• BHP Billiton has approved the development of the oil and gas reserves at the Neptune field in the Gulf of Mexico. Gross costs for the Neptune development project are estimated at US$850 million, with BHP Billiton's share approximately US$300 million.
• Neptune reserves will be produced using a standalone, tension leg platform (TLP). The facility will have the design capacity to produce up to 50,000 barrels of oil and 50 million cubic feet of gas per day.
• Recoverable hydrocarbon reserves at the Neptune field are estimated by the Company at a range of 100- to 150-million barrels of oil equivalent (boe).
• First production is expected by the end of calendar year 2007, with seven initial subsea wells tying back to the TLP.
• BHP Billiton is the operator of the Neptune field. The joint venture participants are BHP Billiton, 35%; Marathon Oil Corp., 30%; Woodside Petroleum Ltd, 20%, and Maxus (US) Exploration, a subsidiary of Repsol YPF, 15%.
• The Neptune field is located in the deepwater, central Gulf of Mexico approximately 120 miles from the Louisiana coast. The field comprises Atwater Blocks 573, 574, 575, 617, and 618.
• Water depths here range from 4,200 to 6,500 feet. The production facility will be located in approximately 4,250 feet of water.
BACKGROUND
Neptune was discovered in 1995 and was the first discovery in the Western Atwater Foldbelt. An initial appraisal well (Neptune-2) was drilled in 1997. BHP Billiton took over operatorship in 2002, subsequently drilling four appraisal wells, with two sidetracks, to delineate the field. These included Neptune-3, drilled in 2002, which encountered 120 feet of net pay; Neptune-5, drilled in 2003, which found 500 feet of net pay; and
Neptune-7, drilled in 2004, which intersected 114 feet of net pay. Atwater Blocks 573, 574, 575, 617, and 618 comprise the Neptune field, located approximately 120 miles south of the Louisiana coast. The Sigsbee Escarpment is the dominant subsea feature of the field, with water depths ranging from 4,200 feet to 6,500 feet. The host facility will be located above the escarpment in 4,250 feet of water.
DEVELOPMENT CONCEPT
The joint venture partners have selected a standalone, tension leg platform (TLP) to develop the hydrocarbon reserves at Neptune. The facility will have the design capacity to produce up to 50,000 barrels of oil per day and up to 50 million cubic feet of gas per day. The proposed facilities, wells, and completions are proven designs that have been successfully implemented in the deepwater Gulf of Mexico. The TLP design is similar to the Chevron/BHP Billiton Typhoon platform in Green Canyon Blocks 237 and 238.
First oil is expected by the end of calendar year 2007, with seven initial subsea wells tying back to the TLP. The wells, subsea systems, flowlines, floating systems, topsides, and risers will be designed, procured, fabricated, and operated by BHP Billiton on behalf of the Neptune joint venture partners. The oil and gas will be exported via new lateral pipelines into the existing Caesar and Cleopatra trunk lines, in which BHP Billiton holds a
25 percent and 22 percent interest, respectively. The new laterals will be installed, owned, and operated by Enbridge Offshore (Gas Gathering) LLC.
Drilling and completion operations will be executed using the Development Driller 1, a newly built and commissioned ultradeepwater semi-submersible drilling rig. In 2004 BHP Billiton signed a two-year contract with the drilling contractor GlobalSantaFe for the use of this rig in the GoM. The DD1 was designed to meet the requirements of drilling in challenging deepwater environments and has been optimized for development drilling and subsea completion projects.