Gryphon Field Development Overview
Authors: Phillips D.R. , Doble P.A. , Knight S.J. , Baxter R.M. 
Published: October 2008

The Gryphon 'A' Floating Production Storage and Offtake (FPSO) facility has been on location in United Kingdom Continental Shelf (UKCS) block 9/18b since 23 September 1993, and on production since 14 October 1993. This first oil date was less than 10 months from UK government approval for the project, a record for a North Sea oil field development.

Production to the FPSO is via a subsea well cluster 1 mile to the south west. Most of the producing wells will have horizontal completion intervals. Peak production of 55,000 BOPD is expected during 1994.

This paper summarises major aspects of the development history of the Gryphon field from discovery in 1987 to current production performance. The evaluation work to optimise the development concept, reduce costs and maximise hydrocarbon recovery is described.

This paper also sets the stage for five other papers (References 1 to 5:Available in full paper) that deal in detail with important individual components of the development.

INTRODUCTION

From early in the appraisal programme of the Gryphon reservoir it was realised that the geological complexity and reserves uncertainty made the economic risks associated with development in the hostile North Sea environment significant.

The objective of the Operator and its Partners was to perform all the technical and commerical evaluations necessary to achieve a low risk, profitable venture. This has been achieved by integrating a philosophy of innovation, flexibility and plain hard work into the reservoir and hardware design, fabrication, hook up and commissioning, drilling, and operational aspects of the project. It is anticipated that these efforts will result in development costs not exceeding US$ 4.50 per barrel versus US$ 6.00 + estimated utilising conventional development alternatives.

The success of the Gryphon Field development is due to a number of creative and progressive accomplishments in the areas of petroleum engineering, horizontal drilling, subsea and floating production technology, and project management strategy. Another contributing factor has been the reduced time from project approval to first oil versus conventional North Sea developments, Conventional schemes delayed first oil to late 1995 or 1996 versus the actual October 1993 start-up. A final essential factor in the success of the development was the close working relationship between the Operator and Partners and relevant Government agencies, which facilitated rapid rapid decision making and approvals.

This paper provides the overview for the development while five associated papers present specific aspects of the project:Gryphon 'A', The First Purpose Built, Permanently Moored FPSO in the North Sea (Reference 1).The Project Management Execution Strategy and Outcome (Reference 2).Water Injection: First North Sea Application of Reinjection of Produced Water Supplemented by an Overlying Aquifer (Reference 3).The Spool Tree: First Application of a New Subsea Wellhead Tree Configuration (Reference 4).Drilling and Completion Design (Reference 5).

These papers highlight the innovative nature of the development and the significant contributions to offshore production technology and project execution procedures that have been made.