Sonangol, as concessionaire, and Total, as operator, announced that the Angola’s deepwater Rosa field in Block 17 started production on June 18. Discovered in January 1998 at some 135 kilometres off the coast of Angola in water depths of 1,350 metres, the Rosa field is located some 15 kilometres away from the Girassol Floating Production Storage and Offloading (FPSO) vessel to which it has been tied back. It is the first deepwater field of this size to be tied back to such remote installation and in such water depths. Rosa, with proven and probable reserves amounting 370 million barrels in 100%, will maintain the FPSO’s production plateau at 250,000 barrels per day until early in the next decade.
The Rosa field will comprise 25 wells, including 11 for water injection and 14 producers, which will be tied into four manifolds. The subsea installation consists of 64 kilometres of insulated production flowlines (Pipe in Pipe) and of 40 kilometres of water injection lines linking the Rosa to the Girassol FPSO. An innovative riser tower docked nearby the FPSO takes the fluid over 1,200 metres from the sea floor up to the surface.
In order to receive the Rosa production, 5,600 tonnes of structure and equipment were installed on the FPSO. The works have permanently mobilised about 400 persons on the vessel, over a period of nearly two years. During the whole period, the treatment of the Girassol oil continued and only some scheduled production shutdowns were required.
With Rosa on stream, all of the produced water from the Girassol, Jasmim and Rosa fields will be reinjected in the reservoirs, thus resulting in produced water not being discharged to the sea. In addition, Total is reducing greenhouse gas emissions by using an innovative process that inerts and recovers gaseous effluent from the FPSO tanks.
The extent of the works and the delicate conditions in which they had to be carried out due to the important safety constraints imposed by continuing the operation of Girassol facilities have made the Rosa development a first in the world on such FPSO.
Sonangol is the Block 17 concessionaire. Total E&P Angola, operator, has a 40% interest in Block 17, alongside partners Esso Exploration Angola (Block 17) Limited (20%), BP Exploration (Angola) Ltd. (16.67%), Statoil Angola Block 17 AS (13.33%) and Norsk Hydro Dezassete a.s. (10%).