SYSTEM FOR HOISTING A LOAD ON A DRILLING RIG

Abstract

A system for hoisting a load on a drilling rig includes: a hoisting means having an elongated hoisting member and an elongated hoisting member drive means; a drill string rotation means suspended from an end of the elongated hoisting member; a support structure having a first side and a second side and being adapted to support at least a portion of the weight the drill string rotation means; a first elongated hoisting member guiding means connected to the support structure; and a counterweight connected to the elongated hoisting member at the second side of the support structure. The elongated hoisting member is reeved over the first elongated hoisting member guiding means from the first to the second side of the support structure. The drill string rotation means is suspended from the elongated hoisting member at the first side of the support structure

Claims

1. System for hoisting load on a drilling rig, the system comprising: a hoisting means including an elongated hoisting member and an elongated hoisting member drive means; a drill string rotation means suspended from an end of said elongated hoisting member; a support structure having a first side and a second side, the support structure configured to support at least a portion of the weight of said drill string rotation means; and a first elongated hoisting member guiding means connected to said support structure, said elongated hoisting member being reeved over said first elongated hoisting member guiding means from said first side to said second side of the support structure; a counterweight connected to said elongated hoisting member at said second side of the support structure; wherein said drill string rotation means is suspended from said elongated hoisting member at said first side of the support structure.

2. System according to claim 1, wherein the weight of said counterweight is less than the weight of said drill string rotation means.

3. System according to claim 1, wherein the weight of said counterweight is greater than the weight of said drill string rotation means.

4. System according to claim 2, wherein said elongated hoisting member comprises two separate portions; a first portion reeved over said first elongated hoisting member guiding means directly connecting the top drive and the travelling block, and a second portion (33) connecting the travelling block and the elongated hoisting member drive means.

5. System according to claim 4, wherein said second portion of the elongated hoisting member is reeved directly from the elongated hoisting member drive means and to an anchor.

6. System according to claim 4, wherein said second portion of the elongated hoisting member connects said elongated hoisting member drive means to said travelling block via a second elongated hoisting member guiding means.

7. System according to claim 1, wherein said elongated hosting member drive means is a winch adapted to accommodate only a single layer of elongated hoisting member.

8. System according to claim 7, wherein said winch is adapted to accommodate a plurality of parallel elongated hoisting members connecting said winch to said drill string rotation means.

9. System according to claim 7, wherein a ratio between the diameter of a winch drum of said winch and the diameter of said second portion of said elongated hoisting member is larger than 30.

10. System according to claim 7, wherein a ratio between a diameter of said first elongated hoisting member guiding means and said first portion of said elongated hoisting member is larger than 30.

11. System according to claim 1, wherein said first elongated hoisting member guiding means is a crown block provided at the top of the support structure, the support structure being a derrick.

12. System according to claim 11, wherein the crown block is connected to the derrick via motion compensation means.

13. System according to claim 9 wherein the ratio between the diameter of the winch drum of said winch and the diameter of said second portion of said elongated hoisting member is larger than 60.

14. System according to claim 1 wherein the counterweight comprises a travelling block.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In the following are described examples of exemplary embodiments illustrated in the accompanying drawings, wherein:

[0029] FIG. 1 shows, in a schematic side view, a system according to the present disclosure;

[0030] FIG. 2 shows, in a perspective view, a winch as used in a system according to the present disclosure;

[0031] FIG. 3 shows, in a schematic side view, a first embodiment of a system according to the present disclosure; and

[0032] FIG. 4 shows, in schematic side view, a second embodiment of a system according to the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSED EXEMPLARY EMBODIMENTS

[0033] In the following, the reference numeral 1 indicates a hoisting system according to the present disclosure. The figures are shown simplified and schematic and they are not necessarily drawn to scale. Identical reference numerals indicate identical or similar features in the figures.

[0034] FIG. 1 shows hoisting system 1 that includes an elongated hoisting member 3, in the form of a wire rope, and an elongated hoisting member drive means 5, in the form of a single-layer winch, is connected to a drill string rotation means 7, in the form of a top drive, at the end of the wire rope 3. The wire rope 3 is suspended from a support structure 9 in the form of a derrick. At the top of the derrick 9 is provided a first elongated hoisting member guiding means 11 in the form of a crown block. The crown block 11 is connected to the derrick 9 via a heave compensator 13 providing the necessary redundancy in case of a winch 5 failure. A first portion 31 of wire rope 3 extends directly from the top drive 7 at a first side 91 of the derrick, over the crown block 11 and to a counterweight 15 in the form of a travelling block at a second side 93 of the derrick 9, the crown block 11 constituting a division between the first side 91 and the second side 93 of the derrick 9 in the shown embodiment. A second portion 33 of the wire rope 3 extends from the travelling block 15 and to the single-layer winch 5, both the travelling block 15, acting as a counterweight for the top drive 7, and the single-layer winch 5 being provided at the second side of the derrick. As also discussed above, the embodiment where the travelling assembly has been split with one part acting as counterweight for the other, also entails the possibility of using different qualities and thicknesses of the two portions 31, 33 of the wire rope 3. The first portion 31 of the wire rope, directly connecting the travelling block 15 and the top drive 7, will have to carry heavier weights than the second portion 33 of the wire rope 3, the second portion 33 running through multiple-part system connecting the travelling block 15 to the single-layer winch 5 as will be described below with reference to FIGS. 3 and 4. The top drive 7 and the travelling block 15 are connected to the derrick 9 by means of not shown dollies.

[0035] FIG. 2 shows a more detailed view of a single-layer winch 5 with a winch drum 51 used in a system 1 according to the present disclosure. The shown single-layer winch 5 accommodates four parallel wire ropes 3 extending from the single-5 layer winch to the top drive 7, where the latter is not shown in this figure. The use of parallel wire ropes 3 and the single-layer winch 5 itself were discussed in PCT/NO2014/050113, and reference is made thereto for an in-depth description.

[0036] FIG. 3 shows a system 1 where the second portion 33 of the wire rope 3 connects the single-layer winch 5 to the travelling block in a two part-system. The second portion 33 of the wire rope is reeved directly from the single-layer winch 5, over the travelling block 15 and to an anchor 17. This means that the single-layer winch 5 have to be dimensioned to handle half the weight of the system's capacity. For instance, in a 1500 ton system, the single-layer winch 5 will have to be dimensioned for lifting 750 tons. In this two-part 1500 ton system, the first portion 31 with six parallel steel wire ropes 3 would have to be made with a thickness of approximately 90 millimetres, while the second portion 33 of six parallel wire ropes 3 would have to made with a thickness of 65 millimetres.

[0037] In FIG. 4, the second portion 33 of the wire rope is shown connecting the single-layer winch 5 to the travelling block 15 in a three-part system, where the second portion 33 of the wire rope also is reeved over a second elongated hoisting member guide means 19 in the form of a sheave. In this embodiment, the single-layer winch 5 only have to be dimensioned for lifting one third of the total load capacity of the system 1. Different braking requirements will typically decide which version to choose. In a three-part 1500 ton system 1 with six parallel wire ropes 3, the first portion 31 of the parallel wire ropes 3 would have to be made with a thickness of approximately 90 millimetres, while the second portion 33 of the parallel wire ropes 3 would have be made with a thickness of 53 millimetres.

[0038] With an D/d ratio in the order of 60 for both the first portion 31 and the second portion 33 of the wire rope 3 in a system 1 according to the present disclosure, it has been found that it is possible to extend the lifetime of the wire rope 3 up to the order of five years, which is a significant improvement from today's two weeks.

[0039] It should be noted that the above-mentioned exemplary embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps that are beyond those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

[0040] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.