The largest structure of the Mariner subsea scope, the pipeline end manifold (PLEM) stopped all traffic in Larvik, Norway as it was transported from the fabrication yard. The subsea steel structure stands 4 metres high, 16 metres long and weights 130 tonnes equivalent to the weight of ten S-92 helicopters.
Up to 65 road signs, lamp posts and other obstacles had to be cut down in advance to make way for the massive construction.
The Mariner field is developed with a production, drilling and quarters platform (PDQ) and only dry wellheads. All wells are to be drilled through well slots on the platform. Despite this, the field development includes an extensive subsea installation scope.
Pipelaying for the Statoil-operated Mariner field on the UK Continental Shelf (UKCS) started Monday 8 June.
Around 40 kilometers of pipelines for gas, oil and diluent will be installed on the seabed from pipelay vessel Seven Navica. A new pipeline end manifold (PLEM) will be installed approximately 33 kilometres east of Mariner. This manifold will be the tie-in point for the gas import pipeline and also provide tie-in options for possible future projects in the area. A subsea safety isolation valve (SSIV) will be installed close to the Mariner A-platform.
The PLEM and the riserbases will be installed in August. All tie-in spools and glass reinforced plastic covers will be wet stored as the last operation in the 2015 campaign.
The subsea work will pick up again in 2016, for installation of the subsea safety isolation valve, flexible risers, tie-ins and pre-commissioning. Finally, the communication cable and control cable will be installed once the platform deck is in place.
Media: Ole Jørgen Bratland/Statoil