Vol. 226 No. 12

New Rig Designs

Automated rig gaining attention

Rig 43AC working in Alberta.

Nabors Industries has been ramping up the manufacture of its Programmable AC Electric (PACE) rigs, equipped with technology that is shortening the drilling cycle. The rig’s features are allowing operators to drill more efficiently and move more rapidly. These include compact, but powerful, equipment; increased pump capacity; top drives; faster-moving features; enhanced safety elements; electronic drilling controls; better power distribution, and greater control of torque and rate of penetration. Safety and ease of use also help to attract and retain experienced crews.

A key feature of the rig design is that it uses variable frequency AC drives (VFD) and Programmable Logic Control (PLC) technology. This, together with a control center and integrated electronic instrumentation, gives the driller better control of the drawworks, top drive, mud pumps and virtually every other significant piece of equipment.

The system includes Nabors’ Commander Class Drawworks, a proprietary, gear-driven design that has no chains or sprockets. It is a safe, modern control system that provides superior control and regenerative braking, and is lightweight, reliable and cost-effective. Technical specifications vary with the model:

Commander 650 and 800

• Single motor input 
• Nominal capacity = 10 lines, 650,000 and 800,000 lb, respectively 
• Eaton air brake, model 336 and 436, respectively 
• Total weight = 43,000 lb and 46,350 lb, respectively.

Commander 1200 and 3000

• Dual motor input
• Nominal capacity = 14 lines, 1.2 and 1.5 million lb, respectively
• One Eaton air brake (Model 1200), dual gearbox/ dual brakes (Model 3000)
• Total weight = 64,000 lb and 97,000 lb, respectively. 

Driller’s console on Rig 43AC.

The Control Center. The rig has an advanced Control Center that allows the driller to view all facets of the drilling operation (see figure). All instrumentation is within an arm’s reach, including the auto-drill touch screen and the driller console monitoring system. All data monitoring is integrated with equipment control through PLC technology, providing a system of checks and balances prior to operating any piece of equipment.

There are several benefits to this technology. For instance, fewer, less cumbersome electrical connections ensure ease of rig up/ down. PLC technology also promotes improved motor and fuel efficiency, fewer emissions, enhanced power distribution and less electrical noise. Finally, greater control of torque and rate of penetration results in faster, better holes.

Fast rig moves. Increasing ROP has sometimes put the weak link in the time chain in moving rigs. To further shorten the drilling cycle, these rigs were designed to move rapidly from well to well within a pad configuration. The company drew on its 40+ years of operating experience in Alaska to design a rig that can move much quicker than more conventional rigs. Within a drilling pad. well-to-well rig moves can occur in less than two hours. Pipe is racked back in the derrick, the BOP is attached to the substructure and the rig is skidded. The backyard remains in place and is only moved after several wells have been drilled. The company is also designing rigs to move efficiently from pad to pad. This includes building rigs with one-piece substructures and integrated top drives, features that make rig-moving not only faster, but safer.

Proven performance history. This rig technology has been rapidly embraced by the industry, with new rigs quickly going to work on long-term contracts. These projects include pad drilling operations in environmentally sensitive areas like the Rocky Mountains and in Canada’s Athabasca tar sands, as well as in other active areas such as Saudi Arabia, Venezuela and the US Gulf of Mexico.

Developed in Canada, the technology behind the rig is being exported worldwide, with fabrication taking place at several international venues. The company is adding three PACE rigs, similar to Rig 784, which is drilling in the Pinedale Anticline of Wyoming and was named “Land Rig of the Year,” in 2004 by Shell, based on safety and operational performance.