Campos Basin: Challenges Still to Overcome
Authors: Minami Kazuioshi , Almeida Alberto S. , Diniz Maurício A.C. , Palagi Cezar L. , Assayag Marcos I. 
Published: October 2008

Petrobras stepped into the third millennium with an ambitious plan for offshore oil production. As a natural sequence of the most recent breakthroughs achieved in deep and ultradeepwater activities, Petrobras now prepares itself to operate in an even more difficult scenario in Campos Basin: deeper water, up to 3,000 m (9,800 ft), with heavier and more viscous oils.

The increase in the ocean depth where it operates will bring challenges in the areas of drilling and completion, naval structures and mooring, risers and flowlines, and subsea equipment. Because of the heavier and more viscous nature of the crude oils found in this environment, several other aspects will have to be addressed: well completion technique aiming t increasing per well productivity, i.e., longer horizontal wells with larger borehole diameter, and sand production control, improved flow assurance technique and artificial lift to deal not only with hydrates and waxes, but also with stable emulsions and ultra-viscous fluids in the subsea production systems.

Several fields already in production are or will soon be in mature phase, when substantial water production is expected. Also, the productivity of the fields will decrease, making harder to keep the production profitable for long time. This article describes the Petrobras plan to face each of these new challenges. The ultimate goal is to develop production systems capable of making profitable the exploitation of heavy oil reservoirs in ultra deep waters, in spite of tougher production conditions.

Introduction

Campos Basin production history dates back to 1977, when the first subsea production systems were put in operation. Details can be found in reference [1]. Since the very beginning, the technological challenges to produce the discovered fields were significant. Sea depths of 120 m (390 ft), considered deep then, already posed huge efforts for Petrobras. Innovative concepts such as the atmospheric pressure wellhead cellars and manifolds, and all subsea systems were examples of novel technologies tried out in Campos Basin.

Through the implementation of aggressive R&D programs, such as PROCAP and PROCAP-2000, Petrobras was able to design, construct and build production systems using high-tech and innovative solutions to operate in Campos Basin, in water as deep as 1,870 m (6,100 ft), before the end of the 20th century.

Many fields such as Marlim, Albacora, Barracuda andCaratinga were developed using the technologies resulted from the PROCAP effort. Several of these offshore fields are now entering advanced production phases, in which, an expected larger amount of water are to be produced, bringing a new set of problems to be dealt with.

With its continued effort to expand business in Brazil, the Company still holds considerable portfolio of fields to be developed, with large proven reserves. Roncador, Marlim Sul, Marlim Leste, Albacora Leste and Jubarte are examples of fields under development. They all lie in deep and ultra-deep waters, and hold relatively heavy (less than 19° API or viscosity higher than 10 cP @reservoir) crude oil.