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2008 pipeline seminar - Flexlife audio Q&A

14:40-15:05 - Annulus Integrity Management – A New Approach - Flexlife

‘Open Forum - Question and Answers’ session at the end of the presentation by John Marsden of Flexlife

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Transcription

Steve Patterson - Shell. You’ve focused very much on detecting corrosion in the wires. There is another scenario where for instance you have well souring and you’ve got a riser that was originally designed for sweet service maybe exposed to H2S through permeation through the pressure sheath but this technology with the UT do you think you could develop it to actually detect cracks within the wires?

John Marsden – Flexlife (Presenter). Yeah there’s no reason in theory why you know what we currently use UT for scanning rigid pipe - why we can’t develop that to scan flexible pipe. The only difference between what we’ve done here with flexible pipe and rigid pipe is that we’re actually using the water here to transmit the signal which is in the past that’s been the preventer to the UT technology on flexible pipes so to answer your question I don’t see it being a problem however we’ve done no testing to date to simulate cracks or laminations within the armour wires themselves.

Hi there Kev Clarke – Genesis. Obviously just using this Neptune tool, so I’m assuming you’d never used the Neptune tool until you knew you had a flooded annulus?

John Marsden – Flexlife (Presenter). No I’m not saying that. I think obviously there are cheaper, I mean its all about market forces isn’t it you know? If you’ve got one riser on your platform, you’re unlikely to mobilise a Neptune to go and scan it - whereas if you’ve probably got twenty odd risers it might be more efficient for you to go and scan it if you’re just looking for flooded annulus. Once you deploy the ROV, if a flexible’s flooded, pretty much it will flood to the surface level so if you go 10, 20 metres below the sea surface you can hit many risers in one go. So I could see in that case Neptune being used but we’re not saying that this is going to replace vacuum or positive pressure testing. What we’re saying is its most likely going to supplement it. In lots of cases legacy pipes where people already know the condition of their annulus, they would probably use the Neptune or if you had lots of risers.

Kev Clarke – Genesis. Ok I take your point. Just one more. Again on the Neptune it looked as if it was very easy to determine if any of the strands or the wires were broken or missing. Now if you went out and done this because you said it could be done kind of online so the information gets fed through the ROV line back onto your DSV. Now it looks very simple to say you’ve got some cables or strands of wires which are missing but to actually do the wall thickness measurements, is that something which should be done almost instantaneously on the DSV or would you have to send that back to the beach and wait a couple of month for your inspection results?

John Marsden – Flexlife (Presenter). Yeah there’s two answers Ok. The first answer is wherever the cursor (you probably didn’t make it out I’m not sure) but wherever the cursor is that we can then see so as we’re scanning Ok and we’ve got the data we move the cursor over an area and we can see the region change in thickness so that gives us a very good indication. If you wanted to perform a more detailed examination then you’re not going to spend the time when you’ve got the DSV on standby to do that so we can do it two ways to answer your question but the purpose of the pitting, what we’d like to be able to do is say we’re just interested in the surface of where the armour wires start to point 2 to point 5 millimetres into that surface and generate a map from that so that’s what we’re currently working on at the moment and then in which case you would have your map as one of your screens and you could see real time where those pits were and then you could investigate at that point with the cursor for the thickness of the wire.


Updated 2012-10-05