Griffin - A State-of-the-Art FPSO and Some Thoughts on FPSO Trends in Australasia
Authors: Hunter K.C. , De Souza P.M.F.M. , De Souza P.M.F.M , Carra C.J. 
Published: October 2008

The Griffin field was developed using a state-of-the-art Floating Production Storage and Offloading facility (FPSO). The field development was complicated by the fact that there were three fields, Griffin, Chinook and Scindian to bedeveloped and that within each field there were two separate and distinctly different producing formations, The subsea configuration was therefore aimed 'at permitting the tworeservoirs to be depleted independently and with high reliability. The FPSO was designed to be capable of producing 12,720 m3day of stabilised crude, Unlike previous FPSO projects, where the gas has been flared, Griffin gas is treated offshore to produce a sales gas stream having a hydrocarbon dewpoint of -5ºC and a water dewpoint of -30ºC. The emergence of tougher environmental and safety rules Icd to the decision to build a so-called double-hulled vessel. The mooring system is an enhanced disconnectable riser turret type nd was engineered and designed by BHPP. The swivel stack is the most complex produced by BHPP to date and comprises 4 × 6 inch and 2 × 10 inch paths as well as an electrohydrauliccontrol swivel. First production was achieved 22 months after project approval. Governments are placing anincreased emphasis on the recovery of associated gas and future developments being planned may see the introduction of simultaneous production of crude and LPG/methanol.

INTRODUCTION

BHP Petroleum has been a pioneer in the use of FPSO echnology in Australia. Since the discovery of Jabiru in 1983, the company has installed four FPSOS each of increasing complexity and capability. The latest development Griffin isa further step along the path towards complete oilfield development using a floating production unit. Australian conditions are somewhat different to other producing areas and present the developer with both challenges and opportunities:The reservoir quality in Australia is generally excellent. Recoveries of greater than 50 percent of the oil-in-place can be achieved with relatively few wells.There is little infrastructure offshore, Bass Strait excepted, therefore developments must be 'stand-aloneâ??.Crude parcel sizes of 650,000 BBL (100,000 m3) are required for economic marketing.Environmental conditions can be severeThe reservoir size is generally small.

The FPSO provides an excellent method of dealing with these conditions in a cost effective manner.

The Griffin Field complex consists of three separate accumulations, at Griffin, Chinook and Scindian. The discovery well Chinook-1, was drilled in 1989. Further appraisal wells were drilled on the Griffin structure and at Scindian by which time it had been established that the field was commercially viable.

There are two quite distinct reservoirs in each field. The upper Birdrong formation is the poorer of the two being characterised as having 15 percent porosity and an average permeability of 30 millidarcies (mD), The lower, the Zeepard formation, is a high quality sand unit having porosity of 17percent and permeabilities in excess of 1,000 rnD. There are two quite distinct reservoirs in each field. The upper Birdrong formation is the poorer of the two being characterised as having 15 percent porosity and an average permeability of 30 millidarcies (mD).