Tanker-Based Floating Production: Startup and Operational Experiences With FPSO II Over the First 18 Months
Authors: Scoles Lee , Quigley Norman , Sozonoff S.S. 
Published: October 2008

An integrated tanker-based floating production, storage and offloading facility, FPSO II, started operation in August, 1981, in 90 meters of water in the Cadlao Field offshore Palawan Island in the Philippines. The FPSO is owned and operated by Terminal Installations, Inc., under contract to AMOCO Philippines Petroleum Company, Production is from two subsea wells located about one mile from the FPSO.

FPSO II consists essentially of a 127 000 dwt former trading tanker permanently moored by the stern to a single buoy storage (SBS) single point mooring system. Processing and gas flare equipment are installed on the vessel's main deck. Produced crude is stored temporarily in the vessel's holds from which it is periodically lifted to export tankers, A complete technical description of this unit has been presented in OTC paper 4274 (May,1982).

After 18 months of successful operation it may be concluded that a tanker-based floating production unit can provide an economic and reliable method of exploiting marginal offshore fields.

This paper describes the experience obtained during commissioning and subsequent operation of the mooring system, vessel production and offloading facilities as well as auxiliary machinery and equipment.

INTRODUCTION

The floating production storage and offloading unit FPSO II is a converted 127 000 dwt oil tanker permanently moored in a 90m water depth by means of a single buoy storage (SBS) system (Fig. 1).

The production equipment having a design capacity of 30 000 b/d is fitted on elevated platforms above the main deck of the tanker (Fig's 2 & 3).

Offloading into shuttle tankers of up to 100 000 dwt is achieved by a tandem mooring system employing a single 12-inch floating hose for crude transfer. A supply vessel is maintained permanently on-site to assist in mooring and standby support.

A crew of 53 persons reporting to the FPSO II superintendent is permanently on board to operate and maintain the unit. Crew changes are effected by helicopter

MOORING SYSTEM

Bearings/Hinges:

The relative motions between vessel, yoke and buoy are accommodated by means of:One large diameter roller bearing for the weathervaning of the vessel in a horizontal plane around the buoy.Two hinges between the tanker and SBS yoke for pitch in the vertical plane (Fig. 4);One thrust bearing, restricting lateral motions due to roll.

The hinges and thrust bearing are of the permanent self-lubricating type, ie. bronze bushes having honeycomb surfaces filled with a solid lubricating epoxy base material. The journals are inconel clad. The hinges require no maintenance except periodic inspection and greasing of the seals to prevent ingress of seawater into the bearings.

Thrust bearing maintenance consists of periodic clearance measurement. Shortly after commissioning and again, after eight' months operation, this clearance had to be readjusted. The adjustment is relatively simple when done during calm weather.

Chains

The FPSO II is moored by means of six 6-inch diameter chains. On the buoy end, the chains are secured in chain hawse/stopper arrangements.