Gemini – Offshore Wind Farm - Geo-Informatie Nederland · PDF file1 Gemini – Offshore Wind Farm Positioning beyond the horizon Dredging and Marine Contractors

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Gemini Gemini –– Offshore Wind FarmOffshore Wind Farm

Positioning beyond the horizonPositioning beyond the horizon

Dredging and Marine Contractors

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Company profile

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Leading international contractor

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Large state of the art fleet

Introduction


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Company profile

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Leading international contractor

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Specializing in:

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Dredging

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Offshore oil & gas

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Offshore wind

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Innovative partner for clients

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Dutch-based, independent family business

Introduction


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Wim Kanneworff

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Hydrographic Surveyor

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28 years with Van Oord

2009–2010 - ADCOP (Habshan Fujairah Pipeline & SPM) project

2011 - Arkutun-Dagi Pipelines project

2012 - Arkutun-Dagi GBS Installation project

2013 - SWPL Stingray

2014-2016 - Gemini Offshore Wind Farm


Introduction

5Dredging and Marine Contractors

Gemini Offshore Wind Farm

Gemini Offshore Wind Farm

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Geodetic Parameters

Offshore

•UTM Zone 31 North

•European Terrestial Reference System 1989

•Lowest Astronomical Tide


Employer Requirements

Installation Tolerances

Monopile / Transition Piece

•XY –

3 m. radius

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After Scour Protection Installation –

1 m. radius

•Z –

0.25 m.

•Verticality –

0.25°

( Deviation ≈

4.3 cm in 10 m.)

•Orientation -

±

5°

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Surface Positioning

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Accurate X, Y and Z

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Real Time

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Low cost / economic


Construction requirements

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Surface Positioning

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Accurate X, Y and Z

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Real Time

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Low cost / economic



Surface Positioning

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RTK-GNSS

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Virtual Reference Station

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Trimble SPS GNSS receivers using vessel internet connection









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Network extension

January 2014 –

Join Gemini project, start survey preparations

February 2014 –

Start of communications with GDF Suez, NAM and SAPOS

April 2014 –

Schiermonnikoog (NAM) signal on-line

April 2014 –

Start of Hydrographic survey as part of UXO (Unexploded ordnance) survey campaign, Multibeam Echosounder data is processed using PREMO

14 May 2014 –

Financial Close Gemini project

June 2014 –

Start UXO survey campaign

10 June 2014 –

Fino-1 (SAPOS) signal on-line

August 2014 –

After several meetings with GDF Suez on permission, equipment location and installation details, GNSS reference station is installed on G17d-A (GDF Suez) and on-line

6 November 2014 –

Interference is experienced

December 2014 –

New Trimble antenna (TRM GA830) is installed, no more interference


Timeline

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Users Offshore

3D Positioning using 06-GPS VRS corrections via NTRIP

•Geo Focus

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Positioning XYZ for MBE survey and ROV Video and ROV TSS

•Aeolus / Pacific Osprey

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Positioning XY for jacking up and monopile positioning

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Positioning Z for establishment of Transition Piece final level

•Nexus / HAM602

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Positioning XYZ for Cable Lay, MBE survey and ROV

•Jan Steen

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Positioning XYZ for MBE survey and Trencher


VRS operational


Survey Vessel Geo Focus


MB survey of Gemini Offshore Wind Farm

ZeeEnergie –

47.5 km--²

BuitenGaats –

48.4 km²

Export Cables to Wester Eems –

23.6 km²

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Checks and controls

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Position Check Objects

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Placed in BuitenGaats and ZeeEnergie

Regular checks by:

Survey vessel

Flexible fall pipe vessel (ROV-MBE)

Cable lay vessel (MBE)

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VRS Location

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BPQ (Base Position Quality) message

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distance to virtual base

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Local Reference Station(s)

Installed on MP R1 (BG) and D3 (ZE),

operational since 13th

August


Quality Control

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BuitenGaats Position Check object

A bundle of chain was left on top of the block, after removal of the chain, the depth changed


Quality Control

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ZeeEnegie Position Check object

During April 2015, the depth changed significantly. Erosion ?


Quality Control

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Dynamic mode vs Static mode

Aeolus measurements while jacked up


GNSS mode Comparison

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Base station on TP

In July 2015 two local reference stations were installed

Base positions were calculated by 06-GPS from logged raw data

Stations run on batteries charged by solar panels


Installation of Local Reference station

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VRS to Local Base

Static comparison Trimble/Hydrins + VRS to Trimble/Hydrins + Local base station


Aeolus comparison

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VRS to Local Base

Dynamic comparison POS MV + VRS to Trimble + Hydrins + Local base station


Geo Focus comparison

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Verticality monitoring during installation

Monitoring –

IHC PIME, Fugro InclinoCam and Leica Total Stations

As-Built verticality –

Level instrument measurements inside the ATPIA

As-Built flange level –

Total Station measurement from calculated offset point


MP-TP installation

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Positioning for Gemini Offshore Wind Farm

The 06-GPS network extension has proven successful

Accuracy / repeatability as expected (in X,Y and Z)

Real time, stop survey is start data processing

Use of Van Oord of the shelf equipment and vessel IT infrastructure

Reliable service, no downtime due to outage

Lessons learned

Network extension —› Start well in advance of the works

Involve IT to break down the firewalls on the vessel side

Install a local reference station as back-up as soon as it is possible

A local reference station will provide a more stable position in the OWF


Conclusions

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Score board

Export Cables

200 km installed and buried (95%)

Monopiles

and Transition Pieces

146 out of 150 installed

OHVS ZE, OHVS BG and LHVS

Installed, commissioning in progress

Inter Array Cables

70 Laid, 58 buried

Surveys executed

2000 +


Gemini Offshore Wind Farm construction status

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Documents

Gemini – Offshore Wind Farm - Geo-Informatie Nederland · PDF file1 Gemini – Offshore Wind Farm Positioning beyond the horizon Dredging and Marine Contractors