Tapping Liberty – ERD on the North Slope

BP is in the process of setting a record for extended reach drilling (ERD) at the Liberty prospect on Alaska’s North Slope.

Elizabeth Bluemink at the Anchorage Daily News has written about the Liberty prospect here.

Imagine a bent straw made out of steel extending 8 miles long and 2 miles deep, plunging through icy water and miles of undersea rock.

That’s how the next major oil field in Alaska probably will be developed.

BP announced Monday that it will spend $1.5 billion — drilling the longest wells in the world — to develop the Liberty oil field under the Beaufort Sea.  Oil could begin flowing by 2011.

A few years ago, BP shelved the idea of drilling Liberty — which lies about five miles offshore in federal waters, farther from land than any other oil field in Alaska’s arctic — by building an expensive gravel island.

At the time, BP said the idea didn’t make financial sense.

Now, BP says it will tap Liberty by enlarging a gravel island built years ago for the Endicott oil field. BP will use a technique called horizontal drilling to reach Liberty six to eight miles to the east.

The project will expand the life span of the Endicott, a 21-year-old field that is now producing only a tenth of its peak output, company officials said.

Liberty, discovered in 1997,  can also claim another first – it will become the first oil field entirely in U.S. federal waters in Alaska when it starts production.  BP officials have previously said peak production would reach 40,000 barrels per day.  Because Liberty lies under federal waters, most of the tax revenue from that production will go to federal coffers, with 27 % of the royalties returning to Alaska coffers. Most of the other Arctic oil fields in Alaska lie on state land.

The Beaufort Sea is about 20 feet deep in the area of Liberty and BP originally conceived a field development plan involving an offshore production island similar to the Northstar field, in the Beaufort Sea around 35 miles to the west, with a subsea pipeline carrying oil to the shore. But after major cost and schedule overruns in the Northstar development, BP canceled the offshore production island concept and came up with an alternative plan to develop the field using extended reach drilling from a shore location.  Bp had already successfully used extended reach wells with horizontal departures of 25,000 feet and more to tap oil from an undersea reservoir in its Wytch Farm field in southern England.

Early extended reach drilling concepts for Liberty involved piping the production from a remote drill site to either the Endicott or Badami facilities for processing.

The distance record for ERD was held by the Wytch Farm site in England for many years, but recent advances in technology have broken the record several times.  The current record is a well drilled by Schlumberger in the Al Shaheen Field offshore Qatar, which broke the previous record length by 2,000 ft., reaching a total depth of 40,320 ft. Total step-out distance from the surface location was 35,770 ft. (6.78 miles). In all, the well set 10 records including the longest well ever drilled, the longest along-hole departure (37, 956 ft), the longest 8 1/2 in. section, the highest ERD ratio, the highest directional difficulty index, the deepest directional control, the deepest downlink, the deepest battery-less operation, the longest reservoir contact (35, 449 ft.) and finally the longest open hole. More information on the Al Shaheen well can be found here.

In order to drill Liberty, BP contracted with Parker Drilling Company to develop the world’s most powerful drill rig. To handle the exceptional demands of rotating and moving a drill string in a well bore that may be anything up to nine miles in length, the rig has to be able to apply an exceptionally high turning force to the drill pipe.

Consequently a key component in the new rig will be the massive top drive, the device slung in the rig derrick to grip and rotate the drill pipe. Although the drive will rotate the pipe at a conventional 130 revolutions per minute, the torque applied to the pipe will max out at 105,000 foot-pounds, compared with the 30,000 to 45,000 foot-pound torque of a typical North Slope rig.

Additional reporting on the Liberty ERD can be found here, here, and here.

This entry was posted in Alaska, Arctic, BP, Liberty, Oil, Prudhoe Bay and tagged , , , , , . Bookmark the permalink.

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