Technical Challenges of Opening the Atlantic Frontier
Authors: Ball Ian G. , Brookes David A. 
Published: October 2008

The deepwater at and beyond the margins of the UKCS West of Shetland Islands, presents a most demanding set of technical challenges to oilfield development. The paper gives an appreciation of the dominant environmental characteristics, including thecomplex high currents which affect all activities in the area.

The Foinaven and Schiehallion reservoirs are relatively shallow and thin, with large area extent, necessitating multiple drilling centres. The crudes have relatively low API gravity and low GOR, and the low reservoir temperature presents particular challenges for wax management at the low seabed temperatures.

The large wave response motions of floating production and construction/support vessels, combined with the high and variable currents, create diffilcult conditions for design, tie-in and operation of flowlines, flexible risers and umbilicals. This paper reviews these challenges and the solutions for the selected options of FPSOS and subsea systems for the Foinaven Development.

Introduction

With discovery of potentially commercial hydrocarbons in the Foinaven field during 1992, the race was on to define, design, and execute a development plan which would achieve the full commercial potential of the deepwater find. There were no precedents on the UK Continental SheIf for this kind of new-frontier deepwater development, so BP and Shell needed to draw upon their own international experience, and that of the contracting sector of the industry, to identify the concepts, technologies and execution approaches which could best deliver the necessary business results for all participants.

In order to set an operational experience and reservoir knowledge baseline from which to achieve this ambitious programme, it was imperative to proceed with the Foinaven development as rapidly as safely possible. This led to adoption of the ‘parallel engineering’ approach, whereby definition of the various elements of the project evolve in parallel with maximum possible cross-discipline communication and co-operative teamwork from start to finish, rather than the more conventional sequential approach. The uncertainties inherent in this fast-track parallel engineering approach demanded incorporation of maximum justifiable flexibility in the evolving engineering solutions, these options having to be maintained for as long as possible. Whilst the reserves were judged early on to be significantly higher than the current average for North Sea projects, it was clear that development costs would have to be very carefully controlled.

An overall Finding and Development cost in the range US$4 - 5 per barrel was established as the target to be achieved for development to proceed, together with a Lifting cost target of US$2 per barrel. This required an innovative attitude to be adopted by all concerned, and led not only to establishment ofclose-knit Alliances with inherent regular internal challenging of all costs, but also to a drive to access selected lower cost safe technologies, even where these may not actually be fully field proven at the time of commitment.