The Girassol field, offshore Angola, is the largest deepwater subsea development ever brought into production.
This development has been marked by three key dates: discovery (April 1996), sanction (July 1998) and first oil (December 2001).
This paper gives a general description of the Girassol development, outlines the main challenges faced during the project phase and introduces the other papers which are presented on Girassol.
The Girassol Field is located 210km northwest of Luanda, the Angolan capital, and about 150km from shore (Fig 1 - Field location).
Girassol was the first discovery made in the prolific Block 17. This was followed by Dalia, Rosa, Lirio, Jasmim, Cravo, Orchidea, etc. The project 's chronology has been marked by three significant dates:
April 1996: Girassol field is discovered on Block 17in deep waters, offshore Angola. This is the first major oil discovery by a consortium led by TotalFinaElf E&P Angola (40%, operator) and its partners - ExxonMobil (20%), BP (16.7%), Statoil (13.3%) and Norsk Hydro (10%). The Block 17 Production Sharing Agreement was signed at the end of 1992 with Sonangol, the Angolan state oil company.
July 1998: The Girassol development project is approved by all parties
December 2001: Less than three and a half years after approval, Girassol comes onstream. By the end of 2001, daily production is 100,000b/d with the production plateau of 200,000b/d to be reached by April 2002.
Girassol is a deepwater giant by many standards:
The reservoir, located in 1,400m water depth, is large (10km by 14km). Estimated oil in place is 1,550mmbbls with recoverable reserves put at 725mmbbls. The oil quality of 32°API is close to Brent specifications. Main reservoir and fluid characteristics are given in Fig 2.
The Girassol development scheme is based on 39 subsea wells - 23 oil producers, 14 water injectors and two gas injectors. The field will be developed in two phases: the first phase, completed in December 2001, includes 11 wells - eight oil producers, two water injectors and one gas injector. The second phase development is ongoing and will be completed mid-2003 (Fig 3: Field development scheme).
The overall investment for the two phases of the Girassol development is US$2.8bn.
In order to bring such a large field onstream in deep waters, it has been necessary to develop and qualify new equipment and to address a number of key issues, such as flow assurance, the need for a flexible subsea layout and reservoir uncertainties.
The Girassol project team had to fulfill three main objectives:
First priority was given to technical quality. An extensive qualification program had to be carried out and offshore procedures had to be tested in both shallow water and deepwater tests.
Second priority was to closely monitor the development budget and contain the final cost.
Third priority was to achieve first oil as early as possible. A very demanding schedule was defined at project sanction with a target start-up date of the end of 2000.
The first and second objectives have been met.