Original subtitles

Chad zdenek: A giant deep-sea oil rig

In the middle of the north sea,

Built to withstand wild and violent weather

And drill deeper than ever before...

...To pump two billion barrels of oil.

Now this extraordinary machine has reached the end of its life.

Now here's the inner workings of an oil rig.

Salvage teams are ready to take it apart...

Oh, yeah, it's going. It's going.

[laughs]

...And sell what they can

To be melted down and recycled.

Give me the honors.

As they strip it back,

I'll get up close and hands on...

It's huge.

...To uncover the five engineering innovations

That made it a giant of its time.

I'm chad zdenek.

I spent seven years building rocket engines for nasa.

Now I'm taking things apart,

Breaking down giants of engineering piece by piece

So I can discover what made them legends of their time.

♪

Hartlepool, on the northeast coast of England,

The final resting place

Of what was once the world's deepest drilling oil rig.

Now, we've all seen oil rigs out at sea on television before,

But few of us have ever gotten this close,

And I can't believe the sheer size of this thing

And can't wait to get inside.

It's 40 stories tall,

Covers 60,000 square feet,

And weighs nearly 26,000 tons.

This huge platform stands on the remains of three giant legs

That once held it above the water

And stretched 500 feet to the seafloor below.

From there, it extracted oil and gas

Almost 9,000 feet deep and pumped it to the mainland.

Now, after 40 years,

The brent delta rig's working life is over.

It's been towed ashore,

Where it will be worth millions of dollars

As recycled metal

Once it's been cut into pieces and melted down.

But this thing was built to be indestructible,

So taking it apart won't be easy.

One of the reasons I'm so excited to join this team

Is that they're attempting something

That's never been done before--

To deconstruct an oil rig of this size on land.

The engineers are literally having to figure it out

As they go along.

The rig is massive,

But its construction is surprisingly intricate.

Duncan manning: It was an engineering marvel

To put these platforms in place in the northern north sea

And extract oil and gas.

Reversing that process now and removing platforms

That were never designed to be removed--

Decommissioning wasn't a design feature--

Presents a real engineering challenge for engineers today.

Chad: So, how much are you guys hoping to recycle?

Manning: What we're trying to aim for is,

Is over 97 percent of this platform

Will be, will be recycled.

Chad: That would net them around $5 million as salvage,

Cash that would help take some of the sting

Out of the huge cost of safely decommissioning this thing.

But getting their money out will be hard work.

Over the next nine months,

I'm going to help the demolition team

Tear the rig apart as they try to do it.

While they salvage what they can to sell for recycling,

I'm going to unlock the five engineering secrets

That made this rig a record breaker--

The incredible drilling system

That bored through the ocean floor,

Then sent oil and natural gas 9,000 feet to the surface;

The tanks that separated the precious oil from water and gas;

The huge safety valve

That burned off dangerous gas in a 100-foot flame;

The supercharged jet-engine-powered generators

That provided nonstop electricity

Over 100 miles from land;

And the blast-proof accommodation block

Built to protect crew from lethal explosions

And some of the worst storms on the planet.

I really want to get to the drill derrick,

But it's right at the heart of the rig,

And we can't just cut it down straightaway.

The whole structure is carefully balanced

On what remains of its three legs.

Take too much weight from the wrong place,

And the whole thing could topple over,

So we have to cut the structure into sections

And pull them out one by one,

Kind of like a giant game of jenga.

Alan graham: Everything on the outside of the rig

Was cantilevered,

So we've had to dismantle the rig into itself.

And we need to keep the center of the gravity.

Chad: And then when we'd have, like, a big accommodation block

Coming off the side, we've got to make sure

There's still enough weight to keep this thing centered.

Graham: That's what it's all about.

♪

Chad: With that in mind,

The demolition team is going to start here,

The rig's power generation module.

It weighs 500,000 pounds

And will be worth tens of thousands of dollars

As scrap metal.

It's also home to an ingenious engineering innovation

Which I want to uncover.

The brent delta needed as much electricity as 10,000 homes

Every single day,

So engineers had to find a way to deliver all that juice.

The problem was shell's brent delta

Was standing all alone in the wild north sea,

100 miles from land and the nearest electrical supply.

The solution was to get the rig

To create its own electrical power,

So engineers installed three huge generators

Powered by three very special engines.

Together they created enough electricity

To run an entire town.

They powered the drilling system,

The oil pumps, the processing units,

And everything necessary to support a crew of 160 men.

The genius of the system

Was that it made the rig energy self-sufficient.

To find out how, I've got to get inside,

Using my trusty flame cutter, somehow.

I've got my burning gear. I'm ready to cut some metal.

Now it's time to say goodbye to the power generation module.

We're starting with the roof.

It's connected by chains to a crane to support it

So we can cut through the beams

That attach it to the rest of the structure.

I'm making the final cut,

Which will leave it dangling from the crane.

[thud]

Whoa! There it is.

It dropped a good inch.

All the weight's on the crane now.

Still hear it creaking.

Now we can lift it clear.

Now, there's something satisfying

About making a final cut on a 22-ton roof

And seeing it lift off.

♪

As the roof and walls are removed,

I'm hoping to see the three engines inside.

It turns out, I'm too late.

They're so valuable, they've already been salvaged

And put back into service on another rig.

All that remains is the housing,

Which our crane is dismantling

To reveal these three open exhaust shafts.

They're all that's left of the genius brain wave

That made the brent delta energy self-sufficient.

It so happens that natural gas

Is a normal by-product of pumping oil.

It gets brought to the surface with the oil,

Where it's separated away

And, for years, was burned off as waste.

But in the 1990s, brent engineers realized natural gas

Was the power source they needed,

If they could figure out a way to harness it.

All the engineers needed was an engine that could run on it,

Compact enough to fit on the oil rig,

But powerful enough to keep the entire platform running,

And for that, they looked to the skies.

The electric lightning was a cold war fighter jet

Used by air forces around the world

In the fifties and sixties.

It had two avon jet engines,

Which provided so much thrust,

The lightning could fly at twice the speed of sound.

Pilots described flying in it

Like being saddled to a skyrocket.

I've come to this overhaul facility in scotland

To see one up close.

The basic design is classic jet engine.

These blades will suck air in here,

And that air is compressed in this section.

The compressed air is mixed with aviation fuel

And then ignited inside the combustion chamber.

Hot exhaust gas will blast out of here

At 1,200 degrees fahrenheit, creating 26,000 horsepower.

The brent delta engineers' ingenious solution

Was to install three of these jet engines

And use them to run the rig's generators.

All they had to do was modify the engines

To run on gas instead of jet fuel.

Then they directed that blast of hot exhaust gas into a turbine

Connected to the generator,

And that way produce the 36 megawatts of power

The rig needed every day.

♪

Since then, the avon engine has become an oil industry standard.

700 are still in use on oil rigs today,

And many get sent to this facility to be overhauled.

I'm helping install new compressor blades on this one

Before it's put back into service.

So, we're working on reassembling

This overhauled engine,

And right now it's in the vertical position,

And the inlet's at the bottom.

So, essentially, the air would come up through here,

And it goes through each of these stages

Of this giant compressor section.

It's going to be compressed more and more

Until at the top, it's going to be mixed with fuel

And then ignited in the combustion chamber.

Believe it or not, this engine is 30 years old.

It's already had 150,000 hours of service,

And after this major overhaul that we're giving it,

It's going to be good for another 30,000 hours.

Considering that this engine has been out in the north sea

On an oil rig for all these years

And it looks this good and still continues to work,

It speaks volumes to the design and the engineering

That's gone into it.

20 years ago, this deck roared with the sound of those engines.

Today, it's the sound of flame cutters.

We're slicing through the final uprights

So what's left of the power module

Can be pulled to the ground in one giant chunk.

That will take brute force.

Pulling down a 400-ton block of metal

Can't be done with normal ropes and cables.

Now, these are some serious heavy wire rope.

It's about two inches thick, and I can barely lift it up.

But the key is that we've got it wrapped around the top

And then down here shackled together,

And we've got the excavator behind me.

It's going to come up

And literally just grab these two ropes,

Start pulling, and then it's coming down.

♪

Okay, time to stand back.

Oh, yeah. It's going. It's going.

The mighty brent delta oil rig has reached the end of its life.

Now, in a world's first,

All 26,000 tons of it is being taken apart on land.

The power generation module,

Which provided electricity to the rig,

Is the first section to come crashing down.

[laughs]

Oh, man!

And now the hartlepool skyline is now changed.

This rig is now on its way to being completely recycled.

But in 1973,

The rig was the solution to an economic disaster.

Announcer: Anwar sadat takes up leadership

Of the arab crusade against israel,

And in 1973, he orders egypt to attack.

Chad: When america supported israel in the yom kippur war

Against egypt, syria, and other arab states,

The arab coalition responded

By drastically cutting the flow of oil.

Within months, american gas pumps actually ran dry.

A new 55-mile-an-hour speed limit

Was introduced to save fuel.

There were even calls for rationing.

Western powers needed oil urgently.

As energy independence became a political priority,

Countries began looking for oil a lot closer to home.

The united states ramped up exploration

In the gulf of mexico.

Meanwhile, britain discovered its salvation in the north sea.

Announcer: Liquid gold-- call it what you like.

Britain now has oil, billions and billions of barrels of it,

And it's been quietly lapping at the doorstep all the time.

It has been estimated that three percent

Of the world's oil reserves lie beneath the north sea.

All these years, britain has been sitting

Beside a fabulous industrial treasure trove.

Great britain has struck it rich.

Chad: In 1974, shell oil commissioned the construction

Of four massive rigs to cash in on the bonanza.

They wasted no time.

By the end of 1978, all four--

Alpha, bravo, charlie, and delta--

Were up and running in the brent oilfield.

From there in the north sea,

The brent delta helped the united kingdom cash in

On more than two billion barrels of oil over its lifetime.

Today there's still money to be made from the rig.

Prices fluctuate, but melted down,

The scrap is worth around $200 a ton.

So, the power generation module

Has hit the deck in dramatic fashion,

And this is all that's left behind.

All that's left to do now is cut up this monster module

And get it to the recycling yard.

So, it's another chance for me to melt some metal.

To do that, we use cutters

That use oxy propane blowtorches

That burn at over 5,000 degrees fahrenheit.

♪

It takes me about five minutes

To cut through this giant pipe,

Which is about two inches thick.

Wow. [laughs]

Now, that's how you cut some steel.

This 250-ton power unit could be worth up to 50 grand.

The steel will be melted down and turned into new sheet metal.

There's enough on the brent delta

To make 200,000 washing machines,

But it could end up as anything--

A railroad car, a construction girder,

Even the hood of your next car.

Every cent they make on recycling

Will help offset the steep cost of decommissioning this rig.

Why is it so expensive?

Because just getting this platform ashore

Was an engineering miracle in itself.

It's taken more than a decade to get this far.

In 2006, engineers began planning

Just how to carry the 26,000-ton brent delta to land,

Where it could be safely dismantled.

It was a daunting prospect.

They knew there was only one ship in the world

Big enough to event attempt to lift it.

[horn blows]

And this is it, the pioneering spirit,

The largest construction vessel on the seas,

As long as six 747s.

Its job was to lift and carry

The enormous weight of the rig platform.

If engineers could achieve that,

This would be the biggest lift ever completed at sea.

After years of preparation and billions of dollars,

In April 2017,

The record-breaking attempt took just ten seconds.

♪

[horn blows]

[laughter]

For now, the three 500-foot legs have been left in place.

They're still not sure what to do with them.

The engineers' next problem

Was where to put the massive 26,000-ton oil platform.

Once ashore, its enormous weight

Would simply sink into the ground,

So the decommissioning engineers designed and built

A $30-million specially reinforced quay

To support the rig when it came ashore.

Even from a technical

Or engineering standpoint,

Just getting it from

The north sea to the dry dock

On land here was a big effort.

Peter stephenson: Very innovative, yes.

There's been a tremendous amount of work, research,

And design engineering done to make sure this went right.

We've built a very big expensive quay here to take this in

Because it's very heavy.

The load pressures coming out here

Is 60 ton a square meter,

Whereas most quays are five ton a square meter,

So it's much heavier

Because all this 25,000 tons just on three legs.

Chad: Everything about this project blows my mind.

The engineering is just incredible.

Everywhere you look,

They're doing something for the first time,

And they're using brand-new techniques.

Now, with the power generation module removed,

I can get to the invention at the heart of this rig--

The incredible drill derrick.

This is the inside of the drilling derrick.

It's been partially dismantled,

But when the brent delta was out at sea,

At its peak, over 500,000 barrels of oil

Would flow through here every single day.

The drilling derrick secured the drill and the pipes

That reached from the surface to the seabed

And thousands of feet beneath.

The derrick is actually just one big lifting tower.

This is the lifting hook.

Normally it would be way up there,

And it was used to lower the pipes into place,

Where oil crews would wrestle them into position.

It drilled to reach oil reservoirs

Almost 9,000 feet beneath the surface of the earth,

Deeper than any other rig on the planet.

The controller would sit in here to run the lift systems.

It's hard to believe now,

But this was the cutting edge of oil exploration 40 years ago.

And it's still basically how rigs operate today.

♪

I'm getting on this rig to show you how to drill for oil.

Drilling deeper than ever

Needed a drill that was longer than ever.

It was pieced together in massive sections.

That's where the 130-foot derrick came in.

It has a big winch called a top drive

To raise and lower giant lengths of drill pipe into position

And turn the drill head thousands of feet below.

Essentially this is the drill that does all the work

At the bottom of a well.

On the brent delta,

This could bore a hole up to four miles deep,

And the way it does it,

It has these three conical heads here which spin,

And the hardened steel tips will crush the rock

And drill the hole.

All right, so, we've got the drill bit here.

We're going to stick it into the well hole,

Drop it down a little bit,

And we've got these slips, which are just friction slips

That are going to hold it in place.

Just this drill bit's about 500 pounds,

And we're up about 40 feet off the ground,

So we got to make sure

This thing doesn't drop all the way down.

On the brent delta,

The bit had to be lowered through 500 feet of water.

But that was nothing compared to the 8,000 feet of rock

It had to bore through after that.

With our drill head held in position,

We can start to attach the first length of pipe.

So, we've got the guy way at the top,

And we're sending the top drive up to him.

He's going to connect up to the top of a 90-foot section.

We move that into place,

And we're ready to connect it right down here at the well.

Just like the brent delta, the winch's top drive

Is controlled by the operator in the control room.

He lowers the pipe into position.

So, now we're just going to tighten this thing up by hand.

Sometimes I feel like I'm going around and around in circles.

And that's as tight as I can manage.

Next, it's over to special hydraulic grips

Called rig tongs.

I managed to exert around 200 pounds of torque

To turn the pipe,

But these things have a bit more muscle.

Now, just to put it into perspective,

These rig tongs have 65,000 foot-pounds of torque.

That's strong enough to tear a car in half.

The rig tongs clamp onto each section of drill pipe,

Then twist them together until they're locked tight.

This is all heavy work,

Which covered workers in wet mud.

One mistake could cost a finger or worse.

Even so, the drill teams worked at high speed,

Like a well-oiled machine.

I can't imagine matching their pace.

I'm only just ready for my second piece of pipe.

We're going to grab another 90-foot section,

Set it on top,

And we're ready to keep going down and down and down.

You're going to keep doing that cycle

And make this as deep as you want.

You can see behind me, we literally have

Thousands of feet of pipe just right here.

Once the chain of linked pipes hit the seabed 500 feet below,

Brent delta workers would fire up the drill.

When we're down into the rock,

This thing will spin at about 150 rpm,

Depending on what we're drilling through,

And we can do either two feet an hour

Or 200 feet an hour, depending on the type of rock.

Oil is held under enormous pressure within porous rock.

By drilling a hole, you release that pressure

And the oil rushes into the bore hole.

External casing pipes around the drill bit

Carry the oil all the way up to the surface.

♪

And that's how to unlock black gold

From bedrock beneath the ocean floor.

Once the oil has been processed at the surface,

It was stored in brent delta's massive hollow legs.

Then it was pumped to the mainland

Through a pipeline on the seabed.

Efficiency is key to the rig's business.

As expensive as they are to operate,

They need the oil to be constantly flowing,

But drilling through the seabed produces a lot of debris.

Clogs were a constant problem.

The answer--pump mud and water down the drill pipe

To flush out the debris and bring it to the surface.

Here, it's filtered out,

And the cleaned mud and water mixture

Circulated back down the drill pipe.

The system meant that the drill could cut continuously.

It also solved another problem.

It prevented the drill head from overheating.

You can picture if you're drilling into a wall

Or a piece of metal or even masonry,

The tip of your bit's going to get really hot.

Well, you can only imagine what it's going to be

When you're going through thousands of feet of rock.

And this water-based mud mixture will act as a lubricant.

With enough pipes connected together,

Brent delta's drill could reach almost any depth,

And with the circulating mud

Removing debris to keep the drill cool,

It could continue drilling even deeper.

After 40 years of that round-the-clock service,

This drill derrick will soon come tumbling down,

But not just yet.

To keep the rig balanced, they have to pull down

All the other modules that surround the derrick first.

One of the biggest is this one, the accommodation block.

It provided workers with a place to live,

Safe from extreme north sea weather

And the risk of deadly explosions.

It's the next innovation I want to get inside

As I uncover the secrets of its blast-proof design.

The brent delta's accommodation block

Was home sweet home to 160 men

Working around-the-clock shifts.

This empty cavern was once a place of rest and friendship

For over 40 years.

Alistair hope: This is where they would live, eat, and sleep,

So here you had a whole bunch of cabins,

And you can just about see the walls of the cabins here.

There would be two people to a cabin typically.

There would be a toilet and a shower over there.

There'd be a desk, two bunk beds,

And a bunch of your cupboards, and so forth.

Chad: So, literally, like this is one wall right here.

Hope: Yep.

Chad: And the other wall right here,

And you have two people that were living in the space.

Hope: Yes.

Chad: Pretty tight.

Hope: Yeah, and people would be out offshore for two weeks.

They developed tremendous friendships,

And some of the people worked on the platform

Literally from the beginning right through to, to the end.

Chad: Recently retired rig worker lawson petrie

Called the brent delta home for most of his career.

Lawson petrie: This was always a very friendly platform.

Sunday roast was the prime for lunch,

And it was the quiz on a Sunday night.

This is where everyone came together--

Deck crew, ops, maintenance, drilling--

We all came together for the brent delta quiz.

And that was one of the simple things

That kept the ethos of the platform going.

Chad: The accommodation block was designed

To keep workers safe from the risk of explosions

Caused by processing

Explosive gas and flammable oil--

Hazards which could be deadly.

In 1988, 180 miles south of brent delta,

A huge gas explosion engulfed a rival rig, piper alpha.

Man: Mayday! Explosion and fire on the piper...

Chad: 167 workers died,

Many of them while sheltering in the accommodation block.

It was positioned right above a unit after a redesign

To process huge quantities of flammable gas,

With devastating consequences.

Brent delta's accommodation block was positioned

200 feet away from the areas processing gas and oil.

And it was reinforced with eight-millimeter-thick

Stainless corrugated sheets

To protect workers from fire and explosion.

But now that thick armor

Makes dismantling this section even harder.

I'm helping the teams take down all the heavy exterior metal

So it's as light as possible when it's toppled.

♪

Weeks of work has gone

Into cutting and clearing the living quarters

To prepare it to be dropped, all 800,000 pounds of it.

All that's left to do now

Is clear out this last pile of metal,

And we'll be ready for the final cuts.

The blast walls and other components

Have been chopped into manageable chunks.

To reduce flying debris when the block is dropped,

We need to throw them over the side.

All right, so, where should we start?

Man: Anything off this pile is light and ready to throw.

Chad: All right. Ready?

1, 2, 3.

♪

♪

Give me the honors.

All right.

♪

All right, doesn't seem like much,

But we got it down to 800,000 pounds,

So now we're ready for the final cuts,

And now we'll pull it down and drop all the rest.

We positioned our cuts hoping that the three stories

Will collapse on top of each other.

I can't wait to see if it worked.

Not exactly, but that's the top floor down.

Two more to go.

♪

One final pull should finish them off.

♪

The accommodation block's armor plating

Offered priceless protection to rig workers.

Now, as scrap, it could be worth up to $100,000

To the demolition team.

With it gone, there's a clear path

To the tallest structure on the rig,

The 300-foot flare tower.

This is the invention that allowed the rig

To extract oil and natural gas safely

Without blowing itself up.

♪

First, we need to pull it down, but we have to be careful.

If we get our calculations wrong,

We could take out an entire building by mistake.

We're four months into the complete recycling

Of the brent delta oil rig.

Now it's time to take down the tallest structure.

Here it is, the flare tower.

This is what gives an oil platform its iconic look.

At the top, there's a flame

That would have been up to 60 feet long,

Generating enough heat that you could feel it

All the way down here.

At sea, you could see this for miles.

And now I want to find out more about it.

Even though the rig's generators were powered by natural gas,

They used only a fraction of what flowed up to the rig,

And it was all highly flammable.

Store it on board,

And you run the constant risk of blowing up the rig.

Simply releasing it into the atmosphere

Was too dangerous.

Engineers needed a way to keep workers safe

From being blown sky-high,

So they designed a system that allowed the gas

To flow to a giant pilot light.

They put this at the top of a high tower

So the gas could burn off in a huge flame

Without risk to the workers.

Alan lawrie is a 40-year veteran of the brent delta

And knows how important the flare tower was.

Alan lawrie: The flare tower is imperative.

We physically couldn't operate the platform

Without having the capability to vent off the gas.

Chad: Yeah.

Lawrie: And that's really why you've, why it's got

The height that it has, because of the radiated heat.

Chad: If you had an event like that,

How big of a flare would you get off the top?

Lawrie: Quite substantial, probably in the region

Of 30, maybe 40 meters long,

So about 100 to 120 feet long.

Chad: So, you could feel that from here?

Lawrie: Oh, most definitely, most definitely.

You could feel the heat being generated off of it.

Chad: So, what would happen if the pilot went out?

Lawrie: We would then light the flare

Using flare gun cartridges, almost like a shotgun.

We would fire that cartridge up into the plume of gas.

[flare gun fires]

We would then get the ignition, and that would then light,

Light the gas and light the pilot.

Chad: Climbing up a 300-foot tower

With a shotgun slung over my shoulder

To ignite a 100-foot flame

Is a job I'm sorry I didn't get a shot at.

But at least I get to help pull the thing down.

It's like felling a tree.

We don't cut all the way through the base.

Instead, we leave one section intact

To control the direction of the fall.

Well, that's the theory, anyway.

In that direction, we have a high voltage power line.

Over here, we have a building,

And over there, we have the ocean,

So our sweet spot is to drop it right here.

The problem is, it doesn't naturally

Want to come down that way,

So what we had to do is we had to clock our cuts

At the bottom of those legs so that as it falls,

It's going to pitch it in this direction,

And if all goes according to plan,

It's going to land right here.

Well, fingers crossed.

Once again, we connect the steel cables.

♪

The excavator increases the tension.

Man, that's a tight rope.

♪

Oh, there it goes.

♪

Yeah!

[crash]

Right in the sweet spot! Woo hoo!

Right away, the demolition team moves in

To start cutting it up

So it can be melted down and reused for manufacturing.

And actually, it's not the first time

The rig has been repurposed.

The brent delta extracted over two billion barrels of oil

In the first 17 years of its life,

But in 1993,

The vast oil reserve under the rig began to run dry,

And just when it seemed the rig's time was up,

It was offered a lifeline

By a brand-new natural gas refinery built onshore.

Now the brent delta's biggest waste product

Could become britain's next source of power.

First, engineers had to find a way to convert the rig

From oil to natural gas.

Their solution cost $1.6 billion.

It's the next engineering innovation I want to uncover,

If I can find it.

Wow! Now, here's the inner workings of an oil rig.

So, I've been going through a maze of walkways and tunnels

And totally lost my way.

Man: Okay, so, we're just coming down here to the separators.

Chad: Are those them over here?

Man: This is one of them. This is the big one.

This is the little one here, the test separator.

And then there's another one, a big one, just over there.

Chad: This is the innovation I've been looking for,

The brent delta's giant separation tanks.

The rig's huge drill may have struck black gold,

But the stuff that comes to the surface

Is actually a dirty mixture of oil, water, and gas.

Imagine a bottle of cola, all shaken up.

The oil, mud, and gas mixture

Is the soda that's inside of this bottle.

Now, when I release the top, that high pressure gas

Is going to want to come out, like that.

Now, if I leave the cap off long enough,

All that gas is going to set off to the top.

That's exactly what's happening inside these separation tanks.

There, the fizzy oil and water mixture goes flat

As the gas is drawn off.

Then the remaining oil and water is separated.

When the oil reserves ran out

And gas became valuable as a fuel,

Engineers made a simple but important change.

They supersized the tanks

To draw off gas in much greater quantities,

And instead of burning it off, they pumped it ashore.

Walking along these tanks

Really gives you the scale and size.

It's gotta be 50 feet long.

It's huge.

But recycling these tanks has thrown up an unexpected problem.

The tanks might not be glowing in the dark,

But it seems they could be radioactive.

So, robert, as I was wandering around,

I couldn't help but notice the "caution,

Naturally occurring radioactive material" sign.

I had no idea that that would even exist on an oil rig.

Where does it come from?

Robert cullen: Yeah, so we call it norm,

So, naturally occurring radioactive material.

And, so when you're producing oil, water, gas

From the reservoir down below the seabed,

It's encased in rock,

And some of that rock comes with it,

So there's bits of sediment.

And between the four of those natural materials,

It can build up a level of radioactivity,

So everything has its own level of radioactivity,

But when you concentrate it over the 40 years of production,

It can build up to a level that might contain a risk.

Chad: But they still have to come out,

So we better handle them delicately.

♪

The separation tanks have been removed,

And the next step is to check for radioactivity,

But first, I got to put my hazmat suit on.

Not every oil reservoir held radioactive material,

So not all the tanks are contaminated.

But if this one shows any sign of radioactivity,

It can't be recycled.

I never expected to have to use a geiger counter on this job,

But I need it to tell me the level of radiation.

Every time a radioactive particle hits the counter,

It measures what's called a click.

[beeping]

The natural environment around here

Is reading .3 clicks per minute.

That's very safe.

Okay, so, now we've got our ambient reading,

And I'm going to read it from inside here,

And as long as it's less than double, then we're okay.

[beeping]

The reading from the tank

Is the same as the rest of the environment.

Okay, you can see these readings are well within the safe limits,

And that means we can start cutting this thing up

And sending it to the recycling yard.

Supersizing the separation tanks allowed the rig to process

Over 500 million cubic feet of gas every day,

And a brand-new gas pipeline on the seabed

Connected the rig to the refinery,

But there was still one more engineering challenge to solve.

Engineers for shell could raise natural gas

From beneath the seafloor.

Now they needed a way to send it to the mainland 116 miles away.

That required a pump with a lot of power.

Once again, they discovered that aviation had the answer.

Another jet engine, this one even bigger

Than the avon they used to power the electrical generators.

This design of jet engine was actually used on 747s.

It produces over 40,000 horsepower.

It was dedicated to pumping ashore

Over half a billion cubic feet of natural gas

Every single day.

The 747 engine was deafening,

So it was housed inside a soundproof enclosure.

Its massive thrust powered a pump

That sent the natural gas through a pipeline,

All the way back to the refinery on the mainland,

Over 100 miles away.

This is part of that huge pipe, a tube of solid steel,

Almost 40 feet around.

That's now being cut into pieces like everything else,

Ready to be recycled.

Six months into the deconstruction,

And all the pipework and tanks

Inside the replacement processing module

Which contained the separation tanks

Have been completely ripped out.

As you can see, the replacement process module

Is almost ready to be dropped.

A lot of work has gone into removing

Those heavy exterior walls and lightening the load inside.

When they're taking off these modules,

Would they ever use the big crane to help lift it off,

Or was it always by these straps?

Paul connally: No.

Chad: No. It's too big?

Connally: That's only good for 45 ton. That's 880, so...

Chad: How heavy is this?

Connally: 880 ton, that's what we're going to be dropping.

Chad: Wow, geesh!

Yeah, so that's not even going to even put a dent in it.

Connally: No, no.

Chad: Stand by for another giant drop.

♪

Wow!

♪

Oh! That's huge!

This chunk of rig will be worth up to $200,000

As recycled metal,

And there's still more where that came from.

It will all help offset

The huge cost of safely decommissioning the rig.

Piece by piece, this enormous machine is coming down,

And we're getting closer to the final drop of the whole project,

The 700-ton drill derrick, the dismantling challenge

That will mark the end of this amazing deconstruction.

It's taken eight months

To dismantle the brent delta platform.

It once weighed almost 26,000 tons.

Less than 10,000 are left. The rest has been recycled.

The flare tower is gone.

The processing modules, vanished,

With their separation tanks.

So has the generator and the accommodation block.

But there's still one amazing piece of engineering

That remains-- the drilling derrick.

It's been left until last

Because it's the rig's center of gravity.

Now everything around it has been removed,

We can finally pull it down.

Graham: We brought the rig back to its base,

This can go now. We don't need this now.

We're back to the three legs.

Chad: Now you're making me nervous.

I feel like I want to get off this thing.

I don't want to put too much weight on one side.

I've seen how the drilling derrick works.

Now I want to see how it's constructed.

It weighs in at 700 tons,

Designed to support the huge weight of the drill pipe

And to stand up to the worst storms

The north sea could throw at it.

Graham: On each side of the I-beams is more I-beams,

Which makes it extremely strong and extremely heavy.

When the guys come to cut these,

They'll be cutting them below the main beam.

We can't cut above that

Because that means we are leaving half the rig behind,

So that's the lowest beam,

So we need to cut the legs as low as possible.

Chad: I'm helping the team on the rig

Make the final cuts so the tower can drop.

So, what we're doing now is we're preparing this back leg

By cutting through the four gussets.

We don't want to cut through too much

Because we don't want to compromise this

In this high wind.

We got to wait till the wind dies down

And then do the final cut.

Everything's been cut except the front left leg,

And everyone's been evacuated off the rig

Down to the safe zone on the ground,

Leaving behind only the top man burner

Who's going to make the final cut.

The top man burner cuts the final section of support away.

Then he goes deep inside the rig to safety

And gives the all clear.

The excavators are going to begin to pull.

When they do, that whole derrick is coming down in one big piece.

♪

The derrick is the last major component to be removed.

The brent delta has been reduced to scrap,

Worth up to $5 million as recycled metal.

We've achieved something

No one has ever attempted before--

Dismantling a giant offshore oil rig on land.

The techniques used here will be applied

To ensure a method for safely taking apart the other rigs,

Protecting the environment,

And recycling billions of tons of metal.

It's been an epic feat of deconstruction,

But the legendary brent delta's journey is finally over.

What was once the pride

Of britain's north sea oil exploration

Is now ready to be sold for scrap.

Big engineering brought the brent delta into being.

Now big engineering has

Almost completely recycled it on land,

Setting one final world's first

In this rig's long list of mighty achievements.