PETROBRAS pioneered the use of subsea electrical submersible pump (subsea ESP) through a successful prototype testing in the subsea well RJS-221, back in 1994. Following its excellent results, three others applications, in successively more difficult scenarios, have been installed. The first was in deep-water, installed in 1998, that operated flawlessly for almost four years; the second, in shallow-water, which after premature failures and appropriate corrections is now working; and the third, handling viscous heavy crude (17° API) multiphase mixture in deep water, is still running.
This paper describes the PETROBRAS stepwise technology development on subsea ESPs and the operational experience gained with these four applications. The several technical challenges that were overcome, and the current status of technological development, for using it even greater water depths, higher horsepower, increased levels of gas handling, longer running life, dealing with heavier crude oil, together with and lower replacement costs, are presented.
As the majority of the Brazilian petroleum reserves are located in deep-waters, a large effort has been expended in researching and developing equipment for submarine exploration in this country.
Historically, the Brazilian company Petróleo Brasileiro S.A. (PETROBRAS) has successfully improved its ESP installations in the Campos Basin. The company's deepest submarine well installation, the RJS-477, which is now not in use, is located at a depth of 1109 m, and was able to produce 600 m3 of oil per day with 40 % of free gas. Since the pioneer submarine well RJS-221, considered the first submarine well in the world to operate with an ESP equipment in deep waters, the company has been planning to install more than 20 deepwater wells with ESP assemblies.
Within the context of producing oil in wells located in ultra-deep water, PETROBRAS is commited to develop an oversized electric submersible pump (ESP) installation. This ESP installation will involve a high-powered motor (>1000 HP) for pumping more than 2000 m3 of heavy crude per day.
The scope of the PETROBRAS research program, for developing oil production in ultra-deep waters, PROCAP 3000, includes a new research and development project to improve the achieved ESP deep-water equipment specifications. However, although the focus of this PROCAP 3000 project is on ESP pumping equipment, the technology developed will be equally relevant to any situation where it is necessary to install any other artificial lift equipment located in ultra-deep wells. Due to the need of producing heavy oil in deep-water submarine installations in the Brazilian Basins, new standard levels have to be achieved by PETROBRAS, which has been the main commitment of its PROCAP 3000 program.
As interventions in the submarine wells involve a costly and time-consuming exercise, an ESP equipment with a highpowered motor (>1000 HP), installed in ultra-deep waters, has to be more dependable than the existing ones.