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The world’s most powerful drilling rig
In a press conference on July 14 announcing BP board approval of the development of the Beaufort Sea Liberty field, Liberty Project General Manager Darryl Luoma described some of the features of the custom rig that Parker Drilling Co. is constructing for the field. To handle the exceptional demands of rotating and moving a drill string in a well bore that may be anything up to nine miles in length, the rig has to be able to apply an exceptionally high turning force to the drill pipe.
Consequently a key component in the new rig will be the massive top drive, the device slung in the rig derrick to grip and rotate the drill pipe, Luoma explained. Although the drive will rotate the pipe at a conventional 130 revolutions per minute, the torque applied to the pipe will max out at 105,000 foot-pounds, compared with the 30,000 to 45,000 foot-pound torque of a typical North Slope rig.
In fact the power of the drive greatly exceeds that in any drill rig worldwide.
“This piece of equipment delivers two times the power requirement to turn the drill pipe as any other piece of equipment out there in the industry,” Luoma said.
Parker factory tested a version of the top drive in late 2007 — BP has actually ordered the fifth version of the drive for use in the rig, Luoma said.
“In fact the Liberty top drive right now is under construction … and will be delivered to this rig early next year,” he said.
BP is developing specially designed drill pipe that is relatively lightweight but can withstand the high torques that the top drive will be able to deliver.
Automatic pipe handling And because an individual well might require 90,000 to 100,000 feet of drill pipe and casing, the new rig layout will include an especially large pipe barn. Equipment to automatically handle the assembly and positioning of the drill pipe will enhance rig safety, Luoma said.
“People won’t have to physically screw the pipe lengths together,” Luoma said. “There’s equipment that picks it up, puts it together and makes it up, and then lifts into the drilling operation.”
The long wells will also require fluid pressures up to 7,500 pounds per square inch, compared with the 3,500 to 4,500 pounds per square inch of a typical Prudhoe Bay drilling operation. And the volumes of fluid involved require an especially large drilling service module for fluid handling.
Natural gas will power the rig, while liquid cooling of the equipment will eliminate the need for noisy cooler fans and blowers.
“Folks working on this rig will be able to have a conversation on the rig floor,” Luoma said.
—Alan Bailey
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