Elf unveils Girassol field development plan

Elf Aquitaine SA and partners have released details of the fast-track development plan for their deepwater Girassol discovery off Angola.

The field lies in about 1,400 m of water on Block 17. Interests in the production-sharing agreement with state firm Sonangol are: operator Elf Exploration Angola 35%, Esso Exploration Angola (Block 17) Ltd. 20%, BP Exploration (Angola) Ltd. 16.67%, Statoil 13.33%, Norsk Hydro AS 10%, and Fina Exploration MBV 5%.

Deep waters off West Africa hold one of the world's hottest plays right now. Girassol partner Esso has just announced its third find on nearby Block 15 (see story, this page).

Girassol's project manager, Antoine Serceau, describes the field as "a deepwater giant." He says the development marks a significant milestone in Elf's deepwater strategy.

With the help of its partners, development of the field will start barely 2 years after discovery in April 1996. First oil is slated for yearend 2000, building to a plateau rate of 200,000 b/d.

This is the first time Elf has taken such a fast-track approach to development, and it is doing so within the framework of a technologically risky project-"risks that we quantify to the limit of what is acceptable," said Serceau.

The Girassol group has telescoped the usual process of field appraisal and delineation, followed by development drilling. For this project, facilities will be constructed simultaneously with early field development.

An initial screening of proposed development concepts enabled the partners to eliminate infeasible, expensive, or risky solutions. This screening phase led to the selection of a subsea production system and floating production, storage, and offloading (FPSO) barge.

The scheme provides the flexibility needed to constantly adapt to uncertainties with regard to well locations, drilling sequence, and the number of wells that will be drilled in water depths of 1,400 m or more. The method is, to a large extent, proven under such conditions to provide better control of costs and schedule, said Elf.

Development plans

Girassol field is about 18 km long and 10 km wide. Its substructure is a meandering sand complex with overlapping channels (see figure, this page).

Because of the good quality of the reservoir and the oil, fewer wells will be needed, and costs will be reduced accordingly. Outlays are expected to total $2.5 billion.

The first development stage will involve Girassol System B reserves, which are estimated at 700 million bbl. The second development stage will involve System C, which lies to the west of B. Reserves there are estimated to be 300 million bbl.

The drilling equipment and FPSO being built for Stage 1 should be able to handle production from Stage 2 as well, said Serceau. Stage 2 development is tentatively slated to begin after the 5-year production plateau of Stage 1.

Elf said Girassol development will involve the largest infrastructure for such depths ever installed, as well as innovative technology. Plans include: 40 subsea wells, of which 23 will be producing wells; 14 water injection wells; and 3 gas injection wells. Production per well will range as high as 40,000 b/d.

The wells will be drilled from one semisubmersible rig and one dynamically positioned drillship. Together, they will cost about $600 million. The first of these two vessels will be built at the Hyundai yard in South Korea for Pride Foramer; the second will be built in Brest, France, for Sedco Forex. Both will be leased by the Girassol group.

Girassol production, treatment, and injection capacities during Stage 1 will be: 200,000 b/d of oil, 180,000 b/d of produced water, 8 million cu m/day of gas injection at 285 bars, 390,000 b/d of water injection at 150 bars, and 400,000 b/d of seawater desalination to produce injection water.

Electricity will be generated by a 235-MW gas-fired power plant.

Contracts signed

Elf and partners recently signed more than $1 billion worth of contracts for Girassol development. The contracts were awarded based on economic and technical qualification tests, as well as on the firms' ability to carry out some of the construction work in Angola, said Elf.

Equipment suppliers who were selected for the contracts were offered what Elf described as "French-style" alliances, in which profits and losses are shared in a cost-plus-fee arrangement controlled by a price target.

The Girassol consortium let a $410 million turnkey contract for 100 km of flow lines, 70 km of umbilicals, and risers to a group called Alto Mar Girassol, a joint venture held equally by Bouygues Offshore SA, ETPM SA, and Stolt Comex Seaway BV (OGJ, July 13, 1998, p. 38).

Alto Mar Girassol's innovative design involves three rigid 1,350-m towers that will house all of the converging risers. The bases of the risers will be connected to the subsea production system via flowline bundles; the tops will be connected to the FPSO with standard flexible risers.

The partners claim the Girassol FPSO-a 300-m long, 60-m wide steel spread-moored unit weighing 350,000 dwt-will be the world's largest. It will encompass all the services and utilities required for field operations (living quarters for about 140 people; oil treatment, storage, metering, and offloading; gas treatment and reinjection). And it will be able to accommodate off- loading tankers in tandem or on a loading buoy.

The FPSO will be built under a $700 million turnkey contract by a 50/50 joint venture of Bouygues Offshore and ETPM called Mar Profundo Girassol. It will have 2 million bbl of oil storage capacity and 200,000 b/d of production capacity.

Mar Profundo Girassol will handle design, engineering, procurement, construction, and installation of the FPSO and offloading buoy. Hyundai Heavy Industries Ltd. will build the steel hull in South Korea and tow it to Marseille, France.

The topsides will involve an innovative "integrated deck" concept. The 17,000-ton deck will be fabricated at Fos-sur-Mer, France, and installed on the hull at Marseille.

Tow-out to final destination and installation of the FPSO and buoy will take place in second half 2000. The 16-line mooring system will consist of 60 km of chain and 6,000 tons of cable.

The Girassol group let a third contract to FMC Corp. subsidiary Kongsberg Offshore AS, Kongsberg, Norway. This contract, valued at $220 million, is for installation and operation of a modular, guidelineless remote-controlled subsea production system called HOST 2500.

Girassol development will mark a record depth for use of HOST 2500, said FMC.

Kongsberg Offshore will operate from a dedicated support and supply base in Luanda, Angola.