Subsea Facilities: Challenges and Interfaces in Jeanne d'Arc Basin Environmental Conditions
Authors: Tveit Egil , Jordan David , Isenor Randy , McInnes Robert 
Published: October 2008

The Terra Nova project is the first subsea development on the Grand Banks area off the east coast of Canada. The area presents a unique set of challenges such as harsh environmental conditions, risk of damage from icebergs and little established infrastructure. To meet these challenges, an alliance approach was established, creating an ideal environment for an integrated team which produced extremely valuable results through optimization across the areas of FPSO, subsea and subsurface. Concurrent with Design Basis development, field development activities were commenced. This included determination of bottom hole location of the wells, seabed facilities including positions and types of manifolds/templates, flowline choice and protection of seabed facilities to minimize risk from iceberg scour.

Introduction

The Terra Nova Development Project is the second Offshore Development on the Grand Banks situated 350 km East-Southeast of St. John's, Newfoundland. The owners of the Terra Nova field are Petro-Canada (29%), Mobil Oil Canada Properties (22%), Husky Oil Operations Ltd. (17.5%), Norsk Hydro Canada Oil and Gas (15%), Murphy Oil Company Ltd. (12%), Mosbacher Operating Ltd. (3.5%) and Chevron Canada Resources (1%). The project is operated by Petro-Canada in one of the world's harshest environments, which required a fresh look at execution strategy to optimize risked N.P.V. and achieve project sanction.

Additional cost items encountered on this project that are not required elsewhere in the world are a disconnectable turret and submudline protection of the wellhead equipment.

When choosing the execution method, Petro-Canada listened carefully to the industry to learn from mistakes and successes of previous projects. After careful consideration Petro-Canada and the other owners opted for one contract to cover the complete field development from well to vessel offtake.

To achieve this Petro-Canada issued pre-qualification documents in late 1995 to various contracting groups and interested parties. Alliances were formed, pre-qualification documents submitted and ultimately three Alliances were chosen to perform a Design Competition, which commenced on 1st April 1996. This was a six months study culminating in the award of the Terra Nova Front End Engineering Design (FEED) to the Grand Banks Alliance (GBA). The GBA consisted of the following companies; Shawmont Brown & Root, Halliburton, FMC (Including KOS and SOFEC), PCL, Doris Conpro, and Coflexip Stena Offshore (see Figure 1).

Figure 1: Terra Nova Alliance (Available in full paper)

The development scenario consisted of a floating production, storage and offloading (FPSO) system with six wells to be completed for start-up. A total of 24 wells are planned for the full field development along with expansion capability of up to a total of 48 wells (including the Far East, which has yet to be explored). The oil production rate is 150,000 bopd. Details of the development scenario are shown above and in Attachments 1 to 5.

With the award of the FEED contract, the GBA became the Terra Nova Alliance, which now included Petro-Canada and the other owners. The FEED commenced in January 1997 and Sanction was obtained in February 1998 with offshore construction activities commencing during the summer of 1998.