|
Vol. 226 No. 12 |
| |
 |
Rig Floor Equipment
DirectDrive top drive improves performance, reduces downtime
Initially developed in the 1980s, top drive drilling systems have become the choice for many top-line drilling operations. Top drive systems are known to safely and efficiently cut pipe-rotating and pipe-handling time, based on fewer connections. These systems also provide more drilling control and more stable directional orientation.
Despite top drive systems’ many benefits, ongoing problems and gearbox maintenance have reduced their utility. One study found that over 40% of top drive problems can be attributed to the gearbox and supporting equipment.
In addition to gearbox problems, previous top drive systems were often forced to sacrifice torque for RPM. This trade-off can reduce the effectiveness and efficiency of top drive systems in certain drilling applications.
LeTourneau Ellis Williams Company (LEWCO) recently introduced a new top drive system that addresses many of the issues plaguing earlier designs. The company’s proprietary DirectDrive top drive system is designed to dramatically increase performance, while reducing maintenance and downtime.
The new top drive uses a specially designed AC motor, developed and patented by its sister company, Oilfield-Electric-Marine. Unique to the system, speed control is provided by this motor. This design eliminates the gearbox, along with the related lubrication system and bearings. Correspondingly, this system eliminates much of the downtime associated with gearbox reliability, as well as related bearing failures and fluid leaks.
The motor is built specifically for the topdrive application, incorporating high-density magnetic steel and a windings design that puts more “copper in the slot.” This design delivers twice the peak torque as conventional AC motors. This additional copper and iron also provides more thermal mass, allowing it to withstand the higher temperatures of continuous topdrive operation.
Available in 500, 750, and 1,000-ton models, LEWCO DirectDrive top drive systems offer the industry’s highest torque, while redundant speed sensing provides operational reliability. In addition, the main stem assembly can be replaced without removing the motor or unrig, which reduces servicing downtime. LEWCO Direct Drive top drive systems are manufactured and tested according to API 8C PSL1 standards. 
|
