Girassol

Location and Geology

The Girassol oil field is located within Block 17 of the Lower Congo Basin, approximately 150 kilometers offshore Angola, and specifically about 210km north-northwest of Luanda.
The field is situated in water depths of around 1,350 meters.
Geologically, the field consists of extremely permeable Tertiary sand reservoirs containing high-quality 32° API crude oil, which results in good well productivity.

The Girassol field was discovered in April 1996 by Elf Exploration Angola.
Official approval for the development project was obtained on July 8, 1998, from Angola’s national oil company, Sonangol, and the Girassol partners.
The development involved a fast-track approach with two phases. Phase one focused on bringing 11 out of the total 39 wells into operation to achieve first oil, which was accomplished in December 2001. Phase two involved the completion of the remaining wells and the installation of necessary infrastructure.

The project includes a network of 39 subsea wells tied to a Floating Production, Storage, and Offloading (FPSO) vessel. These wells comprise 23 producer wells, 14 water injectors, and two gas injectors.
The FPSO is capable of processing 200,000 barrels of oil per day and storing 2 million barrels. It also handles produced water treatment, gas lift, gas compression, and gas dehydration.
The subsea production system includes well manifolds, wellheads, ‘Christmas trees,’ and well jumpers connecting the wells to the manifolds. The production lines are designed in loops to facilitate pigging and to allow the lines to be filled with inert storage oil in case of a production stoppage.
The FPSO is spread-moored with 16 lines connected to suction anchors, and it receives umbilicals and risers from three riser towers. Each riser tower is connected to the FPSO by a riser, and flexible pipelines carry the oil up into the FPSO.

The average production from the Girassol field is approximately 240,000 barrels per day (bpd).
Base-case reserves of the field are estimated at around 630 million barrels of 32° API crude oil.

The operator of Block 17 is TotalEnergies (formerly Total), with a 38% interest. Other partners include Equinor (22.16%), ExxonMobil (19%), BP Exploration Angola (15.84%), and Sonangol P&P (5%).

The Girassol project was an outstanding technological achievement due to the size of the deposit, the water depth, and the degree of innovation required. It involved the use of drilling vessels with dynamic positioning capability and the installation of flexible dynamic production risers with low-shrinkage liners.
The project required complex dynamic analysis of the riser configuration to accommodate the movements of the FPSO and the riser towers. The flexible risers were manufactured in single lengths to ensure uniform quality.

Key contractors and suppliers include FMC Technologies (now part of TechnipFMC) for subsea production equipment, Technip for project management and installation of umbilicals, Aker Solutions for umbilicals and power cables, and NKT Flexibles for the supply of dynamic risers.

The FPSO is equipped with facilities for produced water treatment, gas treatment, and gas re-injection. The living quarters on the FPSO are designed to accommodate 140 people in 80 cabins.

Production from satellite fields such as Rosa and Jasmim is tied back to the Girassol FPSO. The development of approved satellite projects is expected to consolidate production in the Girassol, Dalia, Pazflor, and Rosa fields within Block 17.

The overall project budget for the Girassol development was $2.8 billion, with three-quarters of this amount allocated to phase one.
The project has significant economic implications, with long-term production licenses extended until 2045, allowing for continued exploitation of the reserves in Block 17.