Ask any drilling rig floor hand who has been around a while about top drives and they will tell you it makes less work for them and improves their safety while making holes.
With some motors pushing 1,000 horsepower or more, a top drive turns and hoists the drill string from a mounting suspended below the derrick traveling block. As a replacement for the traditional kelly drive bushing on a rotating table, top drives may be powered by electric or hydraulic motors and are favored by drillers for extended reach and directional wells. Their esteem among drillers has seen an increase in parts availability among aftermarket oilfield equipment suppliers.
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Longer Is Faster
With its ability to move up and down the derrick, a top drive can work with two or usually three joint stands. Longer sections of pipe means the rig can make better progress drilling to depth because it needs to stop for fewer connections. Industry reports of drillers reducing drilling time by 25% have been noted.
Another benefit comes with fewer instances of stuck pipe compared to a rotary table drive. With fewer stops tripping pipe to add more length and less risk of the annulus sticking due to temporarily disengaged fluid pumps, top drive rigs experience less instances of stuck or dropped pipe.
Top drives also bring automation to much of the drilling process allowing for machine control of rotation, maximum torque and weight on the bit.
Fewer Connections Are Safer
Safety is improved because floor hands spend less time at higher risk tasks such as engaging and disengaging fluid pumps, tripping pipe and making pipe connections.
Top drives are generally classified by Safe Working Load (SWL) of the equipment and type and size of the drive motor.
Found on everything from small truck-mounts to massive offshore drilling rigs, top drives are noted for their efficiency, reliability and applicability for most drilling projects and are recognized as a major advancement in drilling rig technology.
