Rig automation, dual activity alters work roles

• The Glomar Explorer (Fig. 1) [376,246 bytes]
• The riser elevator serves to bring 27-ton, 75-ft riser sections from within the ship's hold up to the main deck. Teamwork between the crane operator and assistant driller, both out of sight from one another, is important for smooth operations. The skate cart, located on the far left end, serves as an anchoring device as the riser is brought onto the drill floor (Fig. 2). [44,820 bytes]
• Varco's PRS-4I pipe-handling system allows the Glomar Explorer to handle BHAs and casing strings offline. The upper arm contains a lifting jaw assembly that clamps, hoists, and guides tubular stands. The lower arm contains a claw assembly that encircles the lower end of the stand for stabilization and guidance (Fig. 3). [39,244 bytes]
• Zone management (Fig. 4) [76,554 bytes]
• In contrast to conventional vertical tripping operations using the monkeyboard, the Glomar Explorer runs successive stands in the hole from a horizontal position (Fig. 5). [43,137 bytes]
• The stabbing guide, located in the upper portion of this photo, directs stands to and from the well center. Engineers have integrated this technology with the horizontal pipe-handling machine (Fig. 6). [39,629 bytes]
• The automated iron roughneck has eliminated the need for spinning chains and manual tongs (Fig. 7). [40,314 bytes]
• Glomar Explorer drill floor (Fig. 8)[72,657 bytes]
• The driller's console on the Glomar Explorer, designed by Hitec, has replaced the foot throttle and hand brake with a custom-designed chair that allows automated handling of the drillstring and other hardware (Fig. 9). [42,402 bytes]
• Raised back-up system (Fig. 10)[40,706 bytes]
• Horizontal pipe backer (Fig. 11) [90,833 bytes]
• Horizontal pipe-racking technology has traditionally been Global Marine's choice for tripping and making connections instead of racking back pipe in the derrick or laying down as singles. Westech's pipe racker can hold 35,000 ft of standard 51/2-in. drill pipe (Fig. 12). [53,451 bytes]
• Horizontal pipe handling procedure (Fig.

  13) [111,581 bytes]

• The floorhand's role is changing offshore, no longer requiring long hours of labor-intensive work (Fig. 14). [18,439 bytes]
• Taklift 4, a Smit transport and heavy lift vessel, is shown lowering the first 1,272-metric ton section of Aasgard B's Deck East onto two support pillars at a Kvaerner Oil & Gas facility in Stavanger. Aasgard B, a semisubmerisible gas-production facility, is part of the Den norske stats oljeselskap AS (Statoil) massive Aasgard project in the Norwegian Sea (OGJ, Aug. 17, 1998, p. 66-76). Smit expects to make the final module lifts in June. To lift the heaviest module (1,650 metric tons), Smit will require two vessels, the Taklift 4 and Taklift 7 with a 130-m boom. Aasgard B is expected to be ready for operations in October 2000. [40,813 bytes]

The integration of drilling technologies has initiated sweeping changes offshore in relation to work-flow processes, affecting every crew member from the roustabout to the drilling superintendent.

The Glomar Explorer (Fig. 1), operated by Global Marine Inc., provides an example of how new and old technologies have been packaged together to develop automated, dual-activity systems that produce a safer working environment while reducing cycle time and costs.

This first of a two-part series describes the end result of a $280 million upgrade, relying upon coordinated teamwork among the contractor, service companies, and operator.

The conclusion further describes state-of-the-art station-keeping technologies such as dynamic-positioning, thruster configuration, and motion-compensating systems that allow a rig to stay on location through extended weather windows.

Evolving roles

Ever since the first U.S. oil well was drilled in 1859, work roles on the rig have evolved to coincide with changes in technology. During the age of cable tools, the driller performed most duties including that of toolpusher, petroleum engineer, well-site geologist, and mud engineer.

Thus, the driller was fully empowered to direct the entire drilling process. As time progressed, however, and as new technologies supplanted old, the driller's role diverged into separate professions, resulting in a declining decision-making role for the driller and an expanding array of specialized activities.

Today, the role of the rig worker is evolving again, primarily through the integrated use of computer, telecommunication, and automated drilling technologies that tie together hoisting, pipe-racking, and pipe-handling systems. As a result, these technologies have produced a narrower focus for each activity.

Teamwork

Vince Chrisovergis, assistant driller (AD) on the Glomar Explorer, says the complexity of pipe-handling systems has actually increased the need for teamwork, although drilling personnel are often "out of sight and out of touch." For example, when a crew runs the riser string, the process works much like a relay race where the baton is passed from runner to runner in a smooth, graceful motion.

Instead of a baton, however, crew members deal with 27-ton, 75-ft long, and 193/4-in. OD riser sections that are passed from the bowels of the vessel, up to the rig floor, and finally into the ocean's depths. First, the crane operator (CO), who is stationed at the main deck level 59 ft below the drill floor, uses a bridge crane to load riser sections one by one from within the 46-ft deep riser hold onto the riser elevator (Fig. 2).

Next, the CO sends the riser elevator up to the mezzanine deck, where the AD takes over the operation. During this process, both the CO and AD communicate through an intercom system aided by sensors that indicate when the riser is positioned for transferal. The AD then "grabs the baton," continuing with the motion by bringing the riser elevator up to the drill floor.

From here the AD, floor hands, and driller work together. First, crew members bolt up the riser-handling tool, linking the top drive with the blocks to the top end of the riser. Then, as the driller picks up the riser, the AD simultaneously anchors the tail end of the riser using the skate cart positioned along the track of the riser elevator.

This harmonious operation allows the driller to safely pick up riser sections without the wild swinging motions that would otherwise occur. Chrisovergis says that except for bolting up the riser-handling tool, everything is "hands free."

Changing roles

The need for teamwork and specialization of crew-member activities continues to change traditional duties such as rig management. "Today, the toolpusher is much more active than ever before," said Randy Wolford, drilling superintendent for the Glomar Explorer. "His role is outside, managing the crews, directing the work, seeing that things get done; whereas in the past, this was all done by the driller."

Basically, the driller "is now a captive of the drilling console while the drilling superintendent serves as the liaison between the contractor and operator-between the shore and the rig." Furthermore, there is no longer a need for the derrickman to work the monkey board while tripping, since this activity has been fully automated. Thus, the derrickman can instead concentrate solely on mud-pump and drilling-fluid maintenance.

Evolving technologies have also resulted in a need for high-tech personnel. "Fifteen years ago, your average roughneck could fix anything on the rig floor. Today, there is very little he can repair," Wolford said, referring to advances in PLC (programmable logic control), electronic, and computer technologies.

Byron Hablieb, engineering project manager for Global Marine, says there is a "need for people with 1-2 years of college or technical training. We need to pick up personnel with more computer background and experience in sophisticated hydraulic systems."

Pipe handling

"Dual activity, or the ability to handle casing and bottom-hole assemblies (BHAs) offline (while drilling), is fast becoming a way of life," Wolford explained. On the Glomar Explorer, this process revolves around the following components:

• Horizontal pipe racking system
• Vertical pipe-racking system
• Top drive
• Iron roughneck
• Horizontal pipe stabber
• Raised backup system
• Drawworks.

Through the integration of this equipment, involving cooperative synergies among several service companies, Global Marine has installed an evolutionary drilling package that has already drilled a 7,718 ft water depth record on its first attempt (OGJ, Feb. 22, p. 29).

Safety issues

Wolford says the key issue in the drive for automation is safety. In the Gulf of Mexico for example, "The need for automation is driven by operators such as Texaco and Chevron, not regulations," he explained. "One of the first things an operator looks at is the safety record of that unit. The industry costs per lost time accident is so great-in addition to the incalculable costs of suffering-that you cannot afford to make a mistake."

Thus, the capital investment for advanced drilling equipment can be justified in the safety savings alone. "We spent a few million dollars for the vertical pipe-handling system (Fig. 3). But the thing it gives more than anything else is a safer means of handling drill pipe instead of using a tugger, spinning chain, and manual tongs to make connections. You are simply putting people in harms way. But with automated systems, you are removing those people away from the possibility of injury."

Hablieb said the new drillship design has actually increased the number of positions involved with maintenance and pipe-handling needs. "However, we've improved the operation from a safety perspective by moving people away from the rotary table. We've done away with brute force labor and augmented our procedures with more maintenance-oriented individuals."

Cycle time

In addition to safety issues, the reduction of well cycle time and accompanying costs also play an important role in advancing rig automation. The Glomar Explorer has been designed to handle many critical-path, pipe-handling operations such as running riser, tripping, and making connections from a horizontal position while preparing the BHA and casing preparation offline through the use of vertical pipe-handling equipment.

"Day rates are phenomenal," often more than $180,000/day for a ultra-deepwater vessel. "For instance, when you come out of the hole and have to change out the BHA, you can lose anywhere from 3 to 7 hr," Wolford said. "However, with a dual-activity system, using both horizontal and vertical pipe-handling technologies, the BHA can already be made up and stood back far in advance of getting out of the hole."

Nevertheless, these mixture of technologies, provided through several service providers, have required a level of teamwork most unusual for oil-field companies.

Competitive synergy

"We're all competitors," said Mark Sorensen, sales manager for Hitec Drilling & Marine Systems. "Westech can go into Varco's business and we can go into Westech's business. We fight real hard to get the job."

However, "When the job is let by the contractor as to whose equipment is going to be used, then it is all our jobs to let (the competitive animosity) go to the side. We then have to work together and integrate the systems."

System integration is enhanced by a safety-oriented program technology called zone management. According to Phil Vollands, senior engineer of new business development for Varco, "Each piece of equipment moves in space. What zone management does is set up a model that defines in space where that piece of equipment can move (Fig. 4)."

For example, the top drive, which moves up and down on the guide tracks, will have a modeled space similar to a tall cylinder. However, "Things become quite complicated as pipe is being handled from the horizontal racker into a vertical position," he explained.

Depending on the operation, zone management monitors the position of, and enables or disables, drill floor equipment as each piece crosses the path of another.

A complicated procedure such as a tripping operation will encounter several zones of contact that must be modeled to produce areas of noninterference while allowing constructive interaction. On the Glomar Explorer, adding a drill stand while tripping in the hole includes the following steps:

1. Driller sets slips so that tool joint is positioned 1-2 ft above rig floor.
2. Break out joint with top drive.
3. Clear elevators off drill pipe.
4. Extend elevators out and latch onto additional 93-ft long stand from horizontal pipe racker (Fig. 5).
5. Begin raising latched pipe with top drive.
6. As pipe approaches vertical position, driller initiates stabbing guide located on horizontal pipe racker to tail end pipe stand over to well center (Fig. 6).
7. Retract stabbing guide and stab tool joint into stub positioned in rotary table.
8. Intiate iron roughneck along track (Fig. 7), bring over to well center, spin drill stand, and torque up.
9. Remove iron roughneck from well center.
10. Pull slips and run in hole.

Thus, more than six pieces of equipment including the top drive (Varco), stabbing guide (Westech), drawworks (National Oilwell), horizontal pipe racker (Westech), and iron roughneck (Varco) all must be operated from a centralized control system (Hitec) located within the driller's cabin (Figs. 8 and 9).

Additional equipment interaction is also needed to add sections while drilling. For example, a raised back-up system (works like a back-up tong), mounted on the back side of the guide rail, is used when the drillstring must be set high in the slips (Fig. 10). Otherwise, during a connection, the drill bit will bounce on bottom as the vessel heaves.

This eliminates Step 9 above and requires zonal interaction between the horizontal stabbing guide as it hands off the pipe stand to the raised back-up system.

Horizontal pipe handling

Since 1956, Global Marine's pipe-handling processes have centered on horizontal pipe-handling techniques in place of traditional "stand-it-back in the derrick, vertical pipe-racking technologies."

Although other companies such as Sedco Forex, Sonat, Transocean Offshore Inc., R&B Falcon Corp., and Saipem SpA, have incorporated horizontal pipe-handling systems into their floating rig design, Global Marine pioneered this technology with the CUSS I and continues to incorporate it into its new Hull 456 rig design.^{1, 2}

Hablieb says there are two advantages to horizontal rackers. First, the permanent storage of drillpipe and other tubulars in a horizontal position maintains a more stable center of gravity. This is especially important during rough weather when wave, wind, and current motion produce a hazardous condition when the derrick is full of pipe.

Furthermore, if drill pipe is racked back in the derrick, an upcoming storm will force the crews to lay the stands down, a time consuming affair that is further compounded if the riser string must also be pulled.

Second, Hablieb says that 20-30% of the trip time can be saved using a horizontal system. For example, "When tripping in the hole (vertically), you have to run the elevators up empty, latch onto a stand, make up the connection, then come all the way back down." However, with a horizontal system, the elevators always remain within a short distance of the next tool joint, whether drilling, making a connection, or tripping.

On the Glomar Explorer, the horizontal pipe racker (Figs. 11 and 12), manufactured by Westech HMD of Control Flow Inc. (formerly Western Gear), is controlled through a fully digital electronic control system using PLC technology. This control package allows the unit to be operated by a single crew member, usually a competent floorhand.

The horizontal pipe racker has two control stations, one in the driller's cabin and the other at the far end of the racker. The total weight of the unit is only 350,000 lb, yet can store over 890,000 lb of various-sized tubulars or 35,000 ft of standard 51/2-in drill pipe.

Racker operation

Prior to tripping in the hole, the horizontal racker is configured so that the stands roll to the outboard size of the racker, resting up against the right or left-hand side of the vertical conveyor. The outermost stand is then lifted in a horizontal position to the top part of the racker where it is qued with five to six other stands.

A single stand is then indexed by a ramp arm so that only one stand rolls to the center of the skate track at a time. At this point, the stand lies within the trough, with the pin end cradled by the rolling skate with the box end facing the rig floor (Fig. 13).

When the driller is ready for another stand, the operator engages the skate drive and slides the entire stand towards the rotary table, box end first. The box stops just short of the rig floor boundary, where a lift arm elevates the box end up into the air.

At this point, the pipe is bowed with the box end up in the air, while the pin end remains horizontal in the skate. The stand is then moved towards the rotary, positioning the box end above and slightly past the well-bore center where it ready to be picked up by the elevators (Fig. 5).

The driller then lowers the blocks so that the elevators can be latched around the box end. The driller then raises the elevators, and the box end is pulled up into the derrick. Throughout this operation, the skate moves along with the pin end towards the rig floor, in a tailing fashion.

At the rig-floor boundary, the pin end's forward movement is halted and lifts upward out of the skate. The lower end of the stand is stopped in its forward swing by a bump rail. The pin is now positioned above the rig floor.

Next, the operator initiates the pipe stabber horizontally across the floor (Fig. 6), positioning the pin directly over the well-bore center, above the waiting box end. The driller then lowers the blocks and makes up the stand. This sequence is repeated about every 60 sec.

The tripping out sequence is exactly the opposite of this sequence, except that the storage arms are pitched so that the stands roll to the center of the racker.

Evolving philosophy

Global Marine's pipe-handling philosophy began to change from "purely horizontal pipe-racking systems" to standalone, vertical-horizontal pipe-handling systems in 1996. In 1998, with the upgrade of the Glomar Explorer, followed by future deliveries of the C.R. Russell Luigs and Jack Ryan deepwater drillships, the company's concurrent pipe-handling capabilities have begun a new era of technological innovation, already changing the way rig personnel perform their duties (Fig. 14).

With time and experience, this new wave of automated, computer-assisted drilling will offer substantial opportunities to improve safety and work-flow procedures, not only for floating vessels but for the shelf and eventually onshore.

References

1. Burleson, C.W., Deep Challenge: The True Story of our Quest for Energy Beneath the Sea, Gulf, Houston, p. 59.
2. Dreith, M.W., Garvin, M.D., and Thorson, J.A., "Glomar Hull 456 Class Ultra-Deepwater Drillship," SPE/IADC paper 52858, presented at the SPE/IADC Drilling Conference, Amsterdam, Mar. 9-11, 1999.

Copyright 1999 Oil & Gas Journal. All Rights Reserved.