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Different solutions to inspect platform risers
By:
Robert van Agthoven (Part I)Manager Marketing & Sales PS-PITRotterdam, The Netherlands
Charles Lawther (Part II)Technical Manager Offshore Business UnitAberdeen, Scotland
Event:PPSA SeminarNovember 14th, 2007 Aberdeen
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Contents of the presentation
Focus on inspection of “unpiggable” risersThe operational conditionsType of defects that can be detectedTravel capabilities and range of tethered toolsDeployment examplesNear future challengesOther possibilities for non-intrusive inspections of risers in Part II of this presentation
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Different “unpiggable” riser-lay-outs
WELL
J-TUBE
OPEN?
TIDAL ACTIONINSIDE J-TUBE
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Inspection options & conditions
Off-stream: Open access, allows
internal inspection with tethered UT-tool, also where OD is not accessible (e.g. J-tube)
Riser must be liquid filled for UT-inspection
Liquid may be: crude oil, (sea) water, condensate
For gas risers: use high-friction sealing pig and limited volume of water
On-stream: Must be accessible from
OD Requires diver or ROV
assistance, Apply “screening” tool to
assess general condition
Advantage:No shut-down required
Advantage:UT tools provide quantitative data
A screening tool called “Incotest“ will be explained in part II of this presentation
GAS
HIGH-FRICTIONSEALING PIG
WATER
UT-INSPECTIONMODULE
TETHER
RISER
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What can be detected with ultrasonics,using a tethered inspection tool?
OD CORROSION
ID CORROSIONOVALITY / DENT
WALL THICKNESS
ID GEOMETRY WELD INSPECTION
CRACKS?
FATIGUE CRACKS?
STOP & SCAN WELD
TOFD
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Tethered vehicle capabilities
CONCRETE BASEPLATFORM
STEEL
STR
UCTU
RE
GRAVITY DRIVEN CRAWLER DRIVEN
LIMIT
TOOL ACCESS TOOL ACCESS
CRAWLER CAN PASSBENDS AND HORIZONTALSECTION(S)
LIMIT=CABLE LENGTHAND BENDS
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100% circumferential coverage = MUST!
TRANSDUCERS
32 or 64Fixed Ultrasonic sensors,
Equidistantly divided
Option #1 Option #2
1 rotating sensor,# of measuring points
programmable
REV #1REV #2REV #3
SCAN ALONG HELICAL PATH
Lay-out of ID surface
Lay-out ofwall thickness
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Deployment of Riser Inspection Tool
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Near future challenges
2000 mwater depth!
•SCR’s•TTR’s
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Conclusions - Part I
Today many solutions exist to inspect “unpiggable” risers
For diameters from 4-60”, distances up to 10 km.Both gravity and self-propelled tools do not require liquid-handling or pumping, liquid remains stagnantAccurate tool handling and positioning in vertical section, free-swimming ILI tool cannot stop and may go too fast.Only short inspection window required (few hours)Ultrasonics provide quantitative results with no wall thickness limitationsReinforced tether adds to safety, tool can always be retrieved and allows on-line presentation of results.
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Questions?
After presentation of Part II by Charles Lawther