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Corrosion Inspection of Surface casing and Conductors
of offshore wells with the D-PEC technology
TÜV Rheinland Sonovation
Introduction to TÜV Rheinland Group
A leading provider of test, inspection and conformity services worldwide
Founded in 1872 and headquartered in Cologne (Germany)
Employees: about 19.300
Network: > 500 branches in 66 countries world-wide
Group annual revenues 2014: € 1.73 billion
Introduction to TÜV Rheinland Sonovation
Advanced NDT services
- AUT (TOFD, Phased Array), Acoustic Emission, Corrosion mapping,
Pulsed Eddy Current
Special ANDT Services
- High temperature weld and corrosion mapping inspections
- DPEC offshore well inspections
- Application development, Modelling, Audits
Accredited AUT training and Level III services
Research and Development
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Problem statement
Corrosion may weaken the surface casing and conductor so that it no longer
can carry it’s design load and collapse
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Collapse of Offshore Wells due to corrosion of
Surface casing
Corrosion at Surface Casing and Conductor
• Concentrated near the fluid interfaces within the D-annulus (Region
between the highest (HAT) and lowest astronomical (LAT) tide)
• Top side of the well (cemented wells, moisture)
Results from DPEC measurements on hundreds of wells:
Corrosion did not seem to correlate directly with the age of the well
There is no correlation between corrosion on the conductor and corrosion on
the surface casing and there is also no correlation between wells of the same
platform.
Offshore Well Inspection approach
Wellhead “gap” measurement
Camera inspection
D PEC wall thickness measurements
Fluid water samples
Well Integrity calculations
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Wellhead Gap measurement logsheet
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Camera inspection
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Eccentric casing with conductor Thick layer Corrosion product/cement
on conductor
-Eccentric casing with conductor
-Centralisers available
-Controller DPEC probe
D-PEC Well inspections
PEC introduction
PEC technology is an established solution for corrosion
detection on the surface casing and conductor of offshore
wells.
PEC (pulsed eddy current) is an electromagnetic
technique for measuring the thickness of steel objects.
PEC uses a probe that generates a pulsed magnetic field.
The characteristics of the eddy currents induced in the
steel are measured to determine the thickness of the steel.
No surface preparation required
Collapsing primary field induces eddy
currents, distributes in material and generates
a secondary magnetic field
Inspection of the D-annulus
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Access Solution: Pulsed Eddy Current (PEC)
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PEC cable
Probe
Balloon
Outer casing
Air tube
Sea level
Up to 60 m
Inspection area
PEC tool
X-mas tree
Standard measurement intervals
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Result well TRS 23, platform XYZ (not cemented)
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0
20
40
60
80
100
120
0
2
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40 45
PE
C r
ea
din
g [
%]
PE
C r
ea
din
g [
mm
]
Distance from top of Conductor [m]
Platform XYZ- Well TRS-23 - 20" Casing - 2012PEC wall thickness measurements
D-PEC Nov 2007 (NW)
D-PEC June 2009 (NW)
D-PEC July 2012 (SE)
LA
T
Flu
id le
vel 2009
HA
T
Result well TRS 23, platform XYZ (not cemented)
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0
20
40
60
80
100
120
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35 40 45
PE
C r
ea
din
g [
%]
PE
C r
ea
din
g [
mm
]
Distance from top of Conductor [m]
Platform XYZ- Well TRS-23 - 30'' Conductor - 2012PEC wall thickness measurements
D-PEC July 2006 (SW)
D-PEC June 2009 (NW)
D-PEC July 2012 (SE)
LA
T
Flu
id le
vel2009
HA
T
Result Well XX Cemented to main sea water level
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October 2013 (S)
47.5
6.4
Depth of Min. Wt [m] 1.0
Depth of Survey [m] 28.5
UA-52 Casing
WT loss [%]
Min. Wt [mm]
Result Well XY cemented to main sea water level
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September 2013 (S)
29.0
8.7
Depth of Min. Wt [m] 5.0
Depth of Survey [m] 40.0
UZ-194 Casing
WT loss [%]
Min. Wt [mm]
Conclusions
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• Extend the lives of the offshore assets and onshore plants.
• Proactively and easily check for casing corrosion without
interrupting production.
• Advanced knowledge of well integrity enables better planning of
production and well abandoning activities.
• Saved production and avoidance of unnecessary, costly
remediation on non-corroded wells.
• Regular health checks of the corrosion status of wells will also
help operators to plan more targeted and cost-effective
workover programs.
• Focus on those wells that require urgent attention and remedial
action.
• Considerable reduction of health, safety and environmental risk.
TÜV Rheinland Sonovation BV
Elschot 30
4905 AZ Oosterhout
The Netherlands
Tel: +31 162425588
E-mail: [email protected]
www.tuv.com/ndt
Contact:
Mr. Fred Gabriëls
E-mail: [email protected]
Phone: +31162478374
D-PEC animation movie is on YouTube. Search on D-PEC
http://www.youtube.com/watch?v=L_LZGRq8tQs
