Session: 01-04-02 Design and Anaysis - II

Submission Number: 157626

FPSO Vent Post Gas Dispersion Analysis - Alternatives to Minimize Hydrocarbons Return in Critical Conditions 

FPSO Vent Post systems have strong variations in terms of gas flow and concentrations along the offshore asset lifecycle. Therefore, this paper describes a series of CFD simulations in order to evaluate alternatives to improve the gas dispersion efficiency in terms of minimizing the risk of hydrocarbons plume return to the FPSO in unfavorable wind conditions combined with heavier-than-air vented gas compositions. The alternatives are mostly focused on simple modifications so that they may be considered feasible for offshore platforms in operation. Considering the restrictions to implement modifications on operating offshore units, some alternatives were evaluated such as: redirecting the vent nozzles, reduce the gas flow rate, dilute the tanks internal atmosphere with frequent use of inert gas systems and include air blowers next to the vent exit. The configurations were tested in CFD simulations for the most critical environmental conditions, usually related to very low wind speed. Among the considered options, the alternative of using venturi blowers was selected as one of the most promising on and therefore, some configurations of the blowers next to the venting system were evaluated leading to a final configuration that was installed offshore. Field data indicates that the system was able to reduce the risk of hydrocarbon return under critical concentrations and some limitations of the simplifications of standard gas dispersion could be identified.

Presenting Author: Daniel Carvalho Petrobras

Presenting Author Biography: Daniel Carvalho, PhD in Computational Mechanics from COPPE, Senior Advisor at Petrobras Research Center, has been working at the company for 20 years, participating in research projects in ocean engineering, ocean basin model tests, and computational fluid dynamics simulations. Currently, he is part of the conceptual technological design of production systems, with a focus on low-carbon energy supply for offshore assets decarbonization.