Seafloor based drilling for offshore windfarms

25 April 2016 Hoang Q. NguyenGroup Manager - Geosciences

TABLE OF CONTENT

Overview of seafloor-based drilling (PROD) - comparative advantages

In-situ tests and sampling capabilities

Vessel selection, deck Layout, and weather operating capabilities

Conclusions

Q&A

PROD v’s CONVENTIONAL

OFFSHORE GEOTECHNICAL SOIL INVESTIGATION

Seafloor-based Vessel-based

PROD KEY CAPABILITIES 3000m water depth 150m BML borehole 54m casing depth 8+ tons thrust / 130hp 72mm rotary core diameter 75mm piston core diameter In-situ testing (CPTU, BPT, SCPTU)

PROD KEY FEATURES

3 outriggers/soft feet Soft seabed (1 kPa) Pan & tilt cameras Tilt sensors & thrusters Drilling mud injection +/-25 mm depth accuracy 200 seabed slope Automatic drilling Zero readings from seafloor

PRECISION SEABED LANDING CAPABILITY Maximum preservation of soil fabric/structure preservation, as well as pore

water within the samples Zero mudline disturbance prior to and during sampling via PROD’s unique

footing design and landing sequence (below) Precise borehole depth measurements and measurement of dissolved

hydrocarbons

STEEP SEABED SLOPE OPERATIONS

PROD HAS PROVEN TRACK RECORD OF PRODUCING HIGHQUALITY DATA ON STEEP SEABED SLOPES OF 20 DEGREESAND GREATER

IN SITU TESTING TOOLS

Piezocone Penetrometer – 3,000 m rated, temperature capable

Seismic Probe – Field proven on 4 projects, best in class measurement of Vs parameter.

Piezo Ball Penetrometer - Extensively deployed over last 10 years.

Piezoprobe – Prototype manufacture underway. Standpipe Piezometer Installation – World first installation to

101m BSF. Hydrocarbon Analysis System – real time logging of

methane in drill returns

SOIL PROFILING BY CONTINUOUS CPTU

Dropstones/ Offshore UK

SEISMIC CONE TESTING

Provide robust measurements of true interval Vs profile

Successfully deployed to depth of 76 m BML

Provide high quality in-situ Vs ( Gmax) profiles

SEISMIC CONE TESTING

0 100 200 300 400Time, milliseconds

8

7.6

7.2

6.8

6.4

6

5.6

Sig

nal a

t Dep

th B

elow

Sea

floor

(m)

S-w

ave

Sig

nal a

t Dep

th B

elow

Sea

floor

(m)

Browse Field – Timor Sea, Western Australia

SEISMIC CONE TESTING

Soil description

35

30

25

20

15

10

5

0

Dep

th b

elow

sea

floor

, m

-EOB

Silty fineSANDwith fewclay partings

0 4 8 12 16

Cone resistanceqt (MPa)

0 100 200 300 400

Shear wave velocityVs (m/s)

Stiff to verystiff siltyCLAY

Stiff to verystiff siltyCLAY

0 20 40 60 80

Water contentwn(%)

OffshoreOnshorePlasticity index, PI

1 m

Caspian Sea

MONOTONIC & CYCLIC BALL (BPT)

Residual undrained shear strength and soil sensitivity

PIEZOMETER INSTALLATION

Instrumentation & data logger box

Standpipe made up of PROD drill rods

Luva Investigation, Norway (2009) 1300 m water depth used PROD1 system very accurate depth

control 20 to 100m bml time ~ 4 to 5 hrs for 20 m 100% success rate

Piezometer electronics enclosure

Piezometer tip

Drill rod adapter

Casing

PIEZOMETER INSTALLATION – NO ROV

Autonomous standpipe piezometer

ROTARY ROCK CORING

Extensive experience in the coring of ‘difficult’ geologies

Ultra thin Kerf diamond bit

Thin Kerf diamond bit

Weak Limestones /Offshore Mozambique

Hard Sandstones / Australia

ROTARY ROCK CORING – DIFFICULT GEOLOGIES

Reefal / Coral Limestones /Offshore Mozambique

Drop-stone/Offshore CanadaGravels/Granite Bedrock/ Clio Bay/ Canada

FIXED PISTON SAMPLING

Clear plastic liner enables visual description of soil samples

PROD intact SAND sample used for advanced triaxial testingPreservation of soil fabric/structure

HIGHLIGHTS OF BENEFITS I Safe and environmental stewardship technology

Remote drilling and automation with no manual tool handling on deck while drilling (i.e. safety by design)

Environmentally-safe hydraulic fluid system. Sea water drilling fluid with (only if required) dosing by bio-degradeable viscosifier.

Best recovery of high quality sample and in-situ test data PROD is decoupled from vessel providing a stable drilling platform and

precision control on the seafloor PROD’s three independently controlled footings ensure virgin seabed

samples can be taken right from the mudline PROD’s in-situ tools and sampling/coring technologies are uniquely

designed & innovative. E.g., excellent recovery of undisturbed core even in variably cemented and fractured rock

Significant productivity gains Fast launch and recovery to/from the seabed Efficient wireless drilling technology, i.e. pushing long sample barrel

(2.75m), and continuous CPT pushing by adding rods PROD carries all in-situ tools, piston sampling barrels and rotary coring drills

to the seabed - can readily switch modes at the dictate of geologies or client needs without recovering to deck

PROD can be moved sub-sea between boreholes

VESSEL SELECTIONUnlike drill ships, PROD is unaffected by heave. Rather, it is limited by the acceleration due to heave. Launching mid ship or in longer wave periods increase our operational weather limits.

Vessel Location Length Deployment Wave Period

Operational Hs

Island Enforcer

HILD(North Sea) 125m Port Side 7-8s 5+m

SkandiBergen

LUVA(North Sea) 106m Port Side 7-9s 4-5m

DOF Geograph

CLOV(Angola) 70m Stern 15s 4m

Olympic Commander

Rosebank(North Sea) 93.8m Stern 7-8s 3-4m

NeptuneTrident

Yolla(Bass Strait) 70m Stern 6-8s 2.5-3m

Jaya Valour Block 2(Tanzania) 80m Port Side 6-8s 4m+

OPERATIONAL WEATHER LIMITS OF SELECTED VESSELS (HISTORICAL)

PROD launching mid-ship in 4m swell onboard the Island Enforcer

VESSEL SELECTION AND DECK LAYOUTMid-Ship Launch Operation

Olympic Commander, 2012

Island Enforcer, 2011

Jaya Valour, 2014

VESSEL SELECTION AND DECK LAYOUTMid-Ship Launch Operation

Olympic Commander, 2012

Island Enforcer, 2011

Jaya Valour, 2014

HIGHLIGHTS OF BENEFITS II

Minimum weather/machine downtime PROD decoupled from vessel when drilling – effectively independent of

surface weather conditions Able to be recovered and deployed in high sea states (>3m heave, >5kts

current) Abundant machine built-in contingencies in design and well-maintained

systems

Ability to operate safely close to existing assets Vessel can back away once PROD is deployed to seabed. Minimize any

probability of collision through vessel or DP malfunction

Seabed hazards e.g., UXO, shallow gas.

Olympic Commander, 2012

THANK YOU