Gas Rig Strip-Down Engineering Giants

This is the Indefatigable Lima platform.

It's the last remaining offshore rig

in one of Britain's most productive gas fields.

Made up of 2,500 tonnes of steel and almost 15 miles of pipework,

it's brought over a million cubic metres of gas up

from deep below the sea.

For almost 40 years, it's kept us warm,

supplying gas to five million homes.

We were the young pioneers in those days.

We were the ones bringing oil and gas to the UK.

It was exciting.

Now, this giant is about to be demolished.

It's going to be an immense engineering challenge.

You just keep watching it and your heart's going thump, thump, thump.

Diamond-coated wires

will attack two-inch-thick steel.

It allows the machine to just keep cutting and slicing.

Gas axes burning at 3,500 degrees will bring it to its knees.

It's an emotional time for the men who put her up -

the North Sea Tigers.

That's 40 years of my life. Now gone.

Taking her down

will require remarkable technical skills,

and will provide a unique chance

to see right inside this enormous installation.

Could we get that hook reset, please?

This is Engineering Giants.

Lima was at the heart of the Indefatigable gas field

which was discovered in the 1960s, 70 miles off the Norfolk coast.

Now, the gas has run out, and it's being decommissioned.

The whole project will cost £1.5 billion

and involve the expertise of more than 1,000 engineers.

Removing every last trace of Lima

will take nine months.

I'm Rob Bell, I'm a mechanical engineer,

and I've always loved to get my hands on complex machines

to discover how they work.

I'm Tom Wrigglesworth - I'm a trained electrical engineer

with a passion for big machines.

As Lima makes her last journey, from the North Sea back to British soil,

we'll be taking you through every critical stage

of the engineering process.

And as she's torn apart, we'll uncover the secrets of how

one of the world's biggest machines works.

Few people know Lima's secrets as well as Austin Hand.

He worked on her construction at Lowestoft almost 40 years ago.

It started in Middlesbrough, where it had already slipped on schedule,

so Shell decided to bring it down here to finish it off.

-Right across here?

-Just on a barge, moored against the quayside, yeah.

Austin's come to meet two other Lima veterans -

Bill Lindsay and Mick Needham.

They haven't seen each other in over 20 years.

It's been a long time!

-How are you doing?

-I'd like to say we haven't changed much, but...!

LAUGHTER I'm doing great, really. Yeah.

Probably the first time I ever came across you

-was on Lima.

-That's right.

And you...were the main man!

For me, what's quite special is that you guys

were...the pioneers, really,

of North Sea gas and oil exploration, and getting there,

-getting the platforms out there.

-It's a big learning curve,

for all of us - we were only young lads.

I joined Shell in 1971 as a 22-year-old.

I'd been working power stations, and didn't even know

-what an offshore platform looked like.

-Yeah.

Six years...five years later, I'm building them.

In them days, the southern North Sea was quite a family unit.

We didn't have too many people coming in as, like,

international - it was mainly local lads and you kind of stuck together.

-Right.

-And I think that's...these days, changed.

To your friends and family, who weren't necessarily working

in and around the gas and oil industry, the stories

you must have been coming home with every week, they must have been,

-"What?!"

-It was awfully difficult for the families, because

if you're working in a shop or factory, they've got a perception

of what it looks like, but out there, they had no idea

-what it was like.

-No idea.

-My oldest girl was only about four then,

and I had to bring pictures home of a bed and a table with food on it,

and she was happy then. But she just thought I was working in the sea.

Mick Needham's involvement with Lima

started when she was built.

My relationship with Lima started in 1976,

which, er, entailed putting three new platforms in,

and the first one was in Lima.

More than 30 years later, Mick finds himself back out

in the North Sea, working on Lima again,

at the very heart of the decommissioning process.

I got a phone call saying,

"We need a company rep on board the heavy-lift vessel Stanislav Yudin

"taking out the platforms," would I be interested?

And I said, "Too right, I would."

The challenge of working at sea

makes the complex decommissioning process more costly,

more difficult and more dangerous.

Massive heavy-lifting vessel the Stanislav Yudin,

weighing almost 25,000 tonnes,

has moored up against Lima.

This mobile demolition yard

costs half a million pounds to hire per day,

and will be home to the 120 engineers

who will harvest Lima from the sea.

Their first major job is to plug the wells and sever the gas conductors.

The Lima platform had six wells,

each tapping into a separate section of the gas reservoir,

two miles under the sea.

The only way to bore that deep is to brace the well in sections

as it's drilled.

Each time, a smaller pipe is passed down,

and the join is sealed with concrete.

These are known as conductors.

Now, Lima's wells have been plugged in four places with cement,

and the conductors are ready to be cut.

You end up with pipes within pipes within pipes.

So you've got concentric rings of pipes.

Once the conductors have been cut, you will actually see something

that's like a dartboard effect,

with concentric circles within each other, with concrete between them.

Cutting through these materials would be a challenge on land -

but this surgery needs to be carried out 30 metres under the surface

of a stormy North Sea.

Matteo Mosca helped develop an ingenious cutting solution -

one of the many methods used in North Sea decommissioning.

So, what have we got on there?

On this wire, which is just a steel-strand wire,

you've got embedded these diamond bits,

-these elements, which are covered with synthetic diamond.

-OK.

Then, the wire is constructed as an endless loop,

continuous, endless loop.

-And it grinds its way through.

-Yes, and gives, er,

a good finishing - it doesn't alter the physical structure

of the metal, locally, it doesn't heat it.

So, can we actually see this...cut through?

Yes.

-That's what it's made for, so...

-Let's go.

Back out in the North Sea, this process is happening

30 metres below the surface of the water.

These cameras help guide divers

as they manoeuvre the diamond wire-cutter into place.

-MACHINE WHIRRS

-Let's get cutting!

The amount of friction created

by the cutter can heat up the steel so much

that it begins to warp, so it has to be cooled by water.

The saw working out on the Inde field

has the cold North Sea to do the job.

But for this demonstration here on land,

cold water must be sprayed on to dissipate the heat.

The thing for me which drives home what a clever piece of kit it is -

you've got thousands of tonnes compressing down...

..and this cutter allows you to cut across that

without it getting jammed.

A jam deep under water would halt proceedings

and cost tens of thousands of pounds to put right.

But this, because it cuts all the way round that wire,

not just forwards, but also above and beneath it,

it allows the machine to just keep cutting and slicing

right the way through.

MACHINE WHIRRS

It's a really impressive cut.

On Lima, with the wells plugged and the conductors cut,

they'll be able to move on to a bigger challenge -

removing the 2,500-tonne platform.

This scrapping represents the end of an era.

The North Sea veterans who put Lima up

know how tough it will be.

34 years ago, as a young man,

Austin Hand helped to bring it into the world.

Now, he's in charge of decommissioning

on one of the North Sea's biggest projects.

-Is this you here?

-That's me and my boss, Gordon Box,

who was the guy who actually recruited me into Shell.

I've been involved in that sense for 40 years,

either design and construct..

And initially, my first sort of foray into the offshore business

-was, er, Inde Lima.

-That's Lima in the background?

That's it, parked in the quayside in Lowestoft,

after we'd brought it down from Middlesbrough.

So, that was us beginning to get it ready to go.

The platform has to withstand 15-metre-high waves

and winds of up to 100mph.

The legs - or jacket - is all-important,

fixing Lima to the sea bed.

Removing it is going to be a mammoth task,

and will require as much engineering ingenuity

as went into building her.

So, the jacket's basically a frame, and you place it on the sea bed,

then you put piles in, like, pinning it,

and you drive the piles with a big hammer into the sea bed.

That is a piling hammer. It's about 60ft high.

Now, above all these exciting things to do,

one of my jobs was to stand out all night

with a clicker, counting the number of blows of the piling hammer.

You got all the good jobs!

Lima's removal from the North Sea will involve taking away

not just the jacket, but the piles as well.

And before that happens, I want to understand exactly

how she was constructed and secured out at sea.

-I've got to show you how it works.

-OK.

Right, so, obviously,

on Lima, this was done...

a helluva lot further out at sea!

How do they actually get it out?

-They built this on land, the jacket.

-Yeah?

They took it out on a massive barge, though.

But the jacket is basically only there as a guide for the piles.

And these are what takes the whole force

of the topside - so they go...

slot down into each of the legs. So, on Lima,

these piles...

were being driven 90ft into the sea bed.

Must be a very noisy job!

It IS a very noisy job!

That's why they do it so far out at sea, so they don't disturb anyone!

Ha-ha-ha-ha!

That is going nowhere!

'With the legs firmly embedded, the final part of the construction

'was to add the topside.'

Now, 40 years on, removing that topside

is about to be the biggest test so far

for Lima's decommissioning team.

Weighing in at 1,350 tonnes,

this is the heart of the rig, where the crew lived and worked,

processing the gas before piping it to shore.

Cutting it off the legs will be an enormous challenge,

requiring knowledge, skill and nerves of steel.

The problem is, how do you cut across the legs

but still ensure the platform stays in place until craned off?

If, for some reason, we had a storm blow up,

and we just did a straight cut,

potentially, the wind and the weather could vibrate the topsides

and start to move the topsides.

If it's just on a flat surface, it could start to move,

and potentially, the last thing I want to do is have to go fishing

to get the topsides off the sea bed.

Lives could be at stake if they get it wrong,

and so a simple but ingenious solution

is integrated into how they sever the legs.

The cuts are shaped like castle ramparts.

These cuts are absolutely genius,

and crucial to the whole decommissioning process.

Having made the cut through the jacket,

the topside is resting on that. What the castellations do

is to give the whole thing a lot more structural integrity.

But when you do need it to be lifted, the crane comes in

and it's taken up - genius.

The final, castellated cuts are made to Lima's legs, leaving her

1,300-tonne topside precariously balanced on top.

The worst thing that could happen at this stage

is a storm.

WIND BLOWS

The castellations could be brutally put to the test.

But the morning sun reveals that Lima's topside

is still in place. Now, it faces a new test.

This part of the operation is incredibly dangerous.

It uses a floating crane that can lift 2,500 tonnes.

That's as much as the Blackpool Tower weighs,

which is why it costs almost half a million pounds to hire -

every day. Then, in order to float more than

2,000 tonnes of steel back to land, a barge is needed.

This one is as big as a football pitch.

At this moment, there's only one thought running through Mick's mind.

-Is it going to be level?

-The lift is based on complex calculations,

which allow the crane to ballast itself against Lima's weight.

But these calculations are estimates.

So, you're doing a theoretical model

of, er, not only the topsides' weight,

but where the centre of gravity of the topsides is.

And they're about to find out how close to the truth they are.

The platform is successfully lifted off its legs

for the first time in 30 years.

More than 1,000 tonnes of steel are manoeuvred with precision

safely onto the barge.

With stage one complete, the engineers will

turn their attention to the legs.

These are embedded deep into the bedrock, and must be cut off

below the surface of the sea bed.

The task is tricky, and will require an even more ingenious solution.

As preparation for Lima to leave the Indefatigable gas field continues,

I want to find out more

about why she ended up there in the first place.

For geologist John Underhill, gas and oil exploration

is a lifetime's work.

I have this strange belief that under the sea,

when you go drilling for oil, there exist pools of oil,

pockets of gas, large, you know, sealed-off sections

that we drill and tap into, and it all comes out - is that true?

Well, it's a popular myth, really, that we float

on a reservoir of oil - in reality,

it's solid rock, er, with what's called pore space

between it - so, air pockets that can be filled with gas or with oil.

These air pockets, less than a millimetre in size,

fill up with gas over millions of years.

The pores make this kind of rock soft and easy to drill -

so soft, you can even feel it.

I'm moving grains of sand -

they're coming apart and they're on my fingers,

so that's breaking apart, that is a porous rock.

The very same rock formation

that makes up Lima's gas field off the Norfolk coast

travels the length of England,

and emerges on land here at Tynemouth in the north-east.

This is a core from the North Sea, from the Inde field.

Can I hold this...this precious ingot?

And from a sample like this, once in the hands of the geologists,

and tested for all its components,

you can then say how rich it is in oil or gas or...?

We can calculate how much gas is in the Inde field, for example,

from this and from the mapping of the seismic data.

Geologists calculated that the Inde field

contained 5.6 trillion cubic feet of gas -

enough to fill nearly 2 million Wembley stadiums.

Under the right conditions,

gas is formed from the remains of organic matter,

compressed under rock for millions of years.

This layer is known as the carboniferous layer,

or source rock.

Above this, porous rock holds the gas like water in a sponge,

in the gaps between its grains.

Finally, a layer of hard, non-porous rock,

known as the sealing layer, forms a cap,

locking in all the gas - until someone drills a well.

There are two types of source rock - one is oil-prone,

and comes from either marine, erm, sediments

or lake sediments. The other type

is from woody material - coal, that gives a gas-prone source rock.

So it's marine life that gives us oil, and then...

-land life that gives us gas.

-Primarily, yes.

And here, in the cliff face below Tynemouth Priory,

we can see how the source rock lies beneath the sealing layer -

identical to that found in the Inde field.

At the base, we've got the carboniferous,

which is the...the source rock level.

Above that, we have the reservoir unit, the yellow sands,

and above that, the recess right at the top of the cliff

is the sealing unit, which keeps the gas in the reservoir

underneath the North Sea, and all three are exposed here

in this cliff line.

Out in the North Sea, with Lima's 1,300-tonne topside removed,

the next big challenge is to sever the ten-storey-high,

1,085-tonne legs from the sea bed.

All trace of Lima must be removed

to satisfy a so-called clean sea policy,

triggered by a dramatic event in the North Sea 17 years ago.

The Brent Spar was a gigantic oil storage facility,

from which oil tankers transported the oil to shore.

By 1995, a pipeline had been installed,

so it was no longer needed. Shell had a plan to dump it

by towing it into the Atlantic and sinking it.

Greenpeace saw this as a potential environmental disaster,

so they sailed out and took control of the Spar -

a protest that would make international news.

In a blaze of bad publicity, Shell reversed their decision

and instead towed it to shore to be recycled on land

and put the rest of the Brent field decommissioning on ice.

17 years later, the process has restarted,

and Austin Hand, who began his offshore career building Lima,

is in charge.

Did that kind of act as a precedent for now

how all the fields and platforms are decommissioned?

We thought it was a reasonable and logical thing to do,

to take it out to sea, 2.5 miles down in the Atlantic,

and place it in this kind of valley on the sea bed.

Er, we didn't do a very good job of explaining that, so basically,

that resulted in the Oslo-Paris Convention of 1998, that said,

roughly speaking, "You put them there, you take them away."

-A clean seas policy.

-OK.

-That's what Greenpeace strove for,

and that's what they succeeded in getting.

There's so much involved in this that the cost of decommissioning

-just must be enormous.

-Austin's estimate, Austin's view -

100 billion.

-Of decommissioning...

-In the UK.

There are those that would say, "I don't believe you, Austin,

"you've over-stated it."

We'll see who's right in the end.

Because of the clean seas policy, out in the North Sea,

the Lima engineers now face a really difficult challenge -

cutting the legs of the jacket to remove it from the sea bed

in a way that leaves no trace that it was ever there.

To achieve this, the jacket legs must be cut off

three metres below the sea bed.

This means the only way to cut the legs

is to sever them from the inside.

It's a job that demands a very special type of cutter.

As world expert George Jack explains, there's no blade,

no flame - just water and grit.

Is it the sea water that you're using there?

Yeah, we filter sea water in through our pumps,

take it up to high pressure,

and introduce the abrasive to it as well.

That's the actual garnet that we introduce to the water.

-That's pretty hard stuff?

-Yeah...

'Garnet is a dark red, silicon-based mineral.

Although large crystals are used in jewellery,

some types possess strong atomic bonds, which make them very hard,

and ideal as industrial abrasives.

If you don't have that in your water,

there's not enough, er, friction

-to cut through the actual metal.

-OK.

George is about to demonstrate to me the power

of cutting with water and garnet.

This is the control room, where we control the water pressure,

-the grit monitor...

-So, what pressure are we at at the moment?

-Just now, we're sitting at 6,000 PSI.

-OK...

'That's 300-400 times greater

'than your typical water supply at home.'

-So, abrasives on.

-Yes, that will put your...

introduce the grit into the system, and the pressure comes up.

Here we go!

He-he! Look at that!

As soon as it starts coming through,

you'll see the water coming underneath.

Who-hoah!

-Now!

-Now you can see it's just gone through!

-So, that's 50mm of solid steel, that's just cut.

-50mm, yeah.

Compared to, say, a high-pressure jet hose that you might get for

-washing your car or doing your patio from the hardware store...

-Yeah.

..if you tried to do that with this thing,

-you'd do more damage than good, right?

-Oh, yeah.

The pressure we can barely read on one of these gauges -

the first line on that, it goes up in thousands...

I'm not sure what kind of cut I'm expecting.

Is it going to be a clean cut? Will it be quite jagged?

Here we go.

Wow! That's clean. That's a really

-straight, clean cut.

-Surprising, isn't it?

Bit of the old Paul Daniels, Debbie McGee -

-it's gone right the way through.

-Yep!

-So, this is not for domestic use.

-No.

Not for domestic use, I'm afraid!

The Lima engineers are ready for the high-pressure water cutter.

With the topside removed, they're able to lower it down,

right inside the legs.

In theory, if the severance isn't complete,

the crane could pull the Stanislav Yudin over.

In practice, fail-safe mechanisms would prevail.

But an incomplete severance could still cost millions.

-We control it from the topside using hydraulics and everything.

-OK.

And it'll cut...do a 360 degrees,

sub-sea, just three metres below the sea bed.

Before they begin the cutting, every precaution must be taken.

The system is pressurised to 6,000lb per square inch.

Any leak or breach could be deadly.

An exclusion zone around the cutter is strictly enforced.

We've got high-pressure hoses running across the deck.

If you put your hand up like that...

you're not going to have anything left.

Calculations estimate that the 360-degree cut

of each leg should take 75 minutes.

All Mick can do now is time it and hope.

Once the allotted time has been given to each leg,

special slings are attached.

So all the slings are...

They're not just something you get off a shelf.

All the slings are engineered and designed

and built to the length required.

Now the crane must ballast itself against an unknown payload.

Up to 300 tonnes of extra weight in marine life

could have accumulated over four decades,

making the jacket 1,400 tonnes - as heavy as seven jumbo jets.

All this makes the calculations for the stability of the crane more and more difficult,

puts the ballasting power of the Stanislav Yudin yet further to the test,

and her stability in more jeopardy.

And then the big, tense moment for everybody...

..because we are now going to start to lift the jacket.

But there's one thing we can't do - we can't actually 100% guarantee

they're cut by going and having a look at them.

You hear the crane driver,

he starts taking the weight on the crane...

..1,200, 1,400 tonnes, somewhere in that region.

And if he gets to 1,400 tonnes

and then he starts saying, "I'm at 1,450 now,"

you're thinking, "I hope this is going to move shortly."

And your heart's probably going "thump, thump, thump."

And then, all of a sudden, it just seems to go, "Ooh!"

And it's a great sight, that, and it's a great relief.

After the final lift, engineers work through the night to fasten

Lima safely to the barge upon which she'll make her final journey.

And that was it, it was an end of an era

for, not only myself, but for so many people

that have worked on the Inde field throughout the last 40 years.

In the dead of night, she leaves the Inde field behind for ever

and sets off on the 200-mile journey home to the north-east.

Mick's relationship with Lima has finally come to an end.

Inde produced for so long, it brought lots of people work,

and, more than that, lots of great friends and happy memories.

I think that's what'll stick.

I'm now choking up.

Oh, dear.

I can't believe it.

Excuse me.

But, for Lima, this marks the start of the next phase of deconstruction.

As dawn breaks over the horizon,

Lima arrives at the mouth of the River Tyne.

From here, she'll be taken to the famous Swan Hunter shipyard for demolition.

It's amazing to think something like Lima, how important that was to us.

We just don't really consider that at all, really.

It's delivering all that gas to our homes, keeping us warm, cooking our food...

Well, the Inde field actually produced enough gas

in its lifetime to power the UK for a year and a half.

-Just in one gas field?

-Yeah.

At the Swan Hunter shipyard, they must wait for the tide

to be just the right height, so the barge is level with the quay.

Only then can the painstaking process of sliding

over 2,000 tonnes of steel off the barge on to land begin.

You don't see one of them come over every day, do you?

Four remotely controlled bogies, with a total of 56 axles,

each capable of supporting 36 tonnes of weight...

Fantastic.

..manoeuvre Lima into her final resting place.

Now the next chapter in her story is about to begin.

Ivan Rayne is Geordie born and bred,

and is another person whose relationship with Lima

and her sister platforms goes back to their construction in the 1970s.

I bet you didn't have to wear all this kind of stuff back in the '70s, did you?

Yeah, we did, but once you got offshore,

if you ever mentioned the word "safety,"

you were on the next helicopter home again.

He, too, has come a complete circle.

He's now here to oversee the demolition and recycling of Lima.

All these pipes and valves and the kind of meat, everything we can see,

it's all dedicated to getting that gas up and out of here.

The main function of this platform is to gather gas from the seabed,

and the gas would be brought up through six pipes,

brought into this system here,

and then redirected to another complex, where it is collected

and then it's sent to the UK mainland for refining.

Then it gets redistributed throughout the UK,

then it comes into your house and that's what you use

for cooking your roast beef on a Sunday.

For Veolia's recycling team in charge of the demolition,

this is no ordinary take-down job.

So, this has been out in the North Sea for 40 years.

Where do you start in taking it all apart and recycling it?

The helideck will be cut off and pulled over,

then we'll start dismantling it, section by section.

Once that's flattened, they'll start cutting it up into

very manageable pieces, and the smaller the pieces,

the better the value they get for recycling for transport off the site.

All right, so now we're talking money.

Typically, what are we looking at for recycling this whole platform?

You could be looking at anything from £180-£200,000 scrap value.

After 40 years of service, providing gas to millions of people,

and jobs and even a home to hundreds of North Sea Tigers,

Lima is finally about to be brought to her knees.

First, her infrastructure is weakened by strategic cuts.

Next, it's time for the excavators to really get to work.

Steel wires are attached to the helideck

and the machines go into reverse.

This red accommodation module is next for demolition.

Its fixings to Lima's frame have been severed,

and the excavators are standing by.

'Mick Cubitt spent four years living and working

'on Lima as an electrical engineer.

'It's almost 19 years to the day since she last saw her.'

That is incredible. It's like a bomb...

A bomb has hit the place.

In fact, it's bordering on unrecognisable.

I don't want to pull any more emotional punches on you,

but I think that is your old bedroom,

that red tin shack over that.

I'm afraid so. I spent several... in effect, the equivalent to two years' worth.

-So...

-Four years, half on, half off.

-That's right.

Some 700 nights spent in that little tin box.

We're about to walk into your accommodation block,

-this is home sweet home.

-Home sweet home looks fairly devastating to me.

It's really had the insides ripped out of it.

So this was the living area, was it? This is where you passed the time?

Well, prior to the introduction of satellite television,

we used to show films that were hired in by the company.

-Like your own little Blockbuster!

-Yes!

So, Mick, this must have been pretty cramped. How many people lived in here?

This was accommodation for eight people, two lots of bunks.

Um, the shower for all four was in here.

That's the shower tray, with a wash basin just here.

Shower, wash basin.

That was your emergency exit.

So, it's the middle of the night,

you're asleep in your comfortable abode and there's an emergency alarm.

The worst-case scenario. What's the order of service?

Three offs. The three offs being block off,

we would block in all the wells, stop the gas coming onto the platform.

-You would then vent off.

-What's the third off?

-You just

-BLEEP

-off!

-Follow me.

-OK.

Quickly, Mick, it's an emergency situation!

For Mick's Lima colleagues,

reunited in Lowestoft for the first time in over 20 years, all that's

left are photos and shared memories of their incredible offshore lives.

-Is this you?

-That is me on Lima.

How many times would you have been offshore at that stage, do you reckon?

Probably not many. We used to fish, didn't we, Tony?

-There is some entertainment to be had.

-Made our own entertainment.

What was the food supplies like, did you eat well?

Ate very well. You would have a choice of a fillet steak, a bit of fish.

-That's a decent spread, isn't it?

-It is indeed.

-Christmas crackers.

Explosive devices offshore!

LAUGHTER

If you had a good chef, you had a good platform, and you'd a productive platform.

One thing I really take away from this whole process

is it isn't just the hardware, it isn't just the steel and everything.

-It's the family.

-It's the family of all the people who've built it, worked on it.

How does it feel now that that particular field and Lima platform is not there any more?

Does it kind of sit with you, does it rest with you, or...?

When you finish, you think, "That's 40 years of my life. Now gone."

You just realise how old you're bloody getting!

Back at the Swan Hunter shipyard,

another relic of the glory days of the North Sea has been uncovered,

a stark reminder of just how treacherous it can be.

This looks like a horror story, but I believe it was just a helideck,

when they removed it, it smashed into the front.

-But this is your survival raft.

-Yes, this was the Brucker capsule, as it was known, on the platform.

Awful thing to steer, being circular, and an awful thing to ride in.

Were you the captain?

I've done the coxon's training on here, and I've been to see with guys who are happily throwing up,

and it is not the best place to be, even with a dozen guys in,

when you've got a couple of them throwing up into their hard hat.

I'm hoping that years of training means that my Lima veterans

have grown stronger stomachs,

because I'm about to get my first taste of the Brucker pod experience.

This is exactly the kind of one you had up on Lima, is it?

-Absolutely.

-Yes, identical.

-Identical.

-Luxurious, was it?

-No!

-That's how we became friends!

THEY LAUGH

Pods like these have safely evacuated

more than 2,000 people in over 60 incidents around the world

since Lima was built.

How long is it since you guys have been in one of these?

For me, it would have been 1978, in this particular type.

I've been given the job of releasing the capsule,

and it's fair to say that the speed of the response takes me by surprise.

Right, we're off.

They were designed for the Gulf of Mexico,

but the bobbing doughnut was no match for the waves and currents of an undulating North Sea.

The survival pods, still vital for an industry which

has claimed hundreds of lives, are now usually boat-shaped.

I'm being shown at the ropes by Nick Goldspink,

who's been teaching North Sea Tigers

how to navigate these pods since 1989.

I mean, we're moving around like a boat but, still, this round shape

seems like a very odd design for a boat to me.

Yeah, it's partly to do with strength

and it's partly to do with ease of operation.

The traditional style of lifeboat has got a cable at the front and the back,

and there's a chance that that can hang up.

There is no chance and no possibility of that with this shape of boat.

Obviously, there is a compromise to the shape,

and that is that they do bob around like a cork.

Round boat, though, how do you even steer this?

Yeah, well, that is more difficult than a traditional lifeboat shape,

but the advantage to that is they are very manoeuvrable.

But she's steered, basically, from the tiller, here,

which again, is unusual in a lifeboat,

to steer a boat from the front.

If you were to evacuate,

how long would you be able to survive in a craft like this?

A fairly long while would be the answer to that.

I mean, there's enough water and food for a week.

I would not want to be stuck in here for a week with 27 other people.

You'd get to know them fairly well fairly quickly!

You would become quite an intimate, an intimate team.

-So, how was that, gents? Bring back a few memories?

-Yes.

I have to say, 20 years on, I never thought I'd be back in one of them!

Back on Tyneside, there's nothing shipshaped about Lima,

which is being slowly cut down girder by girder,

making it no longer possible to trace the pathway that gas would have taken,

snaking through miles of Lima's pipework from under the sea to our kitchen hobs.

So, to solve the mystery of how she worked,

I'm going to see an offshore platform in action

and trace the fossil fuel route.

I'm bit anxious, because I've never been on a helicopter before.

Thanks to gas and oil, Aberdeen heliport is Europe's busiest,

ferrying almost half a million passengers offshore every year.

Across the North Sea, more than 100 lives have been lost

since air transfers began,

which is why every possible safety technique is used.

I'm terrified, truth be known. Absolutely terrified.

In the event of the helicopter ditching,

this suit will increase my survival time in the freezing North Sea

from just minutes to about seven hours,

but I hope I don't have to put it to the test.

After an hour of seeing nothing but sea, a platform comes into view.

100 miles offshore from Aberdeen, in the northern North Sea,

this is Nelson, which produces both gas and oil.

The fossil fuel's pathway on Nelson

is very similar to Lima's gas pathway,

so I'm going to track the route from under the sea to our homes

and explore how current technology works.

While Lima had six wells, Nelson has drilled 28.

Nelson's manager, Nick Macleod, is going to show me the drill floor.

Wow!

-Pretty impressive drills there!

-That is impressive.

Our wells here can go down as far as 20,000 feet.

-20,000 feet?

-Yeah.

And eventually we get down to what's called the pay zone, which...

-Pay zone?

-Yeah, the pay zone - that's where the money is!

-Yeah, yeah.

-That's where the oil and gas is.

-OK, what happens then?

It all spurts up, doesn't it? And everyone cheers!

In the old days. Hopefully not these days!

The first crucial stage for the fuel that emerges is the well bay.

Everything is moving about and juddering. It's really noisy.

Absolutely unbelievable.

It's unbelievable to consider that they've made this size of machine.

It is even more incredible

when you realise that we're 100 miles off the coast.

Production engineer Murdo MacDonald

is here to explain the first step of the fossil fuel's pathway...

-Oh!

-There's not a lot of room in here.

..which involves something known in the trade as a Christmas tree.

Why is it actually called a Christmas tree?

Maybe it's because they look like they've got branches coming off.

You've got all the gauges hanging off...

You've got quite an imagination if you...

Aye, you've got quite a bit... You have to with two weeks offshore!

When a well's drilled,

the raw fuel comes up the conductors into the well bay.

On Lima, this was gas. On Nelson, it's gas and oil.

Here, the Christmas trees, large assemblies of valves and gauges,

help control the flow of oil and gas entering the platform.

-I'm ready for my first offshore job.

-Five turn!

Oh, one...two...three...four...

Five turns!

-What have I done?

-You've just closed the choke in about 5%.

Just closed the choke in 5%?

-Which has restricted the oil flow coming up...?

-Absolutely.

Stage two of the pathway is all about separating

what emerges from the well into its constituent parts.

It's like science fiction film.

When a well is drilled, oil comes up the conductors into the well bay,

but it's not pure oil.

It's a mixture of oil, gas and water.

In order to extract the valuable oil and collect the gas,

the whole mixture is sent

to one of the most important devices on the platform - the separator.

I've made a model of Nelson's separator,

to explain to Rob how it works.

It's bafflingly simple.

We have here a bucket, which to the casual observer

appears to be a generic brand of cola mixed with vegetable oil,

which is actually exactly the same as oil, water and gas, all right?

That's from the bottom of the sea.

We've got a pump but, normally, that's got enough pressure to be forcing itself up.

Exactly. That would be pushed up under its own steam.

So, what you do, you separate them out.

-The gas will naturally float off to the top.

-Yes.

-Lighter than both of them.

-So that will normally be tapped and off into wherever else...

Exactly, that'll be tapped and processed, yeah.

Water is heavier than oil.

So, this weir is very important, because the oil floats on the water.

OK, you see that easily here.

So, the brown stuff is the water and the creamy stuff is your oil?

Exactly. So, because the oil is floating on the water,

it flows over the top of this weir,

creating this secondary chamber here, which is pretty much all oil.

So, coming out of here you get pure oil,

coming out the bottom of this section you get flat cola -

-or water.

-Yeah.

-Coming out the top, gas.

-Gas.

This separation stage of the fossil fuel's pathway is vitally important,

because it tells the energy company how much gas and oil they are producing.

To do this, every day, each well is taken out of production

and diverted into the test separator.

-Tom, pleased to meet you.

-You too. How's it going?

In the control room, Pete O'Connor is monitoring results.

So, that's the production valve there -

the diverter valve, which is open.

That's the test one, which is shut.

So, by putting it into the test separator,

it lets us know how the well's performing,

how much oil it's producing, how much water

and how much gas it's producing.

All our wells, now, are starting to water out.

-They're all over 80% water.

-And that didn't used to be the case?

No. No, they all gradually, they gradually decline in oil production.

So, the test separator

is actually testing the mix of oil, to gas, to water?

-For each individual well.

-Yeah.

We have a spot rate there, which, at the moment,

can tell you we're doing 19,357 barrels, near enough,

-today, at the moment.

-Wow!

At that rate, Nelson produces oil

worth around £1.5 million a day.

Not a bad return.

The third and final stage of the fossil fuel's pathway

is exporting it.

Water is cleaned and pumped overboard.

Oil is cleaned and then pumped down the export pipeline to shore,

but it's not all over for the gas.

Some is exported to gas terminals.

Excess is burnt off on the iconic flare stack.

But most of it is diverted to something known as the gas lift

to do an important job.

Because of the weight of the ocean

on this trapped reservoir of hydrocarbons,

it's all under pressure...

-Which is kind of like this.

-Ha-ha-ha!

-So, the moment the drill pierces it, BOOM!

-Wow, you've got oil.

The oil comes out. Now, obviously, quite soon it loses pressure.

So, once they've been tapping the oil off...

-So, it becomes, like, the field becomes flat?

-Yes, exactly.

It becomes flat, it becomes devoid of pressure.

-Yeah.

-So, what you do, instead of pumping it up...

-Yeah.

..you push gas down into the reservoir,

which makes the oil light because it's got gas in it,

which then sends it back up.

-You basically make the world's biggest SodaStream!

-Yeah!

The gas collected from the separator is compressed, repressurised

and then reinjected back down the well via the Christmas tree,

forcing more precious oil up.

The force required to do this is huge.

On the platform, Murdo shows me where they get it from.

It's a gas compressor, which is essentially a jet engine,

and it's one of the noisiest things I've ever experienced.

SHOUTING: The engine drives the power turbine,

that drives the gas compressor.

The gas compressor takes the pressure

from five bar in the separator,

takes it all the way to 147 bar.

'That's 147 times atmospheric pressure.'

That 147 bar is then used in the header to reinject

back down the wells and lift the oil back up again.

They've a powerful blow, those jet engines.

I'd say it's quite a blow, all right.

But while Nelson's conductors are still full of North Sea gas,

Lima's conductors now lie severed from the rest of the platform

on the quayside at the Swan Hunter yard near Newcastle.

Demolishing them is going to be a feat in itself.

Because of the way the wells are drilled and constructed,

they end up with pipes within pipes, within pipes,

all sealed with thick layers of cement.

Turning this into small pieces of scrap metal requires

a process known as bombing.

First, the gas axe is used to cut along both sides

of the long steel conductor.

Then, to get at the inner pipes, the excavator steps in.

Once it's made short work of the concrete,

the inner steel pipes are revealed,

and the process starts over again.

With over a third of a kilometre of conductors to scrap,

it's a lengthy process.

Meanwhile, on the other side of the yard, only Lima's legs -

or jacket as it's known - still remain.

Built from over 1,000 tonnes of high grade steel,

it must be broken up into small chunks to be recycled.

The first stage is to bring the structure to its knees.

Strategic cuts must be made so the legs collapse neatly.

But it's a dangerous job.

As soon as a cut is made, the platform is weakened

and may fall at any time.

-Are you guys responsible for felling the legs?

-Yes, we are.

I wouldn't like to be the guy who does the final cut.

-Who's in charge of that?

-Whoever wants to do it.

The backside gets a bit twitchy when the final cut's made.

I can well understand.

I think if it was me, the moment the axe is finished,

I would be turning and running. Do you actually...?

Oh, no. There's no need to run.

In a carefully controlled and calculated procedure,

towlines attached to the top of the jacket will be used to pull it over.

This is the first time this method has been attempted

anywhere in the world.

We attach two ropes either side of the jacket

and a safety rope to the very back of the jacket,

just to stop the back legs toppling the wrong way.

The engineers have put down a bed of earth for the legs to collapse onto,

to cushion the impact.

-They've got two lines, haven't they?

-Yeah, two pulling lines.

These guys will take the tension up on the wire.

Just give it a little tug.

It's quite exciting, just the anticipation of it.

Before it comes down.

-Everything clear? RADIO:

-'Clear.'

-Don't let anything in now, cos we're about ready.

-'All clear, Mick.'

If the 30-metre-high back legs were to fall in the wrong direction,

they could land on a factory behind the shipyard.

-Excited to see these come down?

-I love it.

-Brilliant.

-Well done.

-Brilliant.

That was awesome. Congratulations.

-And that's the way to do it.

-RADIO: 'Perfect, Ned.'

The demolition of this jacket for recycling is the final act

in the scrapping of the Lima platform.

'Although veteran Lima engineer Austin Hand

'is working in decommissioning,

'he has not seen Lima - the platform he cut his teeth on - for 20 years.'

There she is now.

Wow.

I'm so used to building things,

so to see it dismantled and in pieces is just...

You're probably quite used to it in this condition, in a sense.

I can still see the module, yeah.

-Just on a different curve of its life.

-Yeah.

That really reminds me

of going on and off that barge for months.

Getting it completed, just walking over the gangplank

and working 12 or 14 hour days, every day.

-But it was fun and exciting.

-I'll bet.

-Yeah. That gives me a buzz.

We were the young pioneers in those days.

We were the ones bringing oil and gas to the UK. It was exciting.

Good memories.

So, we've seen, Austin, as this process has unfolded,

the huge machine of Lima

being reduced to small piles of steel rubble.

I was surprised to see so much timber on show.

Can you tell me about this?

They used to say in my day that the rigs were made of wood

and men were made of steel, but that's not actually true.

What this was is we covered the main steel deck with this timber

so that when you were lifting stuff off the supply boats

and landing it on the platform, you had some absorption material

to avoid damaging the deck or even the container.

So, all this timber here was to provide you

with a huge cushioned area to protect the whole thing.

-Like a massive chopping board, in way.

-Absolutely, yeah.

This steel tubing once formed the jacket that supported the topside.

It's now been broken up into sections, ready to be recycled.

'But to the expert eye, even these fragments reveal

'the challenges of these early pioneering designs.'

In the '70s, sometimes the quality wasn't that great.

This is a good example here.

This is a very tough angle for a welder to get in at these points.

-Yeah, you get right down in there.

-Exactly. So, in an ideal world,

that brace would have been at less of an angle.

Very often, the designers just wanted it to be structurally robust.

Then, when it arrived for us to deal with in the construction yard,

you think, "Wow, why did they do that?"

Yes, so on paper, mathematically, it makes perfect sense.

Exactly, but sometimes it wasn't constructible.

But again, this was a learning process.

We'd feed that back in to the next jacket and say,

"Can we do this slightly differently?"

That's how we evolved the industry, getting better and better

and ensuring these wells were sound and solid.

All these things had to be considered, even with a relatively

simple structure like a jacket.

For the final time, the excavators pull on Lima's infrastructure

to bring down her last storey.

The legs are going to go.

There she goes.

It's very sad to see that, something that you built when you were

a 25-year-old, and you're pulling it to bits when you're a 59-year-old.

It just shows you, time moves on. Nothing stands still.

Lima is now unrecognisable,

just heaps of rubble and thousands of tonnes of scrap steel.

Amazingly, some 99% of this will be recycled.

The wood from the decks is pulped and made into paper.

Even the 300 tonnes of algae that collected on the legs

will be recycled for compost.

But most lucrative is the steel.

Once the various grades have been separated out,

it's then smelted and made into new girders and pipes.

Fittingly, just half a mile down the road,

steel from the smelted remains of machines like Lima

are being used to build this...

..a brand-new 21st-century platform.

To put it in perspective, whereas Lima weighed a few hundred tonnes,

this weighs in at a whopping 12,000 tonnes.

Platforms like this are giving the North Sea a new lease of life.

But Lima and its gas field are now just a memory.

Removing it cost more than £200 million, took two years

and over a million staff hours to recycle 2,000 tonnes of steel,

311 tonnes of algae, find homes for two generators

and scrap two toilets and 12 well-worn bunks.

Ironically, some of the North Sea Tigers who pioneered

offshore platform installation are now involved

in the biggest new North Sea industry -

taking them back down again.

Subtitles by Red Bee Media Ltd