North Sea database lists toolsets needed for legacy well P&A

Britain’s North Sea Transition Authority (NSTA) has unveiled its new Tree and Wellhead Information for Subsea Tooling (TWIST) database at the Offshore Decommissioning Conference in St Andrews, Scotland.

This database is designed to help oil and gas companies improve planning for their decommissioning projects and track down potentially hard-to-find tools.

The NSTA developed the pilot version using data on 423 wells supplied by bp, CNR International, Harbour Energy and TAQA, with further input from the Well Decommissioning Steering Group, part of the Wells Task Force.

Wellhead and christmas tree systems come in different shapes, sizes and ratings, and specialist tools are needed to decommission different equipment.

Operators have a legal obligation to fully decommission and seal wells post-cessation of production. Progress has been slow in some cases due to a lack of available technical information on well architecture and tool accessibility constraints.

TWIST provides verified subsea data, including the location, ownership, age and status of wells, as well as the type of wellhead and/or christmas tree installed. It also lists the equipment maker and manufacturer history.

These details can be hard to obtain in fields where ownership has transferred. According to the NSTA, operators can use the information to find what they need, identify others operating wells constructed using the same equipment, then propose a joint multi-well P&A campaign.

TWIST is also said to help operators and suppliers determine whether their existing tools are suitable for future decommissioning projects, rather than having to order new ones.

Next year the NSTA will look to add more operators’ data on subsea wells, christmas trees and tooling, and publish an inventory of available tools under a second development phase, aiming to deliver further efficiencies.

Pauline Innes, NSTA director of supply chain and decommissioning, said, “Operators have told us a lack of visibility of subsea infrastructure and tooling data is holding up their efforts to decommission wells in a timely and cost-efficient manner—an unacceptable situation.”