ST JOHN’S, Canada — The Canada-Newfoundland and Labrador Offshore Petroleum Board (C-NLOPB) is seeking feedback from the public on Cenovus Energy’s planned use of standalone subsea trees (SA XMTs) in the White Rose and North Amethyst fields offshore Newfoundland.
Cenovus, as operator of the White Rose project, plans to use this concept to mitigate the risk of icebergs impacting the subsea wells.
The White Rose Field in the Jeanne d ‘Arc Basin, which started production in 2005, was developed with an FPSO and subsea wells, with further subsea tiebacks added later to the infrastructure.
The subsea drill centers employed excavations in which the wellheads, manifolds and xmas trees were placed to safeguard against iceberg contact. At present, the White Rose development has five excavated drill centers (EDCs), joined later by the North Amethyst drill center and the South White Rose Extension.
According to Cenovus’ amended development application, EDCs were excavated to a minimum calculated depth to reduce the possibility of damage to the critical equipment. The SA XMT concept is said to provide the targeted level of environmental protection by placing an additional set of engineered barriers deep within the well.
These additional downhole barriers replace the barriers in the XMT as the equipment critical to preventing an environmental release. The depth inside the well is said to be sufficient to ensure that the forces from an iceberg contacting the XMTs have no impact on their integrity.
Cenovus has assessed use of the concept in a variety of sizes and water depths, based on engineering analysis and iceberg data compiled from decades of continuous offshore operations.