Recycling of a major Dutch gas field

In the autumn of 2022 AF Offshore Decom signed a major contract for the removal and recycling of installations for a new customer, TotalEnergies EP Nederland. The L7-field consists of ten production platforms in the Dutch sector of the North Sea. The total weight of these installations is around 17.500 metric tons, and the objective is to recycle 98 % of all materials. The structures will be prepared for removal and lifted by selected, fit for purpose vessels from the local supply chain. They will be transported to the purpose-built recycling facility for oil and gas infrastructure, the AF Environmental Base Vats in Norway.

The Dutch L7-field represents the beginning of the Dutch petroleum industry. The field was built between 1975 and 1989 consisting of a “Central Complex” and surrounding satellite platforms.

In addition to be the first contract for a new customer, the scope also includes installation work and preparations for redevelopment of infrastructure for the future use for carbon capture and storage (CCS). The infrastructure will be a part of a study for the industrialization of carbon capture and storage in abandoned gas wells.

"TotalEnergies EP Nederland and AF Offshore Decom have a common ambition to deliver a sustainable project that is cost- and energy-efficient, safe and predictable. As vessel independent, we have shown that we find competitive fit-for purpose solutions. We have a dedicated team that has worked thoroughly with preparations where we have also benefited from new technology. This has shortened the time between contract signing an execution," says Alice Andreassen, Project Director of AF Offshore Decom.

AF Offshore Decom has performed most of the preparations with its inhouse competence, with the purpose to validate the methods and select vessels that are fit-for-purpose. The preparation includes subsea work which is performed from an OCV with Remotely Operated Vehicles. In addition, 3D-scanning is used as a part of the Engineering.

In April, the team mobilized to carry out the actual preparation and removal work offshore. We are about forty people from subcontractors and our own employees who will initially travel to the field from the port in Teesport, UK, says Jeroen Wiskerke, Project Manager in AF Offshore Decom.

Heavy Lift Vessels have been most commonly used to install and remove similar structures in the North Sea. AF Offshore Decom has - as a vessel independent player – chosen for different vessels that are fit for purpose for the different stages in the project. The structures will be transported to the Dutch Coast where they will be set down on a prepared barge. The next step is to transport the structures to our own environmental yard for safe and environmentally friendly dismantling, says Jeroen.

The L7 field was one of the first major offshore gas fields on the Dutch continental shelf. Initial discovery occurred in the late 60’s and development of various reservoirs took place throughout the 70’s and 80’s. From 15 production wells the field produced over 21 billion m3 of natural gas (~140 Mboe) with a recovery factor of >80%). After 40 years of operation the facilities ceased production in 2017. With a 54 bed living quarters, the Central Complex had been key in the company’s operations and a second home to many for decades. Following de-energizing and cleaning the facilities were left in a hibernated status waiting for either removal or redevelopment.