CRANE SYSTEM FOR A CANTILEVER

Abstract

A crane system is for a cantilever belonging to a jack-up rig. The crane system has a crane with a suspension member, the suspension member being arranged over the crane. A skid beam is attached to a lower portion of the cantilever, the skid beam being displaceably connected to a plurality of slides arranged on the jack-up rig, the crane hanging on the skid beam. A method is for using the crane system.

Claims

1. A crane system for a cantilever belonging to a jack-up rig, the crane system comprising: a crane with a suspension member, the suspension member being arranged over the crane, two skid beams attached to a lower portion of the cantilever, the skid beams being displaceably connected to a plurality of slides arranged on the jack-up rig, wherein the crane hangs on one of the skid beams via the suspension member.

2. The crane system according to claim 1, wherein the crane is displaceable along a portion of the skid beam.

3. The crane system according to claim 2, wherein the suspension member is provided with a wheel resting on the skid beam.

4. The crane system according to claim 2, wherein the suspension member includes a driving device arranged to move the crane along a portion of the skid beam.

5. The crane system according to claim 4, wherein the driving device comprises a toothed wheel arranged to engage with a pitch rack attached to the skid beam or the cantilever.

6. The crane system according to claim 1, wherein the crane is provided with a winch.

7. The crane system according to claim 1, wherein the crane is provided with a crane arm.

8. The crane system according to claim 1, further comprising a skid-beam extension arranged on a first end portion of the skid beam.

9. A method of using a crane system connected to a cantilever on a jack-up rig, the cantilever being provided with two skid beams which is attached to a lower portion of the cantilever and is displaceably connected to a plurality of slides arranged on the jack-up rig, the method comprising the step of: providing a crane with a suspension member, the suspension member being arranged over the crane, wherein the method comprises the step of: suspending the crane under one of the skid beams by letting the suspension member engage with the skid beam.

10. The method according to claim 9, wherein the method further comprises the step of: displacing the suspension member along a portion of the skid beam.

11. The method according to claim 9, wherein the method comprises the further steps of: arranging a skid-beam extension on a first end portion of the skid beam; moving the crane to a position on the skid-beam extension; and moving the cantilever from a first, projecting position into a second, retracted position.

12. The method according to claim 9, wherein the method comprises the further steps of: arranging a skid-beam extension on a first end portion of the skid beam; moving the cantilever from a second, retracted position to the first, projecting position; and moving the crane from the skid-beam extension to a position between the skid-beam extension and the slide.

13. The method according to claim 9, wherein the method comprises the further steps of: arranging a second crane in the crane system; and performing a hoisting operation with a hoisting yoke connected to the two cranes.

14. The method according to claim 9, wherein the method comprises the further step of: using the crane to position a body over a well and lower the body into the well.

15. The method according to claim 9, wherein the method comprises the further step of: performing a hoisting operation over an adjacent installation.

16. The crane system according to claim 3, wherein the suspension member includes a driving device arranged to move the crane along a portion of the skid beam.

17. The method according to claim 10, wherein the method comprises the further steps of: arranging a skid-beam extension on a first end portion of the skid beam; moving the crane to a position on the skid-beam extension; and moving the cantilever from a first, projecting position into a second, retracted position.

Description

EXEMPLARY EMBODIMENT

[0044] In what follows, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which:

[0045] FIG. 1 shows an end view of a crane arranged on a skid beam according to the invention;

[0046] FIG. 2 shows an end view, on a smaller scale, of a crane system comprising two cranes arranged on two skid beams;

[0047] FIG. 3 shows a side view, on a smaller scale, of a jack-up rig comprising a cantilever with two cranes arranged on separate skid beams;

[0048] FIG. 4 shows a side view, on a larger scale, of the cantilever and two cranes in an operative position; and

[0049] FIG. 5 shows a side view of the cantilever and the cranes in a transit position.

[0050] FIG. 1 shows an end view of a crane 10A including a suspension member 13 arranged over the crane 10A, the suspension member 13 being displaceably arranged on a skid beam 30. The skid beam 30 is arranged on a lower portion of a cantilever 3. The skid beam 30 comprises a transverse profile 301 and a plurality of braces 306. The skid beam 30 is arranged to slide through several slides 22A, 22B, shown in FIGS. 3-5.

[0051] Between the crane 10A and the suspension member 13, a prior-art slewing ring 15 is arranged. The slewing ring 15 comprises a slip ring for the transmission of electrical signals and a slip ring for the transmission of a hydraulic pressure to a winch 11, a cylinder 14 and a telescopic cylinder (not shown).

[0052] The suspension member 13 includes supporting means, shown here as a plurality of wheels 130, 131. Four wheels 130 rest supportingly against a top side of the transverse profile 310. On either side of the transverse profile 301, two supporting wheels 131 are arranged, adapted for giving the suspension member 13 a stable guiding sideways.

[0053] The suspension member 13 further includes a driving device 16 comprising a hydraulic motor 160. The motor 160 is provided with a toothed wheel 161 arranged to engage with a pitch rack 305. The pitch rack 305 is attached to the cantilever 3 via a plurality of brackets 306. The brackets 306 are also a base for a cable run 307, comprising a plurality of electrical cables and a plurality of hydraulic hoses arranged for the transfer of current, electrical signals and oil to the crane 10A. The cable run 307 is connected, at a first end portion, to the cantilever 3 and is connected, at its second end portion, to the suspension member 13 as shown in FIG. 4.

[0054] The crane 10A comprises a telescopic crane arm 12, a winch 11 and a hydraulic cylinder 14. The crane 10A is provided with the following functions: linear movement for-ward/back, pivot right/left, tilt up/down, telescope out/in, winch cable out/in.

[0055] FIG. 2 shows an end view, on a smaller scale, of two cranes 10A, 10B arranged on two skid beams 30. The cranes 10A, 10B are shown in two different operational positions. FIG. 2 shows how a crane system 1 according to the invention provides a possibility of crane operations in the entire width of the cantilever 3 without coming into conflict with an intermediate structure 31.

[0056] FIG. 3 shows a side view, on a smaller scale, of a jack-up rig 2 including a cantilever 3 with a derrick 31 and a crane system 1 according to the invention. The cantilever 3 is shown in a first, projecting position P1. The cantilever 3 and the derrick 31 are positioned over a jacket rig 5 fixed to the seabed. From the derrick 31 and through the jacket rig 5, a drill string 320 is arranged.

[0057] The skid beams 30 are displaceably connected to the jack-up rig 2 via two slides 22A arranged farthest out on a rig floor 20 and two slides arranged inside the rig floor 20. A skid-beam extension 302 is arranged on a first end portion 301 of the skid beam 30.

[0058] A first crane 10A is positioned on the skid-beam extension 302 and a second crane 10B is positioned on the skid beam 30. The cranes 10A, 10B are arranged on separate skid beams 30 and adapted for carrying out lifting operations on the jacket rig 5.

[0059] By the cantilever 3 being provided with a crane system 1, there is no need for the floor 51 of the jacket rig 5 to have cranes of its own and temporary cranes. This simplifies the lifting operations on the floor 51 of the jacket rig 5 and also increases the safety in that there are no cranes arranged on the floor 51 of the jacket rig 5.

[0060] FIG. 4 shows a simplified section, on a larger scale, of the side view of FIG. 3. The cantilever 3 is arranged in the first, projecting position P1, in which a substantial part of the cantilever 3 is outside the floor 20 of the jack-up rig 2. The cranes 10A, 10B can be moved along a portion L1 of the two skid beams 30, between the skid-beam extension 302 and the slide 22A. Two skid-beam extensions 302 are attached to first end portions 301 of the skid beams 30. Thereby the operational distance of the cranes 10A, 10B may have an increase corresponding to the length L2.

[0061] FIG. 5 shows a side view of the cantilever 3 and the crane system 1 in a second, retracted position P2, known in the technical language as a transit position, typical when the jack-up rig 2 is being raised, lowered and moved. In the transit position, the cantilever 3 is positioned over the rig floor 20 as shown in FIG. 5. The cranes 10A, 10B are placed in a position P3 on the skid-beam extensions 302. By the cranes 10A, 10B being positioned on the skid-beam extensions 302 as shown in the figure, the cranes 10A, 10B will not come into conflict with the slide 22A or the rig 2 when the cantilever 3 is in the transit position P2. If the skid-beam extensions 302 have the necessary strength, the cranes 10A, 10B can be used when the cantilever 3 is in the transit position.

[0062] It should be noted that all the above-mentioned embodiments illustrate the invention, but do not limit it, and persons skilled in the art may construct many alternative embodiments without departing from the scope of the attached claims. In the claims, reference numbers in brackets are not to be regarded as restrictive.

[0063] The use of the verb to comprise and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article a or an before an element does not exclude the presence of several such elements.

[0064] The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.