Decommissioning project
About the L7 field
Since 1970, TotalEnergies has been a pioneer in offshore developments in the Dutch North Sea.
As one of the first large offshore gas fields on the Dutch continental shelf, the L7 field was for many years a flagship and training ground for generations of offshore workers.
But after over 40 years of activity, the field's production shut down is now offering the possibility for the affiliate to learn how to organize offshore decommissioning and prepare itself for a new future.
The main features of the L7 field are as follows:
- 1 central complex (L7CC) consisting of 4 platforms linked by bridges in the following order:
- 1 well head platform (L7C)
- 1 LQ platform (L7Q)
- 1 processing platform (L7P)
- 1 compression platform (L7PK)
- 6 Satellite (wellhead) platforms (L4B, L7A, L7B, L7BB, L7H, L7N)
- 20 wells of which 6 have been P&A’d between 2015-2016 and 5 early 2023
- 2 wells remain to be abandoned as 2 on L7B are considered retained for CCS
- 16” export pipeline to L10A platform, 9 infield flowlines, 2 infield bundles
Recent history of the L7 field
In 2017, the L7-field ceased production and was pre-abandoned. The aim of that operation was to bring the facilities to an inert and safe state with a minimum visit frequency for a period of 5 years. During this campaign, several operations have been performed:
- Plugging of the remaining wells (suspended) but not abandoned
- Isolation and cleaning of process systems and sealines (pigging campaigns)
- Removal scope of loose / powered / degradable items
- Removal of re-usable items (such as compressors)
- Make platform structure safe for +/- 5 years (fabric works)
- Installation of alternative power supply systems (solar panels / hybrid diesel skid) and compulsory Navaid system
In January 2022, an EPRD (Engineering, Preparation, Removal and Dismantling) call for tender for further removal and dismantling of the structures has been launched, aiming to complete the work by the end of 2024, hence concluding the L7 chapter.
The L7 Site Restitution EPRD project hence entails the complete removal of all L7 field platforms (topsides and jacket) plus the L4-B platform with the exception of L7-B jacket that shall stay in-situ for re-use in a coming CCS project. As part of the site restitution scope, a full removal of subsea structure (unburied pipelines, supporting frames etc.) and proper covering of visible left structures will be performed in the direct vicinity of each platform. The aim is to remediate the L7 seabed for license retrieval.
A contract was signed in Q3 2022, resulting in the selected company for the EPRD (Engineering, Preparation, Removal and Dismantling) project is now responsible for all work required to engineer, procure, prepare, remove, transport, demolish and dispose the platforms and carry out the subsea scope.
What does the L7 decommissioning project entail?
In 2020, TotalEnergies implemented a policy of avoiding, reducing and, where necessary, offsetting the footprint of its operations on the environment and on nature by setting up measures to protect environments (air, water, soil) and sustainability using resources (water, soil).
The L7 Site Restitution project completely aligns with this philosophy, while setting the general recycling rate over 97%. With more than 17.000 Metric tons of waste coming mainly from structural steel, concrete, and marine growth a substantial focus has been set on emphasizing on clean, efficient, and high-tech dismantling processes (e.g. hydro-electric powered steel recycling ovens). The three (3) remaining percentages, being directly related to the complex treatment of Hazardous materials is being addressed, with innovative solution for asbestos, NORM, and mercury contaminated steel. With a yearly dismantling capacity of more than 68.000mT and highly efficient/low emission modern dismantling means, AFEBV (AF Decom Environmental Base Vats) has naturally been selected as dismantling yard.
With regards to the offshore preparation & removal campaigns, once again, focus has been set on choosing the best balance between efficiency and low emission from the Marine Spread. Hence, by selecting a jack-up to perform all preparatory works and a towed sheerleg for topside and jacket removal, effort has been put to reduce the global project footprint.
The L7 site restitution project is a major project and one of the firsts of a kind for TotalEnergies.
The Norwegian company, AF Offshore Decom has been contracted for the engineering, preparation, removal, transportation, dismantling and recycling (EPRD) of 10 production platforms from the L7 field in the Dutch sector of the North Sea.
