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Transocean Deepwater Horizon Explosion-A Discussion of What Actually Happened?

 I will start the discussion with this which came in email a moment ago...

Anybody with any thoughts?

April 26, 2010       Transocean
Rig Disaster: The Well From Hell

Once more unto the breach, dear friends, once more. Here's another update on the disaster that befell Transocean Ltd. and BP last week in the Gulf of Mexico.
(Thanks to OI reader Steve, in Texas, for sending some of the photos in today’s alert.)

As you know by now, the drilling vessel Deepwater Horizon exploded, burned and sank last week, with the loss of 11 workers and injuries to many more. What happened? What's happening now? What's going to happen? I've spent the weekend working to piece things together.

An Ill-fated Discovery
According to news accounts, at about 10 p.m. CDT last Tuesday, Deepwater Horizon was stable, holding an exact position in calm, dark seas about 45 miles south of the Louisiana coastline. Water depth in the area is 5,000 feet. The vessel manifest listed 126 souls on board.

Deepwater Horizon was finishing work on an exploration well named Macondo, in an area called Mississippi Canyon Block 252. After weeks of drilling, the rig had pushed a bit down over 18,000 feet, into an oil-bearing zone. The Transocean and BP personnel were installing casing in the well. BP was going to seal things up, and then go off and figure out how to produce the oil -- another step entirely in the oil biz.

The Macondo Block 252 reservoir may hold as much as 100 million barrels. That's not as large as other recent oil strikes in the Gulf, but BP management was still pleased. Success is success --
certainly in the risky, deep-water oil environment. The front office of BP Exploration was preparing a press release to announce a "commercial" oil discovery.

This kind of exploration success was par for the course for Deepwater Horizon. A year ago, the vessel set a record at another site in the Gulf, drilling a well just over 35,000 feet and discovering the 3 billion barrel Tiber deposit for BP. SoDeepwater Horizon was a great rig, with a great crew and a superb record. You might even say that is was lucky.

But perhaps some things tempt the Gods. Some actions may invite ill fate. Because suddenly, the wild and wasteful ocean struck with a bolt from the deep.

The Lights Went out;
and Then.

Witnesses state that the lights flickered on the Deepwater Horizon. Then a massive thud shook the vessel, followed by another strong vibration. Transocean employee Jim Ingram, a seasoned
offshore worker, told the U.K. Times that he was preparing for bed after working a 12-hour shift. "On the second [thud]," said Mr. Ingram, "we knew something was wrong." Indeed, something was very wrong.

Within a moment, a gigantic blast of gas, oil and drilling mud roared up through three miles of down-hole pipe and subsea risers. The fluids burst through the rig floor and ripped up into the gigantic draw-works. Something sparked. The hydrocarbons ignited. In a fraction of a second, the drilling deck of the Deepwater Horizon exploded into a fireball. The scene was an utter conflagration.

Transocean Deepwater Horizon Listing

Evacuate and Abandon

There was almost no time to react. Emergency beacons blared. Battery-powered lighting switched on throughout the vessel. Crew members ran to evacuation stations. The order came to abandon ship.
Then from the worst of circumstances came the finest, noblest elements of human behavior. Everyone on the vessel has been through extensive safety training. They knew what to do. Most crew members climbed into covered lifeboats. Other crew members quickly winched the boats, with their shipmates, down to the water. Then those who stayed behind rapidly evacuated in other designated emergency craft.

Some of the crew, however, were trapped in odd parts of the massive vessel, which measures 396 feet by 256 feet -- a bit less than the size of two football fields laid side by side.( This is one big
Drill Ship) They couldn't get to the boats. So they did what they had to do, which for some meant jumping -- and those jumpers did not fare so well. Several men broke bones due to the impact of their 80-foot drop to the sea. Still, it beat burning.

With searchlights providing illumination, as well as the eerie light from the flames of the raging fire, boat handlers pulled colleagues out of the water beneath the burning rig. In some instances, the plastic fittings on the lifeboats melted from the heat.

The flames intensified.
Soon it was impossible for the lifeboats to function near the massive vessel. The small boats moved away from the raging fountain of fire fed by ancient oil and gas from far below.

Transocean Horizon Burning At Night

The lifeboat skippers saved as many as they could find -- 115 -- but couldn't account for 11 workers who were, apparently, on or around the drill deck at the time of the first explosion. Nine of the missing are Transocean employees. Two others work for subcontractors.

Bankston to the Rescue 

Fate was not entirely cruel that night. Indeed, a supply boat was already en route to the Deepwater
Horizon. It was the Tidewater Damon Bankston, a 260-foot long flat-deck supply vessel.

Damon Bankston heard the distress signal. Her captain did what great captains do. He aimed the bow toward the position of Deepwater Horizon. Then he tore through the water, moved along by four mighty Caterpillar engines rated at 10,200 horsepower. Soon, the Damon Bankston arrived on scene,
sailed straight into the flames and joined the rescue.

Meanwhile, Coast Guard helicopters lifted off from pads in southern Louisiana, and Coast Guard
rescue vessels left their moorings. "You have to go out," is the old Coast Guard saying. "You don't have to come back."

The helicopters flew in the black of night toward a vista of utter disaster. Arriving on scene, the pilots watched in awe as columns of flame shot as high as a 50-story building. The helicopters were buffeted by blasts of super-heated wind coming from the flames, while chunks of soot the size of your hand blew by.

The pilots hovered in the glow of the blazing rig, while Coast Guard medics fast-roped down to the deck of Damon Bankston . The medics quickly assessed the casualties, strapped critically injured crewmen to backboards and hoisted them up to the helicopters. Then the pilots turned north and sped ashore to hospitals.

Uninjured survivors returned to land on the Damon Bankston. And others came out to fight
the blistering flames.

But the Deepwater Horizon wasn't going to make it. The situation deteriorated, to the point of complete catastrophe. The ship was lost.

Transocean Horizon On Fire Sinking

At about 10 a.m. CDT on Thursday morning, 36 hours after the first explosion, the Deepwater Horizon capsized and sank in 5,000 feet of water. According to BP, the hulk is located on the
seafloor, upside-down, about 1,500 feet away from the Macondo well it drilled.

Still Spilling Oil 
On Friday, I told you that the oil well drilled by the Deepwater Horizon was sealed in. The "official" word was that the well wasn't gushing oil into the sea. My sources were no less than U.S. Coast Guard Rear Adm. Mary Landry, of the New Orleans district, as quoted in The New York Times. 

But over the weekend, Rear Adm. Landry and The New York Times reported that the well IS leaking oil, at a rate of about 1,000 barrels per day.

The on-scene information comes from remotely operated underwater robots that BP and Transocean are using to monitor the well and survey all the other wreckage of the Deepwater Horizon. There's now a large amount of equipment and pipe and a myriad of marine debris on the seafloor near the well. It's a mess.

Apparently, the blowout preventer is not controlling the flow of oil. According to Transocean, the blowout preventer on Deepwater Horizon was manufactured by Cameron Intl. (CAM: NYSE). 

What happened? We don't know that just yet. Earlier reports that underwater robots sealed the blowout preventer were wrong. It's possible that the blowout preventer is only partially closed. We'll find out, eventually. Meanwhile, BP and Transocean have announced that they will make another effort to activate the blowout preventer. They need to stop that oil.

BP is also preparing to drill one or more relief wells to secure the site permanently. BP has mobilized the drilling rig Development Driller III, which is moving into position to drill a second well to intercept the leaking well. With the new well, the drillers will inject a specialized heavy fluid into the original well. This fluid will secure and block the flow of oil or gas and allow BP to permanently seal the first well.

Riser Problems? 

According to the Coast Guard and BP, oil is leaking from two spots along what is left of the riser system. Here's a schematic view:

Transocean Horizon Sea Floor Diagram

Originally, the risers (represented by the blue line in the graphic above) were affixed to the blowout preventer on the seafloor, and extended 5,000 feet straight up to the "moon pool" of the Deepwater Horizon. When the drilling vessel sank, it took the riser piping and bent it around like a pretzel.

The remnants of the riser system now follow a circuitous underwater route. According to BP, the risers extend from the wellhead up through the water column to about 1,500 feet above the seabed.
Then the riser system buckles back down toward the seafloor. (Frankly, I'm astonished that it all held together as well as it has. It's a credit to the manufacturer, which I'll discuss below.)

According to the Transocean website, the riser devices on the Deepwater Horizonwere manufactured by VetcoGray, a division of General Electric Oil & Gas. The specific designation is a "HMF-Class H, 21-inch outside diameter riser; 90 foot long joints with Choke & Kill, and booster and hydraulic  supply lines."

Here's a photo of something similar. These are Vetco risers sections that I saw on another vessel, the Transocean Discoverer Inspiration, when I visited that ship last month:

Transocean Horizon Riser Sections

The different color stripes on the risers indicate differing amounts of buoyancy. The idea is to put heavy riser pipe down at the bottom, connected to more buoyant risers above. The buoyancy
keeps the entire riser system in more or less neutral buoyancy, so that the drill ship doesn't have to somehow hoist up the huge weight of all that pipe.

As you can see, there's a large-diameter pipe in the middle of each riser. That pipe is then encased in a buoyant foam substance. The risers are bolted together at the flange sections. The bolts are about as big as the arm of a very strong man. The nuts, which tighten things down, are the size of paint cans.

After the risers are assembled and hanging down from the drilling vessel, the drilling personnel lower and raise drilling pipe through the large-diameter center riser pipe. All the drilling mud stays inside the drill pipe on the way down hole, and inside the riser pipe on the return.

On the side of the riser sections, you can see smaller-diameter pipes. These are choke & kill, booster and hydraulic pipe components. The pipes run parallel to the large-diameter inner pipe. These pipe systems run down to the blowout preventer on the seafloor.

The idea is to keep the drilling process an enclosed system. All the "drilling stuff" -- the drill-pipe, drilling-mud and drill-cutting returns -- stays inside the large-diameter pipe. The smaller pipes
hold fluid to transmit hydraulic power and help control drilling. In particular, the pipes on the side aid in communicating with and controlling the blowout preventer.

Technical Specs 

Ideally, when the risers are working as intended, nothing leaks out into the sea. Then again, you're not supposed to twist and bend the riser sections like a pretzel. So how strong is a riser
system? Extremely strong, actually.

According to technical literature from GE Oil & Gas, the riser equipment is "designed for use in
high-pressure, critical service and deep-water drilling and production applications." The pressure-containing components are rated for working pressures of 15,000 psi. That's the same as the Cameron blowout preventer on the Deepwater Horizon. The materials used in risers have
exceptional tensile and bending load characteristics.

According to Vetco paperwork that I've seen, the Class H riser sections have a 3.5 million pound
load-carrying capacity. That's the equivalent weight of about four fully fueled
Boeing 747s. These risers are super strong.

Still, it's not just any one single piece of riser section that does it all. These sections all get bolted
together, for 5,000 feet in this case. The riser sections all have to work together as a system. The whole string is only as strong as the weakest spot. And yes, even the strongest steel will break if you apply enough stress.

It all has to work together. You've got the riser sections, along with things called HMF flanged riser connectors. Then there are HMF riser joints; flex joints; telescopic joints; and, near the top, things called "fluid-bearing, nonintegral tensioner rings." Together, these all comprise the marine riser system.

In general, the riser components compensate for heave, surge, sway, offset and torque of the drilling vessel as the ship bounces around on the sea surface. The bottom line is to maintain a tight seal -- what's called "integrity" -- between the subsea blowout preventer stack and the surface
during drilling operations.

Down at the bottom, at the seafloor, the risers are connected to the blowout preventer by a connector device. The GE-Vetco spec is for a device that accommodates 7 million foot-pounds of bending
load capacity. That's about eight fully fueled Boeing 747s.

What's the idea? You want a secure connection between the high-pressure wellhead system and
the subsea blowout preventer stack. That's where mankind's best steel meets Mother Nature's high pressures.

High pressures? You had better believe it. And in this case, Mother Nature won. So looking forward, there's going to be a lot of forensic engineering on the well design and how things got monitored
during drilling. Transocean drilled the well, but BP designed it. So the key question is how did the down-hole pressures get away like they did?

What Happens

It's a good thing that the Deepwater Horizon didn't settle right on top of the well. At least there's room for the remotely operated vehicles to maneuver. Also, there's still a lot of riser still floating in the water column. So there's some element of integrity going down to the blowout preventer.

It's absolutely imperative to shut off that oil flow. We just have to hope and pray that the BP and Transocean people can get the blowout preventer shut off. Or that there's enough integrity to the risers somehow to get in there and control the leaks, perhaps with some sort of plug. One other idea is to lower a large "hood" over the leak and capture the oil so it can be pumped up to a storage tanker ship.

Meanwhile, the relief well has to go down -- carefully and safely. This Macondo well is history. Seal it. Mark it. Give it back to the sea. Move on. Don't tempt fate on this
one. And wow... for a relatively modest-sized deep-water discovery, this
thing sure has turned into the well from hell.

Welcome to the World of Deep-water Risk 

As I've said before, this accident is Mother Nature's wake-up call to everyone. Deep-water drilling is a high-stakes game. It's not exactly a "casino," in that there's a heck of a lot of settled science,
engineering and technology involved.  But we're sure finding out the hard way what all the risks are. And it's becoming more and more clear how the totality of risk is a moving target. There's geologic risk, technical risk, engineering risk, environmental risk, capital risk and market risk.

With each deep well, these risks all come together over one very tiny spot at the bottom of the ocean. So for all the oil that's out there under deep water -- and it's a lot -- the long-term calculus of risk and return is difficult to quantify.

There's more to discuss, but I'll end here today. I'll update you as things evolve. This is big news all through the offshore industry. There are HUGE environmental issues, and certainly big political repercussions. I won't go there just now. For now, I'll just send out collective best wishes to the people at Transocean, BP, the Coast Guard, Minerals Management and so many more. I'm sure they're doing their best.

Thanks for reading...

(Name Withheld)

Tags: Transocean, cause, deepwater, discussion, explosion, happened, horizon, what

Views: 14332

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Replies to This Discussion

Took a look at the briefing after the last cement job. Seemed a bit vague about the amount of cement pumped. I interpreted that 500 bbl total was pumped of which 200 bbl went into the formation. That would leave 300 at the bottom of the hole. It is a pretty large hole volume. I likely have got the geometry wrong somewhere but I make the volume (before this cement job) was about 1800 bbl with the production string in the hole and leaving out any cement that may still be in the 7" x 8 1/2" annulus which is not a big volume anyway. The volume of the 9 7/8" x 7" production string I make about 750 bbl and the annulus with the hole about 820 bbl. Don't take too much heed of these figures, I am just suggesting that relatively it may not be a large volume of cement pumped so far and as far as I can see the rest of the hole is full of mud (or pockets of oil) above.

They also talked about (after having done what they have to with the relief well) pulling the BOP and replacing with a new one before proceeding with the abandonment. Does that mean retrieving some or all the 3000 ft drill pipe and setting another cement plug?
There's one number I'd like to have, and that's at what total bbls pumped (cement and chaser) did the well start pressuring up or squeezing off? If we had that volume, our calculations would make more sense

Unless I've missed a big presentation of facts, I still say nobody knows whether that cement and chaser went down the casing or down the annulus.

Have I missed something? All I've read says the powers that be think the flow of oil was coming up the production casing instead of outside of it. With no way to run temperature/velocity logs in the well, I think somebody has been doing some "pie in the sky" speculating.

I can still make a valid (in my mind) scenario where all the flow has been coming up the annulus all of this time, and the casing string and float equipment is still intact.

Holler if you know something I don't. I got a letter from Cooder (he don't believe in email) and he is confused too........tehehehe

Good thought processes and good post John Parkin!

Does Cooder still do his calculations and reports by hand? Must admit electronic calculators had not come in when I started mixing mud. Remember seeing the first one. A petroleum engineer had it. It was about the size of a house brick and could just add, subtract, multiply and divide. I thought "I must get one of those".

Didn't look anything like this did it?

The ole trusty Sharp EL-8 weighs about 3 pounds, before that it was all slide rule. I do still have my Circular Slide rule, and pull it out on location to blow the youngsters mind every now and then. I think my first programmable was a HP-65 got it sometime in '75. That was hot stuff for the times. Texaco bought a few cases of them and issued them out.

But on this day, all we had was slide rules. This is my graduation picture from Texaco Engineering Training School. Front row far right, green as a blade of grass and ready to take on the world in 1967, 23 years old had roughnecked my way through college. Texaco Hire me straight out of college and after two years in their engineering training school, was ready to jump in the deep end. Back then Texaco put you on the "Pony Express" as we called it. You worked rotations in all aspects of the Petroleum industry, before you ever step foot in an office and acted like you knew anything. Six months in the field drilling a drilling rig, six months doing completions, six months at the Port Arthur Plant, and six months at the training center before graduating, it was their way of internship, and weeding out the slackers. Some after 4 years of college thought they were just going to be given a cushy desk job and coast for a while, not at the "Star". Most of those guys in that class had never step foot on a rig, and that was a culture shock straight out. I started roughnecking when I was sixteen, working Morning Tour before I went to school everyday. And One thing that helped me my entire career later, I never forgot my raising, and never forgot what that clanging iron sounded like, or what it took to make a hitch on the rig from the other side of the desk. These young engineers these days get thrown into the deep end not having a clue on what it takes everyday to get the job done. They live a life on Computer Models and spreadsheets, and allow software tell them what should work based on theory. The industry turned the corner a few years ago, and started weeding out the old school engineers, that couldn't keep up with technology, and it physically dismissed 75% of the industry's experience, and sent hands out to pasture that have forgotten more about drilling than this new Pepsi generation will ever know. Don't get me wrong, their are some sharp kids out their, but what's on paper and reality is sometimes a mile apart.
that is well said. But what is the Pepsi generation?
"Pepsi Generation" was an advertising program initiated by Pepsi in 1963. Wikipedia didn't give a date for the conclusion of the program.
It was Pepsi's attempt to capture business from the "generation gappers".....you know, the first kids that got by with saying their parents and teachers were dumb......

Previous to the "generation" ad campaign, Pepsi had competed with Coca-Cola on the volume of beverage per unit price. That jingle said.....

"Pepsi-Cola hits the spot
Twelve full ounces, that's a lot!
Twice as much for a nickel, too
Pepsi-Cola is the drink for you."

In Cass county, Texas we had our own Pepsi slogan. Especially if you didn't have any ice........Went like this......

"Burrrrrrpppp!!!! UGH!!!!! Pepsi makes I.W. Harper taste funny......"

Yes that's exactly the calculator. Went and bought one after seeing it. Up till then used a slide rule. There also used to be a lot more specialist slide rules than you see now. Have a drawer full of them (just pulled out a Reed hydraulic slide rule). It always seems a bit unfair when they say older people are not computer literate. After all we started with computers right from the beginning.
Looks like we were both born the same year, Mark.

Almost 40 years ago I remember dazzling some of my fellow workers with a little battery-operated electronic calculator that 'only' cost me $135. It had four functions like the one pictured above, was a little smaller, plus it had a SQUARE ROOT button!! Hot stuff.

Upgraded to an HP35, then a 45. Hog heaven, until personal computers came along right after that.

Industry would have been a lot better off upgrading the training of their best old-school engineers and paying to keep them on as roving troubleshooters and consultants, than just dumping them. If you cut that experience link with the past, then you get stupid tiny little piddly-a** mistakes like the Deepwater Horizon incident.

In retrospect, just how many roving consultants can they afford, towards preventing such from occurring? Is squeezing every last drop of profit for the shareholders and stockholders so important after all?

Besides, I'll bet a lot of old retired hands are wishing they weren't just sitting around the house collecting dust....
Every time I look at that class picture I notice the blonde lady in the middle of the second row ....it's easier on the eyes or something to be looking there :)
I noticed the lady. Because she is the only one there, quite naturally I wondered how she got on.

I have been out of work 9 months now (would not extend contract due to downturn last Autumn). 69 so presumably retired. Always said I would go rather than someone younger being paid off. Must admit cannot leave it alone though. Maybe it will wear off eventually.
Her name is Sandra Thomas before she got married. She ended up spending over 20 years with Texaco, and still lives up on Lake Conroe, retired, and still quite a looker. She married a nice guy that a few pennies, and they live on the lake. They sailed around the world on Stan's 60 ft Catalina Cutter Catch, out of Kemah. I see them both from time to time, since they live on the Montgomery side of the Lake, usually at Wal-Mart or some other local store.
According to this they don't know exactly where the cement went at the bottom of the hole. However Kent Wells still says it was pumped "down the casing", presumably the production casing.


There is also a transcript as well as the audio.


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