Innovations in a floating production system for optimizing costs

Allan Carre de Oliveira, Luiz Augusto Petrus Levyand, Eduardo Marçal Vilamea (Petrobras), Felipe Ruggeri (USP)

CHALLENGE - Developments for a ship-shape type floating production system to minimize installation and operating costs for a scenario at the Polo pre-salt Santos Basin. Here, there are economic advantages using large diameter rigid lines for oil production and also requirements about oil treatment which increases the process plant weight and area at the production unit. To deal with these new requirements, a model approach has been developed.

SOLUTION - The concept is designed to operate with a large diameter free standing steel catenary riser connected to a structure that may be disconnected from the hull. The possibility of disconnection allows the assessment of this solution in other harsh environmental scenarios, like hurricane areas, where the possibility of disconnection is required or an advantage in terms of safety. The hull form is designed using an optimization process with genetic algorithms that took into account 7 parameters, having analyzed thousands of possibilities in the proposed scenario, focused on the minimization of steel weight in order to consequently minimize the platform construction cost. Based on this solution, hydrodynamic analyses were performed to check the interference effects between moonpool and the riser support buoy inside the moonpool. The optimization flow was implemented in modeFRONTIER software. 

BENEFITS - Based on the optimization results, the design of seven days was considered the optimal solution for the hull configuration, the schematic view seen above. The use of a very small vertical motion floating production unit increases the possibility of subsea system configurations, allowing cost effective solutions. The disconnectable buoy also contributes to economical advantages.