The Deepest 100,000 BOPD Floating Production Unit
Authors: Maselli Alfredo S.S. , Arcadier Arnaldo S. , Lima Jorge A.S. , Alencar Marcio F. 
Published: October 2008

This paper presents the PETROBRAS experience in the management of a 'turn key' contract covering the design, procurement, construction, commissioning, testing, pm-operation and start-up of the PETROBRAS XVIll Floating Production Unit.

THE PLATFORM

PETROBAS XVlll is an oil production semisubmersible unit installed in Marlim Field, Campos Basin, offshore Rio de Janeiro State, Brazil, with a throughput of 100,000 bopd. As of the date of its installation (March/94) it is the largest worldwide offshore production platform operating in a water depth of 910 m.

The platform has the following main features:Total length: 101 mWater Displacement at Operation Draught: 36,500tAccommodation capacity: 130 peopleOil Production: 100,000 bopdGas Production: 2,000,000 Ncu.m/dWater Injection: 150,000 bpdMain Power Generation: 2 × 12.5 MWAuxiliary & Emergency Generation: 2.1 MWNo. of Oil& Gas Wells: 16No. of Water Injection Wells 12Total No. of Hanging Lines: 76No. of Mooting Lines 8Water Depth: 910 m

THE BASIC DESIGN

The structural concept of PETROBRAS XVIII Production Platform was based on GVA 4500 Drilling Platform design, which PETROBRAS had already studied when it was its intention to build two drilling units. Owing to market conditions the drilling units were not built, but PETROBRAS acquired good knowledge on the vessel characteristics.

With the need of new production units to exploit the giant Marlim Field, the basic design for a production unit was developed and adapted by PETROBRAS through its Research Centre, who performed all the necessary alterations in the hull and utilities as well as the design of the whole production plant. The alterations in the hull included upper deck extensions, web frame and bulkhead modifications and the creation of a spider deck below the box bottom in the after part. All the necessary structural and naval checks (including fatigue and stability) were performed for the new environmental conditions, weights and respective distributions. A new special mooring design eight lines chain-wire-chain was developed taking into account the sea bed flowline arrangement, fatigue aspects and high horizontal forces.

This work took approximately 20 months (from May/88 to Dec489) and consumed about 118,000 men.hours. Its scope is outlined hereinafter.

The Basic Design was certified by Det norske Veritas (DnV) and its performance, regarding hull and ship service, was followed up by Gotaverken Arendal (GVA).

THE CONTRACTING PROCESS

Taking into account the magnitude of the investment and aiming at increasing the competition, PETROBRAS decided to hold an international call for bids. The call for bids was made on behalf of BRASOIL - a PETROBRAS overseas subsidiary. It was announced in Feb/90 and established a lump sum basis for the future contract. BidDocumentation included the following:Letter of invitation and enclosures;Basic Design;Contract Draft and Annexes.

The Letter of Invitation and enclosures comprised the general procedures for eligibility, technical qualification, presentation of tender. The Basic Design included the hull scantlings with respective plans