Today's designs are driving down drilling costs with major improvements in efficiency, safety and reliability, both offshore and on land.

The recently announced mega-merger of two of the world's most prestigious names in oilfield technology, National Oilwell and Varco, prompted a look at emerging rig technology. With hundreds of products in dozens of categories, National Oilwell's repertoire reads like a Sears catalogue. Hart visited with Pete Miller, newly appointed president and chief executive officer of the new company, to be named NationalOilwellVarco. We asked him to highlight areas where innovative technology could impact drilling costs.

"We have made advances in several areas," he said. "But if I was limited to naming only a few, they would include our motion compensation systems, our fluids handling systems and our safety systems." Miller explained that any equipment that improves ease of rig-up and operation makes a major impact on training and safety, thus delivering triple benefits. "And our solutions must be scalable," he said. "To satisfy the markets we serve, we must be able to take sophisticated tool systems developed for high-performance offshore rigs and deliver the same advantages in more compact and economical land rig packages." The strategy of developing solutions for offshore and then transitioning them to land has been successful for the company. Miller cited two examples, portable topdrives and Iron Roughnecks that are now available in smaller, more economical packages for land rig use. But the first technology named on Miller's list is pure offshore.

Motion compensation systems

The active heave drilling (AHD) drawworks eliminates costly, heavy mechanical systems traditionally mounted atop the derrick, while improving compensation response and accuracy. Operating over the full load range of conventional drawworks of similar capacity, the AHD instantly responds to the driller's commands while automatically factoring-in compensation for vessel heave. This makes for faster tripping, riser or blowout preventer (BOP) running; better drilling performance; and increased personnel safety. The system weighs less and provides a lower center-of-gravity that improves vessel stability. Typically installed at or near drillfloor level, the AHD is also easier to access for maintenance and service. Easy to install and requiring few rig modifications, the AHD has features that combine to lower CAPEX and OPEX.
When adaptable active/passive compensation is needed, National Oilwell's Crown compensator fills the bill. Lightweight, but rugged, the Crown compensator mounts easily atop the water table beams on most derricks, making it ideal for retrofitting to existing rigs. An active compensation capability can be added if needed. Required hydraulic cylinders mount in the derrick, completely clear of the traveling block or top drive assembly. When the active system option is taken, the skid-mounted power unit and fluid storage tank are located at deck level for easy maintenance. With sufficient capacity to handle tough jobs, a Crown compensator is installed on the high-specification, 10,000-ft (3,050-m) water depth-rated drillship, Saipem 10,000. Easily scalable, the system can be sized in 1,000-ton hook load increments from 600,000 lbs to 1,000,000 lbs.

Fluids handling systems

The new HEX Pump from National Oilwell represents a major change in mud pump technology. The pump has a 45% smaller footprint, 35% less weight and produces near steady-state flow with up to 97% less pulsation compared to conventional triplex pumps.

The HEX Pump doesn't look like a traditional mud pump. Its round design and compact footprint maximizes its ability to be installed in a variety of environments where space is often limited. Dual AC motors drive a rotary cam that strokes six-cylinders arranged in a circle. The cam provides minimum pulsation with more uniform strokes and more consistent flow characteristics due to the precise timing of pressure and suction phases. The reduction in pulsation eliminates the need for dampeners and greatly improves flow characteristics downhole while extending the service life of valves and mechanical components. The pump's AC motors inherently deliver high torque over a wide range of speeds allowing uninterrupted high-flow or high-pressure operations without changing pump liner size. Valves are housed in a single compact cartridge that can be easily swapped out allowing used cartridges to be refurbished offline. Development work for the new pump was completed in Norway followed by installation and testing on a client's land rig. Recently, HEX Pumps have been installed on two GlobalSantaFe rigs, the Adriatic II and Adriatic V, that are beginning an extensive drilling campaign offshore West Africa.

The new HEX Pump produces 2,400 nominal horsepower. Maximum pressure capability is 7,500 psi and maximum flow is up to 1,035 gpm. Increased performance, simplified maintenance, and greater versatility are delivered in a much more compact package than typical triplex pumps.

A significant element in fluids handling systems is effective waste management. Helping reduce costs associated with solids control, the company's Cutting Slurrification unit can quickly render drilling debris to a smooth, benign slurry suitable for reinjection or seabed disposal where permitted. The unit is a key component of a comprehensive family of solids control and waste management tools.

Safety systems

A wide array of safety systems has been introduced recently. Perhaps the most unique is the company's Safety Brick drill floor system that creates and maintains an automatic safety zone wherever moving equipment is located. Basically, familiar non-skid rig floor mats are manufactured to contain passive sensors. These mats are installed on the drill floor, or anywhere personnel detection is required. Workers' safety boots contain complementary transponders that track the workers' positions as they move about the floor performing their duties. A master anti-collision system maintains a pre-set "safety perimeter" around the worker and continually compares the workers' positions with the track of fully or semi-automated rig floor equipment, such as Iron Roughnecks or automatic pipe handling robots. If any equipment reaches a worker's safety perimeter, it is stopped at once, preventing the collision and possible injury. The system is adaptable to any drill floor, but is particularly effective on high-specification rigs that utilize a lot of automated robotic equipment. In addition to preventing collisions with workers, the system can be configured to track personnel movement in virtually any area of the drilling facility.

On a smaller scale, but nonetheless important in reducing worker fatigue and injury, is the Rotary Round Power Slip. Lightweight, compact and adaptable to any rotary table, the power slip takes the backbreaking work out of drilling and tripping. Operated from any location on the drill floor, the power slips quickly and consistently grip the string using the rig's existing manual slips. The tool can be used on rigs with top drives, and does not extend outside the turning portion of the rotary table. The power slip can remain installed on the table even if rotation is necessary while minimizing tripping hazards.

With continued emphasis on efficiency, economy and safety, NationalOilwellVarco is poised to deliver the benefits of its synergies to further improve performance while reducing drilling costs.

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