Britannia Pre-Drilling Programme Performance : Performance Drilling through Knowledge Management and Supply Chain Integration
Authors: Leiper A. , Robertson J. 
Published: October 2008

The Subsurface & Well Operations Team formed a division of the Britannia Field Development Project, a jointly managed project by Conoco (U.K.) Ltd and Chevron UK Limited. The Subsurface Development plan for the Project called for an extensive drilling program, from two drill sites, using extended reach drilling technology, due to the areal extent of the reservoir. A robust alliance strategy was adopted in the selection and development of a small integrated Subsurface & Well Operations Team, to execute the 17 well pre-drill program. The team was highly focused and intent on producing industry "best-in-class" performance, safely and within strict environmental & well quality targets. An interdependent risk/reward "gainshare" scheme linked delivery of specific environmental, safety, well construction quality and business objectives directly to enhanced profit and underpinned the integrated team ethos of success through cooperation.

Introduction

Although Britannia Field was discovered over 20 years ago, it was not until 1987 the full commercial potential of the field was identified.

The field is situated 210 kilometres (130 miles) north-east of Aberdeen in the UK North Sea and covers approximately 112 square miles kilometres (70 square miles). It underlies a separate oil field, Alba, which was discovered by Chevron in 1984 and has been onstream since 1994. Britannia's reserves of gas and condensate are held in cretaceous sandstone at a depth of around 4,000 metres (13,000ft). Once Britannia reaches full production it has the potential (at 740 million standard cubic feet per day of gas and 70MBPD condensate) to supply around 8 percent of the total UK gas demand at plateau period in the early years of production. Britannia's reserves of 3.1 TCF gas and 145 MMBBL condensate are being developed through a single drilling, production and accommodation platform at the east-end of the reservoir. The platform has 36 well slots and is supported on an eight-legged jacket in 140 metre deep water. There is also a subsea well centre with 14 well slots, located 15 kilometres (9 miles) west of the platform.

When the Britannia field was discovered in the mid-1970's it was given different names by two of the oil companies which held interests in the five seperate licensing blocks it straddled. To Conoco it was Lapworth; to Chevron it was Kilda. Their agreement on the name "Britannia" was to become the symbol of the spirit of co-operation which has underlain the entire development philosophy and which embraces not only the interests of the co-venturers in the field but also the many service providers involved in bringing the project to successful completion. This paper compares the Project Subsurface Division challenges and goals originally envisaged in early 1994 and the results delivered over the subsequent two years pre-drill program leading to first production.

Subsurface Development Plan

One of the key challenges in the early conceptual development studies, was to formulate a viable subsurface plan to economically recover the reserves over the immense field area, whilst minimising facilities and drilling capital costs. Much of the early work done in the subsurface arena revolved around optimum well count and well design, to generate maximum production rates, to support the overall field development economics. Early in 1994 a Field Development Budget of Â£1.85 billion was generated, but failed to meet a revised aggressive economic criteria set out by Co-venturer's as a prerequisite to project sanction. Consequently, each project division conducted a rigorous technical and budget review to identify more cost-effective s