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Publication Date: 2017-Feb-27

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The Prior Art Database


A hoisting system for a drilling rig, which has a crown block for attaching to a derrick, the crown block comprising a plurality of sheaves; a travelling block suspended from the crown block via a hoisting cable, the travelling block comprising a plurality of sheaves and being connectable with a payload, the travelling block being arranged to move along a workpath; the hoisting system further comprising: a floating block comprising a plurality of sheaves reeved on the hoisting cable; wherein the floating block is configured to move between: a first arrangement in which the floating block is fixed relative to the crown block; and a second arrangement in which the floating block is fixed relative to the travelling block; wherein the hoisting system is arranged such that, when the floating block is in one of the first or second arrangement, the sheaves of the floating block overlap a sheave of the crown block or travelling block in a direction of the workpath.

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The present disclosure relates to a drilling rig hoisting system, for example for use on

any vessel or infrastructure used to perform operations associated with wellbores. 5


Hoisting systems are used in multiple applications for handling payloads, such as on

offshore vessels, platforms, rigs and the like associated with the oil and gas industry.

For example, hoisting systems are used on drilling rigs for supporting drilling operations, 10

for example for supporting the upper end of a drill string. Hoisting systems may also

support other lifting operations, including deployment/retrieval of equipment, such as in-

well equipment (e.g., casing or liner strings, completion equipment, and the like) and

subsea equipment (e.g., Blow Out Preventers (BOPs), Xmas trees and the like).


The term payload refers to all of the items suspended from the travelling block. A payload

map be considered to include a string of components which extend from the hoisting

system into the wellbore, connected to a top drive, which is used to apply torque to the

string of components located below the top drive. The various components which may

be suspended from the top drive may include, for example, drill bits and a plurality of 20

tubing elements. Collectively, the components connected to the top drive are referred to

herein as the net-payload.

The lifting capacity of a hoisting system is a significant consideration, and in many cases

is a limiting factor in the ability to exploit particular drilling rigs. This issue is becoming 25

more prominent as the offshore oil and gas industry seeks to operate in deeper water

and under increasing well pressures (e.g., up to and beyond 20 kpsi), which necessitates

the use of heavier equipment and the like.

In known pulley based hoisting systems additional load capacity can be gained by 30

utilising additional pulley sheaves. However, while an increase in load capacity can be

achieved, hoisting speed is compromised and wire wear is exacerbated, which is not

desired, especially where a single hoisting system may be required to handle a full range

of loads, as well as heave compensating such loads during short or extended periods of

time. In some instances, for example, a hoisting system may be designed and deployed 35


in accordance with a maximum anticipated payload, with a corresponding limited hoisting

speed. This limited hoisting speed may therefore be present for all payloads, which for

many lifting operations may be below the maximum design load.


An aspect or example relates to a hoisting system for a drilling rig, the hoisting system

may comprise:

a crown block for attaching to a derrick; the crown block may comprise a sheave

or a plurality of sheaves; 10

a travelling block suspended from the crown block via a hoisting cable; the

travelling block may comprise a sheave or a plurality of sheaves and may be

connectable with a payload. The travelling block may be arrange...