Drilling rig system with self-elevating drill floor

Abstract

A transportable drilling rig having a self-elevating drill floor includes a base structure comprising multiple base towers that can be transported to a wellsite and positioned around an intended wellbore location. A horizontal base frame is installed between lower regions of the towers to form a stable rig base structure, and a drill floor can then be constructed over the base frame and between the base towers. A suitable rig mast can then be erected on the drill floor. Floor-lifting cables are anchored to upper regions of the base towers and disposable around corresponding sheave assemblies associated with the drill floor. The free ends of the floor-lifting cables can be engaged by the traveling block in the rig mast, whereupon the rig's drawworks can be actuated to elevate the drill floor and mast as required and then locked to the base towers.

1 . A drilling rig system comprising:
 (a) a plurality of base towers spaced apart in a selected layout;   (b) a horizontal base frame interconnecting lower regions of the base towers to form a base structure;   (c) a drill floor overlying the base frame and vertically movable relative thereto; and   (d) floor-lifting means, for elevating the drill floor above the base frame.   
     
     
         2 . A drilling rig system as in  claim 1  wherein:
 (a) the drill floor incorporates a plurality of floor-lifting sheave assemblies, each said floor-lifting sheave assembly being associated with one of the base towers; 
 (b) a plurality of floor-lifting cables, each said floor-lifting cable being anchored to an upper region of one of the base towers; and 
 (c) the floor-lifting means comprises a drawworks and traveling block associated with a rig mast erected on the drill floor; 
 
       such that the floor-lifting cables can be threaded around the associated floor-lifting sheave assemblies and extended upward to engage the traveling block, whereupon actuation of the drawworks will cause the traveling block to move upward within the rig mast, thereby elevating the drill floor relative to the base structure. 
     
     
         3 . A drilling rig system as in  claim 1 , further comprising locking means for locking the drill floor to the base towers to maintain the drill floor at a desired elevation. 
     
     
         4 . A drilling rig system as in  claim 3  wherein the locking means comprises hydraulic latches. 
     
     
         5 . A drilling rig system as in  claim 1 , further comprising guide means associated with the base towers, to promote uniform upward movement of the drill floor and to provide lateral stability to the drill floor during drill floor raising operations. 
     
     
         6 . A drilling rig system as in  claim 1 , further comprising adjustment means for adjusting the vertical and lateral positions of the base towers. 
     
     
         7 . A drilling rig system as in  claim 1  wherein the floor-lifting means comprises a plurality of worm gear drive mechanisms and a plurality of mating rack gears, with each rack gear being incorporated into one of the base towers and one worm gear drive being incorporated into the drill floor adjacent to an associated rack gear. 
     
     
         8 . A drilling rig system comprising:
 (a) a plurality of base towers spaced apart in a selected layout;   (b) a horizontal base frame interconnecting lower regions of the base towers to form a base structure; and   (c) a drill floor overlying the base frame and vertically movable relative thereto; and   (d) floor-lifting means, for elevating the drill floor above the base frame;   
       wherein:
 (e) the drill floor incorporates a plurality of floor-lifting sheave assemblies, each floor-lifting sheave assembly being associated with one of the base towers; 
 (f) a plurality of floor-lifting cables, each floor-lifting cable being anchored to an upper region of one of the base towers; and 
 (g) the floor-lifting means comprises a drawworks and traveling block associated with a rig mast erected on the drill floor; 
 
       such that the floor-lifting cables can be threaded around the associated floor-lifting sheave assemblies and extended upward to engage the traveling block, whereupon actuation of the drawworks will cause the traveling block to move upward within the rig mast, thereby elevating the drill floor relative to the base structure. 
     
     
         9 . A drilling rig system as in  claim 8 , further comprising locking means for locking the drill floor to the base towers to maintain the drill floor at a desired elevation. 
     
     
         10 . A drilling rig system as in  claim 9  wherein the locking means comprises hydraulic latches. 
     
     
         11 . A drilling rig system as in  claim 8 , further comprising guide means associated with the base towers, to promote uniform upward movement of the drill floor and to provide lateral stability to the drill floor during drill floor raising operations. 
     
     
         12 . A drilling rig system as in claim  81 , further comprising adjustment means for adjusting the vertical and lateral positions of the base towers. 
     
     
         13 . A method for assembling a drilling rig structure, comprising the steps of:
 (a) positioning a plurality of base towers in spaced relationship in a selected layout at a wellsite;   (b) erecting a horizontal base frame interconnecting lower regions of the base towers to form a base structure;   (c) erecting a drill floor overlying the base frame and vertically movable relative thereto, said drill floor incorporating a plurality of floor-lifting sheave assemblies, each said floor-lifting sheave assembly being associated with one of the base towers;   (d) erecting a rig mast on the drill floor, including a drawworks and a traveling block;   (e) anchoring a floor-raising cable at an upper region of each base tower;   (f) threading the floor-raising cables around their associated floor-lifting sheave assemblies and engaging the free ends of the cables with the traveling block;   (g) actuating the drawworks so as to raise the traveling block and the drill floor relative to the base structure, until the drill floor is at a desired elevation; and   (h) engaging locking means to lock the drill floor to the base towers.   
     
     
         14 . A method as in  claim 13  wherein the locking means comprises hydraulic latches. 
     
     
         15 . A method as in  claim 13 , further comprising the step of providing guide means in association with the base towers, to promote uniform upward movement of the drill floor and to provide lateral stability to the drill floor during drill floor raising operations. 
     
     
         16 . A method as in  claim 13  wherein the base towers are provided with adjustment means for adjusting the vertical and lateral positions of the base towers.