Decommissioning the brent field

Stephen Tetlow in vision

“OK. Thank you for that. The next question, one in the front here, and let's take the one at the back. We'll come back to you in a minute. OK? Thanks. Gentleman with the beard up there in the back. Thank you. Sir.”

Ian Ashcroft off camera

“It's Ian Ashcroft here from Arup.- I was just wondering if there'd been any lessons learnt in what can be done in the design of new platforms to make them easier to decommission?”

Stephen Tetlow in vision

“Thank you for that one. I'll take that question up there. Thank you. You're being attacked from both sides by the look of it.”

Alex off camera

“Hello, I'm Alex. I work in Defence. That was fascinating. It's all very new to me, so I apologise if these are slightly naive questions. I'm interested in the gravity base structures and your decision to leave them where they are. Is the problem that there's going to be this structure protruding out of the sea, causing an obstruction or are they going to decay over time, cause contamination? And when you looked at how to get rid of them, if they were on land you could conventionally use explosives to take out a structure like that. How did the use of explosives factor in your options to take them out?”

Camera re-frame: pulls out to see wide of audience

Stephen Tetlow in vision

“Would you like to answer that one first?”

Duncan Manning in vision

“So, yes, the legs will protrude above the surface of the sea. In order to understand what the impact of that is we commissioned a study to understand what the collision risk to that was and it was about one collision every 10,000 years, so well under an ALARP level. And that assumption is very conservative, because it makes no allowance for an uplift in technology over time. So if you can think about the last 15 years as we've had GPS technology starting to be developed. The assumption based on that very low collision risk makes no assumption for an uplift in technology. And of course, the two main users of the sea up in that area are first of all those related to oil and gas, and that will decline, but secondly, the fishing industry. When you engage with the fishing industry, actually their preference is leave the legs up, what you can see you can avoid. We remain liable in perpetuity, so whilst in a period of 200-250 years the tops of the legs will fail at sea level, we remain liable to ensure that they are marked. We also, in addition to making sure they're marked in charts, and ensure they're marked with ACE Navigation. They're also marked within the fishermen's FishSAFE system so they have an alarm system in the cabin of the fishing vessels which enables them to have an audible alarm when they get close to decommissioned infrastructure to allow them to steer away. Actually, when you talk to the fishermen, they're probably looking at unmanned fishing vessels in that duration far out. So that's the first part of your question. Relating to explosives, yes, we did look at the use of explosives, and whilst explosives aren't prohibited for decommissioning, there are some quite tight guidelines under which you need to operate. The concern from a leg perspective is if we were to cut the legs, we needed to have cut them at minus 55 metres to adhere to International Maritime Organization guidelines. That's an 18m diameter cut you'd have to do and then, having made the cut, conduct a 6,000 tonne lift. When you conduct a cut like that, you need to be absolutely sure that you've gone all the way through the structure. And the problem with explosives is you can't necessarily guarantee you've severed the rebar. I think that's a high level overview.”

Camera re-frame: zooms in to three-shot of Duncan Manning, Stephen Tetlow and Alistair Hope on stage, a few audience members’ heads at bottom of shot; slight further re-frame later in the answer

Alistair Hope in vision

“Yes, just to add to that…When you see a tower block come down, you need to place explosives on virtually every floor, drill it into the concrete structure. So if you did that with the leg, you'd be doing a huge operation of drilling and adding small charges all the way up. So that, coupled with the noise to marine mammals, it wouldn't really be a viable option.”

Stephen Tetlow in vision

“OK, thank you. Lessons learnt?”

Alistair Hope in vision

“In terms of new platforms, since the mid-90s offshore oil and gas facilities have been designed with removal and decommissioning in mind. So there aren't too many concrete gravity base structures, but occasionally they are used in areas where there's a lot of ice. So Shell have one in Sakhalin, in Russia, and that's been designed to be refloated, as an example.”

Stephen Tetlow in vision

“Thank you. OK. Next, there's a gentleman up there at the back...and a gentleman down here in the front row, please. Thank you.”

Mathias off camera

“Thank you again. My name is Matthias. My question is centred around cost again. We know in every project there's bound to be accidents and in the case of decommissioning it's a very [inaudible] operation. If for any reason there's this unknown situation where spills actually occur on the ocean who actually is going to bear the cost? Because I'm aware that the UK government is going to fund 50% through tax rebates. And I know Shell, equally, all the operators are going to have 50% of the cost in decommissioning. But if, for any reason, there's some accident that occurs in the process of decommissioning on the sea, who is actually going to bear the extra cost? That's my question. Thank you.”

Stephen Tetlow in vision

“We'll just take that one first, then come back to the gentleman down here.”

Alistair Hope in vision

“Very interesting question. Obviously, as the operator of the field, our prime concern is to do things safely and environmentally responsibly and we go to a huge amount of effort, every day, to do that. So in the first instance if there was a spill or something like that, it is the operator who is accountable through the courts and through the various statutory tools. The costs of that, I think that's probably one of the last things we think about when something bad happens. Our first concern is to make sure it never happens again.”

Stephen Tetlow in vision

“Right, gentleman here. Thank you.”

Matthew Stevenson off camera (1:09:12)

“Hi, I'm Matthew Stephenson from Suez. With a 20-year project lifespan and a world where technology is changing all the time, how do you make sure that you're not missing out on technologies or innovations that could help the project and save money?”

Alistair Hope in vision

“It's a great question. So I think you've got to be externally focused, continue to listen to good ideas, continue to talk to the supply chain. I think probably we need to get slightly better at describing the problems and challenges we have to the supply chain rather than asking for specific solutions. But over the course of this project, technology has changed, and we have had to go back and rethink things. We're probably not at the end of that. And I think under the regulations, we will get, hopefully, an approved decommissioning programme but if technology changes, we can be asked to come back and review it and if necessary, make changes.”

Stephen Tetlow in vision

“Thank you. I think we've probably got time for one more question, to take one from the audience. So gentleman up there on the back row, up there…back row, there. Thank you…in the light shirt.”

Duncan Manning in vision

“He's scratching his head now so think very quickly.”

Tim McClelland off camera

“Hi there, it's Tim McClelland, I work at Mars Chocolate. A question around the regulations: you said that you'd been trying to meet the regulations, in some circumstances obtaining derogations. Is there anywhere where you've gone over and above to meet your own ethical standards?”

Duncan Manning in vision

“So I think actually our ethical standards are pretty aligned with the regulations in place. And a comparative assessment is a useful tool to understand what on balance is the right thing to do, weighing up a number of different options. So understanding the impact to society, to the environment, the technical feasibility of what's being conducted, safety and cost, and I think those are useful benchmarks. But in addition to that we've stress tested. Whilst we've weighted each of those equally as a starting point, we then stress tested the comparative assessment by overweighting one to see whether you'd come up with a different conclusion if you were to overweight one by 40 per cent and underweight the others accordingly. Actually, it doesn't change the overall outcome from that comparative assessment process. What we have been pretty thorough about is that stakeholder engagement process to ensure that we have been as diligent, as open, as transparent and as thorough as we could have been over a protracted period of time. We've got a website where you can read as much or as little as you want to on Brent Decommissioning on that website. We put as much information on that, as early as we possibly can, to ensure that we are being as transparent as we can be, but also take questions from those who send them in, responding to the website. But also we're usually pretty quick to respond to requests for one-to-one engagements to talk to people. So the process itself is pretty closely aligned, I think, to Shell's ethical standards anyway. So it hasn't required too much, if any, adaption.”

Stephen Tetlow in vision

“OK. Well, thank you very much indeed. I'm going to draw proceedings to an end. I'd very much like to thank the IMechE team here for organising the evening, especially, also, the Shell team here for all your support. I'd very much like to thank you all for attending, and for some really interesting and insightful questions. Thank you very much indeed for doing that. And finally, I'd like to thank on your behalf our two speakers for a really interesting insight into the scale of this technical challenge that Shell is facing, and for bringing to us all a really well-explained and very clear exposition of what you're up to. We wish you the very best of luck at what is going to be an enormous industry with huge challenges, but also enormous opportunities for the next generation of engineers. So thank you very much to you all. I hope you enjoyed the evening. Thank you.”

[Audio]

Applause

White screen

Text: www.shell.co.uk/brentdecomm

[Audio]

[Video footage]