Post on 16-Oct-2021
Soliton Early Warning System for Offshore ApplicationsOffshore ApplicationsAlastair Stagg, Martin Goff, Gus Jeans,Liam Harrington-Missin (Fugro GEOS Ltd);C l B h i (ENI K M Ltd)Carlo Baschenis (ENI Krueng Mane Ltd)
May 2010
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Contents Menu
IntroductionSoliton TheorySoliton Early Warning SystemSynthetic Aperture Radar (SAR) Desk StudyReal-time Warning SystemSoliton AnalysisConclusions
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Contents Menu
IntroductionSoliton TheorySoliton Early Warning SystemSynthetic Aperture Radar (SAR) Desk StudyReal-time Warning SystemSoliton AnalysisConclusions
www.geos.comMarch 2010
Introduction
Offshore exploration and development operations are impacted by oceancurrents, waves and adverse weather.currents, waves and adverse weather.
Internal waves (solitons) pose a specific risk to rigs, vessels, ROV and subseaoperations.
USD$ Millions rig repositioning costs
Broken drill strings
Supply vessels forced into rigs
Anchor chains parting
ROVs lost
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Excessive rig listing
Contents Menu
IntroductionSoliton TheorySoliton Early Warning SystemSynthetic Aperture Radar (SAR) Desk StudyReal-time Warning SystemSoliton AnalysisConclusions
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Soliton Theory
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Soliton Theory
Sea surface
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Soliton Theory
Sea surface
WaterWater depth
(m)
450 m
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-1.0 ms-1 1.0 ms-1Eastward current velocity
Soliton Theory
Horizontal Current Velocity1.0 ms-1
30 m below sea level
0 0 ms-1
46 m below sea level
0.0 ms
62 m below62 m below sea level
78 m below sea level
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(Hours)0 6 18 24
Soliton Theory
Seawater temperature30º C
18º C0 4 6 8 10 12 14
(Hours)0 4 6 8 10 12 14
50 m below sea level30º C
80 m below sea level
110 m below sea level
18º C
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(Minutes)0 12060 804020 100
Soliton Theory
Vertical Current Velocity0.25 ms-1
146 m below sea level
-0.25 ms-1
0.0 ms-1
162 m below sea level
0.25 ms
178 m below178 m below sea level
194 m below sea level
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(Hours)0 12 36 48
Soliton Theory
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Solitons observed from an offshore platform – enhanced surface waves
Contents Menu
IntroductionSoliton TheorySoliton Early Warning SystemSynthetic Aperture Radar (SAR) Desk StudyReal-time Warning SystemSoliton AnalysisConclusions
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Soliton Early Warning System
ENI Krueng Mane Ltd (Indonesia) affected by solitons in a previous drilling campaign in the Andaman Sea.
Rig pushed off location 3 of 5 wells up to 189mRig pushed off location 3 of 5 wells up to 189m
Drill pipe torn off at BOPp p
ENI required a Soliton Early Warning System (SEWS) for 2008/2009 d illi i i th A d Sdrilling campaign in the Andaman Sea
Minimum of 10-hours warning period requiredMinimum of 10 hours warning period required
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Contents Menu
IntroductionSoliton TheorySoliton Early Warning SystemSynthetic Aperture Radar (SAR) Desk StudyReal-time Warning SystemSoliton AnalysisConclusions
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Soliton Desk Study
218 satellite images with 77 images subjected to detailed analysis
Propagation speed and direction calculated (1.7ms-1)
Generation zone identified
Confirmed need for a SEWS
Identified best locations for SEWS
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moorings
Real-time Warning System - Mooring Locations
SolitonSoliton generation zone
Andaman Sea
Malacca2 x Real-time SEWS moorings Malacca Strait
Sumatra
2 x Real-time SEWS moorings
SEWS#1
SEWS#2
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Contents Menu
IntroductionSoliton TheorySoliton Early Warning SystemSynthetic Aperture Radar (SAR) Desk StudyReal-time Warning SystemSoliton AnalysisConclusions
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Real-time Warning System - SEWS Moorings
Jack Bates
Direction of
SEWS#1 SEWS#2
soliton propagation
•Oceanor Wavescan Buoy with Iridium data t i i
Thermocline
transmission
•TRDI 75kHz Longranger ADCP
•Aanderaa DCS3900Aanderaa DCS3900
•3 x Seabird SBE-37 CT Sensors
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Real-time Warning System - SEWS Moorings
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Real-time Warning System - SEWS Moorings
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Real-time Warning System - SEWS Moorings
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Real-time Warning System - SEWS Moorings
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Real-time Warning System - SEWS Moorings
Both SEWS buoys deployed 2-weeks prior to the Jack Bates’ arrival on well location.ocat o
Soliton and current i i dwarnings required
during the soliton sensitive rig tow and anchoring operations.
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Real Time Warning System
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Real-time Warning System
All sensors set to 2-minute sampling intervals.
Data transmitted to a web server hosted byFugro Oceanor every 10-minutes.
Data displayed on a dedicated, passwordprotected web display as time series plots anddata tables.
Real-time data used to identify solitons:
– Pulses of increased horizontal and vertical current speed
– Immediate reversal in current directioned a e e e sa cu e d ec o– Current shear– High frequency oscillations in the
thermocline
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Real-time Warning System - Soliton Monitoring
Warning Level Current Speed Actionsg p(knots)
LOW < 1 5Record the solitons in daily 24-hour summary, but no warning required orLOW < 1.5 summary, but no warning required or action to be taken by the rig
MEDIUM 1.5 to 2.0 Issue soliton warning by email, but the rig will probably not take action
HIGH 2.0 to 3.0Issue soliton warning by email and follow up by calling OIM. The rig will tighten anchor wires and standby
VERY HIGH > 3.0Issue soliton warning by email and follow by calling OIM. Rig will prepare for possible disconnect
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Real-time Warning System - Soliton Monitoring
SOLITON WARNING LEVEL HIGHMany solitons observed over the 3-month SEWS deployment, particularlyd i i tid
SOLITON WARNING LEVEL HIGH
during spring tides.
Most below the warning threshold, or later downgraded at SEWS#2
A packet of 5 solitons were observed at HIGH LEVEL warning threshold (2.0to 3.0 knots). Soliton warning email issued, followed by a phone call to theOIMOIM.
Approximately 12-hours later on the next tide, another packet of solitonswere observed with similar current speedswere observed with similar current speeds.
The rig tightened the anchor wires facing into the solitons and loosened theanchor wires at the rear to avoid additional rig movement
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anchor wires at the rear to avoid additional rig movement.
March 2010
Real-time Warning System - Soliton Monitoring
Jack Bates Radar – solitons approaching from northwest
Solitons observed approaching from the Jack Bates Helideck
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Real-time Warning System - Soliton Monitoring
Solitons approaching and passing the Jack Bates – seen as enhanced surface waves
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Real-time Warning System - Soliton Monitoring
Rig tilt observed from Helideck as solitons passed through
NOTE: this was AFTER appropriate action taken
Did the SEWS avoid the previous fate -pushed off location up t 189 d b kto 189m and a broken drill string?
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Contents Menu
IntroductionSoliton TheorySoliton Early Warning SystemSynthetic Aperture Radar (SAR) Desk StudyReal-time Warning SystemSoliton AnalysisConclusions
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Soliton Analysis
All current profile and seawater temperature and salinity data downloaded for further data processing and analysisand analysis.
3-hour running means subtracted from 2-minute horizontal velocity data to identify short duration y yhorizontal currents associated with solitons.
327 individual soliton events were identified at SEWS#1SEWS#1
207 at SEWS#2.
Soliton propagation speed calculated at 1.70ms-1, consistent with SAR desk study results and observations and forecasts during soliton monitoring.
Data available for future field development
More accurate predictions provided on when solitons
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More accurate predictions provided on when solitons were most likely to occur.
March 2010
Soliton Analysis
‘Classic’ soliton packet observed at SEWS#1
0 m0 mNorthward Velocity (m/s)
250 m0 E t d V l it ( / )0 m Eastward Velocity (m/s)
250 m12 10 8 6 4 2 0 2 4 6 8 10 12
0 6 0 20 4 0 0 2 0 4 0 6
-12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 (Hours)
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-0.6 -0.2-0.4 0 0.2 0.4 0.6Current Velocity (m/s)
Soliton Analysis
-60 -40 -20 0 20 40 60(Minutes)
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-0.6 -0.4 -0.2 0 0.2 0.4 0.6Current Velocity (m/s)
Soliton Analysis
0 m Northward Velocity (m/s)Solitons observed at SEWS#2
250 m250 mEastward Velocity (m/s)0 m
250 m30º C
-12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 (H )
18º C
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(Hours)Current Velocity (m/s)
-0.6 -0.4 -0.2 0 0.2 0.4 0.6
Soliton Analysis
30º C30 C
(Minutes)-60 -40 -20 0 20 40 60
18º C
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(Minutes)
-0.6 -0.4 -0.2 0 0.2 0.4 0.6
Soliton Analysis
50Frequency of solitons
No. of solitons
SEWS#1SEWS#2
solitonsPeak soliton current speeds were predominantly higher at
25 SEWS#1 than at SEWS#2 due to attenuation of energy over the distance travelled fromthe distance travelled from soliton generation zone.
0
0 0 2 0 4 0 6 0 8 1 0 1 2
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0 0.2 0.4 0.6 0.8 1.0 1.2Peak current speed (m/s)
Contents Menu
IntroductionSoliton TheorySoliton Early Warning SystemSynthetic Aperture Radar (SAR) Desk StudyReal-time Warning SystemSoliton AnalysisConclusions
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Conclusions
Fugro GEOS were approached by ENI Krueng Mane Ltd to provide a soliton early warning system for drilling operations on the Jack Bates semiearly warning system for drilling operations on the Jack Bates semi-submersible rig. A 10-hour minimum warning period was required.
A combination of a SAR desk study, followed by real-time measurements across the thermocline and soliton monitoring provided this requirement.
Solitons were successfully observed and when thresholds were exceeded, early warnings were issued. As a result the rig took the necessary action to avoid significant rig movement.
Post processing and analysis of the data proved the SEWS effectiveness.
ENI Well Operations Manager would have the SEWS again for soliton sensitive areas.
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Thank You
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