So son..ya wanna work on an oil rig and earn the big bucks

[kiwigeo]

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Originally Posted on: Fri Apr 23, 2010

Transocean's "Deepwater Horizon" blazing away in the Gulf of Mexico. The rig has sunk since these pics were taken and 11 crew are still missing.

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[Nick]

Saw this on the news last night and at that stage the rig was listing but hadn't sunk.It was funny because we were just talking at work yesterday about the perils of sparks (the use of cushioned 'spark safe' tools) e.t.c on gas rigs. Goes to show why you guys get well reimbursed, it ain't all beer and skittles!

[kiwigeo]

Too early to state exactly what happened but looks like a blow out that happened once they'd cased and cemented the well. Sounds like once the gas got into the riser and above the Blowout Preventer all hell let loose.

[Nick]

Sounds like once the gas got into the riser and above the Blowout Preventer all hell let loose.

Bit like me after a curry but without quite the same consequences.

So if this is what happened has a system failed, (do they have double backups?) or some procedure not been strictly adhered to?
Whichever way it cuts, nobody should be lost or killed while working, so it's sad from that perspective.

[Dennis Leahy]

Can I just comment on how funny it is to read this very serious topic, and see two sheep conversing, one wearing garters, stockings and high heels.

You guys crack me up!

Dennis

[Nick]

Can I just comment on how funny it is to read this very serious topic, and see two sheep conversing, one wearing garters, stockings and high heels.

You guys crack me up!

Dennis

Sheep take an interest in current affairs too Dennis!

[John Steele]

Good to hear a perspective from someone who has spent considerable time on these things. (thx Martin) For the sake of the families and loved ones of the missing 11; I hope they find them pissing hammered in a raft singing motown. Between the 29 miners and now this, I keep telling people freakin' use less and they'll need to produce less. It's that simple. 'k, off my soap box back to the comfy chair.
J

[kiwigeo]

Bit like me after a curry but without quite the same consequences.

Hard to say Nick...theres alot of conflicting reports going around. I went to an account of the disaster from a Transocean Executive....Transocean own the rig.

In a normal well you have a series of barriers against uncontrolled release of high pressure fluids from the formation into the wellbore. In this case there would have been the cement they pumped around the shoe of the casing along with the float collar that sits in the bottom joint(s) of casing, there would have been a column of fluid (Im assuming mud) inside the casing (exerts a hydrostatic pressure to counteract formation pressure) and the last line of defence is always the blow out preventer (BOP) which in this case sits on the sea bed. The BOP is a huge structure containing various devices that allow control of a fluid ingress into the well. There's also provision for pumping of heavy mud down the well to kill same. IOn the case of a well on a production platform the BOP is replaced by a subsurface valve that can be used to shut a well in.

If all the normal barriers fail then the BOP is the last line of defence against a blow out. If warning signs don't get noticed or the blowout happens very fast and the ingress of fluid gets above the BOP into the riser then things get serious. As a bubble of gas heads to surface it expands and by the time it gets to the rig floor it's arival is usually announced by a huge eruption of mud and hydrocarbons and if theres any ignition source you end up with what you see in the photos posted earlier.

[xray]

what is your job description martin? do you work in the line of fire so to speak or are you safer somewhere away from the pipes? This would have to have you worried and appreciating the simple things?

[kiwigeo]

I'm a Geologist and although I'm not slogging it up on the drill floor with the boys a blowout is a threat to safety of everybody on board the rig no matter where they work. While Im not usually on board during completion operations such as the one that was going on when The Deepwater Horizon went up I am on board during drilling operations during which there are ample opportunities for similar scenarios to develop. Another operation when the rig can be vulnerable to kicks is when we're tripping our drill string in or out of the hole (eg for a bit change)....pulling out to fast can create a swabbing effect which can lower the actual hydrostatic pressure at the bottom of the hole and result in an incursion of formation fluid into the well bore (=a kick).

I haven't experienced a kick during a trip while working offshore but in my early days when I worked in the desert on land rigs operated by cowboys I was on a few jobs where we took kicks during trips out of the hole. Have vivid memories of one kick where I spent half the night up on the mud tanks with the mud engineer and the derrickman furiously cutting open bags of barites and dumping them into the mixing hopper to make up enough kill mud to get the well under control. Theres a photo floating around somewhere of myself and the mud engineer covered in mud and barites with a look of sheer exhaustion on our grimey faces.

As an aside....a few months ago a nearby rig to the one Im currently working on off WA took a kick which then developed into an underground blowout. Luckily they got the well shut in with the BOP but there was potential for a more serious chain of events. In the latter case the root cause of the incident was a bunch of people missing a whole bunch of early warning signs that the well was about to kick on them.

[Nick]

Latest news I've read off of Stuff.co.nz :

The oil rig Deepwater Horizon rested below 1525 metres of water in the Gulf of Mexico on Sunday, spewing crude oil from two newly discovered leaks in a lengthy conduit connecting the sunken rig to a well site 457 metres away, officials said.

"The estimate - and there is a strong emphasis on the fact that it is an estimate - is the rate of (the leaks) is 1000 barrels a day," Ron Rybarczyk, a spokesman for BP Production & Exploration, said.

A 32km sheen of the emulsified crude spread over the gulf, approximately 64km (40 miles) off the Louisiana coast, according to a joint statement released on Saturday by BP, Transocean, the Coast Guard and the federal Mineral Management Service.

The status of a second pollution source - 700,000 barrels of diesel fuel stored on the Horizon when it sank - remained a mystery on Saturday.

"The disposition of the diesel fuel is unknown," BP spokesman Rybarczyk told AFP.

The bad news about the crude oil leaks came one day after Coast Guard officials said visual images and sonar data from a remotely operated robot found that the well head had stopped leaking oil.

But on Saturday, a second robot found two oil leaks in the 1525m riser - a conduit of pipe that connects the wellhead - to the sunken rig, Rybarczyk said.

"We have had a visual image of the (sunken) rig," he noted. "We know that the rig is stable and it is staying in one place. Our approach now is to make the best fix toward getting those release points stopped."

With oversight from federal technical teams, BP and Transocean officials are evaluating two traditional plans of attack on the crude oil leak.

The optimal approach is to get the blow-out preventer - an iron hydraulic device near the well on the ocean floor - "fully engaged" in sealing off the crude oil source, Rybarczyk said.

"The other method being discussed is a relief well. We have those resources available but we have not deployed them."

More time-consuming than the blow-out preventer option, a relief well would involve drilling a new hole near the BP well, intercepting the leaking conduit, then pumping cement or heavy mud down into the hole until the BP well is fully sealed.

Meanwhile, sea-surfaced skimming operation involving a flotilla of oil spill vessels has recovered at least 127,667 litres of crude oil since Tuesday's accident, officials said.

However, thunderstorms and rough seas hampered skimming operations Saturday.

"It wasn't an optimal day for recovery." Rybarczyk said.

US Coast Guard Rear Admiral Mary Landry, the top federal commander of the Horizon incident, said: "Our response plan is focused on quickly securing the source of the subsurface oil emanating from the well, clean the oil on the surface of the water, and keeping the response well offshore."

"This is a devastating spill," said Anne Rolfes, an environmental activist and founding director of the Louisiana Bucket Brigade. The group is bracing for wild fowl rescue efforts on Louisiana's fragile wetlands, should the sheen of oil reach the coast.

There was no news of the 11 missing Horizon crew members on Saturday - 24 hours after the Coast Guard announced the end of an exhaustive search by sea and by air.
There was no information on how the explosions and subsequent oil spill has affected marine life. Representatives from the US Department of Fish and Wildlife were listed on media advisory for a Saturday news conference on the oil spill but did not attend.

Hopefully they can seal the leaks quickly.

[kiwigeo]

A very confusing report. Not really clear what theyre talking about with the leaks. It sounds like the well isnt secure and thats where any oil will be coming from. By conduit I assume theyre talking about the marine riser. I doubt this will be intact if the rig is on the sea bed and 457m away from the well.

If the BOP is still intact and attached to the wellhead there is an option to try and manually shut the well in. BOPs usually have a set of bottles attached which can supply enough charge to shut rams in the event the normal control lines to surface are not operational. A set of manual valves on the BOP can be operated via the robot arm on an ROV (robot sub).

If they cant shut the well in via the BOP or other means then the remaining option is going to be to drill a relief well and then fill the main well with heavy mud or cement via same...this is a time consuming and expensive operation requiring a second (deep water) rig. This is what they did to kill the West Atlas well that blew out recently up in the Timor Sea.

[kiwigeo]

Back at work now and have been learning some more about the Horizon disaster. Information to hand:

1. the well was completed with a liner. Rather than being a single string of casing that hangs off the wellhead a liner usually runs from the bottom of the well to up inside casing of a larger diameter set higher in the hole. The top of the liner has a hanger and seal assembly which is set inside the casing. The liner is set and cemented and then the hanger seal assembly is set and should normally be pressure tested to test the seal is functional.
2. a balanced suspension plug had been set above the top of the liner. The heavy drilling mud inside the liner and casing had been displaced to seawater. At this time they had the well shut in at the BOP (probably using blind rams) so the latter was working at this stage.
3. They had re-opened up the well and were displacing the riser from mud to sea water when they took the kick. I suspect a bubble of oil/gas got past the BOP and into the riser and quickly shot up same to surface. Being above the BOP there was not much they could do to stop the blowout.
4. The blowout and fire knocked out the BOP surface control systems. By this time I would hazard a guess that the incursion of fluid through the BOP would have caused damage to the rams and valves in same rendering the system inoperable even if they had been able to operate surface controls.

[Nick]

Thanks for the update Martin, good to have a man on the 'inside'
Now perhaps you could explain why they wait until the thing goes up before building the coffer dams, is this 'standard practice amongst the industry? I can't understand why they don't have a few of these things built (for a 'just incase' scenario) and stored somewhere ready to go, could have saved a few thousand barrels pouring into the ocean.

[kiwigeo]

Nick,

The coffer dams are custom built for the situation....BOP stacks vary in size and the number and location of leaks from damaged riser would vary infinitely.

My final comments are still based on a assumptions.....the official investigation will reveal exactly what went wrong and alot will be learnt about how to avoid a disaster like this happening again.

My experience with liners has been that they often cause problems....9 time out of 10 the problem is with the hanger/seal assembly...its the part of the riser with the moving parts. A full string of casing has less risks associated with it but once you get into deep wells casing string weight reaches a point where the rig can no longer handle same. A liner weighs alot less and also costs alot less than a full string of casing.

[kiwigeo]

An interesting evening being spent here talking with the Subsea Engineer out here on the rig I'm currently working on.

[Lillian]

Care to elaborate?

[Nick]

Care to elaborate?

Oh he's a tease isn't he Lillian?

[kiwigeo]

Nothing like talking to a guy whos worked with BOP systems most of his working life to learn something about BOPs.

The press are making a big thing about the lack of a thing called a BOP acoustic actuator on the Deepwater Horizon. This device is an alternative way of issuing a command to the BOP stack on the seafloor and telling it to shut in rams and preventers (normally done via a MUX cable running down side of the riser). From talking to our subsea engineer all the Transocean rigs of the same class as the DWH normally carry an acoustic actuator kit. The kit is stored in the subsea engineering workshop and in the event of a blowout the kit gets hurled into a liferaft which then gets deployed. Once in the water the kit is opened up and a sonic transmitter is hung into the water and some of the functions on the BOP can be operated via same. The kit normally gets tested every 30 days. Of course if you have a huge blowout that catches fire straight away as happened on the DWH an acoustic kit isnt going to help you.

The press are also talking about a deadman system on all BOP's that operates the BOP if power to the stack is lost. We certainly dont use them in Australia and the guy I was talking to hasn't seen them used alot outside Australia. In my mind if you do a risk analysis on such a system then theyre actually quite a dangerous thing to have. If for example you have a rig generator go down and your UPS fails to kick in (not that uncommon) and you've got a drill string in the hole....your shear rams activate and you then have half your string sheared off and down the hole.

Over the last few days Ive seen alot of misinformation and in some cases total rubbish appearing on various websites covering the DWH disaster. The really annoying sites are the looney right wing sites that parrot on about North Korean subs having torpedoed the DWH or how dropping a nuclear bomb down the well will kill the blowout. The people currently handling the situation know what they're doing...they're the best in the industry and the best chance of getting the blowout under control.

IMHO the feasible options for killing the well at this stage are as follows:

1. shear off the riser from the BOP stack and stab in a second BOP and shut in the well using the latter.
2. drill a relief well(s). One relief well has already been spudded and a second rig is on its way to start a second relief well. This method has a high chance of success but it will take about 2 months to get each well drilled.
3. Attempt a top kill operation. This would involve modifying the control pod on the BOP (already in progress I believe) and going into the well through the BOP and pumping large amounts of lost circulation material and then heavy weight kill mud. Sounds a bit like a bullheading style well kill. If they have one of the caissons over the BOP to control the oil flow then a top kill operation may be difficult.

Ive had a chance to see alot of the information on the chain of events filtering out via some relatively reliable sources and have been able to establish the following:

1. At the time of the blowout the DWH had drilled the well and a 7" liner had been run and set. The liner would have been hung off a larger diameter casing string higher in the hole (Im assuming 13 3/8" diameter).
2. The 7" liner had been set and cemented and the seal assembly at the top of the liner was PROBABLY set and SHOULD have been pressure tested as well as inflow tested (ie testing for leaks both ways across the seal).
3. a cement suspension plug had been set in the casing above the top of the liner.
4. The hole had been displaced from mud to seawater. During this process they would have had the BOP shut (either preventer or pipe ram). This indicates the BOP WAS working at the time.
5. The kick seems to have happened around this point. It either happened when they reopened the BOP after displacing the hole to seawater or when they started displacing the riser from mud to seawater. When youve had your BOP closed for some time its good practise to first check for pressure trapped under the stack by monitoring the coke and flow lines. I assume they would have done this..its standard oil field practise.
6. The only path for the formation fluid ingress to get to the riser is either through a breach in the liner or via bad cement behind the liner and then into the well via the seal at the top of the liner. My feeling is cement and liner seal integrity could be the root cause of the incursion.
7. there are some accounts of a BOP test being conducted but this information seems a bit strange. BOP's are normally tested on a regular basis (2 weeks here in Oz) and also prior to certain events (eg new hole section, drill stem testing etc). Its unsualt to be testing a BOP just before you unlatch the BOP from a welllhead and pull up your riser prior to leaving the location. The presence of drill pipe sticking out of the riser in some of the ROV photos indicates there was a string in the hole at the time. Its either the string they used to run and land the 7" liner or a BOP test tool on drill pipe. Its also possible that its the liner running string with the BOP test tool included.

Anyway the above is mainly me thinking out loud and to be treated purely as my opinions based on data that cannot be regarded as 100% reliable.

[John Maddison]

ABC Online - Oil spill footage released (by BP)

[John Steele]

How shall I put this....

S H I T H E A D S !!!!!


They're talking 'maybe' August having the relief well drilled and then they're not even sure it will hit right.

[Lillian]

Criminal and Civil charges are being investigated. Their stock took a serious hit today. Not looking very good for BP.

[kiwigeo]

How shall I put this....

S H I T H E A D S !!!!!


They're talking 'maybe' August having the relief well drilled and then they're not even sure it will hit right.

Relief wells have a very high chance of success when one is drilled to kill an out of control target well. BP are increasing the chances of success even further by drilling two relief wells. They'll also have the best directional drillers in the business guiding the relief well.

I dont see why the relief wells wont hit the target. The procedure involves drilling to a target determined by directional data recorded while drilling the original well (surveys usually taken every 30m with an MWD survey tool in the drillstring and also probably recorded during wireline operations). Because there is a margin of error in these surveys theres a high chance the relief well wont hit the target wellbore on the first pass. What happens then is they plug back the lower section of the relief well and then run a ranging tool which will tell more accurately where the casing in he target well is relative to the relief well. Using this new data a new more accurate target is set for the relief well. It could take up to 10 passes to hit the target well but they will get it.

Once they hit the target well they'll pump in heavy weight kill mud followed by cement which will permanently plug the well. Once thats done theyll go in through the top and put permanent plugs in place over the upper section of the well.

Accurate accounts of the chain of events leading up to the blowout are still not clear so I wont make comments on same at this stage. I will say that all the major operators are reviewing procedures as a direct result of the DWH disaster. On my last job we received a whole bunch of new procedures from head office. Eg...the ROV stab in function on BOPs now have to be tested prior to running the stack and latching up onto the wellhead.

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