NO20170908A1 - Low Built Weather Deck Hoist - Google Patents

Abstract

A low built hoist is particularly adapted for use in a location with limited free height, such as a weather deck on an oil rig. The hoist comprises a main body (1) with a cavity (23a), at least one winch (6, 7) arranged within said cavity (23a) and an A-frame (5) hingedly attached to the outside of said main body ( 1). The A-frame has at least one sheave to guide a hoisting wire (10, 11) from said at least one winch (6, 7).

Description

L<OW>B<UILT>W<EATHER>D<ECK>H<OIST>

Technical Field

[0001] The present invention relates to lifting equipment, and in particular a hoist to be used on the weather deck of an oil or gas drilling rig.

Background Art

[0002] The weather deck is the uppermost continuous deck on an oilrig. It is very convenient to place hoisting equipment here because it provides access to all the decks below. Hence, the weather deck is equipped with hatches that can be opened to feed hoist wires through the deck.

[0003] However, due to the versatility of the weather deck of an oil or gas-drilling rig it often contains obstacles, especially in the form of skidding rails for derricks and the like. Such rails are arranged with a relatively short distance to the deck, such as less than 1 metre. It is therefore difficult to move hoisting equipment on this deck. Special hoisting equipment that can be moved below the skidding rails have therefore been developed.

Summary of invention

[0004] The present invention relates to such a low built weather deck hoist, which can be used for inter alia offshore well intervention operations on various types of platforms, such as fixed platforms, tension leg platform and floaters. It provides lifting possibilities in areas where coverage by platform crane is limited or not available, thus also allowing for simultaneous operations on the same installation.

[0005] To be able to work on a weather deck, the hoist of the invention is equipped with winches that enables wireline equipment rig-up and handling of operational tools. Typically, such operations involve installation of wireline BOP (Blow-Out Preventer), lubricator system and change of bottom-hole assemblies. The low built weather deck hoist of the present invention is equipped with a so-called A-frame functionality, which provides suspension points to accommodate one or more wireline top sheaves and transfer wireline operational load onto strong deck beams. The hoist device of the present invention is capable of self-handling of deck hatches, i.e. opening and closing, thus simplifying installation sequence.

[0006] The mobility of the hoisting device of the invention is assured by wheels that preferably are hydraulically driven and that can turn at least /- 90 deg., allowing for movement in all directions. It is preferably equipped with jacking cylinders that can lower the unit frame to deck level, and thereby increase the stability of the unit during lifting operations and assure proper load distribution on a deck.

[0007] The hoisting device of the invention is preferably equipped with its own, dedicated hydraulic power unit that ensure efficient operations.

Brief description of drawings

[0008]

Figures 1a-f show an embodiment of the hoist according to the invention: Figure 1a in isometric view,

Figure 1b in isometric view from a different angle,

Figure 1c with the A-frame in a raised position,

Figure 1d in planar view.

Figure 1e in elevation view,

Figure 1f in elevation view with the A-frame in a raised position Figure 2a shows the hoist of figures 1a-f with the top cover removed;

Figure 2b shows a similar view to figure 2a, but with the various functions of the hoist highlighted,

Figure 3a shows an elevated view of a wheel frame with wheels,

Figure 3b shows a planar view of the wheel frame with wheels,

Figure 3c shows an isometric view of the wheel frame with wheels, Figure 3d shows a section through one wheel suspension assembly, Figure 3e shows a section of the hoist of the invention with one wheel frame with wheels,

Figure 3f shows one wheel suspension assembly in planar view,

Figure 4a-d show another embodiment of the hoist of the invention:

Figure 4a in isometric view,

Figure 4b in isometric view with the A-frame in a raised position, Figure 4c in isometric view from a different angle,

Figure 4d in use above a hatch,

Figure 5a shows a section of the A-frame with different hang-off options, Figure 5b shows a section of the A-frame with different hang-off options in isometric view,

Figures 6 – 26 shows a step-by-step performance of an operation using the hoist.

Detailed description of the invention

[0009] Figure 1a shows a first embodiment of a low built weather deck hoist according to the present invention.

[0010] The hoist comprises a main body 1 that has a lower cover 2 and a top cover 3. Between the two covers 2, 3 is a frame structure 4 (best shown in figures 2a and 2b). An A-frame 5 is hinged to the main body 1. A pair of winches 6, 7 is mounted on the lower cover. The A-frame 5 is equipped with sheaves 8, 9, over which a respective hoist wire 10, 11 can extend. The hoist wires 10, 11 are spooled on a respective winch drum of the winches 6, 7.

[0011] The winches 6, 7 may be identical or may be of different capacity. The hoist may also be equipped with more than two winches, provided that there is sufficient space and width on the lower cover 2

[0012] The hoist body has a mouth 23 defined therein. The lower cover 2 covers the inner part of the mouth 23. The mouth 23 is at its narrowest at the edge of the lower cover 2. Thereby a cavity 23a is created above the lower cover 2. The winches 6, 7 are arranged within the cavity 23a. The significance of this mouth 23 will be explained later.

[0013] Figure 1b shows the hoist of the invention from a different angle. Here is shown an operating interface 12 for manual operation of the hoist.

[0014] Figure 1c shows the hoist with the A-frame 5 in a raised position. As can be clearly seen from this figure, the A-frame is generally U-shaped with two arms 13, 14 and a U-shaped connecting section 15, connecting the two arms. At the opposite end of the arms 13, 14 from the connecting section 15, the arms 13, 14 are hinged to the hoist body 1 at pivot journals 16, 17. The connecting section 15 is telescopically received by the arms 13, 14, so that the A-frame 5 can extend outward from the hoist body 1. The raising and lowering is accomplished by a pair of hydraulic actuators 18, 19 that are mounted to act between the body 1 and a respective arm 13, 14.

[0015] The sheaves 8, 9 are mounted on sliding members 20, 21 so to be displaceable along a straight transverse part 15a of the connecting section 15.

[0016] By lifting the arms 13, 14, the sheaves 8, 9 can be brought to a high elevation, such as 4, 5 meters above the deck.

[0017] Figures 1d, e and f also show the hoist of figures 1a-c in different views.

Figure 1d shows the hoist in planar view with the A-frame 5 in its lowermost position. Figure 1e shows the hoist in elevated view with the A-frame 5 in its lowermost position. In this figure wheels 32e of the hoist 1 can also be glimpsed.

[0018] Figure 1f shows the hoist in an elevation view with the A-frame 5 in almost its upper position. It shows schematically the telescoping mechanism of the A-frame, comprising a hydraulic actuator 22 arranged within a hollow interior of a respective one of the arms 13, 14 and within a hollow interior of the connecting section 15. The A-frame is capable of being lifted by the actuators 18, 19 to a position where the sheaves 8, 9 are situated vertically above the outer part of the mouth 23, within the boundary of the hoist body 1 but outside the boundary of the lower cover 2. This is equivalent to an angle of about 45º of the arms 13, 14 relative to the deck.

[0019] Figure 2a shows the hoist with the top cover 3 removed. The frame structure 4 is visible in this view. The frame structure 4 consists essentially of a multiple of beams that have been connected, e.g., welded or bolted together, to a general outer shape similar to the top cover 3. In addition a pair of beams 4a, b have been added at the inner portion of the mouth of the lower cover 2.

[0020] The frame also defines the cavity 23a.

[0021] Within the frame structure 4 is arranged a pair of wheel frames 24, 25, which are suspended in the frame 4 by lift actuators 33, and which will be described in detail later, an hydraulic power unit 26, which provides power to all hydraulics in the hoist, a control unit 27, which controls the functions of the hoist, rotary actuators 28 (only one of four visible), which turn the wheels, and the aforementioned winches 6, 7. The winches 6, 7 are mounted on skidable platforms 29, so that their positions on the lower cover 2 can be changed.

[0022] Also shown in figure 2a are hydraulic actuators 30 that can shift the sliding members 20, 21 along the connecting section 15.

[0023] One of the hydraulic actuators for telescoping the A-frame 5 is also shown, as well as one of the actuators 18 for raising and lowering the A-frame 5.

[0024] The hoist of the present invention is preferably remotely operated, such as by radio signals, with manual back-up option through the interface 12.

[0025] Possible functions that can be controlled are listed below and also denoted in figure 2b:

[0026] The shifting of the winches (movement S7 or S8) and the shifting of the associated sheave, i.e. the sheave that the wire from a winch extends over, (movement S9) are possibly synchronized. Thereby a load hanging from the wire can be shifted sideways without moving the hoist as such. It is also possible to shift sideways only one of the loads carried by the winch without affecting the other load(s).

[0027] The wheel frame and wheel suspension assembly will now be described, referring to figures 3a-f.

[0028] Figures 3a, b and c show one of the two wheel frames 25. The wheel frame 25 comprises a longitudinal beam 31, which has attached a ring-shaped wheel carrier 32 at each end. The wheel carrier comprises a fixed ring 32a and a toothed slewing ring 32b, which is rotatable relative to the fixed ring 32a.

[0029] At the inside of the slewing ring 32b a wheel motor 32c is attached to the slewing ring 32b by a bracket 32d (best shown in figures 3d and 3f). A wheel 32e is attached to the rotator of the motor 32c.

[0030] As best shown in figure 3e, the wheel frame 25 is attached to a pair of body lift actuators 33 through brackets 34. The frame structure 4 of the body 1 is equipped with a pair of pins 35, which are received in holes 36 in the wheel frame 25. Through the action of the actuators 33, the wheel frame 25 is capable of sliding up and down the pins 35. Thereby the body 1 of the hoist can be lifted vertically from a lower position where it is resting with the frame 4 on the deck to a raised position with clearance to the deck. In the raised position, the hoist can be driven by rotating the wheels 32e.

[0031] The teeth of the slewing ring 32b are meshing with a hydraulic rotating actuator (not shown), which rotates the slewing ring 32 so as to turn the wheels 32e in their direction at least 90 degrees, preferably /- 90 degrees. Thereby the hoist can drive in any direction and turn around any axis, depending on the direction of the wheels 32e.

[0032] Figures 4a-d show an alternative embodiment of the hoist, which does not have a mouth at one edge. Instead, it has a large central opening 40 in the top cover 3 and the frame structure 4 and a smaller opening 41 in the lower cover 2. The winches 6, 7 are situated next to the lower opening 41.

[0033] This embodiment also has an A-frame 5, which operates in general in the same way as the A-frame of the preceding embodiment. The A-frame 5 can be lifted from a substantially horizontal position to a position where the top of the A-frame, i.e. the transverse part 15a is vertically above the central openings 40, 41.

[0034] As shown in figure 4d the hoist can be used directly above an opening in a hatch cover on the weather deck, without the engagement of the A-frame. A wire from one or both winches 6, 7 may hang through the lower opening 41 and the hatch opening (not clearly visible in figure 4d).

[0035] With the A-frame in the raised position as shown in figure 4b, the hoisting wires can also extend through the opening 41 via the A-frame (sheaves similar to the sheaves 8, 9 in the first embodiment may be attached to the A-frame 5).

[0036] Figures 5a and 5b show that in addition to the sheaves 8 and 9, one or more separate blocks 42 can be attached to support additional hoisting wires. Such extra wires can be run from one of the winches on the hoist, but may also be run from a stationary winch on or close to the weather deck.

[0037] An operation for attaching a wireline stack-up to a BOP will now be explained referring to figures 6 – 26.

[0038] In figure 6 is shown an upper weather deck 50, which has a plurality of hatches that are covered by hatch covers 51. A pair of skid beams 53 for a derrick extend above the weather deck with a small clearance to the deck (such as between 1⁄2 and 1 meter), which makes it difficult to use conventional hoisting gear.

[0039] Below the weather deck is an intervention deck 54, which also has a plurality of hatches covered by hatch covers 55.

[0040] A BOP 56 extends through one of the hatches. A wireline stack-up 57 is lying horizontally on the intervention deck.

[0041] The first step is to drive the hoist to a position above the hatch that is directly above the BOP, as shown in figure 7. This may be a surface BOP, which is mounted on top of a riser (not shown). When the hoist is in the correct position above the hatch, the hatch cover 51 is attached to the A-frame 5 by means not shown. These means may be a pair of hook coupled to wires running over the sheaves 8, 9 and being coupled to the winches 6, 7, or it may be hooks attached directly to the A-frame.

[0042] The A-frame 5 then lifts the hatch cover 51 off the hatch and the hoist is driven to a position where the hatch cover 51 can be detached and placed temporarily, as seen in figures 11 - 14.

[0043] A special hatch cover 58 with an opening 58a adapted for running through a hoist line (see figure 10) is then picked up by the A-frame (see figure 15) and brought to the hatch where the hatch cover 51 just has been removed from, se figures 16 - 19.

[0044] Then a sheave block 59 is attached to the A-frame 5 (see figure 20).

[0045] A hoist wire is fed through the sheave block 59 and through the opening in the hatch cover 58 as shown in figures 21 and 22.

[0046] Finally, the sheave block is also fed through the opening 58, as shown in figures 23 and 23a. One end of the hoist wire is then connected to one of the winches 6, 7 in the hoist.

[0047] The other end of the hoist wire is then coupled to the wireline stack-up 55, as shown in figure 25 and the lifting can commence to place the wireline stackup 55 on top of the BOP 56, as shown in figure 26.

[0048] During the operation above, the A-frame is telescoped outwards or inwards as needed to move the hatch covers 51 or 58 or place the block at the appropriate position.

Claims (14)

Claims

1.

A low built hoist particularly adapted for use at a location with limited free height, such as a weather deck on an oilrig, characterised in that the hoist comprises a main body with a cavity, at least one winch arranged within said cavity and an A-frame hingedly attached to said main body, said A-frame having at least one sheave to guide a hoisting wire from said at least one winch.

2.

The hoist of claim 1, characterised in that said main body comprises a frame structure and a first cover on one side of said frame structure and a second cover on an opposite side of said frame structure.

3.

The hoist of claim 1 or 2, characterised in that said main body defining a mouth extending from an outer edge of said main body.

4.

The hoist of any of the preceding claims, characterised in that said A-frame is moveable from a first position where it is substantially in the same plane as said main body and a second position where it extends at an angle relative to said main body.

5.The hoist of any of the preceding claims, characterised in that said A-frame is of general U-shape and said at least one sheave is attached at a middle portion of said U-shape.

The hoist of claims 3, 4 and 5, characterised in that said A-frame middle portion is extending across said mouth when in said first position.

7.

The hoist of any of the preceding claims, characterised in that it comprises a plurality of wheels that are turnable over at least 90º.

8.

The hoist of claim 7, characterised in that said wheels are height adjustable relative to said main body so that said main body can be lowered onto a surface on which the hoist is travelling.

9.

The hoist of any of the preceding claims, characterised in that said main body has an opening through which a hoisting wire can extend.

10.

The hoist of any of the preceding claims, characterised in that said A-frame is telescopically extendable.

11.

The hoist of any of the preceding claims, characterised in that said at least one sheave is shiftable along the A-frame.

12.The hoist of any of the preceding claims, characterised in that said at least one winch is shiftable relative to said main body.

The hoist of claims 11 and 12, characterised in that said shifting of said at least one sheave and said shifting of said at least one winch are synchronized.

14.

The hoist of any of the preceding claims, characterised in that said A-frame is attached to said body on the outside of said main body.