In October/1994 Petrobras, leading a team of six companies has installed for the first time in the world an ESP in a subsea well. The subsea ESP system in the well RJS-221, located in 86 meters water depth, in the Carapeba oilfield has completed in June/97, 32 months in operation without failures. The success with this installation has encouraged Petrobras to proceed with this project on a second Phase, in order to extend the application of this technology to 1150 meters water depth. This paper presents the developments achieved by Petrobras and the Companies associated, from the initial studies that led to the first subsea ESP installation, and the new efforts towards a deepwater installation in the well RJS-477, in 1107 meters water depth. East Albacora-oilfield.
The oil in Brazil is mainly produced in the Campos Basin, offshore Rio de Janeiro State. In this area, giant reservoirs were discovered in deepwater and due to an increasing oil demand in the country are now the main scenario for the new investments.
In order to produce from this Basin, Petrobras has over the years made use of fixed towers, having 13 installed (all of them in shallow waters up to 300 meters), but has strongly adopted floating production systems (FPS's), that receive the oil directly from satellite wells or through subsea manifolds. FPS's have allowed for a very important flexibility and particularly for anticipation of production. It is not necessary to mention the advantages of these two characteristics in offshore oilfield development. For deepwater, Petrobras has adopted the same system, based on semi-submersibles and mainly on oil tankers. These are now being converted to operate as FPSO's, at the same time that the increase in local oil production reduces the need for these carriers to import oil.
These systems are based in subsea wells and some years ago, after having developed a pioneer template-manifold for deepwater. Petrobras has recognized in the Manifolds the same characteristics of the FPS's and adopted them.
With Floating Vessels, flexible flowlines and control umbilicals, subsea wells/subsea trees, subsea manifolds, Petrobras have been progressing towards deepwater.
But a limitation had always to be faced: the distance from the platform to the wells could not be increased without important losses. The exploitation lay-out was determined by the capability of reservoir pressures, that may be insufficient to produce over long distances. The alternatives were then to try, by one side, to reduce pressure decline by water injection, with limits of course, and on the other side, to reduce the backpressure with gas lift, the only artificial lift method available. Gas lift loses a lot of efficiency in long horizontal flowlines typical of subsea wells, as well as with the BSW increase and the results were that, as the reservoirs moved into deepwaters the FPS's so did.
A new method was then required for oil production over long distances, specially from deepwater wells, allowing the platform to be placed in shallow waters, and for a reduction in the number of platforms, thus simplifying the production layout and reducing the investments.
Within the PROCAP 2000 Program for deepwater technology development, a project was created by the end of 1992 in order to develop such a method.
From the available alternatives, Petrobras selected the Electrical Submersible Pumps (ESP), utilized on and offshore, specially in the eight fixed towers of the North-east Pole of Campos Basin, where a total of a 132 wells have been producing with this method. ESP's presented characteristics to be a potential alternative to meet the enhanced requirements for the production of subsea wells. P. 451^
