sealant, and the space between the main body shell 2 and the sub-body shell 3 is filled with high-temperature sealant. The above-mentioned high-temperature sealant is epoxy type A glue or epoxy type B glue. The pouring process should use matching special tools to ensure that no cavities or bubbles are generated in the sealing cavity 4 during the pouring process, and to reduce the sealing failure caused by the pouring process; and in order to ensure the high temperature performance and mechanical properties of the overall structure, the inner wall surfaces of the main body shell 3 and the sub-body shell 2 are coated with high-temperature resistant optical fiber coatings.

[0043] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the utility model in detail. It should be understood that the above description is only the specific implementation method of the utility model and is not used to limit the protection scope of the utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model.

Claims

1. An optical fiber sealing device for use in high temperature and high pressure environments, characterized in that: include: A main body shell (3), wherein the main body shell (3) is provided with a sealed cavity (4) for fixing the optical fiber (1); A secondary main body shell (2), wherein a cavity for accommodating the main body shell (3) is provided inside the secondary main body shell (2), the secondary main body shell (2) is further provided with a first diameter-changing portion (5) which changes diameter toward the middle of the secondary main body shell (2), and the main body shell (3) is provided with a second diameter-changing portion (6) which matches the first diameter-changing portion (5).

2. The optical fiber sealing device for use in a high temperature and high pressure environment according to claim 1, characterized in that: The main body shell (3) and the end portions of the auxiliary main body shell (2) are welded by lap welding.

3. The optical fiber sealing device for use in a high temperature and high pressure environment according to claim 1, characterized in that: There is a gap between the outer wall surface of the main body shell (3) and the inner wall surface of the auxiliary main body shell (2).

4. The optical fiber sealing device for use in a high temperature and high pressure environment according to claim 1, characterized in that: The sealing cavity (4) is filled with high-temperature sealant.

5. The optical fiber sealing device for use in a high temperature and high pressure environment according to claim 1, characterized in that: The space between the main body shell (3) and the auxiliary main body shell (2) is filled with high-temperature sealant.

6. The optical fiber sealing device for use in a high temperature and high pressure environment according to claim 4 or 5, characterized in that: The high temperature sealant is epoxy type A sealant or epoxy type B sealant.

7. The optical fiber sealing device for use in a high temperature and high pressure environment according to claim 6, characterized in that: The inner wall surfaces of the main body shell (3) and the auxiliary main body shell (2) are both surface treated by sandblasting.

8. The optical fiber sealing device for use in a high temperature and high pressure environment according to claim 1, characterized in that: The inner wall surfaces of the main body shell (3) and the auxiliary main body shell (2) are both coated with a high-temperature resistant optical fiber coating.

9. The optical fiber sealing device for use in a high temperature and high pressure environment according to claim 1, characterized in that: The first diameter-changing portion (5) is formed by connecting rectangular or circular tubes with different diameters.

10. The optical fiber sealing device for use in a high temperature and high pressure environment according to claim 1, characterized in that: The axial cross-section of the first diameter-changing portion (5) is in the shape of a trumpet with the diameter gradually decreasing towards the middle.

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