Dual draw works heavy hoisting apparatus

• US 5,762,279 A
• Filed: 04/09/1997
• Issued: 06/09/1998
• Est. Priority Date: 04/09/1997
• Status: Expired due to Term

• Current Assignee: Deep Oil Technology Incorporated
• Original Assignee: Deep Oil Technology Incorporated
• Inventors: Horton, Edward E. III
• Primary Examiner(s): MATECKI, KATHERINE A
• Application Number:
  US08/833,773
• Time in Patent Office: 426 Days
• Field of Search: 254/278, 254/284, 254/285, 254/286, 254/290, 254/337
• US Class Current: 254/285
• CPC Class Codes: E21B 19/02 Rod or cable suspensions

Abstract

A dual draw works hoisting apparatus. A single derrick structure is provided for two drilling rigs. The crown block platform receives the crown blocks for both drilling operations such that both crown blocks are slidable along the crown block platform. The hoisting lines are reaved in a conventional manner, except for the dead lines. The dead lines from the two crown blocks are connected together by means of a sheave assembly which is locked in position during normal independent operation of the crown blocks and their respective travelling blocks. To provide increased lifting capacity for lifting the drilling riser, the crown blocks are moved closer together on the platform such that the travelling blocks may be attached to a spreader bar to be positioned above a drill slot and attached to the drilling riser. The sheave assembly connecting the two deadlines is unlocked to allow relative movement between the two deadlines during simultaneous use of the draw works for both travelling blocks. This allows the dead line loads to be equalized even though the separate draw works do not rotate at precisely the same speed.

Claims

1. In a structure used for drilling or producing hydrocarbons and having two drilling rigs, a dual draw works hoisting apparatus, comprising:

a. a derrick attached to said structure, said derrick having a derrick floor and a crown block platform;

b. two hoisting apparatuses, each hoisting apparatus having a crown block, draw works, traveling block, fast line, and deadline, with the crown block of each hoisting apparatus being slidably received on the crown block platform of said derrick such that the crown blocks are movable between a first position for normal drilling operations and a second heavy hoisting position;

c. a deadline connecting assembly which receives the deadline from each hoisting apparatus and connects the deadlines to each other; and

d. means for selectively locking said deadline connecting assembly in a stationary position such that each hoisting apparatus acts independently, or unlocking said deadline connecting assembly to allow movement thereof whereby said two hoisting apparatuses may be used in combination as a single hoisting apparatus.

2. The apparatus of claim 1, further comprising a spreader bar attached between the travelling blocks of said hoisting apparatuses during their combined use.