Oil

The first deep offshore field developed in the Gulf of Guinea, Girassol is now a benchmark for the global oil industry. Combining an array of technological innovations, it is an outstanding demonstration of Total's ability to develop resources in the deepest waters.

A gift of the Congo River

Girassol was discovered in 1196, the first find made under the deepwater exploration program initiated by Total in 1993 in Angola's deep offshore Block 17 license in the Gulf of Guinea. The field is located 150 kilometers off the coast, in an area where the waters reach a depth of 1,400 meters. Its reservoirs, buried 1,000 to 1,300 meters below the seabed, are the product of a highly unusual geological history. They were formed by the accumulation of enormous amounts of sediment rich in organic matter, swept along to the mouth of the powerful Congo River. Forced down to the ocean floor during gigantic avalanches, the sediment was deposited there and driven ever deeper over the millennia.

A world first

After appraising the immense field's potential, Total took on the challenge of developing it. Just three-and-a-half years later - a veritable tour de force given the host of technical challenges met in order to manage this extreme production configuration - Girassol produced first oil. The largest ever deep offshore development at the time, Girassol was hailed as a major event by the oil industry, which recognized the excellence of Total's technological expertise with a prestigious award.

Working around extreme conditions

At these depths, all production equipment, controlled remotely from the surface, must be designed specifically for the subsea environment. It has to be ultra-reliable, since it is meant to remain on the seabed throughout the field's life of 20 years or more. Another major challenge is protecting production across the thousands of meters it has to travel in subsea lines from the extreme cold (4°C) and pressure (140 bar) prevailing at the bottom of the ocean. The main risk is that plugs of ice, known as hydrates, will form, paralyzing the system. With the support of a strong R&D program, Girassol met each of these and the many other challenges associated with deepwater operation through an impressive number of technological innovations.

Nearly 150 kilometers of subsea lines

The subsea production system totals 39 wells. Each wellhead, flush with the seafloor, is capped by a high-tech control unit known as a Christmas tree. A core production component, it was very thoroughly tested to make sure it could withstand the harsh conditions at these depths. Once out of the well, the oil is gathered by long subsea lines, whose loop shape easily accommodates regular cleaning by a small robotic device called a pig. Made of two nested steel pipes separated by high-performance insulation, these production loops feed the oil to a vertical line, or riser, that carries it to the surface. A major Girassol innovation, this riser tower system is a narrow rigid line 1,250 meters high and 1.50 meters in diameter. A slender structure that shields the oil produced from the cold by means of insulation devised specifically for the application, it also has all the mechanical properties needed to withstand currents. Other networks include systems to inject water and gas into the reservoirs so as to maintain reservoir pressure and optimize production and a network of electro-hydraulic control cables to manage and monitor all subsea equipment.

A gigantic floating factory

To develop the Girassol deepwater field, Total designed a huge floating production, storage and offloading (FPSO) vessel to manage production rates, treat the effluent to separate the oil from the gas and water naturally mixed with it, store the oil and transfer it to an offshore loading buoy for tankers. Three soccer fields in length, the Girassol FPSO was the largest ever built at the time. The 25,000 metric tons of topsides can process 250,000 barrels of crude oil per day, while its gigantic hull is capacious enough to store 2 million barrels.

An intrepid industrial and human adventure

Like other large-scale oil projects, the immense industrial and technological jigsaw puzzle that is Girassol was the work of thousands of men and women all over the world. In the United States, South Korea, France, Norway, Angola, Brazil, Sweden, Germany and elsewhere, they worked at the yards that machined the parts or installed and assembled them on the ocean floor using remote-controlled robots in a vast undertaking. People safety was an absolute priority throughout, as was environmental protection, assured through an independent environmental auditing system to monitor changes to the deepwater ecosystem within the operational perimeter.

Both a technological and human adventure, Girassol also helped spur Angola's economic development by creating a number of local jobs. Transferring our technological knowledge and skills is a core component of our strategy, and was achieved through recruiting and training Angolan technicians to operate the FPSO.

Optimizing and anticipating

Nearly two years to the day after Girassol came on stream, Total gave this remarkable project a second wind. We tied in production from Jasmim, a satellite field located five kilometers away that was too small to warrant separate development, to the FPSO. The additional eight wells have increased Girassol's output. We strive to optimize use of the Girassol installations by developing neighboring reservoirs to offset the natural decline in production from this trailblazing field.