Patent Publication Number: US-8534387-B2

Title: Drawworks device on a drill floor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefits of priority under the Patent Laws of the United States of Norway Application Number 20062853 filed Jun. 19, 2006; and International Application Number PCT/NO2007/000195 filed Jun. 7, 2007 published as International Publication Number WO 2007/148977 A1 on Dec. 27, 2007—all of which applications and publication are incorporated fully herein for all purposes. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a drawworks. More particularly it relates to a drawworks on a drill floor, the drawworks including an upper pulley assembly connected to a heave-compensated or fixed mounting, and a main block connected to a pipe mount which is laterally movable relative to the drilling centre of the drill floor in at least one direction, the pulley assembly being rotatable about a horizontal first axis perpendicular to the direction of lateral movement. 
     2. Description of Related Art 
     A main block belonging to a drawworks on a drill floor is often connected to a drilling machine (top drive) which is arranged to be connectable to a drill string, for example, and which is movable along a vertical rail. 
     To facilitate the joining or removal of, for example, pipe lengths into/from a drill string, it is also usual for the drilling machine to be laterally movable relative to the drilling centre of the drill floor. 
     In earlier constructions the pulley axes of the upper pulley assembly and main block were oriented perpendicularly to the direction of lateral movement. Thereby there was no oblique pull on the wire of the drawworks even if the main block was moved sideways. 
     However, experience went to show that the main block, which is of considerable dimensions, was obstructive to the work on the drill floor when oriented with the pulley axis in said direction. In more recent drawworks the pulley axis of the main block is in the same plane as the direction of lateral movement, whereby the main block takes a position which is, to a considerably degree, less obstructive to the work on the drill floor. 
     However, when, in its position laterally offset, the main block is hoisted towards its upper position, there is in this more recent construction an unfavourable wire angle between the hoisting wire and the wire pulleys of the upper pulley assembly. This unfavourable wire angle leads to unnecessarily great wear to the pulleys of the upper pulley assembly and to the wire. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art. 
     The object is achieved in accordance with the invention through the features, which are specified in the description below and in the claims that follow. 
     A drill floor drawworks in accordance with the invention, the drawworks including an upper pulley assembly which is connected to a heave-compensated or fixed mounting, and a main block which is connected to a pipe mount which is laterally movable relative to the drilling centre of the drill floor in at least one direction, is characterized by the pulley assembly being rotatable about a horizontal first axis perpendicular to the direction of lateral movement. 
     The main block is typically rotatable about a second axis, which is parallel to the first axis, the pipe mount normally including a drilling machine. The heave-compensated or fixed mounting may be formed by a crown beam. The first axis, about which the pulley assembly rotates, may be provided by means of a hinged adapter, which is connected between the crown beam and the pulley assembly. 
     The device according to the invention provides a solution to a technically challenging and costly weakness of prior art drawworks. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In what follows is described a non-limiting example of a preferred embodiment which is visualized in the accompanying drawings, in which: 
         FIG. 1  shows a drawworks according to the invention together with some adjacent components, a pipe length hanging from the drawworks above a drill floor; 
         FIG. 2  shows, on a larger scale, a prior art drawworks; 
         FIG. 3  shows, on a larger scale, a section of the draw-works of  FIG. 1 ; and 
         FIG. 4  shows, on a further enlarged scale and in perspective, a detailed view of the mounting of an upper pulley assembly to a crown beam. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the drawings the reference numeral  1  indicates a drawworks including, apart from a winch not shown, an upper pulley assembly  2 , a main block  4  and a hoisting wire  6 . 
     The upper pulley assembly  2  rotates about a rotational axis  18  to raise and lower the main block  4  via the hoisting wire  6 , and is connected to a mounting  8  in the form of a crown beam by means of a hinged adapter  10 . 
     The hinged adapter  10  includes an upper portion  12  which is connected to the crown beam  8 , and a lower portion  14  which is connected to the pulley assembly, see  FIG. 4 , the upper portion  12  and the lower portion  14  hinging relative to each other about a first axis  16 . 
     The first axis  16  is approximately perpendicular to the direction of lateral movement of the main block  4 . 
     The main block  4  is connected about a second axis  20  to a drilling machine  22  including a pipe mount  24 . The second axis  20  is parallel to the first axis  16 . 
     The drilling machine  22  is connected, in a manner known per se, to a carriage  26  by means of pivotal arms  28 . The carriage  26  is movable along a vertical rail  30 . 
     The pivotal arms  28  are arranged to move the drilling machine  22  and thereby the pipe mount  24  between the drilling centre  34  of a drill floor  32 , see  FIG. 1 , and a position laterally offset, see  FIG. 3 , from which a pipe  36  for example, see  FIG. 1 , can be moved in to the drilling centre  34  to be connected to a drill string  38  projecting from the drill floor, without the drilling machine  22  obstructing the operation. 
     When the hoisting wire  6  moves the carriage  26  together with the drilling machine  22  and the pipe mount  24  in the position laterally offset upwards along the rail  30 , the upper pulley assembly  2  will pivot about the first axis  16  so that an oblique angle “a” between the hoisting wire  6  and the pulley assembly  2 , see  FIG. 2 , created in prior art equipment, is reduced to a substantial degree.