The Ships of the BP Blowout

[George.]

I wonder if it would be possible for us to have a nautical thread about the different ships that are out there trying to stop the BP oil leak, complete with technical discussions and lots of pictures of ships. A thread without politics or blame or rants about oil companies - just the ships that are trying to fix it, what they do, how they work. We have people near the scene (on the scene?) and experts in many relevant fields here. It could be interesting.

[Clan Gordon]

OK, here is a start

All the vessels are DP. That means that they have multiple thrusters taking power from a central power station (diesel electric). The power and direction of the thrusters is dictated automatically by position referencing systems (including DPGS).

Kongsberg (Norway) is a prime supplier of these DP systems.

The thrusters are supplied by Lips (Holland) or Rolls Royce (Finland, Norway).

The engines are mostly from Wartsila (Finland), MAN/B&W (Germany) or (on the smaller ships) Bergen diesels (Norway).

Discoverer Enterprise
- the big drillship recovering the oil from the inserted riser pipe
- displacement around 100,000 tonnes
- owned by Transocean (same as Deepwater Horizon)
- hull built in Spain in late 1990s
- drilling package added in USA

Development Driller II
- semi-sub, drilling one of the relief wells
- design by US company
- owned by Transocean (Transocean is not Swiss, it is American)
- built in Far East after 2000
- large capable, modern, deepwater rig - but not designed for harsh enviroment (North Sea)

Development Driller III
- as for DD II

Skandi Neptune
- smaller red vessel with white deckhouse
- operated by Subsea7 (UK) - but owned by DOF (Norway)
- has deepwater 3000m ROVs and a deepwater crane
- you see that name on the pictures of the oil coming out of the ruptured riser
- has vertical lay system (tower) that can deploy pipes etc to deep water

Boa Deep C
- Norway owned
- has ROVs and a deepwater crane
- I think it is the one with the logo "Aker Marine Contractors" (also from Norway) on the ROV pictures

There is also an Eidisvik one there (the orange one with the backwards sloped Ulstein X bow)
- Owner - Norway
- not sure what she is doing

Q4000
- the one that lowered the dome - and also acted as command vessel for the "top kill"
- owned by Helix (US contractor)
- twin hull SWATH type design, built in US - very painfully
- drilling tower and cranes from Huisman in the Netherlands

HOS Iron Horse
- black hulled ship
- built recently by Merwede in the Netherlands
- owned by Hornbeck (US company)

A bunch of US supply boats that are unable to do anything on the sea bed

There were (maybe still are) people lobbying to apply the US Jones Act to the specialised vessels working in the offshore oil - arguing that transporting objects from a shore port to a point in the Gulf of Mexico was covered by the original Jones Act. That would bar the bulk of the above foreign owned and built vessels from contributing to the relief operation. But then again, if the Jones Act was enforced in this manner and applied to mobile drill rigs, there would be no offshore deepwater drilling possible in the US Gulf - since the deepwater rigs have virtually all been built overseas. So no oil spill.

Hope someone else can add the pictures.

[donald branscom]

No pictures!!!!! wow

[George.]

Here is the Q4000:

http://www.marinelog.com/IMAGESMMII/caldive49.jpg

[Songololo]

A shot in the dark:

http://farm4.static.flickr.com/3407/4642106939_c351267207.jpg

[Songololo]

Not sure what vessel this is:

http://farm4.static.flickr.com/3405/4642724882_b2f6792571.jpg

[Songololo]

The Discoverer Enterprise:

http://farm5.static.flickr.com/4071/4642123781_1c21b889ef.jpg

[mmd]

Development Driller II

http://media.bmt.org/bmt_media/bmt_images/54/DevelopmentDrillerII-b.jpg


Discoverer Enterprise

http://blogs.trb.com/news/politics/blog/assets_c/2008/06/Transocean%20ship-thumb-425x383.jpg


Development Driller III

http://www.jotun.com/www/com/20020116.nsf/viewunid/8DFF94F499318B60C1257338004114A9/$file/GFS+Development+Driller+II+400x300.jpg


Skandi Neptune

http://www.mediabasen.no/d/16609-2/20060615_019_Skandi_Neptune.jpg


Boa Deep C

http://media.shipspotting.com/uploads/thumbs/rw/944591_800/Ship+Photo+BOA+DEEP+C.JPG


Eidisvik

http://www.marinelog.com/IMAGESMMIX/vikpos520.jpg

[Songololo]

The Scandi Neptune:

http://farm5.static.flickr.com/4008/4642737538_7b0be9d3a6.jpg

[mmd]

Q4000

http://www.offshore-technology.com/projects/bombax/images/image2.jpg


generic anchor-handling offshore supply boat

http://irmarineind.files.wordpress.com/2008/01/aht-for-post.jpg

[donald branscom]

Thanks for the photos!!!
This is the Deepwater Horizon
http://i46.tinypic.com/2qltqgp.jpg

[Clan Gordon]

The Scandi Neptune:

http://farm5.static.flickr.com/4008/4642737538_7b0be9d3a6.jpg

The ugly sides you see on the hull are due to the fact that the ship was widened - to make her more capable of carrying various pieces of equipment, pipeline.

The vertical lay system is the tower located at the stern. Made in Holland.

The crane is 140 tonnes capacity, made by Hydralift, Norway. Capable of deepwater and heave compensated.

The ROV hangar is the space with the open doors just aft of the accommodation.

The ROVs on this ship are deployed over the side. On some ships they go via moonpools.

Not sure what the power of these ROVs might be, but could be around 150 hp. Some are up around 300hp.

At the time of Ixtoc 1, this type of powerful deepwater ROV technology was unavailable.

Without these ROVs - none of the present effort would be possible. But then again, without ROVs, the original well could not have been drilled.

[Clan Gordon]

Q4000

http://www.offshore-technology.com/projects/bombax/images/image2.jpg




Note the extra blisters on the columns (legs) that were not originally intended. Evidence that this vessel turned out to be heavier during the design/build than its conceivers had intended.

[mmd]

Gee, did they employ the same designers as that boat in Montreal? <wicked grin>

[Clan Gordon]

The Discoverer Enterprise:

http://farm5.static.flickr.com/4071/4642123781_1c21b889ef.jpg

Nice picture of the Discoverer Enterprise.

This shows her dual drilling derrick. You can see two top mounted assemblies at the top. This allows this vessel to drill with one of the derricks while doing "offline" stuff with the other.

Since these vessels work in deepwater, anything that they can do to get work off the critical path of pulling/retrieving pipe/riser through the water column is a great advantage.

She drills through a moonpool beneath the derrick. The BOP is also deployed through that moonpool via the derrick.

On this ship the moonpool is around 25m long and 10m wide.

The drilling derrick will be able to raise and hoist the drillstring with a total weight of around 1000 tonnes. And it will be heave compensated to keep a steady weight on the drill bit at the bottom of the hole even as the ship heaves.

The riser through which the vessel drills is the key to this deepwater drilling. It is a larger diameter pipe of say 18 inches. To keep it standing upright in 12,000ft of water it has buoyancy attached to its outside. Also on the rig are big riser tensioners, which help keep it in tension. These can pull up to around 2000 tonnes - and these are also heave compensated.

You also have to adjust the heave compensators for the daily variations in the tide.

It is sadly a possibility that one reason for the Macondo BOP to fail to operate could be the presence of a downhole tool in the way of the BOP rams. That tool might have been there becase of a miscalculation/correction for the tide. But that is only speculation. There are many other possibilities in the whole operation which on their own would have been OK, but collectively led to this fatal accident.

[Clan Gordon]

The riser through which the vessel drills is the key to this deepwater drilling. It is a larger diameter pipe of say 18 inches. To keep it standing upright in 12,000ft of water it has buoyancy attached to its outside. Also on the rig are big riser tensioners, which help keep it in tension. These can pull up to around 2000 tonnes - and these are also heave compensated.


Big IF....................
If the Deepwater Horizon had not sunk (or been sunk)
AND the fire had been put out
AND the Deepwater Horizon could have been kept in position - perhaps by tugs

............the oil would have been flowing to the surface through the riser, not pluming up all over the place through 5000ft

..............then "all" they would have had to do would be to collect the oil from the surface locally - or perhaps even get some kind of connection to the flow onboard

I am still not sure why the rig sank. Only thing I can think of is that the fireboats sank her. The fire water should not normally have got below, but perhaps the original explosion opened up enough paths for that to happen.

[Andrew Craig-Bennett]

There is a lot of expert knowledge being deployed on this thread. Thank you, gentlemen.

And the cost of this little fleet must be absolutely awesome - some of the most expensive offshore units in the world, with their owners in a seller's market.

(I write as someone who once had the immense satisfaction of saying to Pemex, who, in those days, were a nightmare to work for and never paid on time, "unless your money is in our account in Hong Kong by midnight your time, our monitors are going to be turned off, we are going to be pulling away, and we will leave you to fight your fire on your own...they paid... )

[LeeG]

Clan Gordon, how are heavy items maneuvered around the wellhead? I'd think with a 5000' cable it would be awfully hard to control placement of things. How close can adjacent cables be located without worry of them wrapping around each other?

[Andrew Craig-Bennett]

Big IF....................
If the Deepwater Horizon had not sunk (or been sunk)
AND the fire had been put out
AND the Deepwater Horizon could have been kept in position - perhaps by tugs

............the oil would have been flowing to the surface through the riser, not pluming up all over the place through 5000ft

..............then "all" they would have had to do would be to collect the oil from the surface locally - or perhaps even get some kind of connection to the flow onboard

I am still not sure why the rig sank. Only thing I can think of is that the fireboats sank her. The fire water should not normally have got below, but perhaps the original explosion opened up enough paths for that to happen.

My thought as well. Note the gradual increase in list. Could be fifi water or (frankly unlikely after Ocean Ranger) a ballast panel malfunction caused either by the explosion the fire or the fifi water.

[willmarsh3]

Eidisvik

http://www.marinelog.com/IMAGESMMIX/vikpos520.jpg

That is one funky looking bow. Any particular reason for this design?

[Captain Intrepid]

It's supposed to decrease pitching and heaving accelerations and decrease drag in heavy seas.

[WX]

So no oil spill
Yeah but you wouldn't have had the benefit of all the oil raised before the spill either.
No one complained about BP or the rigs till it affected them.

[WX]

just a comment, not trying for thread drift.

[Clan Gordon]

It's supposed to decrease pitching and heaving accelerations and decrease drag in heavy seas.

Yes - thats the idea - from the Ulstein yard in Norway. However, the reduction in pitching accelerations works best in head seas. In following seas, when the stern is lifted by the sea, you can imagine that it might be nice to have a bit more reserve buoyancy at the bow.

In principle it is not much different from the ram bow used on WW1 dreadnoughts (not much reserve buoyancy above the waterline forward) - or the bow for the US Navy ill fated new destroyer program DDX (DD1000).

[Clan Gordon]

Clan Gordon, how are heavy items maneuvered around the wellhead? I'd think with a 5000' cable it would be awfully hard to control placement of things. How close can adjacent cables be located without worry of them wrapping around each other?


Lee, I am not sure if you are thinking of the cables associated with the ROVs or other things.

For the ROVs, they descend from the surface on an umbilical. That umbilical comes from a winch located on the ship. Then they move horizontally using a separate umbilical called a tether. This tether can be 500m or 1000m long. Of course this needs a handling system (tether management system) associated with the ROV to avoid it getting snarled up. This method allows the ROV ships and their umbilicals to be located on the surface some distance away from each other without having to worry too much about getting in each others way.

But the concern does exist. During seabed pipelaying operations, ROV tethers can get trapped under pipes. Or nearer the surface they can get chewed by the thrusters.

For heavy items deployed from the surface by crane, an ROV on the seabed will observe the load as it descends. If the load must be got closer to the target point, the ROV information will be used to move the ship (on DP) the required 40ft or so to the north/south etc.

In these deep waters it is nicer to have a crane that can handle the load with a single wire. A double reeved (or worse) crane hoist can twist up.

Most of the big heavy offshore floating cranes (5000t or 7000t rating) used to build the offshore platforms, cannot reach deep water. They are designed for surface operations. In deep water the self weight of the crane wire makes it difficult to deploy very heavy weights to the seabed.

The drilling rigs deploy their drillpipe using the drillpipe and the riser using the riser. They don't need wires to deploy these.

For the control umbilicals and choke kill lines associated with the BOP, these are normally an integral part of the riser system - attached outside the riser pipe. So they don't have a life of their own and are not an interference problem.

In the present Macondo operations, I guess there will be a whole lot of extra control umbilicals and "top kill" lines from the surface attempting to replicate what would have been a part of the original riser system. I don't know what they would have done to avoid these lines getting snarled up. I guess normal rules of "engagement" will have been suspended for what was an emergency and short duration.

Many drilling operations use/used guide wires attached to the well head (by ROV). These two light wires run to the rig from opposite sides of the wellhead. By putting these wires through corresponding holes in the BOP etc - you can guide the BOP to the wellhead. If I recall correctly, these are more trouble than they are worth in deep water, and with modern ROVs and moving the ship on DP you can achieve the same end.

[LeeG]

thanks, while watching the LMRP being moved around on a basket I was trying to imagine how it would be brought into place if the ocean is rising/falling and there's any kind of bending of the cable with currents.

[George.]

For heavy items deployed from the surface by crane, an ROV on the seabed will observe the load as it descends.

Visually? What's visibility usually like down there? I imagined they would have some sort of ultrasound system to locate and place things.

[mmd]

"What's visibility usually like down there?"

Unless something has stirred up the bottom sediments, it is surprisingly clear (not much micro-life clouding up the water) and absolutely pitch-black. Because the ROV's are 'flown' by human operators topsides, and because humans operate best using visual cues that they are familiar with, most ROV manoevering is done using bright lights and a camera feed to the ROV operator's console. There are other methods, including a form of SONAR range-finding, but the primary method is real-time visual.

My niece is an ROV technologist currently working out of Singapore on the Saipem 10000 drillship.

[Oyvind Snibsoer]

That is one funky looking bow. Any particular reason for this design?

A few videos to show how it works IRL:

http://www.youtube.com/watch?v=Mqcpe5au_7M

http://www.youtube.com/watch?v=3zZ_tzndh1U&feature=related

[willmarsh3]

Thanks for posting those. There's less spray and green water up to the bridge and she pitches less.

[Oyvind Snibsoer]

Yes, and as a result Bourbon Orca is able to go much faster against the storm than the other supply ships.

[Andrew Craig-Bennett]

But, as Clan Gordon says, because the bow is even more dissimilar to the stern than in conventional supply boat hulls, she is even more uncomfortable when running with the wind and sea.

[Clan Gordon]

Yes, and as a result Bourbon Orca is able to go much faster against the storm than the other supply ships.

In the well known video of the Orca steaming into head seas beside a red supply boat (cannot remember her name) they omit to tell you that the Orca has something like 10MW propulsive power and the supply boat something like 2MW.

[willmarsh3]

Eidisvik

http://www.marinelog.com/IMAGESMMIX/vikpos520.jpg

This is the M/V Viking Poseidon. More info here: http://www.ulsteingroup.com/kunder/ulstein/mm.nsf/lupGraphics/Yard%20281%20Viking%20Poseidon_Produktark2.pdf/$file/Yard%20281%20Viking%20Poseidon_Produktark2.pdf

[Lew Barrett]

I've nothing to add apart from thanks everyone for a most informative thread.

[banjoman]

Relaying questions from another forum because some of you guys know what you are talking about.

RE. the ROV systems

- how do ROVs 5000' underwater know their position? What's the underwater equivalent to GPS? I mean you plunk one in the water - how do you know where to steer it to find the BOP needle in the ocean's haystack?

- how do they counteract the force of a spinning blade and not spin the ROV in the opposite direction? Is it all thrusters providing the reaction? Or does the ROV physically anchor itself to the pipe/sea bed/ etc?

[mmd]

I'll try to contact my neice (an ROV technician aboard the Saipem 10000) in Singapore to answer the first question.

To your second question, yes. <grin>

Primarily the ROV holds position against tool reactions by azimuthing its thrusters to counteract the force. One of the things the technicians do is specify how powerful a tool may be used on a given ROV, based on the thrust of the on-board thrusters. However, if the ROV has a grappling arm free and a convenient place to grab, it is not unusual for the ROV to 'hang on' while performing a subsea operation.

[banjoman]

Passed it on..

Thanks!

[Oyvind Snibsoer]

Re ROV positioning, they place acoustic beacons on the seafloor.

http://www.dosits.org/images/dosits/Calculating_ROV_position_with_transonder_network1. jpg

http://www.dosits.org/people/navigation/navigateunderwater/

[Peerie Maa]

Back in the day, ROV operators were recruited from the ranks of helicopter pilots, they were better practised at thinking in six degrees of freedom
I notice that Ulstein have added a outward sloping bulwark to the X bow. Just saying.

[Bill R]

Question for the smart guys here- specifically the NA's.

A lot of the ships pictured here have very low transoms, specificly the anchor handling vessel pictured above. I understand the configuration is due to what the ships are designed to do, but wouldn't it play hell with a following sea? If not, why?

[Tom Lathrop]

I've nothing to add apart from thanks everyone for a most informative thread.

Me too. Many thanks to all those qualified posters and to those who avoided all references to politics. Great thread.

[Bill R]

Me too. Many thanks to all those qualified posters and to those who avoided all references to politics. Great thread.

Ditto.

[Clan Gordon]

A lot of the ships pictured here have very low transoms, specificly the anchor handling vessel pictured above. I understand the configuration is due to what the ships are designed to do, but wouldn't it play hell with a following sea? If not, why?

The anchor handler does indeed have a low transom, and is probably of a size/type that would no longer be acceptable in heavy weather parts of the world (North Sea etc). But OK for GoM.

GoM is a benign sea (apart from hurricanes). Skandi Neptune and Boa Deep C have decent freeboard - no problems in a following sea.

The ship in post 6 does have a low transom for no obvious good reason (no anchor handling roller there).

See below for a couple of good (old) videos of low aft deck supply boat types in North Sea weather. Due to the low freeboard aft, the men on the anchor handlers did a very dangerous job in the past - but more care is taken now.

http://www.youtube.com/watch?v=JShGZXCpLeA

http://www.youtube.com/watch?v=9eZiNrdsdQ4&feature=related

[Andrew Craig-Bennett]

bump

[Clan Gordon]

What have the vessels been doing recently...................?

Congestion has (not suprisingly) been a problem.

DEVELOPMENT DRILLER II and III have been drilling ahead on the relief wells.

BP plans to intercept the Macondo well at a depth between 16,700 feet and 17,000 feet below the drill floor.

On Friday, Development Driller 3 was at about 15,670 feet and had begun to angle the well 23 degrees toward the Macondo bore.

Development Driller 2 was about 9660 feet below the drill floor on Friday.

When the bit gets close to the Macondo wellbore they will use magnetic sensors to locate the wellbore.

The relief well will then continue down and relocate the bore again a couple of hundred feet further downhole.

At first, the plan is to drill into the casing to begin circulating mud, but if the drill pipe (which could still be in the wellbore at that level) is providing a flow path for the oil, they may need to drill into the drill pipe as well.

Once they do intercept the well bore, the rig will begin a bottom kill, pumping mud into the well to suppress the hydrocarbon flow and then cementing the well to plug it permanently.

The above mostly from Upstream.

Next something on the "production" ships.

[Clan Gordon]

re the "production" ships............................the armada has been getting larger

DISCOVERER ENTERPRISE

As ACB mentioned on another thread, this system had to be taken off line temporarily because a vent in the "dome" was accidentally closed (by ROV impact) and hydrate risk formation existed.

Also, this system had to be taken offline temporarily due to lightning in the area on Sunday and Monday.

The DISCOVERER ENTERPRISE has already had a fire at the top of the derrick since she began handling the Macondo flow. This was probably caused by lightning igniting the gas vent at the top of the derrick (placed there for that reason).

Around 103,000 barrels of collected oil was transferred from storage on the Discoverer Enterprise to the OVERSEAS CASCADE tanker (first US shuttle tanker) Thursday and Friday last week.


HELIX PRODUCER 1

This is a strange new boy on the block. A monohull floating production vessel without any storage. Based on a converted Danish train ferry, converted in Croatia. Monohull FPS normally have tank storage to provide a buffer for offloading (and no need for pipeline). For normal oil production, this one does not make sense to anyone outside of Helix (and now apparently BP, who plan to use her from this week).

She does have a proper topsides processing capacity (30,000 barrels of oil per day and 70 million cubic feet of natural gas per day), rather than being a drill rig or well intervention vessel doing something a bit out of the norm.

Since she has no storage, she will have to be permanently offloading to a shuttle tanker as part of the new production system. Increased risk of incidents.


TOISA PISCES

Another new boy on the block................

A small well testing vessel, belonging to Greek/UK Sealion Shipping, previously working offshore Mexico.

Toisa Pisces can process up to 20,000 barrels per day but again has no storage. From early July, she will apparently offload to the LOCH RANNOCH, a shuttle tanker many times her size - with a capacity of more than 1 million barrels which has come across the Atlantic for the purpose. This will mean another semi-permanent connection on the surface. More congestion and another connected operation taking place with two ships on DP.

The riser will connect to the Toisa Pisces via a flexible hose, which will allow it more flexibility than the current rigid riser system to DISCOVERER ENTERPRISE.

Originally the plan was that once the new PISCES system is in place, the Discoverer Enterprise will move off location. Remains to be seen if that will happen.


Q4000

She has been on site from the start, and has (since 16th June) been taking oil and gas from the BOP stack (via the choke and kill lines through a subsea manifold and flexible hoses).

The Q4000 also does not have any storage capacity - and so uses a specialised clean-burning system to flare all the oil and gas that she takes onboard.
This system will apparently be able to handle 10,000 bpd.

She was designed for well intervention work (basically light drilling) - but I would be very surprised if she was appropriate for handling this amount of hydrocarbon over this period of time.

BP had told the Coast Guard that the Q4000 will not flare with four production vessels on Macondo, which is planned. Between the HPI and the Toisa Pisces, BP expects to be able to handle between 40,000 and 50,000 bpd. That is in addition to the amount to be collected by the drillships Discoverer Enterprise and/or the Discoverer Clear Leader.


SEILLEAN

I have heard/read somewhere that BP might be trying to get this large DP monohull production vessel back from Brazil. She would be ideal for this job.

She was specified by BP and built by Harland & Wolff in the late 1980s to go around on DP (much more difficult in the shallow North Sea than in deepwater GoM) and suck up oil from "stranded" small oil fields. SEILLEAN is Scottish Gaelic for "honeybee"

She was a bit ahead of her time - a significant technical achievement at the time - with some good, enduring features but one or two basic errors in specification.

After about 10 years, she was sold off by BP (to a company which is now part of Transocean IIRC) and now works in Brazil for Petrobras - in very deep water - with nothing but computers preventing her from drifting/driving off and tearing her oil production riser apart. She (on DP) offloads oil to DP tankers. Petrobras were the first to adopt this practice in any signifcant way.

The events that led to conception of SEILLEAN may have been one of the final nails in the coffin of BP's large central engineering group, which was decimated in the early 1990s, as alluded to by ACB in another post.

[Clan Gordon]

The congestion issue............


Traffic congestion sparks concern as armada gathers to deal with rogue well

INCREASING traffic congestion 5000 feet above the Macondo well is making BP uneasy as the chances of a collision or other mishaps rise with the US government's imperative for back-up vessels for capturing the oil and gas billowing from the well blowout in the deep-water Gulf of Mexico.

Anthony Guegel 18 June 2010 02:27 GMT

It may be the first time ever that multiple vessels have been outfitted for simultaneous production from a single well. BP chief operating officer Doug Suttles expressed his concern about the "multi-vessel containment operation" in a 13 June letter to Coast Guard Rear Admiral James Watson.

"The risks of operating multiple facilities in close proximity must be carefully managed," Suttles wrote. "Several hundred people are working in a confined space with live hydrocarbons on up to four vessels.

"This is significantly beyond both BP and industry practice," Suttles continued. "We will continue to aggressively drive the schedule to minimise the pollution, but we must not allow this drive to compromise our number one priority, that being the health and safety of our people."

According to the US Coast Guard, about 27,000 personnel - including onshore clean-up crews - and more than 8000 vessels are deployed across the US Gulf, from Texas to Florida, in response to the oil spill.

The lead choreographer is Coast Guard Admiral Thad Allen, who is in charge of co-ordinating the armada as National Incident Commander from command posts set up in Houma, Louisiana, and Mobile, Alabama.

Published by UPSTREAM: 18 June 2010 02:27 GMT | Last updated: 18 June 2010 02:27 GMT

[mmd]

To answer a previous question about AHTS (Anchor Handling Tug Supply) vessels' low transoms, the answer lies in their usage. But first, it must be noted that the low freeboard at the transom is somewhat relative - they may look low to the water, but that is mostly due to perspective of the size of the ship. The deck of a modern AHTS is actually about six to ten feet above the water surface. However, the answer to why they are like that is a combination of the need to have the transom low to the water so that cables, anchor chains and anchors can easily be dragged up on deck, and when the boat is towing it wants to keep the tow cable low to the water so that the water column over the cable acts as a 'shock absorber' on the cable. Finally, the vessels spend a rather small amount of their time at sea actually going someplace; rather, they are usually engaged in either tugging and pulling at stuff or merely standing by the rig to be available if needed. Since they never (well, almost never) tug and pull at stuff in bad weather, the low transom is not an issue for those operations. When they are in stand-by mode, they lie-to with their nose pointed into the wind and waves, so being pooped is not very likely. So, in a nutshell, the transoms are low because it aids the operations that the ship was designed for and it isn't a problem in following seas because the vessel is rarely in those conditions and hardly ever doing anything that required guys on deck in those conditions.

Lastly, if you google a bunch of pics of AHTS vessels, you will note that the newer ones have solid steel tall - usually around 10-ft (3 metre) - bulwarks along the side decks where the older ones had 'normal' height (3.25 feet or 1 metre) bulwarks with a monster pipe rail above. It has been determined that this keeps big green meanies from rolling over the side of the boat while in operation, which is a common occurance on ships without the high bulwarks.

But don't think that working on deck of one of these beasts is easy, even with 'bigger and better' - it is slippery, wide-open, no-hand-holds, gut-busting work around very heavy equipment and big cables that tend to move around by their own free will. The deck of an AHTS is a dangerous place to be, sometimes even when tied up to a dock.

[lagspiller]

Can't add anything intelligent to the thread, but as a BTW, my neighbour owns DOF and the Scandi ships involved. A lot of their captains are from the neighbourhood, too.

[Andrew Craig-Bennett]

http://www.offshore-technology.com/contractor_images/sealion-shipping/1-toisa-pisces.jpg

Toisa Pisces, above.
http://www.oilonline.com/Portals/0/Images/logos/Helix_Producer_I.jpg


Helix Producer One

[Andrew Craig-Bennett]

http://www.offshore-technology.com/projects/roncador/images/roncador5.jpg (http://www.offshore-technology.com/projects/roncador/)

Seillean

[Andrew Craig-Bennett]

Loch Rannoch:

http://i535.photobucket.com/albums/ee352/acraigbennett/Loch_Rannoch_and_Schiehallion.jpg?t=1277222814

[Clan Gordon]

Thanks for the pictures Andrew.

In the picture of the SEILLEAN - you can see the offloading hose reel at the bow (normally they are at the stern of FPSOs, but SEILLEAN was designed to operate stern into the weather).

When built she did not have an offloading capability - so had to disconnect and sail to port to discharge. That was one basic mistake in her design - easily corrected.

The other basic mistake was to use valuable hull volume to accommodate the process plant instead of putting it above deck - like all other FPSOs do. From the picture she has had equipment added above deck.

[Andrew Craig-Bennett]

I recognise those symptoms, James.

Caused by the engineers and, saving your presence, naval architects, sitting round a table and designing the best possible vessel without adequate input from the commercial side.

The converse, of course, is worse.

One skill that I claim to possess is the ability to manage that situation - I'd name Sir JohnParker as a referee!

[Peerie Maa]

I recognise those symptoms, James.

Caused by the engineers and, saving your presence, naval architects, sitting round a table and designing the best possible vessel without adequate input from the commercial side.

The converse, of course, is worse.

One skill that I claim to possess is the ability to manage that situation - I'd name Sir JohnParker as a referee!

Nah, it was probably some process engineer allergic to a little rain and spray.

[mmd]

Sadly, there are all-too-many situations where the most knowlegeable persons are sidelined during the design & construction process. While it occasionally takes some deft handling of the personalities present to keep the process moving along, having the client involved during the whole design/build process is much more likely to produce a good ship than not.

[Peerie Maa]

Sadly, there are all-too-many situations where the most knowlegeable persons are sidelined during the design & construction process. While it occasionally takes some deft handling of the personalities present to keep the process moving along, having the client involved during the whole design/build process is much more likely to produce a good ship than not.

If the customer has an adequate knowledge base. Ours don't understand that steel is cheap and air is free, so they always try for a stretch requirement in the smallest possible hull.

[Andrew Craig-Bennett]

Yes, I've never understood why your customers do that.

[Peerie Maa]

Yes, I've never understood why your customers do that.

The paymasters in the Treasury are always behind them, and they had crappy oversimplified algorithms for modelling cost. As to the stretch requirements, if you can achieve them everyone wins. The problem is when a naive supplier enters the competition and does not realise that they are stretch requirements.

[mmd]

While not attempting to discredit Nick's comment about knowlegeable customers (they are as much a pleasure as they are rare), perhaps it is a function of the type of vessel being produced, as well. This yard's normal output is quite semi-custom so client input is valuable. Even the profoundly ignorant client is useful when it comes to the "where is the best place for..." questions. The deft part comes in handling the client so that the shipyard gets the benefit of the client's stated desires while limiting their input to only those areas where their input and opinions have some value, and keeping them far away from any discussions of things that they don't know anything about. For example, I will happily spend hours with a client to get the wheelhouse console layout just to their liking, but will not let them peek underneath it to see where and how we run the cabling that services all those instruments... <wink, grin>

[Peerie Maa]

You don't know how lucky you are with only one customer to deal with.
We have three, the commercial customer, who leads. The technical experts who think that they know how it should be done, but never go to sea, and the third level of customer, the ships crew. They change and are replaced every two years, each new lot having their way of doing things, which always differs from what is in the contract and the opinion of the technical experts.

[mmd]

Oh, I understand, Nick. Oh, god!, how I understand... <grin>

On this build I actually have three customers, too. The client corporation's project manager (the money and schedule person), the client's agent (an employee of the designer, contracted to look after the client's - and designer's - interests), and the deputy fire chief (whom actually knows about boats, and fireboats in particular). My little scenario in post #61 alluded to the deputy chief. I have to employ different gambits to function properly with the other two folks.

But heck, if it weren't challenging, where would the fun be?

[Peerie Maa]

Fortunately our life is getting a lot easier now. Competition has closed down most yards so the customer now has to work with monopoly suppliers. They now content them selves with defining requirements that are worded to avoid preselecting solutions, e.g. one I had to deal with was something like: the vessel must be held stationary along side a quay, in such and such weather, to allow for the discharge and shipping of materials.
As the vessel had both tunnel thrusters and was to have azipod main propulsion I could have saved a mint on first cost by not specifying any mooring system at all.

The upshot is that as we are a monopoly supplier the customer can give us the design from the get go, rather than have to produce an indicative design for a bidding contest. Things should go more smoothly now as we can apply our product knowledge from the start.

[Clan Gordon]

DEVELOPMENT DRILLER II and III have been drilling ahead on the relief wells.

BP plans to intercept the Macondo well at a depth between 16,700 feet and 17,000 feet below the drill floor.

On Friday, Development Driller 3 was at about 15,670 feet and had begun to angle the well 23 degrees toward the Macondo bore.

Development Driller 2 was about 9660 feet below the drill floor on Friday.

When the bit gets close to the Macondo wellbore they will use magnetic sensors to locate the wellbore.

The relief well will then continue down and relocate the bore again a couple of hundred feet further downhole.


Update on relief well drilling for this Friday................

Development Driller 3 reached a depth of 16,275 feet on 23 June before the drillstring was removed from the well to carry out the first magnetic 'ranging' run using wireline.

During the ranging run, the Macondo well was successfully detected. Subsequent ranging runs will be needed to more precisely locate the well.

Drilling and ranging operations will continue over the next few weeks towards the target intercept depth of approximately 18,000 feet, when 'kill' operations are expected to begin.

The Development Driller 2, which spudded on 16 May, is drilling ahead at a measured depth of 10,500 feet.

[Clan Gordon]

http://www.offshore-technology.com/contractor_images/sealion-shipping/1-toisa-pisces.jpg

Toisa Pisces, above.


Note the grey fire/blast wall extending to the ship sides just aft of the accommodation - intended to protect the living quarters and evacuation equipment from a hydrocarbon explosion on the working deck.

[v10builder1]

Here we have one or more people who know about deep water drilling. Myself, I would appreciate if you knowledgeable folks would help me understand a bit about the actual deep well configuration - I read about the incident in the mainstream media, but I cannot find a concise description anywhere.

Terms bandied about are casing, annulus, drill pipe, drill string, centralizers, and half fast explanations of the various functions of blowout presenter.

A summary, if you would.

Also some Questions:
1. Where is the cement placed?
2. It appears that all the oil/gas is escaping from the one vertical riser(cut off atop the blowout preventer). Is this the case?
3. How can a hydraulic operated shear be expected to work after sitting for days/weeks at that temperature and pressures?

Thanks.

[Peerie Maa]

Here we have one or more people who know about deep water drilling. Myself, I would appreciate if you knowledgeable folks would help me understand a bit about the actual deep well configuration - I read about the incident in the mainstream media, but I cannot find a concise description anywhere.

Terms bandied about are casing, annulus, drill pipe, drill string, centralizers, and half fast explanations of the various functions of blowout presenter.

A summary, if you would.

Also some Questions:
1. Where is the cement placed?
2. It appears that all the oil/gas is escaping from the one vertical riser(cut off atop the blowout preventer). Is this the case?
3. How can a hydraulic operated shear be expected to work after sitting for days/weeks at that temperature and pressures?

Thanks.
Question 1. A good starter for ten (http://en.wikipedia.org/wiki/Casing_(borehole))
Question 2. Yes, if it is escaping from anywhere else there is a serious problem with the well, but ultimately no additional worries, as the relief wells should cure the problem either way.
Answer 3. 'Cos that is what it is designed to do. That sounds like a glib answer, but your question was a bit like how does the piston in a cars engine survive when you consider the temperatures and pressures of the combustion.

[Clan Gordon]

http://www.offshore-technology.com/projects/roncador/images/roncador5.jpg (http://www.offshore-technology.com/projects/roncador/)

Seillean

For the best part of a decade she was by far the largest DP ship in the world - with a displacement of 76,000 tonnes, and length of 250m.

She is an all-electric ship, using a combination of gas turbines and diesel generators to supply power to her grid. This particular combination was implemented about one decade before a few cruise ships tried the concept, followed a decade later by some smaller naval ships.

Unlike these other vessels, SEILLEAN's gas turbines can burn the gas obtained from the well stream as fuel (in addition to liquid fuel). Which makes sense, as the gas would otherwise be flared.

Some later vessels have diesel generators which can burn gas as well as liquid fuel - although the vibration of the reciprocating engine presents a greater challenge in terms of avoiding a hazardous gas leak in the engine room.

[v10builder1]

Thanks, Peerie Maa for the wikipedia link.

So, as you point out and the well head videos indicate, all the gas/oil flow is coming up through the casing, and the blow out preventer. So why is the cementing suspect since it appears that the cement is placed between the casing and the bore hole?

Regarding my not too well asked question about the hydraulics - in this case, the shear did not do what it was designed to do.

Hydraulic systems, while very powerful and usually reliable, do have certain quirks. Foreign material can get under pilot valve seats and seals, and most outdoor systems I have familiarity with either continuously circulate and/or heat the hydraulic fluid to improve reliabliity. More problems occur when temperatures are lower. It appears these shears have but a hydraulic accumulator for the energy source - I am just wondering if in fact the shear failed due to the environmental conditions and difficulty of servicing at the location, or perhaps the signal to activate was not/could not be sent down due to the fire on the rig. Endless speculation - but had the shear worked, we would have had a potential mess instead of a real one.

Just wanted to let you know this is not some rant against oil or deep water drilling - like everyone else in the US (and the rest of the world to that extent), I need about 70 gallons of gasoline per month to get to work.

Thanks.

[Andrew Craig-Bennett]

Unlike these other vessels, SEILLEAN's gas turbines can burn the gas obtained from the well stream as fuel (in addition to liquid fuel). Which makes sense, as the gas would otherwise be flared.

Some later vessels have diesel generators which can burn gas as well as liquid fuel - although the vibration of the reciprocating engine presents a greater challenge in terms of avoiding a hazardous gas leak in the engine room.

The sensible place to put a gas powered reciprocating engine drriving a genset is on deck.

Perfectly do-able at the design stage.

[Clan Gordon]

The sensible place to put a gas powered reciprocating engine driving a genset is on deck.

Perfectly do-able at the design stage.

Indeed (and has been done on some FPSOs) - although as we have seen, the SEILLEAN project did not even want to put the process plant on the open deck. The space above the tanker deck is classed as a hazardous area (under ship rules, not offshore rules) - but raising equipment 3m above it gets out of that difficulty.

As you know, the jury is still out on the use of dual fuel four stroke diesels for burning the boil-off in the post-steam LNG carrier fleet. So far I believe only three ships of that type have been built (at CdA, St Nazaire).

[Andrew Craig-Bennett]

You can guess my position on that one! A great increase in complication and maintenance for rather a small benefit.

[SBrookman]

Somewhat smaller boats that might be involved in the BP mess:
http://image3.examiner.com/images/blog/replicate/EXID18204/images/dragonfly6%281%29.jpg
I saw in the news that Jimmy Buffet is funding a small fleet of these to aid in the wildlife rescue effort. Seems like an Atkins tunnel drive, Rescue Minor type, would come in handy down there.

[Peerie Maa]

So, as you point out and the well head videos indicate, all the gas/oil flow is coming up through the casing, and the blow out preventer. So why is the cementing suspect since it appears that the cement is placed between the casing and the bore hole?
Journalists, (people who make money by telling stories) have reported the opinions of some who might be in the know that the design of the casing and cementation might not be as good as it could be. At the moment you can sell a lot of newspaper by slagging off BP.

Regarding my not too well asked question about the hydraulics - in this case, the shear did not do what it was designed to do.

Hydraulic systems, while very powerful and usually reliable, do have certain quirks. Foreign material can get under pilot valve seats and seals, and most outdoor systems I have familiarity with either continuously circulate and/or heat the hydraulic fluid to improve reliabliity. More problems occur when temperatures are lower. It appears these shears have but a hydraulic accumulator for the energy source - I am just wondering if in fact the shear failed due to the environmental conditions and difficulty of servicing at the location, or perhaps the signal to activate was not/could not be sent down due to the fire on the rig. Endless speculation - but had the shear worked, we would have had a potential mess instead of a real one.


There is another web source quoted in one of these threads that suggests that the shuttle valves controlling the rams on the BOP are known to be unreliable.

[Andrew Craig-Bennett]

For the gallery, the first US flag vessel in the list, the 46,000dwt OVERSEAS CASCADE, built by Aker Phildelphia in 2009:



http://www.akerphiladelphia.com/upload/images/012floated_sm.jpg

Yard picture moving to the filling out berth - note that in the picture the freefall lifeboat has not been fitted yet.
http://www.seafarers.org/log/2010/012010/Images/oscascade.jpg
completed.

[Clan Gordon]

A 1,100 foot long (320,000 tonnes deadweight) ore/oil carrier converted in Portugal (straight from newbuild yard in Korea) for oil/water skimming and separation duties is now near the site of the spill, awaiting approval for use.

Looks like this is an entirely private venture by the Taiwanese owner of the ship (named A. WHALE), and it is not entirely clear from the limited information if/how the proposed method will work. Apparently he has other vessels named B WHALE, C WHALE and A. ELEPHANT (the latter to receive the skimmed oil).

http://www.youtube.com/watch?v=yV1Q5gEraJ0

[Andrew Craig-Bennett]

This ship has arrived, heralded by a great deal of controversy, much of it stirred up by the owner's US advisers, and an almost complete dearth of technical data. Looks like good old fashioned settle and decant, but I'd like to know more.

Equasis saith:
TMT Co. Ltd,

IMO no 0405319

10th Floor, 245, Dunhua S Road, Section 1, Da-an District, Taipei City, 10489, China, Republic of (Taiwan)

Formerly and better known as Taiwan Maritime Transportation (do not confuse with Chinese Maritime Transport - CMT - which is a Tung Group company)

An old established Taiwanese shipowner, active in wood chip carriers, car carriers and recently tankers and ore oilers.

LR classed, entered for P&I with Brittannia, all looks pukka, but there are 25 ships in the fleet of which only this one and her sister are under the age of 20.

[Clan Gordon]

Looks like good old fashioned settle and decant, but I'd like to know more.


Yes - looks like No. 1 cargo tank is made open to the sea by these "teeth" in the bow. By ballasting the ship they will presumably get these slots at the water level and thus skim in the surface mixture into the No. 1 tank.

But that means No. 1 tank will fill up quickly. So perhaps they will transfer water from the bottom of No. 1 tank to the other tanks and hope to keep as much as possible of the oil in No. 1 tank. Or perhaps they have a clever system (high suction) to decant the oil on the surface of No. 1 tank into the other tanks, and then let further settling take place.

Either way, congratulations to the class society who must have approved these modifications in a bit of a rush. Hope nothing major has been overlooked.

[Clan Gordon]

Update on the relief wells

From Upstream Online on 2nd July



The first relief well for the Macondo blowout is drilling at about 16,817 feet measured depth.

Development Driller 3 has about 1000 feet more of vertical drilling to do and needs to narrow the horizontal distance between the two bores from 20 feet to five feet.

BP will continue “ranging” to pinpoint the location of the Macondo bore about every 15 feet as crews continue drilling.

BP tripped the pipe out of the hole for its first two ranging operations, which allows the signal to reach farther from the wellbore, but from now on, ranging will be done from sensors inside the pipe. The change cuts the time needed for the job from two days to about a half day and allows BP to use a pair of sensors, one above the other, which will increase accuracy.

The relief well design calls for setting a 9-7/8-inch casing (which will be run as a liner) and then drilling about 200 more feet before intercepting Macondo a bit below its own 9-7/8-inch casing.

Once BP hits the Macondo bore, it will immediately begin pumping drilling mud down the bore. BP already has about 44,000 barrels of roughly 14-weight drilling mud on location already in case the relief well nicks the Macondo bore earlier than planned.

Development Driller 3 has about 8,800 horsepower on the vessel to pump the mud and BP has brought in additional pumping capability on 3 other vessels as well.

The second relief well, spudded 16th May continues downhole at about 12,775 feet.

[BrianW]

14lb mud is fairly heavy.

[Andrew Craig-Bennett]

This will probably be a silly question to anyone who has done drilling, but this puzzles me:

"Once BP hits the Macondo bore, it will immediately begin pumping drilling mud down the bore. BP already has about 44,000 barrels of roughly 14-weight drilling mud on location already in case the relief well nicks the Macondo bore earlier than planned.

Development Driller 3 has about 8,800 horsepower on the vessel to pump the mud and BP has brought in additional pumping capability on 3 other vessels as well. "


I know about pumping mud from a supply boat's mud tanks to a rig, but this seems to envisage using pumps on other vessels to contribute to getting the mud down the hole. I don't get it.

[Peerie Maa]

14lb mud is fairly heavy.

I think that it needs to be to overcome the flow rate and balance the driving pressure.

[Clan Gordon]

This will probably be a silly question to anyone who has done drilling, but this puzzles me:

"Once BP hits the Macondo bore, it will immediately begin pumping drilling mud down the bore. BP already has about 44,000 barrels of roughly 14-weight drilling mud on location already in case the relief well nicks the Macondo bore earlier than planned.

Development Driller 3 has about 8,800 horsepower on the vessel to pump the mud and BP has brought in additional pumping capability on 3 other vessels as well. "


I know about pumping mud from a supply boat's mud tanks to a rig, but this seems to envisage using pumps on other vessels to contribute to getting the mud down the hole. I don't get it.

Andrew - my guess is it could be one of two things....

1) while the main driller sends its mud down the main riser in the normal way, perhaps the other rigs can be connected by hoses to the choke and kill ports on the BOP (independently of the riser from the main driller). In this way they could pump something into the well, but the flow rate will be small due to small dia of the choke and kill lines. The choke and kill connectiions were what was used for the "top kill" on the original Macondo bore

2) the "other vessels" could connect up to the main driller with HP hoses and use their mud pumps to add to what is being sent down the riser by the main driller. This would be similar to "tender assisted" drilling, where a semi or jackup comes along side a fixed platform (which has its own drilling tower, but not mud pumping or processing gear) and supplies the power and mud pumping to the fixed platform.

[Peerie Maa]

I googled mud pumps, all I could find were recip units. If that is all that is used, the additional pumps will have to be manifolded to increase the flow rate rather than pressure. Which probably makes sense when trying to overcome the flow of oil.
Anyone here able to confirm this?

[Clan Gordon]

Looks like the weekend trials of the A. WHALE were inconclusive. Apparently due to bad weather !

Her owners are reported as saying she can process 21 million gallons of oily water per day (0.5m bbls/day = 83,000 cu.m per day).

[Clan Gordon]

I googled mud pumps, all I could find were recip units. If that is all that is used, the additional pumps will have to be manifolded to increase the flow rate rather than pressure. Which probably makes sense when trying to overcome the flow of oil.
Anyone here able to confirm this?

The pumps on the rigs are manifolded. The pumps are triplex piston type.

They could manifold the pumps of the other rigs with a seabed manifold beside the BOP. But then these would face the restriction of the choke and kill ports.

[Peerie Maa]

The pumps on the rigs are manifolded. The pumps are triplex piston type.

They could manifold the pumps of the other rigs with a seabed manifold beside the BOP. But then these would face the restriction of the choke and kill ports.

Why not manifold them on the surface and send it all down the new wells casing?

[Clan Gordon]

Quite possibly - that is option 2) in post 84

[Andrew Craig-Bennett]

Didn't Halliburton buy Boots and Coots?

[Venchka]

West Sirius. My brother is or will soon be on this semisubmersible boat. Be safe Bro!

http://www.offshore-technology.com/projects/kaskida-field/images/1-west-sirius-rig.jpg

[George.]

Question: does the cement extend all the way down the hole to the depth at which the relief wells will intercept it?

[Peerie Maa]

Question: does the cement extend all the way down the hole to the depth at which the relief wells will intercept it?

Have a look at the link to Wiki in post#68. That suggests that the cement is only placed where it is needed. As the oil is contained by the casing, the relief well will have to drill either through the casing, or intercept the well below the last casing string. As they use magnetometery to detect the well, I guess that they are aiming at the casing.

[Oyvind Snibsoer]

Perhaps a brief explanation of drilling, mud and casings are in place. I am by no means an expert in the field, by I do have a grasp of the basics.

To begin with, any and all sub-sea sediment is saturated with water. The water fills the voids between the mineral particles that make up the rock. As the depth of the well increases, so does the pressure of the water in the rock. This is known among geologists as pore pressure.

As we all know, pressure in a column of water increases in a linear and quite predictable fashion. One of the challenges of oil drilling is that, once you're down in the sediments the pore pressure no longer increases in a purely linear fashion, but is dependent of the specific gravity and other properties of the sediments that are above the drill bit, i.e. the overburden.

Now, a major challenge when drilling is that the pore pressure has to be matched by the pressure of drilling fluid in the wellbore. Too much pressure, and mud cracks open the sediments and escape. Too little pressure and the wellbore may cave in, jamming the drillstring. To add to the complexity, different sediments have different properties WRT how much pressure deviation they will tolerate before they start acting up.

So, this is where the weight of the mud comes in, to maintain the correct pressure at the current depth. However, the mud weight that is appropriate for a given sediment 3000 meters below the ocean floor is probably not appropriate for all the sediments above that depth. Which is why you install casings.

When planning for a new well, the number and length of casings are planned according to the depth of the well and the expected properties of the sediments that you are to drill through. The well is started with an oversize drill bit. At a predetermined depth, the drill string is pulled and the first casing is put in place, at which point a sigh of relief can be heard throughout the rig. The wellbore with the casing is now secured, and is no longer susceptible to cracking or caving in, regardless of the mud pressure. Drilling commences with a smaller drill but until a new, smaller casing is put in place etc.

[George.]

Thanks, Oyvind.

So the mud they used for the top kill all leaked out because the casing and/or the cement were compromised, correct?

But deeper down, they hope that the mud will not leak out, which assumes that it will have balanced the pressure of the well before it rises to the level where it leaked out during top kill. Is this correct?

[Oyvind Snibsoer]

Thanks, Oyvind.

So the mud they used for the top kill all leaked out because the casing and/or the cement were compromised, correct?


Could be. The reservoir pressure is supposedly around 11 000 psi, or 760 bar. In order to stop the flow with a top kill, they needed to get a fairly tight seal between whatever contraption pumped the mud, and what was left of the wellhead, and then pump enough heavy mud into the well so that the reservoir pressure could be countered. If the mud leaked out through the casing, they were probably not able to inject enough mud into the well to slow down and stop the flow.

It's seemingly quite common for casings to be damaged in the event of a catastrophic blowout, however. So the fact that the casing may be compromised now, is not necessarily proof that it was compromised before the blowout.



But deeper down, they hope that the mud will not leak out, which assumes that it will have balanced the pressure of the well before it rises to the level where it leaked out during top kill. Is this correct?

Deeper down, hydrostatic pressure is on the driller's side in this case. If the reservoir pressure is 11 000 psi, then that is the force you have to counter with the mud. So if you can just pump mud into the wellbore, that has a pressure of more than 11 000 PSI at the depth where the relief well intercepts the Macondo well, they should be able to stop the flow.

Actually, when looking at these figures and doing some quick calculations, what puzzles me is what I perceive as a fairly reservoir pressure. I don't know that much about this beyond the basics, but consider this:

At 18 300' / 5577m, a column of sea water would exert a pressure of approx 558 bar, or 8 093 psi. I know absolutely nothing about what kind of reservoir pressure one would normally expect at these depths, but I do find it strange that it is only slightly more than 1.37 times the pressure of an equivalent column of sea water, considering the fairly substantial overburden.

Dunno, but it would seem to this remote observer that unusually low, and not high, pressure may have been the cause of the problems that led to the disaster. This would seem to be in line with some reports I've read, that BP wanted to use pure seawater for mud...?

[Clan Gordon]

So the mud they used for the top kill all leaked out because the casing and/or the cement were compromised, correct?



I don't think so.

I think a big part of the mud leaked out of a big hole just above the seabed - the big hole that the oil was leaking out of.

Just like that is going to be an issue this time around unless that troublesome hole was closed. Or the friction losses as the oil/mud mixture leak up the old casing and failed BOP give sufficient back pressure to permit a dynamic kill at the intercept. Facilitated we hope by a combination of the static head and the mud pump pressure in the new hole and the back pressure in the old hole.

More generally, I think somewhere on this thread or others I referred to how the relief well needs to switch from a dynamic kill to a static kill.

[Clan Gordon]

This would seem to be in line with some reports I've read, that BP wanted to use pure seawater for mud...?

If you are referring to the displacement of mud by seawater - and implying that this was a bad thing to do because SW is less heavy than mud, then please note that the only way to do the negative pressure testing on the casing is to have SW in the casing (giving a lower pressure inside than out). They had already done a positive pressure test (from casing outwards to the reservoir). I believe they also did a NEGATIVE pressure test on the casing which required displacement of the mud by SW.

[Oyvind Snibsoer]

OK,
there are several reports in the press about BP replacing drilling mud with seawater, and some disagreement between BP and the contractors on how this was done. But this could very well refer to the process you describe above, and not actually drilling with pure seawater as I implied.

[Clan Gordon]

OK,
there are several reports in the press about BP replacing drilling mud with seawater, and some disagreement between BP and the contractors on how this was done. But this could very well refer to the process you describe above, and not actually drilling with pure seawater as I implied.

Indeed there are - and the reports tend to focus on how rash and stupid it was to replace the mud with seawater without knowing that the well had been properly tested etc etc. Of course these reports are made by people who don't realise that the ONLY way to do an INFLOW test on the well casing is to remove the MUD from the casing so that the interior is at less pressure than the exterior.

But I don't wish this thread to become one about who made what mistake when - so I will stop there.

[Clan Gordon]

New ship on the block (or perhaps moving off it)

GECO TOPAZ

Prior to starting the intended well shut in and pressure tests (see next post), BP have performed a seismic survey of the region to better understand the shallower horizons of the field and give “baseline” data that will be needed if the well bore proves to be ruptured at some point.

WesternGeco’s seismic vessel Geco Topaz completed a 2.5-mile north to south shoot of the location and will begin processing the data.

During the survey, all other vessels needed to be moved off location.

Perhaps someone else can find and add a pic of this ship.

[Clan Gordon]

WELL SHUT IN UPDATE – 13th July - paraphrased from Upstream

BP is preparing to attempt to shut in Macondo starting around mid-day today 13th July to test for well integrity. If successful this could mean the end of any more oil flow.
The shut-in may be possible because of the new three-ram containment cap which was landed on top of the spool assembly at 6:20 pm Houston time on 12 July.

Currently there are five flow paths for production from the well; the choke and kill lines on the original blowout preventer, the choke and kill lines on the new cap, and the main bore (a.k.a. the leak).

1) BP will begin the test by closing the choke and kill lines on the original blowout preventer.
2) Then it will being actuating a ram in the new cap that will close the main bore (the leak), followed by one that will close the kill line on the new cap.
3) Finally, BP will begin to close the choke line on the new cap, which is the only valve that can be closed incrementally.

At each step, crews will monitor pressure inside the new cap.

Those pressure readings will tell BP if the casing and cement in Macondo can withstand the full pressure of the well.

Ideally, BP would like to see pressure increase to between 8000 pounds per square inch and 9000 psi. If pressure builds to that level, it would indicate that all of the production is flowing up the wellbore.

A pressure reading lower than that would likely mean that hydrocarbons are leaking out of the bore at some point between the mudline (seabed) and the producing reservoir. Such a reading would complicate efforts to try to kill the well. See posts above - it means that if the fluid escapes low down in the bore there will be less back pressure than if it escapes higher up the old bore.

The bore/casing could have been damaged during the blowout or have been degraded afterwards during the failed top kill attempt and subsequent flow out of the producing zone.

The process will take anywhere from six to 48 hours to complete, because BP will stop at intervals to make sure the well can sustain the pressure.

If necessary – as a result of the integrity tests – Macondo will be opened back up and oil collection at our two friends HELIX PRODUCER (decent process capacity, no storage) and Q4000 (no storage, small process capacity) will restart.

Afterwards, small well test vessel TOISA PISCES will be brought in to connect to the second freestanding riser.

The big drillship DISCOVERER ENTERPRISE (with small process plant) could also return.

[Clan Gordon]

RELIEF WELL UPDATE 13th July

The first relief well is now at 17,840 feet depth and a little more than 4 feet away from the original bore.

Another ranging survey is being run to confirm distance and inclination from the original Macondo well bore to make sure the relief well is lined up for the final 30 feet of casing run, scheduled for 18 July. They are on track for the Macondo well bore entry around the end of July. Once penetrated, the kill operation can begin.

The second relief well from Development Driller II, will likely halt operations when the relief well begins to penetrate Macondo. The rig will stand by in case it is needed.

[B_B]

http://www.vikoma.com/images/prod/envirocat.jpg

There was an auction in town on Saturday. Two of these (http://www.vikoma.com/product/38.aspx?page_id=2) (except older orange fibreglass ones) along with about 5 miles of boom, assorted skimmers, separators etc. were sold.

Apparently when the BP oil spill started the Coast Guard here contacted Coast Guard HQ in Ottawa, who contacted US Ambassador, offering all this equipment for free, as it was surplus to their requirements.

They were told no thanks so it all sold here for under $10,000 - no demand. All the stuff will be broken down and parted out. And the rest of it trashed.

[The Bigfella]

I spent a few hours with a couple of BP execs yesterday. Interesting conversation.... especially given the CEO situation.

[Clan Gordon]

UPDATE FOR FRIDAY 30th JULY (paraphrased from Upstream)

The first phase of the operation to kill the well – the static top kill – likely will start on Tuesday 3rd August.

Right now, it looks like the weather over the next week will be clear at the location.

When the static top kill begins, the Helix Energy Solutions vessel Q4000 will pump drilling mud through the kill line of the old Macondo blowout preventer.

The Q4000 is already in place, hooked to mud and pumping vessels, but BP wants to make sure the relief well is cased and secure (see below) before beginning the job.

Most likely the mud will be followed by cement but BP will not make that decision until after mud has killed the well and it has been monitored. The whole process will take about 24 hours.

The top kill (or hydrostatic kill) should potentially bring the pressure at the well cap to zero.

Pressure on the capping stack that has kept Macondo shut for two weeks is at about 6969 pounds per square inch and rising at less than 1 psi per hour.

Monitoring has not revealed any concerns about the integrity of the well.

The top kill operation is designed to take care of any flow through the main bore but it cannot circulate through the annulus. Hence the bottom kill (from the relief well).

BOTTOM KILL UPDATE

After the top kill, Development Driller 3 can begin drilling the final 100 vertical feet into the annulus of the original Macondo well. This is expected to take about five days because crews will stop every 20 to 25 feet to locate the Macondo wellbore.

When the rig hits the annulus it will begin pumping mud for the bottom kill operation. Once any flow in the annulus has been stopped, the mud will be followed with cement.

Finally, the DD3 will drill into the main bore to ensure that the kill and cement job from the static kill was effective.

They hope that the static top kill will take care of all the flow in the main bore - but regardless of that the DD3 will drill into both areas to make sure.

RETURN TO THE RELIEF WELL

BP had shut the well in with a temporary storm packer and pulled the drill string to about 10,000 feet below mud line when moving the rig off in anticipation of Tropical Storm Bonnie. When Bonnie fizzled out over the Gulf, the rig returned.

By Tuesday 27th, the storm packer that was placed in the bore to secure it during Tropical Storm Bonnie had been released and would be removed over the next couple of days.

By Wed 28th, the riser of the DD3 had been connected to the lower marine riser package and DD3 had begun testing the blowout preventer while the crew circulated fluids from the bottom up to clean up the bore.

Development Driller 3 then had to run 2000 feet of 9-7/8 inch casing and cement it in place – but this work was delayed following the re-entry after the shutdown for the tropical storm. This process is expected to take until Monday 2nd August at least.

After the casing is set, Development Driller 3 can begin drilling the final 100 vertical feet into the annulus of Macondo while the top kill is underway.

The relief well could intercept the Macondo bore by about 8 August.

[Andrew Craig-Bennett]

This has been an outstanding thread.

[xsboats]

I am currently employed as a captain of a Fast Boat [a 33' Yellowfin w/ 3 350hp Merc. Verados] in which I drive clean-up supervisers and inspectors around the Gulf of Mexico. I am currently operating out of Grande Isle, Louisiana , since our operations in the mouth of the Mississippi were shut down last week. I am waiting for a card reader to be sent to me by my wife, and then I will post photos of many of the diverse craft that are employed in the Vessels of Opportunity fleet cleaning up the oil.

[Andrew Craig-Bennett]

Good - thanks!

[B_B]

Good - thanks!
+1 !
And yes, this has been an outstanding thread, thanks all.

[Eric D]

I awai further pictures as well. I am also one of the peanut gallery VERY impressed with the knowledge and info shared on this thread, thanks.