Detecção de alagamento de anular em dutos flexíveis usando a técnica de transmissão da radiação gama

Abstract

Flexible pipes are modular constructions made up of several layers. They are broadly employed in oil & gas industry, playing an important role in the Brazilian Pre-Salt production. The seawater ingress in some parts of this pipes structure’s can significantly reduce their service life, especially due to a mechanism known as CO2 Stress Corrosion Cracking (SCC-CO2). Therefore, it is very important to provide an inspection tool suitable for submarine use in order to detect annulus flooding before the failure of the flexible pipe. In the scope of this thesis, an inspection tool based on the gamma radiation transmission was developed, which was designed in partnership between PETROBRAS and the Federal University of Rio de Janeiro, focused on detecting flooding condition and with real possibility of overcoming the limitations of other inspection tools available in the market. The approach focused on counting the number of photons whose energy intensity corresponded to the photopeak of 137Cs, focusing on an array of CsI(Tl) detectors after interaction with the annular region of the pipe. The reliability of this solution was statistically evaluated, showing that none false calls was reported in the last tests of deployment of the tool for shallow water inspection.Também disponível on-line.