2. • Casino assets
• Need for pipeline inspection
• Challenges with conventional ILI run
• Need for novel inspection techniques
• External inspection for top-of-line corrosion
• Internal inspection for directionally drilled shore crossing
• Benefits
Overview
3. Image courtesy of Google Earth
Casino
Project
Let’s start with an idea of
where we are working
4. Image courtesy of Google Earth
There are three production
systems in close proximity
1. Minerva - shown in green.
2. Otway project - shown in black
3. Casino – multi-coloured pipeline
5. T
The Bay of Islands coastal park extends
along the whole coast in this area. We
chose a shore crossing where we could
traverse the coast with directional
drilled holes and reach deep water to
allow the pipelay vessel access.
6. • Our shore crossing
approach consisted of
limestone cliffs 50 metres
high.
• Directional drilling was the
only way to cross the coast.
• We started the drilling ½
km behind the coast and
finished 1 ½ km beyond
the coast in sufficient water
depth to allow the pipelay
to be initiated.
7. Top of line corrosion in flowlines and at pipeline tees
Two areas of risk that warranted inspection
Pipeline in horizontal directionally drilled hole section
1
2
9. • Multiphase pipelines
• High condensation rate
• Inadequate corrosion
protection of top of line
Top of Line Corrosion
10. Internal inspection
• Internal inspection tool utilised
• Deployed offshore to onshore
Options to inspect the pipeline for top-of-line corrosion
External inspection
• Localised inspection
• No concrete weight coat
• Saturated Low Frequency Eddy Current
(SLOFEC) tool on outside of pipe wall
11. Image courtesy of Google Earth
Deadleg pipeline from Pecten
East to Netherby
• Contained inhibited seawater
• Isolated from the main pipeline by
closed isolation valves on the
Pipeline End Manifolds
• Options evaluated included:
• Displace the water with
nitrogen
• Disconnecting the pipe
extension and storing it
on the seabed
12. Image courtesy of Google Earth
We couldn’t displace the
water into the gas plant
without causing massive
problems handling the salt
water onshore. We also were
going to introduce a major
hydrate risk in the gas
pipeline. And we had nothing
to push the PIG with.
13. Image courtesy of Google Earth
And at the end of the
campaign we would
want to return the
deadleg backed to
inhibited storage.
14. Pipeline End Manifolds
• Contained double-block and
bleed valves and included a 6”
flowline tie-in
• Disconnection of water filled
section required seabed
intervention to test isolation,
break the flange and relocate
pipeline to clear access to the
PLEM
• Once the pipeline was out of
the way a subsea pig launcher
could be fitted
17. Seaway Falcon pipelay vessel as it initiated
the pipeline lay during the initial project
18. Image courtesy of Google Earth
We pushed the PIG offshore by
injecting high pressure gas from the
gas plant, and returned the PIG to
the valve station by drawing gas
from the line.
19. • Connected to multiple gas
pipelines, operates with
multiple pressures and is
connected to several gas
storage reservoirs.
• The plant can draw gas from
a pipeline and inject into
another gas pipeline. It can
then reverse flow to receive
the PIG.
Iona Gas Plant
21. • Red line shows PIG’s
calculated position from
shore valve station
• C5 is Casino 5 and C4 is
Casino 4, 30+km offshore
• Blue line is calculated
velocity of PIG
• As the pressure increased
the velocity fell, due to
compressibility of gas
Pig run results
23. Positive Indication of PIG passing Casino-5
• The PIG is a tight fit in the
pipeline and requires
differential pressure to
move along the pipeline
• The blue line shows the
trend before the PIG arrived
• The red line shows the
pressure after the PIG
passed the tee
24. Gauge Plate and Brush Runs
“Technical success”
with the cleaning.
The PIG could be
conveyed out to
Casino 5 but would
come back dirty.
27. We were quite eager
to confirm the
distance the PIG had
travelled the second
time so our Rosen
team went straight
into data download.
28. • Primary inspection objectives were fully met
• Lower cost (<25% of alternative)
• Faster schedule
• Avoided HSE risk with diving operations
Summary
29.
30. DISCLAIMER
This presentation has been prepared by a representative of Advisian.
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Advisian as a whole, its officers or executive.
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control of, and may be unknown to, Advisian.
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