L7 Decommissioning Project
INTRODUCTION
While TEPNL's production is mature and steadily declining, new challenges and opportunities are arising for the company for the next decades. One of these challenges is decommissioning which starts with the L7 Site Restitution Project. After over 40 years of production and 5 years of pre-abandonment, the time has come to prepare for the final abandonment, removal, and recycling of the remaining wells and facilities.
Where we have some limited experience in well abandonment in 2015-16, the removal and disposal scope are completely new to TEPNL. TEPDK has some relevant experience with this scope as part of the Tyra redevelopment project, but generally there is a lot of unpaved road to cover. There are some very specific aspects in the decommissioning of these aged platforms in both the HSE and technical fields.
This website aims to give a short but comprehensive overview of the project and its objective, scope, timeline, challenges and organization.
DESCRIPTION OF L7 FIELD
The L7 field is composed of a central complex L7-CC with four platforms: L7-PK, L7-P, L7-Q and L7-C. This main complex was the central hub for the L7 field including gas treatment and accommodation facilities. L4-B, L7-A, L7-B/BB, L7-H and L7-N are satellite platforms, linked to L7-CC by pipelines. Special attention must be taken to L7-B/BB platforms, which are being considered for re-purpose for CO2 storage as part of the ARAMIS project.
HISTORY
After obtaining the exploration license in 1968 for the L7 field, and discoveries in the early 70's, TotalEnergies, Petroland B.V at the time, began construction of the production sites L7CC and L7B. First gas extraction began in 1977 and in the following decade the field was further developed with additional satellite platforms and the compression platform L7PK.
P&A CAMPAIGN 2015
Driven by the availability of a drill-rig, a plug & abandonment campaign was executed in 2015/16. 6 out of the 11 L7 wells were safely and permanently abandoned i.e.: L4-B1, L7-A1, L7-B5, L7-B6, L7-N1 and L7-N2.
PRE-ABANDONMENT 2017
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
- 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
ENGINEERING, PREPARATION, REMOVAL & DISPOSAL (EPRD)
A call for tender for the removal and disposal of the L7 facilities is currently ongoing. The scope has been divided into 4 work packages.
WORK PACKAGE 1: L7CC
This scope covers the preparation, removal, transport, load-in and disposal of the 4 L7CC platforms L7C, L7Q, L7P and L7PK and 4 associated bridges.
WORK PACKAGE 2: L7B/BB
This scope covers the preparation, removal, transport, load-in and disposal of the L7B topside + L7BB platform and 1 bridge. The L7-B jacket and wells will stay in place for ARAMIS CCS project, hence are not part of this scope
WORK PACKAGE 3: SATELLITES
This scope covers the preparation, removal, transport, load-in and disposal of 4 satellite platforms: L4B, L7A, L7H and L7N.
WORK PACKAGE 4
The Scope of Work for Work Package 4 covers the preparation, removal and disposal of the subsea asset around the platforms of the L7-field. This comprises, but is not limited to Pipelines removal from jacket to burial point
- Anti-scour frame / foundation piles removal
- Any subsea skid removal
- Mattresses removal, depending on their integrity
- Debris removal 500m around platform
L7-B RE-USE
As part of the ARAMIS project for Carbon Capture and Storage (CCS), L7-B is being considered for re-purpose as a CO2 storage facility. Accordingly, Work Package 2 not only includes L7-B topside removal, but also the installation of a new topside module, designed according to the CCS project demands.
An overview of the work to be done on L7-B is illustrated above. All 4 topside modules need to be removed completely, with particular caution for the removal plan of module B1 since the wells need to be carefully protected during lifting operations. Re-installation of a brand-new supporting frame is planned to strengthen the structure and support the wells. The solar powered NAVAID system will be re-installed, and the site will be ready for further re-development by the ARAMIS project.
PLANNING
A rig tender for the plugging and abandonment (P&A) works was launched, ahead of the facilities scope, in 2021. An award is at hand, and the actual work should start during the course of 2022 and finish before end of 2022 to avoid a conflict with the removal activities.
The L7 pre-project was completed by late 2021, with an approval to proceed to the facilities removal tender phase. The call for tender for the facilities removal was launched early 2022. The goal is to award in summer 2022 and to start engineering works shortly after. This should allow the offshore execution to start in Q2 2023 with an execution window until end of 2024.
Due to a large Seagull colony on L7B, removal will be executed at the end of the campaign in winter 2024/25. As such, their breeding season is not disturbed and a potential shift of the colony to any other L7 asset is avoided.
TEAM
The decommission works are supported by a lot of people within TEPNL, and it is impossible to list all of them. A few key players
- The drilling and wells Department with Saskia SCHILS, Evgeny DOBRYNIN, Lars JACOBS and others
- The DEP Decommissioning Department with Arnout VAN DER POL, Norbert VAN-DEN DRIES, Arthur BOULEAU and Robert PLUIM & Kim JACKSON from the Engineering department
- Coen LUIJDENDIJK & Annie BERVELING-TAN from CPD
- Tom vd KAMP and Gerry VAN DER MEIJDEN from HSE,
- and many others
NEWS SECTION
- Monday January 17: Launch of the call for tender for the L7-field decommissioning campaign