DRILLING TECHNOLOGY:
Top Drive Drilling Systems 

Top Drive Drilling Systems are one of the greatest contributions to the offshore drilling industry. Until 1982 the drillstring was handled and rotated by a Kelly Joint and a Rotary Table. Drilling and making connections on offshore rigs had been virtually unchanged for years. Then development of the Top Drive, which rotates the drillpipe directly and is guided down rails in the derrick, replaced the need for a Kelly Joint to rotate the drillstring. It performs normal hoisting requirements such as tripping and running casing. It also added the ability for drilling with triples, circulating and rotating during tripping, and back-reaming and/or freeing stuck pipe. The first use of this unique technology was in 1982 on a Sedco Jack-Up rig drilling for ADNOC in the Arabian Gulf. Working with Duke Zinkgraf of Sedco, George Boyadjieff of Varco designed a Pipe Handler as part of the Top Drive. This unique feature allowed back-reaming while circulating drilling fluid and making/breaking connections near the top of the derrick.  

Recognizing the pioneering efforts of the following individuals and companies who contributed to the development of this technology: 

George Boyadjieff, Varco International (now National Oilwell Varco); Duke Zinkgraf, Sedco (now Transocean).