KR20000010926A - Slip joint - Google Patents

Abstract

PURPOSE: A slide joint is provided for a riser between a well and a floating petroleum installation, such as an oil platform, comprising an outer pipe and an inner pipe being adapted to move telescopically relative to one another to compensate for changes in the distance between a sea bed and a platform. CONSTITUTION: A slide joint (10) for a riser (16) between a well and a floating petroleum installation, e.g., an oil platform, comprising an outer pipe (12) and an inner pipe (11), which pipes are adapted to move telescopically relative to one another to compensate for changes in the distance between the sea bed and the platform. The inner pipe (11) is connected to a piston (27), which piston is responsive to actuation by hydraulic pressure in order to provide tractive force on the riser (16). The outer diameter of the inner pipe (11) is adapted to the diameter of the outer pipe (12) so as to form an annulus (25) between the pipes. The piston (27) is fixedly connected to the inner pipe (11) at or near the downward oriented end thereof, the annulus (25)above the piston (27) being subjected to hydraulic pressure. Below the piston (27) is provided a protective sleeve (29), which is slidingly disposed within the outer pipe (12).

Description

Sliding Joint

A sliding joint of known type is shown in FIG. 1. In order to maintain tension in the riser, a plurality of wires are attached to the upper end of the outer tube, and these wires are connected to a plurality of tensioning devices that apply a constant tension to the riser. Wires, tensioners, accessory collection reel risers, etc., associated with tensioning devices for risers require considerable space and are heavy. In addition, the wires are placed under considerable tension and must be replaced frequently.

The present invention provides a sliding joint for a riser between a well and a floating petroleum plant, such as an oil platform, including an outer tube and an inner tube superimposed on each other to compensate for changes in distance between the seabed and the platform. joint).

1 is a view showing a sliding joint according to the prior art,

2 is a view showing a sliding joint according to the present invention,

3 is a view showing in detail the sliding joint,

4 is a detailed view of a riser with a sliding joint,

5A-5F are cross-sectional views of various components of the sliding joint and riser,

6 is a schematic view of a hydraulic system according to the present invention.

Explanation of symbols on the main parts of the drawings

10: sliding joint 11: inner tube

12: outer tube 13: flexible connector

14: hydraulic accumulator 15: hydraulic hose

16 riser 17 manifold ring

18: opening 19: upper tube of the outer tube

20: lower pipe of the outer tube 21: flange connection

24, 28, 30, 33: packer (25), 31: annular portion

26: automatic shutoff valve 27: piston

29: protective sleeve 32: boring

34: passage 36: scrape ring

37 pump 38 air tank

39: preliminary pressure tank 40: accumulator

41, 42: valve 43: pressure tank

44: hose

It is an object of the present invention to replace wires, tensioning devices, collection reels and other equipment connected to them with less space and with much simpler and lighter equipment. It is also an object of the present invention to provide a sliding joint with improved functional efficiency and greater reliability.

This object is achieved by connecting the inner tube to a piston that responds to the action of hydraulic fluid to provide traction on the riser.

The apparatus according to the invention can reduce the equipment weight of 100 tons, which is a significant weight even on large oil platforms. Moreover, the device is less space constrained and provides improved functional efficiency that allows it to swing freely in the vertical plane without the obstacles of tight wires. Since the traction force applied on the riser is entirely axial, no opposite lateral force occurs on the riser. Maintenance is also very simple, since the only frequently replaced parts are hydraulic hoses. The hydraulic hoses are in dual sets, allowing the hoses to be replaced one after another without interrupting the system.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 shows a sliding joint 1 according to the prior art. The sliding joint 1 is composed of an inner tube 2 and an outer tube 3. The outer tube 3 is connected to the pedestal of the riser 4 which extends into the well (not shown). The outer tube 3 has a collar 5 at its upper end, which is connected to a number of wires 6 which are connected to a tension device 7. Moreover, the collection reel 8 for the wire 6 is provided. The inner tube 2 is connected to a production facility (not shown) on the platform via a flexible connector 9. Also shown in FIG. 1 are two hoses connected to a blowout preventer (BOP) via a duct in the riser 4, one of which suppresses the return from the well and the other into the well. Can be pumped.

2 shows a sliding joint 10 according to the present invention. The sliding joint 10 here also comprises an inner tube 11 and an outer tube 12. In addition, the inner tube 11 is connected to the production equipment of the platform through a flexible connector (13). However, the sliding joint 10 is attached to the hydraulic accumulator 14 for supplying hydraulic pressure to the sliding joint 10 so that the riser 16 is placed in the extended state through the hydraulic hose 15.

3 shows the sliding joint 10 in more detail. Also shown are inner tube 11, outer tube 12 and flexible connector 13. The hydraulic hose 15 is attached to the manifold ring 17 connected to the upper end of the outer tube 12. In FIG. 4, the riser and the sliding joint 10 are shown in a position that is shaken 10 degrees laterally. This outward swing is made without interference from wires or other equipment. Thus, the sliding joint 10 may swing outwards until it is very close to the edge of the opening 18.

In Figure 5, the sliding joint is shown in more detail. The outer tube 12 is composed of two parts, that is, the upper tube 19 and the lower tube 20 coupled to each other by the flange connection portion 21. The lower tube 20 has an inner diameter that is narrowed at its lower end 22.

5A to 5F will be described below. FIG. 5A is a cross-sectional view of the upper end 23 of the outer tube 12 and shows a portion of the inner tube 11 and the outer tube 12. A packer 24 is formed on the upper end 23 of the outer tube 12 to form a seal between the inner side of the outer tube 12 and the outer side of the inner tube 11. Under the packer 24, the manifold ring 17 is in hydraulic communication with the annular portion 25 between the inner tube 11 and the outer tube 12 via an automatic shutoff valve 26.

5b shows the portion of the sliding joint at the lower end of the inner tube 11. Also shown is a piston 27 connected to the inner tube 11. The piston 27 is sealed against the inner side of the outer tube 12 by the packer 28. Thus, the annular portion 25 is isolated except in hydraulic communication with the hose 15. FIG. 5B also shows the top of the protective sleeve 29 with a packer 30 that engages the piston and forms a seal against the inner surface of the outer tube 12. In FIG. 5E, the packer 30 is shown in detail. The packer 30 does not form a complete seal to the inner side of the outer tube 12, but some leakage and mud from the annular portion 31 formed between the protective sleeve 29 and the outer tube 12. And some leakage between the protective sleeve 29 and the piston 27 to the boring 32 for the transfer of petroleum products. The reason for allowing such a slight leak is described below. FIG. 5C shows the portion of the outer tube 12 at the flange connection 21 between the upper tube 19 and the lower tube 20 and the portion of the protective sleeve 29 slightly below at its upper end. Here, the outer tube 12 has a packer 33 shown in detail in FIG. 5F. The packer 33 forms a seal for the protective sleeve 29. Directly above the packer 33 is provided a passage 34 for supplying a pressure medium, such as air or water, to press the annular portion 31. This is also explained later. 5D shows the portion near the lower end of the outer tube 12 and the lower end of the protective sleeve 29. It can be seen from this figure that the outer tube 12 begins to narrow at point 35. The protective sleeve 29 has a guide and scrape ring 36 at its lower end, which has an outer diameter greater than the smallest diameter of the outer tube 12 at point 35. .

When the hydraulic pressure is supplied to the annular portion 25 between the inner tube 11 and the outer tube 12 through the hydraulic hose 15, the inner tube 11 and the outer tube 12 slide so as to overlap each other. As such, riser 16 is placed in an extended state. The tension can be adjusted by increasing or decreasing the hydraulic pressure. Working in deeper oceans using relatively heavy risers requires much greater pressure than those required for risers used in low oceans.

Tools such as mud, petroleum products, or drill heads scratch the inner surface of the outer tube 12 or otherwise in such a way that the piston 27 can no longer slide along the inner surface of the outer tube 12 without difficulty. In order to avoid damaging, a protective sleeve 29 is provided to protect the inner surface of the outer tube 12. By supply of fluid through the passage 34, the protective sleeve 29 is always in contact with the piston 27. The pressure provided to the annular portion 31 through the passage 34 is constant. Allowing some leakage through the packer 30 prevents mud or petroleum products from penetrating into the annulus 31. The lower end with the scraping ring 36 does not move above the lowest position for the piston 27 because the protective sleeve 29 is quite long.

6 shows a hydraulic system. Also shown in FIG. 6 is a sliding joint 10 and protective sleeve 29 with an inner tube 11 and an outer tube 12. Pump 37 delivers air to multiple air tanks 38. One of the air tanks 38 functions as a preliminary pressure tank 39 and always maintains a pressure of 210 bar for the case where the inner tube 11 has to move quickly relative to the outer tube 12. The tanks 38, 39 are connected to the accumulator 40 via a valve 41. In addition, a valve 42 is mounted between the preliminary pressure tank 39 and the air tank 38. The accumulator 40 is connected to the annular portion 25 via a hydraulic hose 15 with an automatic shutoff valve 26 at each end.

In addition, a pressure tank 43 is provided through the hose 44 which puts the annular part 31 under moderate pressure to maintain the contact of the protective sleeve 29 against the inner tube 11.

During normal operation, the pressure in the air tank 38 can vary between 20 and 210 bar, depending on the specific speed at which the sliding joint 10 must move and the magnitude of the force that is generated. However, if desired, the pressure in tank 39 may be 210 bar.

6 shows another embodiment of the connection between the protective sleeve 29 and the inner tube 11.

Although the protective sleeve 29 may be permanently fixed to the inner tube 11, this may make handling of the sliding joint difficult at the stage of transportation and mounting.

Since the outer tube 12 is divided into two parts, the upper tube 19 and the lower tube 20, the outer tube 12 can be divided at the flange connection 21. If so, the protective sleeve 29 must be placed in the lower tube 20, while the inner tube 11 must be placed in the upper tube 19. Thus, the sliding joint can be made in two parts and can be mounted by first installing the lower tube 20 together with the riser 16 so that the riser is lowered until the flange connection 21 is at an appropriate level. The upper tube 19 may be equipped with the lower tube 20.

To ensure that the inner tube is protected during handling, a lowering procedure has been established for the BOP to be fitted with a sliding joint, the BOP being held in the retracted position and hydraulically fixed. The procedure also makes it possible to connect the hydraulic hoses as well as the throttle and shutoff hoses at a suitable level prior to the mounting of the BOP. All hoses are collected on the main manifold ring 17. Manifold ring 17 is held in place when the sliding joint slides through the rotary bore. Special processing tools are used to mount the BOP and to tie the sliding joints. When the BOP is anchored to the seabed, the traction on the sliding joint is applied, the inner tube 11 is pulled out and the suspension head is mounted and fixed to the suspension socket.

Claims (4)

Sliding joints (10) for risers (16) between floating oil installations and oil wells, such as oil platforms, with outer tubes 12 and inner tubes superimposed on each other to compensate for changes in distance between the seabed and the platform. 11), wherein the inner tube (11) is fixedly connected to the piston (27) at or near its lower end, and the piston (27) is hydraulic to provide traction on the riser (16). In response to the operation, a first annular portion 25 is formed between the inner tube 11 and the outer tube 12, the first annular portion 25 is the oil well fluid and the surrounding environment (e.g., For example, in the sliding joint, which is isolated from all of the sea water and the first annular portion 25 above the piston 27 is affected by the hydraulic pressure, A protective sleeve 29 is slidably disposed inside the outer tube 12 below the piston 27, and the protective sleeve 29 is pressurized to contact the lower end of the inner tube 11 so that The second annular portion 31 formed between the protective sleeve 29 and the outer tube 12 is subjected to a constant pressure to seal the piston 27 from contact with the oil well fluid, and the protective sleeve 29 Has an upper piston 30a, and the annular region of the upper piston 30a on the side of the second annular portion 31 is on the opposite side of the third annular portion 30b on the opposite side of the upper piston 30a. Since it is larger than the annular region of the upper piston 30a, the upper piston 30a is moved in the direction from the second annular portion 31 to the third annular portion 30b on the opposite side of the upper piston 30a. Leakage of the fluid passing through occurs, and the outer tube 12 It is composed of two structures can be divided into the upper tube 19 and the lower tube 20, the inner tube 11 is accommodated in the upper tube 19 and the protective sleeve 29 is the lower tube ( A sliding joint, characterized in that it is received within 20). The protective sleeve (29) according to claim 1, wherein the protective sleeve (29) includes an upper packer (30) sealing against the outer tube (12) and a packer (30) sealing against the piston (27) or the inner tube (11). Sliding joint, characterized in that the upper tube, the outer tube (12) has a lower packer (33) at the lower point of the upper packer (30) sealing against the protective sleeve (29). 3. The packer between the protective sleeve 29 and the inner tube 11 and the upper packer 30 are provided between the protective sleeve 29 and the outer tube 12. A sliding joint, which is designed to allow a small amount of fluid to pass from the second annular portion (31). The method of any one of the preceding claims, wherein a double set of hydraulic hoses (15) are in hydraulic communication with the upper portion of the piston (27) and shut off the hydraulic passages if a leak occurs in the hydraulic hoses (15). Sliding joints, characterized in that the valve 26 is provided at each end of the hydraulic hose 15 so that the sliding joint 10 can be operated without problems even with one hydraulic hose 15 which is not damaged. .