Abstract
This paper explains the efforts to assess the integrity status and to extend the life of the subsea system connected to a Floating Production Storage and Offloading vessel (FPSO) moored offshore in Brazil, at 700m water depth, set up in 2003 as the first IOC operated assets in Brazil.
The work performed covered the assessment of flexible risers, flowlines, umbilicals and rigid gas export line, comprising studies on operational history, simulations, in-loco special inspections (AUT, EMAT and Direct and Indirect flexible riser tensile armour inspections) and actual FPSO and risers' movement monitoring. Subsea equipment as Christmas trees, manifolds and PLETs were not included, as design life was sufficient.
The results found that some equipment was in remarkable good shape, whilst others had compromised integrity. Assessments demonstrated that some METOCEAN and motion data for the FPSO, utilized during the design phase, were non-conservative when compared to the real case, which led to under design of risers' fatigue life. In-loco verification of some equipment integrity revealed damages, probably related to fatigue associated with corrosion.
Improvements on the existing system and new monitoring techniques applied to the field, to assure safe operations past its original design life, are also depicted.
The work performed was pioneering on life extension of a subsea system for a field operated by an IOC in Brazil and can contribute to other operators facing ageing assets in the country.
