Market: Oil and Gas 
Scope of Work: Transport and installation of L-13 monotower
Location: Dutch sector North Sea
Client: Nederlandse Aardolie Maatschappij
Period: May 2017
HLV: Rambiz

The L13-FI-1 project is located in the NAM Onegas Asset in the Dutch sector of the southern North Sea in license Block L13.

The L13-FI-1 platform comprises of a new monotower installation with a 7km 12” sub-sea tie-back to the existing K15-FA-1 platform. Flow assurance will be provided by injection of KHI and CI, where KHI will be supplied from the K15-FA-1 platform via a 2-inch piggyback pipeline. The monotower comprises of a 4-deck structure located on a large diameter column and connected to the seabed with a driven pile.

Scaldis Scope

Scaldis was contracted for the complete transport and installation scope of the L13-FI-1 monotower.

The monotower consisted of 3 structures: a pile, a column (transition piece) and a topside. All structures were transported to the field on a barge that was delivered to the fabricator’s yard in Rotterdam.
First the pile was driven into the seabed with a Vibro Lifting Tool up to 6 meters before target penetration, final depth was reached by piling with an impact hammer. The vibrohammer was also be used for lifting and upending the pile from the barge, so no specific lifting and upending tool was required. Acting as a clamping device as well, there was no need for a gripper frame nor subsea template to position and hold the pile, which would be required when working with a conventional impact hammer. Verticality of the driven pile was well within tolerance.
After pile installation, the column was subsea stabbed into the pile sticking out from the seabed. Finally the topside was placed on top. Both interfaces (pile-column and column-topside) are grouted connections, grouting activities were executed in one campaign after topside installation. During grout curing various completion works were executed, e.g. installation of navigation lights.

Equipment

HLV Rambiz
AHT Multratug 4
Cargo barge, UR901, with tug, Mustang
CAPE vibrohammer, CV-960 VLT-U
Menck impact hammer, MHU 1200S