A method of offshore installation of a flexible liner pipe

Abstract

The application discloses a flexible inner lining pipe offshore installation method, which comprises the following steps: removing the expansion bends at the two ends of the flat pipe section of the pipeline to be repaired, pulling and cutting the inner lining pipes at the two sides of the flat pipe section by means of the steel wire rope and the inner lining pipe and the winch, discharging the seawater between the inner lining pipe and the flat pipe section through the drainage one-way valve arranged on the joint sleeve, installing the expansion bend, and restoring the pipeline. The flexible inner lining pipe offshore installation method can complete the whole construction without the marine platform at the two ends, that is, the whole project construction is carried out by penetrating the flat pipe section, the riser and the expansion bend are separately replaced, the inner lining pipe penetrating process is carried out on the seabed, and the problems, such as the large pulling force caused by the multiple bends and the easy breaking and explosion of the inner lining pipe at the gaps between the flanges, are solved. The method has the advantages of obvious operation feasibility, high construction efficiency and high pipeline repair quality.

Description

Technical Field

[0001] This invention relates to the field of subsea pipeline maintenance technology, and in particular to a method for installing flexible inner liner pipes at sea. Background Technology

[0002] Flexible liners are non-metallic pipes installed inside steel pipes to address corrosion issues, allowing for the reuse of the original steel pipes. Their use in offshore oil pipelines demonstrates good economic viability and feasibility. However, due to the complex offshore conditions, especially the presence of multiple bends on a single pipeline (two for two risers and four for expansion bends), the liner experiences excessive tensile stress, potentially damaging the pipeline and offshore platform facilities, leading to safety accidents. Another reason is the large number of segments in a single crude oil pipeline, including risers, expansion bends, and horizontal pipe sections, resulting in at least six flange connections. Currently, subsea pipelines use steel ring seals between flanges, leaving gaps. After the liner is installed and pressurized, it can bulge towards these gaps, posing a burst risk. A third reason is the multiple bends encountered when inserting the liner from the platform, leading to twisting at each bend. This can cause the liner to become knotted within the steel pipe after the pipeline is operational, directly causing transportation failures. Based on the above three reasons, the overall plan to insert the inner liner from the offshore platform is too risky and not feasible in practice. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a method for offshore installation of flexible inner liner pipes. This method can effectively avoid the aforementioned risks and complete the entire construction without using the offshore platforms at both ends. The entire project construction starts with the horizontal pipe section and replaces the riser and expansion bend separately, so that the entire inner liner pipe installation process can be carried out on the seabed.

[0004] To achieve the above objectives, this application provides the following technical solution:

[0005] A method for installing a flexible inner liner pipe at sea includes the following steps:

[0006] Remove the expansion bends by using ships C and D to remove the expansion bends at both ends of the flat pipe section.

[0007] A wire rope and an inner liner are threaded through the flat pipe section. One of the ships C and D is equipped with a wire rope winch, and the other is equipped with an inner liner winch. After the wire rope of the wire rope winch is threaded out of the flat pipe section, it is connected to the inner liner of the inner liner winch. The wire rope is pulled in the opposite direction to drive the inner liner out of the flat pipe section.

[0008] Install the inner liner pipe joints at both ends of the horizontal pipe section, connect the inner liner pipe joints to the inner liner pipe, and drain the seawater between the inner liner pipe and the horizontal pipe section.

[0009] The inner lining pipe joint is installed and connected to the expansion bend.

[0010] Furthermore, the inner lining pipe joint includes a joint outer sleeve, a joint core, and a blind flange. The two ends of the joint outer sleeve are respectively provided with a first flange and a second flange. The first flange is provided with a first groove for installing the joint core. The blind flange is connected to the first flange, and the second flange is connected to the end of the flat pipe section. The blind flange is provided with a pressure injection port, and the joint outer sleeve is provided with a glue injection valve and a drain check valve.

[0011] Furthermore, the connector sleeve is an axially hollow stepped hole, the stepped hole including a large hole near the first flange and a small hole near the second flange, the glue injection valve is provided corresponding to the large hole, and the drain check valve is provided corresponding to the small hole.

[0012] Furthermore, the wall of the large hole is provided with a spring pressure plate, and the outer wall of the connector core is provided with a second groove corresponding to the spring pressure plate.

[0013] Furthermore, a second sealing ring is provided on the second flange.

[0014] Furthermore, the steps for installing the inner liner pipe fitting include:

[0015] Install the connector sleeve and connector core. The connector sleeve is connected to the flat pipe section and connector core respectively. The connector sleeve and connector core are installed on the outer and inner sides of the inner liner pipe respectively. Inject curing adhesive into the inner side of the connector sleeve through the glue injection valve.

[0016] Install a blind flange at the outer sleeve of the joint;

[0017] Pressure drainage: Pressurize and inject water into the inner liner pipe through the pressure injection port, and discharge the seawater between the outer side of the inner liner pipe and the inner side of the flat pipe section through the drainage check valve.

[0018] Remove the blind flange.

[0019] Furthermore, the curing pressure range of the curing adhesive is 20–25 MPa.

[0020] Furthermore, in the step of threading the steel wire rope and inner lining pipe into the flat pipe section, the launching tube and the receiving tube are used to thread the steel wire rope and the inner lining pipe.

[0021] Furthermore, a serving tube flange is installed on the serving tube, and a first sealing ring for sealing the steel wire rope is provided on the serving tube flange.

[0022] In summary, the technical effects and advantages of this invention are as follows:

[0023] The subsea steel pipe repair project can be completed without using the offshore platforms at both ends. The entire project is carried out by interlacing horizontal pipe sections, with risers and expansion bends replaced separately. The lining pipe interlacing process is carried out on the seabed, which solves the problems of high traction caused by numerous bends and easy bursting and breakage of the lining pipe at the gaps between flanges when interlacing on an offshore platform. This method has significant operational feasibility and features high construction efficiency and high-quality pipeline repair. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the expansion bend connection state in one embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the removal of the expansion bend in one embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the installation of the launching and receiving tubes in one embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the ball mounting in one embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the ball entering the tube in one embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of a wire rope seal in one embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of a water-filled ball in one embodiment of the present invention;

[0032] Figure 8 This is a schematic diagram illustrating the completion of the ball passage in one embodiment of the present invention;

[0033] Figure 9 This is a schematic diagram of a wire rope being pulled onto a winch in one embodiment of the present invention;

[0034] Figure 10This is a schematic diagram of the inner lining tube and the steel wire rope being bound together in one embodiment of the present invention;

[0035] Figure 11 This is a schematic diagram of the inner liner tube pulling process in one embodiment of the present invention;

[0036] Figure 12 This is a schematic diagram showing the inner liner tube being pulled in one embodiment of the present invention;

[0037] Figure 13 This is a schematic diagram of the removal of excess inner liner tubes in one embodiment of the present invention;

[0038] Figure 14 This is a schematic diagram of the removal of the launching and receiving tube in one embodiment of the present invention;

[0039] Figure 15 This is a schematic diagram of the connector jacket installation in one embodiment of the present invention;

[0040] Figure 16 This is a schematic diagram of the connector core installation in one embodiment of the present invention;

[0041] Figure 17 This is a schematic diagram of the glue injection valve in one embodiment of the present invention;

[0042] Figure 18 This is a schematic diagram of blind flange installation in one embodiment of the present invention;

[0043] Figure 19 This is a schematic diagram of pressure testing in one embodiment of the present invention;

[0044] Figure 20 This is a schematic diagram of pipeline restoration in one embodiment of the present invention.

[0045] In the diagram: 1. Side riser (A); 2. Side riser (B); 3. Expansion bend; 4. Horizontal pipe section; 5. Launching tube; 6. Receiving tube; 7. Wire rope winch; 8. Liner winch; 9. Foam ball; 10. Launching tube flange; 11. Wire rope; 12. First sealing ring; 13. Launching tube water inlet; 14. Liner pipe; 15. Joint outer sleeve; 16. Glue injection valve; 17. Drain check valve; 18. Second sealing ring; 19. Joint core; 20. Blind flange; 21. Pressure injection port; 22. Liner pipe joint; 23. First flange; 24. Second flange; 25. Spring pressure plate. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0050] This embodiment provides a method for installing a flexible inner liner pipe at sea, including the following steps:

[0051] S1. Remove expansion bend 3. Use ships C and D to remove expansion bends 3 at both ends of the horizontal pipe section 4; for example... Figure 1 and 2 As shown, there is a riser 1 and an expansion bend 3 on side A of the offshore platform, and a riser 2 and an expansion bend 3 on side B of the offshore platform. The expansion bends 3 on both sides are installed at both ends of the horizontal pipe section 4 of the pipeline to be repaired. The expansion bends 3 at both ends of the horizontal pipe section 4 of the pipeline to be repaired are removed using ships C and D.

[0052] S2. Thread the wire rope 11 and the inner liner pipe 14 through the horizontal pipe section 4. One of ships C and D is equipped with a wire rope winch 7, and the other with an inner liner pipe winch 8. In this embodiment, ship C is equipped with the wire rope winch 7, and ship D is equipped with the inner liner pipe winch 8. After the wire rope 11 of the wire rope winch 7 exits the horizontal pipe section 4, it is connected to the inner liner pipe 14 of the inner liner pipe winch 8. Pulling the wire rope 11 in the opposite direction causes the inner liner pipe 14 to exit the horizontal pipe section 4. Preferably, in this embodiment, the launching tube 5 and the receiving tube 6 are used to thread the wire rope 11 and the inner liner pipe 14. Specifically, the following steps are included:

[0053] S20. For example Figure 3As shown, staff entered the seabed and installed launching tubes 5 and receiving tubes 6 on both sides of the horizontal pipe section 44 to prepare for threading the rope.

[0054] S21. As Figure 4 and 5 As shown, prepare to thread the rope. Insert the foam ball 9 with the steel wire rope 11 into the launching tube 5. The other end of the steel wire rope 11 is on the steel wire rope winch 7 on ship C.

[0055] S22. For example Figure 6 As shown, one end of the wire rope 11 is connected to the foam ball 9, and the other end is connected to the wire rope winch 7 on the ship. The wire rope 11 can be sealed by the first sealing ring 12 on the launching tube flange 10, thus ensuring that the wire rope 11 can freely enter the pipeline while preventing seawater from entering the pipeline. The wire rope is first passed through the launching tube flange 10 and then connected to the foam ball 9. The launching tube flange 10 is connected to the end face of the launching tube 5 by flange bolts. The launching tube 5 and the receiving tube 6 are existing structures and will not be described in detail here.

[0056] S23. For example Figure 7 As shown, high-pressure water is connected to the water inlet 13 on the serving tube 5 to drive the foam ball 9 from the serving tube 5 into the receiving tube 6, thus completing the rope threading process.

[0057] S24. For example Figure 8 As shown, after threading the rope, remove foam ball 9.

[0058] S25. For example Figure 9 and 10 As shown, the steel wire rope 11 of the foam ball 9 is pulled onto the ship D, and the inner liner tube 14 and the steel wire rope 11 are securely tied together.

[0059] S26. For example Figure 11 As shown, the wire rope winch 7 on ship C is started to pull the inner liner tube 14; the inner liner tube 14 is stored on the inner liner tube winch 8 on ship D. When the wire rope 11 is in a taut state, the inner liner tube winch 8 is started and the inner liner tube 14 is released synchronously.

[0060] S27. For example Figure 12 As shown, the inner liner tube 14 is pulled out from the ball-launching tube 5.

[0061] S28. For example Figure 13 As shown, the excess inner lining pipe 14 is cut off from both sides of the flat pipe section 4.

[0062] S29. For example Figure 14 As shown, remove the ball launching tube 5 and ball receiving tube 6 on both sides of the horizontal pipe section 4.

[0063] S3. Install the inner liner pipe joint 22. Workers enter the sea and install the inner liner pipe joint 22 at both ends of the horizontal pipe section 4, so that the inner liner pipe joint 22 is connected to the inner liner pipe 14, and the seawater between the inner liner pipe and the horizontal pipe section is discharged.

[0064] Specifically, the inner liner pipe joint 22 includes a joint outer sleeve 15, a joint core 19, and a blind flange 20. The joint outer sleeve 15 has a first flange 23 and a second flange 24 at its two ends. The first flange 23 has a first groove for installing the joint core 19. The blind flange 20 is connected to the first flange 23, and the second flange 24 is connected to the end of the flat pipe section 4. The blind flange 20 has a pressure injection port 21. The joint outer sleeve 15 has a glue injection valve 16 and a drain check valve 17. Further, the joint outer sleeve 15 is an axially hollow stepped hole, including a large hole near the first flange 23 and a small hole near the second flange 24. The glue injection valve 16 is positioned corresponding to the large hole, and the drain check valve 17 is positioned corresponding to the small hole. Further, the wall of the large hole has a spring pressure plate, and the outer wall of the joint core 19 has a second groove corresponding to the spring pressure plate. Further, the second flange 24 has a second sealing ring 18, which prevents seawater from entering the interior of the flat pipe section 4.

[0065] The specific steps for installing the inner lining pipe joint 22 include:

[0066] S31. Install the connector sleeve 15 and connector core 19. The connector sleeve 15 is connected to the flat pipe section 4 and the connector core 19 respectively. The connector sleeve 15 and connector core 19 are installed on the outer and inner sides of the inner liner pipe 14 respectively. Inject curing adhesive into the inner side of the connector sleeve 15 through the adhesive injection valve 16. Figure 15-17 As shown, the second flange 24 is first connected to the flange at the end of the flat pipe section 4 using flange bolts, and then the connector core 19 is installed using flange bolts. The connector core 19 is located in the first groove of the first flange 23; optionally, the connector core 19 is completely located in the first groove. Curing adhesive is injected into the inner liner connector 22 through the injection valve 16 located on the connector outer sleeve 15. The spring pressure plate 25 collapses due to the inward pressure of the curing adhesive. The inner liner 14 is flexible, and the spring pressure plate 25 squeezes the inner liner 14, causing it to deform. After the curing adhesive reaches the curing pressure, the spring pressure plate 25 and the inner liner 14 fit tightly against the second groove of the connector core 19, thus fixing the inner liner 14 and the connector core 19. For the small hole portion of the connector outer sleeve 15, since the aforementioned injection point is located at the large hole, there is still a gap between the inner wall of the small hole and the outer wall of the inner liner 14 for seawater to flow. The spring pressure plate 25 is a commercially available product and will not be described in detail here. Optionally, epoxy resin can be used as the curing adhesive; the curing pressure range of the curing adhesive is 20-25 MPa.

[0067] S32. Install blind flange 20 at both ends of the joint sleeve 15; if Figure 18 As shown, blind flanges 20 are installed at both ends of the connector jacket 15. A sealing ring is also provided between the surfaces of the blind flanges 20 and the connector core 19 to ensure the sealing of the connection between the two and facilitate pressure drainage.

[0068] S33. Pressure testing and drainage: Because the installation process takes place on the seabed, seawater will flow into the inner liner 14 and the horizontal pipe section 4. The purpose of this pressure testing and drainage is to drain the seawater from the area between the inner side of the horizontal pipe section 4 and the outer side of the inner liner 14. Figure 19 As shown, water is injected into the inner liner pipe 14 through the pressure injection port 21 on the blind flange 20. Under the pressure of the high-pressure water, seawater between the outer side of the inner liner pipe 14 and the inner side of the horizontal pipe section 4 flows through the gap between the small hole of the connector sleeve 15 and the inner liner pipe 14 to the drain check valve 17, and is discharged through the drain check valve 17. The drain check valve 17 is pre-set with pressure, and it can only drain water from the inside of the horizontal pipe section 4; seawater from outside the horizontal pipe section 4 cannot enter the pipe. The water inside the inner liner pipe 14 is drained before subsequent oil transportation.

[0069] S34. After pressure testing and drainage are completed, remove blind flange 20.

[0070] S4. The inner lining pipe joint 22 is installed and connected to the expansion bend 3. For example... Figure 20 As shown, the first flange 23 of the connector jacket 15 is connected to the flange of the expansion bend 3 using flange bolts. After installing the expansion bend 3, the pipeline is restored, and inner-lined pipe connectors 22 are installed at both ends of the horizontal pipe section 4. The riser and expansion bend 3 are repaired and replaced separately.

[0071] In summary, the technical effects and advantages of this invention are as follows:

[0072] The subsea steel pipe repair project can be completed without using the offshore platforms at both ends. The entire project is carried out by interlacing horizontal pipe sections, with risers and expansion bends replaced separately. The lining pipe interlacing process is carried out on the seabed, which solves the problems of high traction caused by numerous bends and easy bursting and breakage of the lining pipe at the gaps between flanges when interlacing on an offshore platform. This method has significant operational feasibility and features high construction efficiency and high-quality pipeline repair.

[0073] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for installing a flexible inner liner pipe at sea, characterized in that, Includes the following steps: Remove the expansion bends by using ships C and D to remove the expansion bends at both ends of the flat pipe section. A wire rope and an inner liner are threaded through the flat pipe section. One of the ships C and D is equipped with a wire rope winch, and the other is equipped with an inner liner winch. After the wire rope of the wire rope winch is threaded out of the flat pipe section, it is connected to the inner liner of the inner liner winch. The wire rope is pulled in the opposite direction to drive the inner liner out of the flat pipe section. Install the inner liner pipe joints at both ends of the horizontal pipe section, connect the inner liner pipe joints to the inner liner pipe, and drain the seawater between the inner liner pipe and the horizontal pipe section. The inner lining pipe joint is installed and connected to the expansion bend; The inner lining pipe joint includes a joint outer sleeve, a joint core, and a blind flange. The two ends of the joint outer sleeve are respectively provided with a first flange and a second flange. The first flange is provided with a first groove for installing the joint core. The blind flange is connected to the first flange. The second flange is connected to the end of the flat pipe section. The blind flange is provided with a pressure injection port. The joint outer sleeve is provided with a glue injection valve and a drain check valve. The joint sleeve is an axially hollow stepped hole, which includes a large hole near the first flange and a small hole near the second flange. The glue injection valve is provided corresponding to the large hole, and the drain check valve is provided corresponding to the small hole. The wall of the large hole is provided with a spring pressure plate, and the outer wall of the connector core is provided with a second groove corresponding to the spring pressure plate; a second sealing ring is provided on the second flange; The steps for installing the inner liner pipe fitting include: Install the connector sleeve and connector core. The connector sleeve is connected to the flat pipe section and connector core respectively. The connector sleeve and connector core are installed on the outer and inner sides of the inner liner pipe respectively. Inject curing adhesive into the inner side of the connector sleeve through the injection valve. First, connect the second flange to the flange at the end of the flat pipe section through flange bolts, and then install the connector core through flange bolts. The connector core is completely located in the first groove of the first flange. Inject curing adhesive into the inner liner pipe connector through the injection valve on the connector sleeve. The spring pressure plate collapses due to the inward pressure of the curing adhesive. The spring pressure plate squeezes the inner liner pipe, causing it to deform. After the curing adhesive reaches the curing pressure, the spring pressure plate and the inner liner pipe fit into the second groove of the connector core, thus fixing the inner liner pipe and connector core. For the small hole portion of the connector sleeve, there is still a gap between the inner wall of the small hole and the outer wall of the inner liner pipe for seawater to flow. Install a blind flange at the outer sleeve of the joint; Pressure drainage: Water is injected into the inner liner pipe through the pressure injection port, and seawater between the outer side of the inner liner pipe and the inner side of the flat pipe section is discharged through the drain check valve; water is injected into the inner liner pipe through the pressure injection port on the blind flange, and the drain check valve is pre-set with pressure so that it can only drain water from the inside of the flat pipe section, and seawater outside the flat pipe section cannot enter the pipe; Remove the blind flange.

2. The method for offshore installation of flexible inner liner pipe according to claim 1, characterized in that, The curing pressure range of the curing adhesive is 20~25MPa.

3. The method for offshore installation of flexible inner liner pipe according to claim 1, characterized in that, In the step of threading the steel wire rope and inner lining pipe into the flat pipe section, the launching tube and the receiving tube are used to thread the steel wire rope and the inner lining pipe.

4. The method for offshore installation of flexible inner liner pipe according to claim 3, characterized in that, The serving tube is equipped with a serving tube flange, and the serving tube flange is provided with a first sealing ring for sealing the steel wire rope.

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