Up to 6 ERD wells in works for Liberty
 Click here to go directly to this story within the full PDF version of this issue, with any maps, photos or other artwork that appears in some of the articles.
Email it to an associate.
Wells from Endicott satellite island for BP’s second Beaufort Sea oil project will break new records for extended reach drilling
Alan Bailey Petroleum News
After several years of project evaluation and a progression through various field-design concepts, BP has submitted a detailed plan of development for the Liberty field to the U.S. Minerals Management Service. And, as we’ve previously reported, that plan involves the drilling of ultra extended reach wells from the Endicott field satellite drilling island — Endicott is located five to eight miles west of Liberty (see “BP begins application process for Beaufort Liberty prospect” in the May 13 edition of Petroleum News).
The Liberty field lies about 5.5 miles offshore in an area of the Beaufort Sea where the water depths are about 20 feet. BP abandoned an original concept for a Northstar look-alike at Liberty, involving the construction of an artificial island and a subsea pipeline. Instead the company has decided on the less environmentally invasive extended reach drilling concept.
In its new development plan BP says that it will drill one to four producing wells and one or two water injection wells — waterflood will provide the primary oil recovery system. BP will also use high-pressure gas lift, with carbon-dioxide injection perhaps coming into play at some stage.
“A late-life carbon dioxide flood may also be employed in conjunction with major gas sales,” BP says.
The waterflood operation will use both high salinity water from a conventional waterflood arrangement and low salinity water from a BP trademarked system. The low salinity system will require a special module that filters salt from water from the Endicott seawater treatment plant.
BP hopes to recover about 105 million barrels of medium-gravity crude oil from the field, depending on the level of success with the extended reach drilling.
Similar to Endicott The geologic setting of the Liberty oil accumulation resembles the Endicott field and BP says that the company’s experience at Endicott is enabling the company to “determine the most efficient method to maximize oil recovery in the Liberty field.”
“The exceptional rock properties and the simple structural geometry (of the field) make it possible to develop the reservoir with relatively few wells,” BP says.
But those wells will involve pushing the limits of extended reach drilling beyond what the oil industry has achieved to date — the Liberty wells will require horizontal departures of 34,000 to 44,000 feet from the surface wellheads, to target an oil pool about 10,000 feet below the surface.
“Drilling studies support departures of 39,000 to 44,000 feet,” BP says. “Departures beyond 44,000 feet have not been studied.”
One or two producer wells will tap the up-dip section of the reservoir, the closest side of the field to Endicott, with one or two injector wells placed in the central part of the reservoir. Depending on the capabilities of the extended reach drilling, one or two additional producers would then tap the down-dip side of the reservoir. Maximum oil recovery will depend on success with all of those wells.
“The intent is to maximize resource capture as drilling performance is proven,” BP says.
Purpose-built drilling rig With extended reach drilling requirements beyond the capabilities of any existing North Slope drilling rig, BP is commissioning the construction of a purpose-built rig for the Liberty project. Construction of the rig should start in the first quarter of 2008, with completion slated for the third quarter of 2009. If all goes according to plan the first well should spud in 2010 and production hook up would occur early in 2011.
According to BP, the Liberty wells will be “up to four or five times longer than a conventional North Slope well.”
“The well design work already completed has confirmed that there are no rigs currently operating anywhere in the world that are capable of successfully drilling and completing Liberty uERD wells,” BP says. “The demands placed on the rig for drilling the Liberty wells are mainly in the areas of rotating torque capacity, hydraulic horsepower, pipe management and fluids management. … The Liberty rig may be the largest land rig operating in the world.”
The rig will require a derrick with a top drive and a rating of 1.5 million pounds. The drilling will involve the use of casing flotation techniques, to minimize the drag of the casing against the well bore.
The conceptual design of the rig envisages four main modules that can move along a straight line of wellheads using a self-propelled skidding system. Well spacing would be 30 feet. Drilling waste would be hauled to the central grind and inject facility at Prudhoe Bay.
The Liberty drilling pad and associated facilities will require a 20-acre extension to the existing Endicott satellite drilling island, to convert the island from its existing square shape to more of an L shape.
Water for waterflood will come from the Endicott facilities through a new pipeline that is to be constructed from the main Endicott production island. The Liberty project will also involve the construction of a gas-lift pipeline parallel to the water pipeline. Other construction requirements include upgrade of the west Sagavanirktok River bridge, or possibly the construction of a new bridge (the existing bridge is in unsuitable condition to support the loads and traffic requirements of the Liberty project).
Facility sharing BP says that it is in the process of negotiating a facility sharing agreement with the Endicott field owners. The company has also applied to the U.S. Minerals Management Service, the Alaska Oil and Gas Conservation Commission, the Alaska Department of Revenue and the Alaska Department of Natural Resources for permission to commingle Liberty and Endicott production.
As envisaged in the development plan, production from Liberty would commingle with Endicott production at the satellite drilling island, for processing through the Endicott production facilities. Liberty oil would pass with the Endicott oil through the Endicott pipeline to Pump Station 1 of the trans-Alaska pipeline. Gas produced from Liberty would be used for fuel and gas lift in the Liberty field, with any excess gas injected into the Endicott field. Produced water would commingle with produced water from the Endicott field and be used for waterflood at Endicott and Liberty.
Although BP anticipates first oil production from Liberty in 2011, full operation of the field will take three years to ramp up. Fabrication of the low salinity waterflood module is planned for 2011-12, with the module moving to the North Slope by sealift in the 2012 open water season (BP anticipates the drilling rig modules and other equipment being trucked to the project site). Construction of the waterflood and gas-lift pipelines from the main Endicott island would occur in 2012.
BP says that in submitting its Liberty development plan to MMS the company is initiating the permitting process for the project and a review under the National Environmental Policy Act. The company has already applied to the U.S. Army Corps of Engineers for a permit to expand the Endicott satellite drilling island. The company says that it will also apply for incidental harassment authorizations or letters of authorization under the terms of the Marine Mammals Protection Act for any potential incidental take of marine mammals.
| 
