Moving on Liberty
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SDI, river bridge upgrade and drilling rig construction near completion
Alan Bailey Petroleum News
After years of planning and design there are now tangible signs on the ground of progress towards first oil from BP’s 100 million-barrel Liberty field, offshore in the Beaufort Sea, about 15 miles east of Prudhoe Bay.
On the North Slope workers are putting the finishing touches to the extension of the Endicott satellite drilling island, where Liberty’s drilling rig will be located, and to the upgrades to the Sagavanirktok River road bridge, an essential component of the transportation support infrastructure for the Liberty project; and in Vancouver, Wash., fabrication of Parker Drilling’s massive Liberty drilling rig is nearly finished, Darryl Luoma, BP’s general manager for the Liberty project, told the Alaska Support Industry Alliance April 23.
“We’re on track to begin drilling next year and that’s exciting,” Luoma said. First oil is expected in 2011, he said.
Alternative plans Following field discovery in 1997, the original concept for Liberty was a Northstar lookalike, a gravel island, armored against the ravages of the sea and ice and connected to shore by a buried subsea pipeline. But in 2005 BP came up with an alternative plan to develop the field using extended reach drilling from a shore location, perhaps at Point Brower, on the west side of Foggy Island Bay, and to connect the field production into the nearby Badami pipeline. That plan then morphed into the concept that the company eventually sanctioned, the drilling of ultra-extended reach wells from the satellite drilling island for the Endicott field, about 8 miles to the west of Liberty.
“In developing Liberty in this way we eliminated the need for new offshore islands; … we eliminated the need to put new processing facilities in place; and we eliminated the need for new buried pipelines to bring processed crude back to shore,” Luoma said.
And the use of the Endicott facilities will channel substantial new production through those facilities, thus extending the viable life of the facilities and, hence, the life of the Endicott field. Endicott, constructed in the mid-1980s, peaked at production rates of more than 100,000 barrels per day of crude oil but has since declined to rates of 13,000 to 14,000 bpd, Luoma said.
“So producing Liberty through a great existing facility like Endicott makes good sense,” he said.
Massive rig But world record-breaking horizontal departures of 34,000 to 44,000 feet from the surface wellheads to the Liberty oil reservoir require a massive drilling rig: The rig that Parker Drilling has been fabricating in Vancouver, Wash., will be the world’s most powerful land rig, a piece of kit that Luoma characterized as an enabling technology, a breakthrough design without which project success would be impossible. The design has to accommodate the need to handle huge lengths of drill pipe, apply enormous torques to the drill string and when necessary be able to pull the drill string from the well bore, an operation that by itself might take a week to accomplish, Luoma said.
“One of the key elements in designing the rig is the efficient handling of pipe,” Luoma said. “… One of the big modules on that (rig) is a pipe barn. It’s a pipe-handling efficiency machine.”
The Liberty top drive, the electric motor assembly hung from the drill derrick for turning the drill string, now constructed, acceptance tested, and sitting at the rig site in readiness for the arrival of the rig, dwarfs conventional drive units.
“That will be the most … powerful top drive operating anywhere in the world, putting out 105,000 foot-pounds of torque,” Luoma said. “Typical top drives in Alaska are … maybe 40,000 foot-pounds of torque.”
Drill pipe And to handle the torque applied by the drive to the drill string, to turn the drill bit while overcoming the frictional forces in well bores up to more than 9 miles in length, without the drill string becoming excessively heavy, BP has had to come up with another enabling technology, the Liberty drill pipe, made of a new steel alloy that combines high strength with light weight. Some of the pipe has already been delivered to the North Slope and has been undergoing field trials, Luoma said.
To accommodate the drilling rig, with its line of Liberty wellheads and a camp for on-site workers, BP has been expanding the Endicott satellite drilling island from an area of about 11 acres to about 30 acres by laying a new area of gravel skirted by a sheet-pile sea wall. Nanuq Inc. and Alaska Frontier Constructors, in a joint venture with Kuukpik Corp., the village corporation for Nuiqsut, are putting the finishing touches to this work and BP expects the drilling island extension to be completed by the end of April.
“This has been a challenging project completed in the heart of a cold and challenging Alaska winter,” Luoma said.
Installation of the workers’ camp on the island should start in May, with the camp becoming operational in July.
And on the mainland, contractor Alaska Interstate Construction is within days of completing the major upgrade to the Sagavanirktok bridge. The bridge is more than 30 years old and had been suffering from the effects of wear and tear — refurbishment has involved replacing the topsides of the structure, Luoma said.
Rig completion In Vancouver, Wash., structural assembly of the drilling rig is almost complete and outfitting of the rig is in progress. The rig is being assembled into eight major pieces for transportation to the North Slope on two huge barges, scheduled to leave the construction site at the beginning of July and arrive at Endicott in August. Crowley Marine is handling the sealift operation, Luoma said.
“Once it arrives at the satellite drilling island this August, the rig will be assembled … outfitting completed and the rig fully commissioned, we expect, by the end of this year, early next year,” Luoma said.
That will enable drilling to start in early 2010.
The design and fabrication of the rig power module and fuel gas system have been completed, and ASRC Energy Services is outfitting this equipment in Anchorage, in preparation for transportation to the Endicott satellite island in June. BP plans to commission the equipment in August, to provide power for remaining project activities on the island.
Meantime BP is preparing the detailed plans and procedures for operating and maintaining the drilling rig, and for drilling the wells. The company is also in the process of assembling the team that will do the drilling.
“We’re now in the process of building the … well operations team,” Luoma said. “… We’re currently in the process of getting the team in place and starting the training. This will clearly be one of the most capable ERD teams operating anywhere around the world.”
On-site training Once the drilling rig has been commissioned the team will spend about 90 days on the rig, going through extended on-site training and focusing on the key aspects of drilling extended reach wells.
“We’ll also drill and complete a cuttings re-injection well in that period,” Luoma said. “And once we deem that that team is ready to start the first ERD well, we’ll authorize that well to start the program. We think that’ll be in the 2Q of next year, about one year from now.”
BP plans to drill up to six ultra extended reach wells to hit targets 2 miles underground, anywhere from 6 to 8 miles from the surface well location at Endicott. The drilling plans involve drilling downwards from the Endicott satellite island and then deviating the wells to the east into near horizontal configurations. Then, as the drill bits grind their way close to the Liberty field location, the drillers will deviate the wells down into the reservoir.
In the summer of 2008 CGGVeritas conducted a high-resolution 3-D seismic survey along the drilling corridor between Endicott and Liberty using a water-bottom cable technique, to provide the subsurface information that is essential to the planning of these difficult wells. The data from that survey have been processed and delivered to BP, Luoma said.
Drilling complexities And at an April 22 meeting of the Alaska Geological Society, BP development geologist Steve Jones explained some of the complexities that the drillers will face.
Jones said that for the well planning, in addition to using data from the 2008 seismic survey, BP commissioned Savant Resources to log the subsurface above the oil prospect in the Kupcake well that Savant recently drilled near Liberty.
The Liberty drilling will use rotary steerable technology, involving a rotating drill string that turns a drill bit, controlled from the surface through a communications technique that involves sending signals in the form of pressure pulses through the drilling mud. The composition of the mud itself has to be designed to work in the very long wells without causing pressure shocks that might damage the rock above the well bore, Jones explained. A single well will likely take about 180 days to drill, he said.
Some of the well casing, the steel tubing installed in the well bore, will be run into the well using conventional techniques, while some will be floated in, with air at the bottom of the casing string and mud at the top. During drilling, friction-reducing devices on the drill pipe will help the pipe turn and move inside the casing, Jones said.
The drillers will first drive a 26-inch hole near-vertically through a thick layer of unconsolidated sand and gravel under the rig, with deviation of the well bore towards Liberty starting about 300 feet below the surface. With every subsequent piece of drill pipe having eventually to pass through this section of the well, the deviated well trajectory needs to accurately follow a curve shape called a catenary, to minimize the drag on the pipe. The existence of permafrost to a depth of about 1,500 feet will add to the drilling challenges.
“There are issues with permafrost; there are big chunks of wood in there that can cause … problems,” Jones said. “It looks basically like stuff that’s on the river bank, down on the modern Sag River.”
Hard layers Then, as the drillers guide the drill bit along the near-horizontal section of the well, the bit will start to encounter a series of especially hard rock layers.
“Normally you just … blow right through those,” Jones said. “… The problem is that if you’re drilling at these extreme inclinations and you’re very sensitive to dog legs because of (drill pipe) drag considerations, you want to be very sure that you’re not bouncing off these hard streaks.”
Lignite-grade coal seams, further down along the drilling path and known from nearby wells, will cause well bore stability issues, especially since the low angle of the well bore relative to the near-horizontal coals will result in the well remaining within individual coal seams over distances of more than 150 feet.
The wells will also pass close to an ancient, buried subsea erosion channel, previously known from seismic data and clearly depicted in seismic cross sections from the 2008 survey.
“We’ve actually tried to avoid going through that because we couldn’t image what was in there very clearly on the old seismic and we didn’t have any wells that actually go through the middle of it,” Jones said.
And the well designers envisage the well trajectories steepening as they approach the Liberty field, in part to avoid well bore stability problems in an interval known as the HRZ, an interval notorious for stability issues when drilling on the North Slope, Jones said.
Challenging future Luoma said that although Liberty faces many technical challenges, new technical challenge is probably going to become the norm for North Slope oil and gas projects, projects that are likely to involve modest-sized fields in a business environment where costs have risen and where there has been increased pressure from taxes.
On the other hand the more than $1 billion dollars that BP will eventually plough into the Liberty development will produce many benefits, including Alaska jobs, contracts for many Alaska companies, and federal royalties, a portion of which will be shared with the state, Luoma said. (Because the field is located less than 6 nautical miles offshore, the state will receive 27 percent of the federal royalties from field production.)
To date, there have been more than 1,000 people involved in the project and once the drilling is under way 250 to 300 people will work on the field development, Luoma said.
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