|
Rigs to meet Arctic challenges; Parker, Nabors show innovations
Amid the technical wonders of steerable drilling bits, ultra extended reach drilling and measurement-while-drilling techniques, it’s easy to overlook the humble drilling rig that makes the whole drilling operation happen. But at the Alaska Support Industry Alliance Meet Alaska conference on Jan. 23 Nabors Alaska Drilling and Parker Drilling Co. sought to set the record straight by describing some of the innovations in rig design that have dramatically broadened the range of drilling possibilities in recent years.
Between 2005 and 2009 Nabors is spending about $250 million dollars on new rigs and rig upgrades for Alaska, Don Korach, engineering manager for Nabors Alaska Drilling, told the conference attendees. And that marks the latest phase in a program of rig innovation that Nabors has pursued since the company started operating in Alaska in 1962.
For example, Nabors modified a couple of rigs for operation in the limited space of BP’s Northstar Island and Pioneers Natural Resource’s Oooguruk Island in the Beaufort Sea, Korach said.
“We have a unique moving system that can move these rigs fully loaded with pipe and drilling fluids, saving hours at a time in rig moves and fluid handling, and reducing the chance of a spill,” Korach said.
AC rigs But one of the biggest rig efficiency improvements in recent years has been the introduction of alternating current, or AC, electrical power for rig drives, Korach said.
In the 1970s most rigs used an engine to drive the rig machinery through a mechanical transmission. Then came SCR rigs in which a silicon controlled rectifier (or SCR) converts diesel generated AC electricity into direct current, or DC, to power and control a DC electric motor drive.
“It was a new way to distribute and manage power in a rig more efficiently,” Korach said. “For years SCR rigs were the backbone of the drilling industry and they still are today.”
But with advances in microprocessing and computers, AC drive technology has started to come into use. An AC motor is much less susceptible to sparking than a DC motor, Korach said.
And, unlike a DC motor, an AC motor can be stalled or locked without burning out.
“This key difference opens up a whole new world for drilling with new features,” Korach said.
The motor can now be used as a drilling brake. Then by inputting parameters such as pipe weight, mud pressure, mud flow and safety limits to a computer that is hooked up to the motor, the drillers can exert a heightened level of control over the drilling operation.
“Nabors started developing this technology in the mid-‘90s … and in early 2000s started doing it for the (rig) drawworks,” Korach said. “… Nabors was the first to introduce AC technology to Alaska with (Rig) 19AC.”
Mobile exploration rigs In 2007, Nabors designed and built two mobile AC exploration rigs — Rigs 105 and 106, Korach said. Anadarko has been using Rig 105 to explore in the Brooks Range foothills, while Chevron has been using Rig 106 for its White Hills exploration south of Prudhoe Bay.
“These rigs are equipped with the latest AC technology top drives and are fully winterized for high Arctic conditions,” Korach said. “These rigs are designed to rig down to 35,000-pound loads and are re-assembled in the minimum of time.”
The rig modules can be carried by helicopter, Rolligon or truck, but the rig can also be moved in larger pieces for rapid transit where there is an appropriate road infrastructure.
“They can get out earlier than the standard rig and can leave later in the drilling season,” Korach said.
The rig operator works inside an air-conditioned cab with a clear view of the rig floor. The operator controls the drilling operation using a joy stick connected to the computer-based control system.
“The computer assists and limits the driller from operating the rig beyond its design specifications, (thus) decreasing down time and accidents,” Korach said.
CDR2 Nabors is about to transport to Alaska a new AC powered rig, the CDR2 rig, for coiled tubing drilling and conventional drilling. Coiled tubing drilling, which is typically used to drill sidetrack wells from existing well bores, uses a long length of flexible tubing rather than conventional drill pipe.
“Our experience with AC technology and coiled tubing really allowed us to design and build a new lightweight, state-of-the-art AC hybrid coiled tubing rig for Alaska,” Korach said. “We have worked closely with ConocoPhillips to incorporate new innovations.”
And for the drilling that ExxonMobil plans in the Point Thomson field, Nabors has modified its Rig 27E to meet the demands of deep drilling into the hot and exceptionally high-pressure Point Thomson gas and condensate reservoir. Fabrication for the upgrade started in June 2008 with an eventual cost of $40 million, Korach said.
“We are happy to report that we will be ready to mobilize the rig as required this Wednesday,” he said.
The rig is rated at 9,600 horsepower, as compared with the 3,000 horsepower of a typical Prudhoe Bay rig, while the hoisting capacity, mud capacity and blowout preventer rating of the rig are all around double their more usual values.
Growth opportunities Joey Husband, Alaska general manager for Parker Drilling Co., talked about how new drilling rig technologies are providing new growth opportunities for Arctic oil and gas drilling. Parker Drilling is returning to Alaska after a 10-year absence.
New technologies reduce drilling costs, thus enabling new drilling possibilities, Husband said.
“The technology today actually allows us to drill the same or more footage with less rig,” Husband said. And the reduction of the drilling footprint as a consequence of directional drilling from a single rig at a single drill site reduces the environmental footprint.
But new drilling opportunities involve an increasing number of stakeholders. For example, Parker Drilling hires where it works, to develop the local workforce, Husband said.
“The community is a stakeholder in what we do,” Husband said.
And then drilling success trickles through to increased economic activity and jobs for many people.
Alaska origin Much Arctic drilling rig technology originated in Alaska in the late 1960s during exploration on the North Slope, Husband said.
“A lot of the technology was focused on mobilizing rigs from remote locations,” Husband said.
Technologies for air lifting rigs to the slope were developed, for example.
Subsequently people developed wheel or other move systems to reduce rig move times. Then came techniques such as the use of offshore gravel islands.
While rig development continued in Alaska, Arctic rig technology such as rig winterization migrated from Alaska to regions like the Caspian Sea and Siberia.
Oil developments on Russia’s Sakhalin Island then saw a wave of new rig innovations, including rigs that could withstand earthquakes and new offshore platform designs. And innovations in places like Alaska and Sakhalin have led to a worldwide network of new drilling rig technical knowledge.
Liberty rig Parker Drilling has been able to use its Sakhalin experience to migrate new extended-reach drilling rig technology back to Alaska to build a rig for BP’s Liberty project, Husband said. BP is planning to use record-breaking extended-reach wells to develop the Beaufort Sea Liberty field from an existing drilling island at the Endicott field.
The massive Liberty drilling rig requires huge quantities of drilling pipe, extreme drilling torques and the capacity to move vast quantities of drilling fluids, Husband said.
To avoid the need for an unrealistically large rig substructure, the rig design will enable the horizontal assembly and storage of stands of drill pipe, offline from the drilling operation. A specialized 1,250-ton top drive will deliver the required torque to the drill string from a 239-foot mast. Four 2,200-horsepower mud pumps will handle the hydraulics. All equipment is AC powered.
Parker Drilling is also building two new specialized Prudhoe Bay three-module infield rigs, called Alaska Arctic drilling units, for use by BP. The new design pays special attention to rapid rig moves, efficient pipe handling and dealing offline with activities such as blowout preventer handling, Husband said.
The rigs will use AC powered equipment. Specially designed wheel arrays will distribute the module weights at fast move speeds, and cantilevered blowout preventer and riser systems will eliminate the need to remove well houses. The command unit for each rig will be onboard, thus eliminating the need to wire up a separate control unit and minimizing the rig’s footprint on the drilling pad. Stands of drill pipe can be assembled offline.
“We believe that with this technology and the right crews we will be able to improve on what is a very good performance today … on the slope,” Husband said.
In both its Liberty and Prudhoe Bay rigs Parker Drilling has taken a fresh look at drilling hazards, Husband said. By engineering hazards out of the rig operation, the company can improve its safety performance, he said. For example, remote controlled derrick handling eliminates the need for someone to work at height within the drilling derrick.
Arctic Learning Center And to develop personnel resources Parker Drilling is commissioning an Arctic Learning Center in Anchorage, Husband said. The center will provide operational support for Parker Drilling’s customers, will provide training, including safety training, and will act as a repository for information about drilling technology.
“We also have equipment commissioned … to simulate critical safety equipment … and the drilling equipment on the rigs themselves,” Husband said. “… Instead of people having to go out for the first time and run equipment on a rig that’s been built for the first time in the industry, we get them on simulators.”
Parker Drilling also plans to open up the center for general use by industry in Alaska, Husband said.
“This is Parker’s commitment to its return to Alaska,” he said.
—Alan Bailey
| 