East Sean

Location

The East Sean field is situated approximately 94 kilometers east of the UK coast, within Block 49/25a of the Southern North Sea (SNS) gas province on the UK continental shelf (UKCS).

History and Production

The Sean gas field, including the East Sean field, was discovered in 1969 and has been in production since 1986. The field is nearing the end of its productive life, prompting the initiation of decommissioning activities.

Ownership and Operation

One-Dyas UK, a subsidiary of the Dutch exploration and production company One-Dyas, holds a 50% interest in the field and serves as the operator. The remaining interest is held by Rockrose UKCS15 (formerly known as SSE E&P UK).

Infrastructure

The Sean gas field, which includes East Sean, is developed with three platforms:

• Sean Papa Infrastructure: This includes a wellhead and compression platform (PD) and a production and accommodation platform (PP), interconnected by a bridge.
• Sean Romeo (RD): A not permanently attended installation (NPAI).

Field Details

• East Sean, North Sean, and South Sean: The Sean gas field comprises these three separate fields.
• Platforms: Sean PD features ten well slots, with eight currently producing, while Sean RD has six well slots, with two in production.

Production and Export

• The gas produced from the Sean field, including East Sean, is transported to Shell UK’s Bacton Terminal in North Norfolk, UK, via a 106.5 km long and 30-inch diameter gas export pipeline named PL311.

Decommissioning

• The decommissioning program includes the removal of the three fixed steel platforms, associated subsea infrastructure, and related pipelines.
• The topsides and substructures of the platforms will be completely removed and transported onshore for dismantling, recycling, or disposal. The substructure piles will be cut 3 meters below the seabed before removal.
• The PL310 pipeline and the onshore section of the PL311 pipeline will be decommissioned. The wells will be plugged and abandoned in compliance with guidelines issued by Oil & Gas UK.

Timeline

• The cessation of production is expected by 2025, while the decommissioning activities are scheduled to be completed by 2029.