of a top drive,” Sergei Izhboldin, head of the Technical Dept. at Gazprom Burenie, told OGE.
The key advantage of top drive systems, and the one that has changed the development of horizontal and directional drilling, is the opportunity to build up the drillstring using stands and singles. The industry’s first concept of drilling horizontal wells existed in the 1940s but it became cost-effective only with the introduction of top drives. This is because it allows operations to be done simultaneously that cannot be accomplished with a simple kelly drive.
Having longer sections of drillpipe allows the drilling rigs to drill deeper sections of the wellbore, thus making fewer connections of drillpipe. A conventional rotary table type rig can only drill 30-foot (9.1 meters) using single drillpipe sections while a top drive can drill double or triple of that, 60-90 foot as it uses 18-27-meter stands. This improves drilling efficiency.
“Top drives can drill 95 feet without making a drillpipe connection. Before top drives, we could only drill 30 feet at a time,” said Milo Brown, drilling supervisor for the U.S. drilling consultancy DTC Energy Group, which works on the Bakken shale in North Dakota. His remarks were quoted on DTC’s corporate website. Bakken has experienced extensive rig upgrades in the past decade, replacing many 30-year-old rigs and adding top drives, devices used to better manipulate the drillstring during the drilling process. “Top drives have been in use for many years but didn’t start making an appearance in the Bakken until roughly five years ago, mainly because of their high cost. Due to their time-saving ability and versatility, top drives are now being used on the overwhelming majority of rigs in the Bakken today,” Brown added in his comments.
“The technology of shale hydrocarbon production includes construction of a horizontal well and stimulation operations using hydrofracturing. For well construction, a top drive is required both technologically and by Industrial Safety Regulations of the Russian Federation (“Safety Rules for the Oil and Gas Industry”, PB 08-624-03 – OGE) if the horizontal section is over 300 meters,” Artyom Khoroshansky, CEO of the St. Petersburg-based top drive manufacturer, PromtekhInvest, told OGE.
“High continuous torque, reduced downtime and reinforced key components are required to perform any horizontal drilling project,” said Oleg Fedorovskikh, managing director of Bentec LLC Drilling & Oilfield in Russia.
Top drive solutions by Aker Solutions are specified to perform both vertical and horizontal directional drilling, says Geir Ingebretsen, drilling consultant at Aker Solutions. However, three of the main capacities for selecting the optimal top drive for extreme horizontal sections are torque, lifting capacity and AC drive motors, which are designed to hold the torque without stalling the motors. Rotating while steering technology is today’s preferred method, though the “backup” solution will always be “steering the tool face” by use of the top drive which is included in our design,” adds Ingebretsen.
Top drives by foreign manufacturers Aker Solutions, National Oilwell Varco, Canrig Drilling Technology, Tesco Corporation, Bentec and Drillmec