Suction Pile Jackets ExperienceWinddays Rotterdam WTC 13-14 June 2018Mark Riemers

EOWDC- Newcastle Yard

• SPT Offshore Introduction

•Ørested Borkum Riffgrund 1 WTG demo

• Statoil Dudgeon trafo jacket

•Vattenfall Aberdeen (EOWDC) 11# WTG SPJs

•Conclusions

Overview

Borkum Riffgrund 1 - SBJ

Dudgeon OWF Substation

Capabilities• EPC Contractor• T&I Contractor

Technologies• Self-Installing Platforms• Self-Installing Monopiles• Suction Pile Jackets .

SPT Offshore – Specialised Contractor

Founded in 1997> 500 suction piles

installed in O&G and renewables sectors

Independent, specialized contractor in suction pile foundations and anchors

Track record• Borkum Riffgrund 1 SBJ• Dudgeon OWF substation platform• Doggerbank 2x Metmast Removals• Ophir Wellhead Platform T&I• EOWDC (Aberdeen) Trial Installations• EOWDC Detailed Design Piles• EOWDC 11x SIWT Installations

EOWDC – Aberdeen, UK

•2-4 km offshore

•Water depth 19-32 m

•11 Suction Pile Jacket foundations

•92.4 MW peak capacity

•309 GWh annual power production

• Industry first:• MHI Vestas V164-8.4 turbines• Full wind farm on suction pile foundations

EOWDC – Foundation Design Contractors

Concept DesignH1 2016

Detailed DesignH2 2016 – H1 2017

Suction InstallationH1 2018

Jacket

Suction Piles

Developer

BoP Contractor Turbine Supplier

EOWDC – Fabrication

• Suction Pile Jackets fabricated throughout Europe and assembled with Suction Piles at Smulders yard in Newcastle

EOWDC – Site Conditions

•Water depth 19-32m

• Soil consists of 2-8m loose to medium dense sand over competent glacial clay soils

• Shallow bedrock at 20-25mbelow seabed

•This makes site unsuitedfor driven (mono)piles

EOWDC – Site Conditions

Suction piles selected because of:

•Very fast offshore installation• Sediment above bedrock well

suited for foundation•Virtually noisefree (100 dBa)•Minimal impact on marine

life•No need leveling systems•Easy removal -> reverse

installationEOWDC – Small Scale Pile Trials

EOWDC – Installation Experience

•From trial installations to jacket installation • 3 locations

EOWDC – Design Process

EOWDC – Foundation Stiffness Matrix

Iteration process with Jacket Designer• Foundation stiffness matrix instead of

p-y curves as used for piles

𝑭𝑭𝑲𝑲 = 𝑲𝑲𝟏𝟏𝟏𝟏 ⋯

⋯ 𝑲𝑲𝟔𝟔𝟔𝟔

EOWDC – Jackup Spud Can interaction

EOWDC – Shell Buckling Check

EOWDC – Scour Protection

Pre-installed Filter Layer

After installed Armour Layer

Alternative SPT Scour Protection System

• Frond mats pre-installed onshore onto the suction piles• Umbrella-like system, self-deploying during installation of the suction piles• Diverless deployment, immediate scour protection, marine life friendly• Cost reduction 50 ~ 60% compared to rock scour protection for a 3-legged

jacket

Alternative SPT Scour Protection System

TRL 1-2

• Concept Design

TRL 2-3

• Experimental Proof-of-Concept

TRL 4-5

• Validate in Hydraulic Lab

TRL 6-7

• Offshore Prototype

TRL 8-9

• Commercial Operation

• Self-deploying ‘umbrella’• Immediate scour protection• Marine life friendly

• Test of deployment system• In still water tank• Outriggers with mini frond mats

• Test of scour protection performance• Currents and waves in hydraulic lab• Frond mats around monopile and jacket

2018

• Full scale test in offshore conditions• At North Sea Offshore Wind Farm• Award of innovation funding pending

• Reduced LCOE for offshore wind• No extra offshore time or equipment• No rock dump, lower carbon footprint

To be announced

EOWDC – Installation Experience

•From trial installations to jacket installation

• Standard SPT rental pile testing early in design process• High L/D of 2.5 aim for refusal to test mitigating measures• Results used for further design optimizations

• Full sized suction Pile (L/D = 0.8)• Verify installation procedures• Verify installation performance• Verify mitigating measures

• Well-controlled, fast & predictable installation

Full-Scale Pile Tests

Small-Scale Pile Tests

Suction Pile Jacket

Installation

EOWDC – Small & Full Scale Suction Pile Tests

Small scale• 3 locations • 9 tests

• Normal installation• Pressure cycling

EOWDC – Small Scale Pile Trials

Full scale• 8 tests

A. Normal installationB. 1-way cyclingC. 2-way cyclingD. Cycling + water injection

EOWDC – 11 Suction Pile Jackets Successfully Installed

• Suction time 1 - 3 hours•Time HLVs on site 8 - 25 hours (average 12 hours)•All penetrations well within spec achieved 5cm vs allowed 30cm•All SPJ within 0.01 deg vs allowed 0.25 deg

EOWDC – Transport from Newcastle to site © Jim Scott, https://geordiecam.wordpress.com

Suction Pile Jackets – Conclusions

• It works!

•Fastest offshore installation ever

•Noisefree -> no impact on marine life

•Test Installations not required, but:• Optimize suction piles -> save steel• De-risk

EOWDC – Transport from Newcastle to site © Jim Scott, https://geordiecam.wordpress.com

Thank you!

Thank you