Draw-works is the machine on the rig consisting of a large-diameter steel spool, brakes, a power source and assorted auxiliary devices. The primary function of the draw works is to reel out and reel in the drilling line, a large diameter wire rope, in a controlled fashion. The drilling line is reeled over the crown block and traveling block to gain mechanical advantage in a "block and tackle" or "pulley" fashion. This reeling out and in of the drilling line causes the traveling block, and whatever may be hanging underneath it, to be lowered into or raised out of the wellbore. A modern draw-works consists of five main parts: the drum, the motor(s), the reduction gear, the brake, and the auxiliary brake.
The number of gears in Draw-works could be one, two or three speed combinations. It is according to the speed, power and the depth of the well. Below is an example of Draw-works according to the one, two and multi speed.
1. Draw-works – multi-speed gear-driven
Standard multi-speed gear-driven draw-works is designed for the highest level of performance to fulfill the latest requirements of offshore and onshore drilling technology. Drive configurations are available in AC or DC with a range of 1 250 hp to 6 000 hp.
2. Draw-works – two-speed gear-driven
The two-speed draw-works completes range of single and multi-speed draw-works. It is powered by two drive motors and available in either AC or DC configuration. This type of draw-works combines high performance with a space saving foot print to accommodate tight drill floor layouts, available from 1 500 hp to 3 300 hp.
3. Draw-works – single-speed gear-driven
The AC powered single-speed gear-driven draw-works offers a design unique to the industry, available in a range of 1 500 hp to 6 000 hp. This type of draw-works combines a simple design with few mechanical parts, a small footprint and a light weight. A further advantage is the minimized maintenance work....