Ultra-deepwater oil field development
The Bacalhau oil field (previously known as Carcara) is located at a water depth of 2,050m, approximately 185km off the coast of Sao Paulo, Brazil.
Jointly owned by Equinor (40%, operator), ExxonMobil (40%) and Petrogal Brasil (20%), the Bacalhau oil field will be the first integrated subsea production system (SPS) and subsea umbilicals, risers, flowlines (SURF) project in Brazil.
The final investment decision (FID) for the project is expected to be taken in late 2020, while the first oil is anticipated between 2023 and 2024.
The Bacalhau oil field is located across the BM-S-8 and Bacalhau North blocks in a pre-salt area of Santos Basin, offshore Brazil. The project encompasses the development of the two blocks that cover a total area of 2,610km2.
The field contains high-quality crude oil with low sulphur content and API gravity of approximately 31o. It has estimated recoverable reserves of more than two billion barrels of oil equivalent (Bboe). The BM-S-8 licence area has recoverable volumes of approximately 700 million to 1,300 million boe from Bacalhau and additional exploration prospects.
The field was discovered in March 2012 on the same geological trend as the Lula field, near the Libra area. The National Petroleum, Natural Gas and Biofuels Agency (ANP) approved the evaluation plan of Carcara discovery.
The Carcara exploration well 4-SPS-86B was drilled to a water depth of 2,027m and encountered a continuous column of 171m of oil.
New oil samples with 32o API were also collected from reservoirs located in a water depth of 5,910m.
An appraisal well 3-SPS-104DA, also known as Caracara NW, confirmed light oil potential in the field. It was drilled approximately 6km to the north-west of the discovery well. The well was drilled using a managed pressure drilling (MPD)-equipped rig for penetrating the pre-salt reservoirs.
Drilled in 2015, the second appraisal well 3-SPS-105 (Carcara North) successfully proved the extension of the discovery. The well confirmed the presence of a 358-m oil column in continuous and interconnected carbonate reservoirs below the salt layer at a depth of 5,820m. Two drill stem tests (DSTs) carried out in Carcara North further established the high productivity of the discovery.
The discovery and appraisal well confirmed gross pays between 318m and 402m of light oil with API 31o, without the contamination of hydrogen sulphide and carbon dioxide. The overpressured reservoirs were found to have the same pressure gradient.
The Bacalhau oil field development will involve the development of 19 wells and the installation of 130km of flowlines and rigid risers and 35km of umbilicals.
A new floating production storage and offloading (FPSO) vessel will be deployed at the field to produce oil. It will be permanently moored by a spread mooring system.
MODEC’s M350 hull, a next-generation hull for FPSOs, will be utilised for the vessel. To be built in China, the vessel will have a full double hull design that will be able to accommodate bigger topsides and provide enhanced storage capacity and service life.
The topside modules of the FPSO will weigh approximately 20,000t. The FPSO will have the production capacity of up to 220,000 barrels of crude oil a day. It will produce and inject up to 530 million standard cubic feet (Mmscf) of associated gas per day, and inject up to 200,000 barrels of seawater each day to maintain pressure in the formation. The minimum crude oil storage capacity of the FPSO will be two million barrels.
MODEC was contracted for the design and construction of the FPSO vessel in January 2020. The company secured the contract after successful execution of the pre-front end engineering design (Pre-FEED) contract received in December 2018. The mooring system for the FPSO will be supplied by SOFEC, a subsidiary of MODEC Group.
Aibel signed a letter of intent (LOI) with MODEC for the FEED phase of the vessel covering management and basic engineering services. The LOI includes an option for an engineering, procurement and construction (EPC) contract for the topside modules for the FPSO.
Equinor contracted Subsea Integration Alliance, a strategic alliance between Subsea 7 and Schlumberger’s OneSubsea division, to conduct FEED study on the Bacalhau field.
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