The Internal Corrosion Integrity Strategy on the Development of New Offshore Production Areas in Brazil
Authors: Ferreira Pedro Altoé , Bezerra Marcio  Felix Carvalho , Loschiavo Roberto 
Published: October 2008

This paper illustrates the importance of internal corrosion management and integrity strategy in the development of new offshore production areas at shallow and ultra deep waters in Brazil, where there is no other production facility nearby. Starting production activities in these areas without any facility, especially pipelines, is a challenge as the investment necessary is high, particularly when the first area to be produced is a gas block. The financial feasibility of a small or medium size gas field with very low condensate production is extremely delicate as such kind of project usually demands high initial investments, particularly with topside facilities, platform structures and pipelines.

The scenario worsens as the first investment should consider not only the area to be put in production but also other potential nearby areas with exploration still underway. To foresee fluid composition and all flow parameter scenarios is a complex but necessary exercise to reduce risk and keep the OPEX as low as possible.

One of the aims of this paper is to show Petrobras experience in the design of offshore gas fields in the shallow waters of EspÍrito Santo - Brazil, where pipeline corrosion management and integrity strongly affected the CAPEX and OPEX factors as its flow rate capacity was over designed to transport future production from adjacent fields. This Paper discusses issues related to the CO2 corrosion risk assessment and the integrity strategies as some of them are new in Petrobras.

Regarding the ultra deep water fields, the paper also briefly discusses some current key issues related to areas of uncertainties due to internal corrosion, like pipelines operating under super critical flow and steel catenary risers under corrosion-fatigue environment.

Introduction

This paper highlights the importance of pipeline corrosion management and integrity strategy in the development of new offshore production areas in Brazil.

In the last years, Petrobras found gas and light/heavy crude fields in new offshore areas in shallow and deepwater depths without any other production facility nearby. Starting production activities in areas without any facility, especially pipelines is a challenge as the investment necessary is high, particularly when the first area to be produced is a gas block. The life cycle cost of marginal gas fields with very low condensate production is extremely delicate as such kind of project usually demands high initial investments, particularly with top side facilities, platform structures and pipelines which should be compensated by the gas market potential consumption needs and its tariffs which are usually low.

The scenario becomes more complex as pioneer projects should contemplate the opportunity to produce not only the block with known and proven reserves but also potential vicinity blocks with exploration still underway as we can see today in new offshore areas in Brazil and West Africa. It is very important because pioneering projects can have a significantly positive effect upon operators future spending plans. The project should consider in some cases to build oversized pipeline and separation facilities considering the opportunity of production of part of the reserves from these vicinities areas. One alternative usually done by operators is to cut investment cost reducing platform structure and topside facilities sending all production to shore under corrosive multiphase flow where treatment facilities are installed.