BP Oil Spill – Last fragment before Jan 2011?

The final words of a BBC TV documentary, Horizon transmitted on 16 November 2010, were  “When BP’s well blew out, there was no plan to fix it“.

The bulk of the programme was excellent giving a clear description of the problems and final success of the spill recovery. I say that stemming the flow from the leaking well was a ‘success’. The problem that is still being worked out is to ameliorate the damage to people and wildlife caused by the previous eighty seven days of the oill flooding into the sea .

To return to the programme, it was excellent in that it concentrated on relaying the words of those, from BP, the US government and other commercial outfits who had been instrumental in the battle. The programme was written and directed by Tristan Quinn and the editor was Aidan Laverty.

They were wrong on at least two levels. The first was that the the footage in the programme showed the large number of vessels and engineering staff that rapidly poured into the area and attacked the immediate task. They were not conjured from nowhere.

There is however another level that is much more fundamental. Preparing to recover from any one of very large number of potential future accidents is very difficult. What one has to do is to take steps to avoid having the accident in the first place. This is the true preparation.

These were there with all the procedures and checks and safety hardware. The significant fact is that they all failed but in ways that could and should have been avoided one way or another. The fact is that as the model in my previous post suggests, the failure of these existing procedures and hardware were together an extremely unlikely event that led to catastrophe. Carry out the necessary actions to reduce these to an even more unlikely event is the only and proper way to go.

The portentious voiceover  “…..there was no plan to fix it” could only appear profound to a TV writer or producer. The statement is not: it is instead the deepest nonsense as is shown by both pictures and facts.

This having been said, The Lad really does not want this blog to get regularly involved in who said what in which medium. That is the preserve of the politicians and those who wander in the halls of hype and mirrors exposing endless conspiracies. So The Lad intends that, as far as he can, this blog will stay grounded in the real world.

Catenary Support Eyesores

The Government has announced recently that £billions will be spent on UK Transport rail infrastructure. I assume that this will include the High Speed 2 plan linking London and Birmingham by electric railway. Those on the ground will always oppose the planned routes due mainly to the damaging effect on their house values.

But many also will cite visual horrors of the railway cutting through the contryside. The Lad, although an engineer, can understand that to some degree. The trains and their sounds are soon passed at any given spot. But the masts, skeletal arms and the wire arcs are permanently on display.

US array of cables
It should be possible to do better.

The Lad is not a catenary support designer but, in the UK, notes that it appears that standard RSJ uprights and other ugly components have been flung together. The idea?? of using standard parts or RSJ material is assumed to be the best way to achieve cost-effective structures. There does not appear to be any thought for the visual effect. See the pictures, which come from the excellent website, http://www.theoverheadwire.blogspot.com/ with the kind permission of its author Jeff Wood of San Francisco.

Second view of wire and mast array
Let’s design aesthetically better designs than this.

The Lad advocates a more holistic design. special components, possibly multi-use, could not only look better but also, he is sure, be more structurally and dynamically efficient. The cost of specially designed parts would not be more expensive. Why? Because in the hundreds of miles of line lengths there are multiple tracks and so there would be thousands of each given component. What happens to properly designed, component cost with large quantities? It plummets.

This post is The Lad’s quick response to a problem that has been irritating him in the back of his mind for some years. I will develop a strategy to try and move the idea forward. I will try to find the movers and shakers in this area and see if he can begin any sort of dialogue. The Lad will keep the blog in touch with any progress or none as transpires.

Fingerprints were the answer?

A reporting team wrote an article in the UK Sunday Times, on the satisfyingly weird date of 10/10/10, that ventured into the murky world of realpolitik and espionage. The team and those of us, like The Lad, who were brought up in the world of John Le Carre know that it is a world of uncertainties. However engineering for this team, and many others, is equally uncertain though they may not realise it.

Reporting on the nuclear programme of Iran, they describe damage to a number of the enrichment centrifuges as follows. ” … those assembling the centrifuges did not wear cloth gloves. Beads of sweat were transferred to the rotors that spin inside the centrifuges and put them off balance, causing some to explode.”

Now, it’s true that the rotors rotate at enormously fast rates and they need to be well balanced to run smoothly, but I feel that the unbalancing effect of of the minute mass of beads of sweat will be as likely an effect and as true as the fable of the Princess feeling the pea under the 15 mattresses.

The Lad suggests that acid fingerprints from ungloved hands, yes, was a problem but with a different, less direct outcome. The acidic prints would have started corrosion and cracks in the exquisitely controlled material of the rotor walls. The resultant stresses from the cracks at the high rotation speeds would soon make the rotors explode or distort or leak. The only recourse would be to take them out of service as reported.

Making its Mark

 

Whole block
The whole scribing block-© 2010

Engineering was a craft before the Industrial Revolution but then much changed. Is this a “statement of the bleedin’ obvious” as Basil Fawlty would have said. No. I am not referring to the invention of the Steam Engine and the various weaving machines in themselves.

Simply put, it was the knock on effect, of interchangeable spares for those and other machines. Before the Industrial Revolution each machine was made by hand. Each of its parts was made to fit sufficiently accurately and smoothly with only the other parts of that particular machine. As more machines went into service and, with time, they needed replacement parts. It was expensive and a pain to have to go to the machine in question and make a new part to fit. Not only a pain: possibly in a working assembled machine it would be impossible to ‘find the sizes’.

Someone had the brilliant idea  to make all the parts sufficiently accurately that any part would fit into any machine. The phrase “sufficiently accurately” is the secret here. All sorts of machine tools and techniques had to be developed to do the job but The Lad describes here only one.

Much increased accuracy was needed compared to woodwork. Before, wood could accomodate some inaccuracy due to its flexibility, lesser rigidity, and its usual static not dynamic function. Before you can make something accurately to size, you have to know what that size is [See my later post on the micrometer]. Then you have to mark the material accurately to that size. One component of the marking out process was actually a pair of items. The surface table and the scribing block.

The material that you are trying to make into an accurate component must be marked acurately, much more highly accurately than had been done previously. They need very fine lines permanently marked to a very accurate position. Then you can remove material to the marks. So: you stand the component on a very flat table usually made of cast iron, sometimes granite. If it is already machined, you may coat the surface with blue dye or copper sulphate to give a blue or coppery surface to make any scribed marks easy to see. A hard point mounted on a heavy block with a flat surface can then be set to a given, accurate height. As it smoooooooothly glides, steel on cast iron, over the table’s flat surface, it scribes a fine line on the material.  Turn the component through a right angle, reset the scriber to a different height perhaps and scribe another line crossing the first. There you have it. At the intersection, is the place to drill a hole accurately in position.

The surface table is too big to form part of the current collection of The Lad. But the scribing block is not. Here it is in pictures.

lower pivot
The left thumb screw provides fine adjustment of the pillar and the right locks.© 2010

As well as the heavy base, note the heavy sections that give us a rigid structure. Under the small scribing load, this rigidity leads to almost zero deflection and thus mark-up accuracy.

Pins & vee
The pins have been pushed down through the base. The vee is for a cylinder mount.© 2010

Sometimes the engineer is scribing several parallel fine lines on a horizontal surface rather than a vertical one. If so, she can use the machined straight edge of the table using the pins pushed down as shown to run along the edge. Even a cylindrical guide to the scribing can be used if she finds it necessary by mounting the vee in the base on the cylinder.

Scriber mount
This shows the rigidity of the scriber clamp to the post. © 2010
Pins up and rainbow
A handsome protective finish on the base. The pins are up here. © 2010

The whole unit weighs 1.1kg. The makers say that this one was made around 1965. The surface finish shows a slightly raddled beauty: it must have been very striking when it was new. I asked the Wolfson Heat Treatment Centre what the effect was. Derek Close and his colleagues suggest that it was made by steam blueing, a process where a component at greater than 600 degC is immersed in dry steam.

The Centre is at http://www.sea.org.uk/whtc which operates within the Surface Engineering Association at http://www.sea.org.uk/

It certainly has some corrosion resistant properties. I say this because all but the, ground, corroded, lower surface of the base is steam blued and is not corroded.

This is one of the artefacts that The Lad collects. The essence of it is that it and the others in his collection are all things that The Lad has used albeit briefly. A scribing block has been around for a long time and its pedigree is tightly intertwined with engineering history.

This tool was called a “surface gauge” in the Buck and Hickman 1958 catalogue at £2.60. This catalogue is a weighty gem from The Lad’s 1960’s collection of engineering books. The Lad has always called it a scribing block so he will stick to that. Moore and Wright still exist by the way in Sheffield and Hampshire but are owned by Bowers Metrology Group [http://www.moore-and-wright.com/]. As an indication of a classic tool, the identical design of scribing block can still be bought new from Buck and Hickman that is also still thriving in 2010, http://www.buckandhickman.com/ .  The current price is instructive though.

Screw threads, slots and watches

Have you ever noticed when you screw in a group of wood screws into your flat pack wardrobe that when they are fully tightened the slots are always at different angles to others in the group? The same effect is seen in any engineering structure. The engineers do not worry about the bolt hexagons on car engines or gas turbines, say, being at different angles to each other.

This means that the start or finish of all screw threads, be they wood screws or more high technology screwed fasteners always vary in their position relative to any other feature of the fastener such as slots or the hexagon of a bolt. This is because the production engineers exert no control over where on the screw blank or in its matching hole the rotating thread die starts to cut to form the thread. Sometimes, in alternative processes, the blank rotates and the die or even a still single point tool is still. Relatively speaking, all these are the same. See if you can visualise all this.

Lots of engineers have good 3D visualisation. It may well be a helpful capability for any engineer.

Whole Graphic
Shows a model and real watches

The Lad was reminded of all this when he saw recently an advert for a famous make of expensive, high quality watch. There had been some sort of retro styling decision letting the engineering be partially visible. The watch has screw heads visible around the watch face.

The plaster or talc model shows every one of the screw slots tangential to the crystal bezel outer circle. So that’s what the marketing people seem to prefer or want.

Model
Slots aligned in model

But note that a close look at the ‘real’ watches shown below have the screw slots at random. It seems as though the engineers have not accommodated the marketing vision. I wonder why.

Real
Slots not aligned on real watches

Normal slots are at random angles. The Lad is not a production engineer but I am sure that, with some effort and careful manufacture of the screws and the matching female thread and control of the bezel flange thickness the watch engineers could arrange for the slots in the actual watches to align tangentially with the bezel circumference. A better way would be to arrange a collection of under-head washers of different thicknesses and choose a suitable one to orientate each screw perfectly. Such washers are commonly used for other purposes by design engineers. They call them shims or adjusting washers.

You only have to contemplate the magical miniaturisation of any watch movement to realise that the first approach would be well within their engineer’s capability. Don’t even get me started on the vanishingly minute screw thread diameters that they use routinely. It makes The Lad’s engineering look like that of a giant.

By the way, in what way is a wood screw fastening different to that of a machine screw fastening?

David Blunkett spins off

But where to?

David Blunkett, the former home secretary, has many admirable attributes but recently, on Oct 27th 2010, he got a little carried away. This is not a political attack on him nor on the policies of the coalition government. I want this blog to be apolitical as far as that is possible. I must also assume that he was accurately reported [http://www.guardian.co.uk/politics/2010/oct/27/david-blunkett-cuts-english-nationalism].

Blunkett was describing the possibility of  increasing nationalism  in England due to spending cuts. He spoke of civil society being ‘the glue that holds us together‘. It is also ‘the driving force…to assist each other‘. He also told us how ‘scarce resources are … pulled like a magnet into  …. the Olympic Games’.

Apart from from being a somewhat febrile rush of mixed metaphors, these seem to make sense.

Then, however we are told, ‘The denial that there is such a thing as regional identity pulls the centrifugal force of England into London and alienates those who are hardest hit by the cuts.’.  …Pause…. I’m sorry! What was that again? I have never heard before of anything ‘pulling a force’.

Let’s talk about centrifugal force. At this time of year it seems to be proper to consider a conker on a string. If you whirl it around, the conker moves in something like a circle and the string is stretched straight. Newton’s First Law tells us that any body tends to move only in a straight line so a force has to be exerted on the conker by the string to make it move in a circle. That force is provided by your hand [it feels a pull outwards] holding the string. This is a centrifugal force. While we are about it, the conker feels a force towards your hand, as you do pushing towards the centre when you ride on a roundabout. This is a centripetal force. Newton’s Third Law tells us that the centrifugal and centripetal forces are equal to each other.

Try Wikipedia, of course, at http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion     .

Alternatively a more funky site seems to be at http://www.physics4kids.com/files/motion_laws.html   .

Most of that could be said to be as much GCSE Physics as engineering. But I claim an engineering interest because, as I always define it, engineering is entirely about handling forces very often in terms of Newton’s Laws. I will say that, every single day, engineers who design and make jet engines and other turbines have to work very hard and continuously to reduce the risk of accidents due to centrifugal forces.

Anyway, none of this clarifies Mr Blunkett’s last phrase. I was reminded of the description “…inebriated with the exuberance of his own verbosity…” . I discovered [http://quotationsbook.com/quote/30923/] that this was said by Disraeli of Gladstone. Perhaps that is too much. Let’s say at the loss of some euphony “a little tipsy with the exuberance…” shall we?

BP ‘Deepwater Horizon’ Oil Spill Two

 

Part Two –The cause

What, then, did cause the BP ‘Deepwater Horizon’ Mexican Gulf oil leak? Part One explained what did not. This is what The Lad has learnt about what the engineers involved believe so far in October 2010.

This drilling did not succeed: it failed. This time there were failures on gigantic scale. This cannot and must not be denied. The even bigger job of recovering from the blow out and the vast leakage needed even bigger teams of engineers and took 87 days; but the engineers did, in the end, succeed.

In most of the great engineering undertakings the teams succeed. Not because they make no errors but because of a combination of good practice, planned operational checks and balances and, if and when occasional potential errors still get through, other team members pick them up. There are thousands or hundreds of thousands of such projects at any one time that proceed to a satisfactory completion using the built in checks and balances and the judgements of the engineers.

There is a simple, descriptive model that I think casts some light on the tragedies of real world engineering.

The likelihood of one error in a job occurring has a probability and the checks and balances correct it. Two errors in the same job have a smaller probability and they are also corrected. Likewise, for a job to have a larger and larger number of errors, there is a smaller and smaller [called monotonic] probability. That is, they become less and less likely to occur. In this model, if even just one of the errors are spotted and corrected, the chain of error is broken and problems averted.

Consider venturing even further into very, very unlikely events, that is of very, very low, low probability. We could arrive at a job where there are more errors than there are existing checks and balances or some are not applied or without any team members picking them up. What might happen then? Catastrophe, that’s what.

In a big job there is a possibility everywhere and all the time of one or more errors lurking due to human mistakes or by malign circumstance. It is the enemy that he or she has to fight as part of the engineer’s professional task. That’s one of the things that engineers do.

There are the previous, rare cases where such multiple errors occurred and none are picked up. Take the Piper Alpha, UK, North Sea gas production platform accident; the Flixborough Nypro plant explosion; the West Gate Bridge collapse in Australia or even the horrifying Baby P case. Each one had multiple errors all in the same project and none put right. BP ‘Deepwater Horizon’ Mexican Gulf oil leak was undoubtedly another such. A chain of uncorrected errors dragged the rig and a group of its engineers into death, flame and pollution.

To repeat, all great disasters that I know of are due, not to one error great or small, but to a chain of mistakes. A chain where one correct decision would have averted a catastrophe or at least resulted in failure made small. It seems to me to be a valid, general rule.

 THE ERRORS

I believe that the general outline of what went wrong is here, as described in the BP early analysis.

  1. Bad choice of concrete mix
  2. Seals in the bottom-most section leaked
  3. The pressure tests that should have shown that the concrete and seals were inadequate were misinterpreted as showing them to be adequate.
  4. The instrumentation in front of the controller’s seat showed a small whisper reaching the surface which was the quiet first stirring of the fierce, violent power of the hydrocarbons hurtling from the bowels of the earth. Those sitting in that chair should have fastened onto the whisper and recognised it. Then they could probably have acted to at least mitigate the problem. None of the crew Involved in the drilling operation recognised the whisper.
  5. In the last terrifying moments as the catastrophe took its gigantic form on the rig, the team could have sent the gas into one of two directions. One was overboard and the other was into a tank. The choice of an effectively infinite volume overboard could have given time to respond and the consequences lessened. Someone chose the tank. The finite volume tank was soon overwhelmed and gas flooded the rig. A rig power supply engine fed on the flammable gas rather than air went into howling over-speed. The gas entered parts of the rig with unprotected electrics and somewhere here a spark turned the gas cloud into a massive incendiary bomb.
  6. The Blow out Preventer failed entirely to close off the well. Not one of the three independent ways of it doing its job.

As the BP ‘Deepwater Horizon’ Oil Spill ground its way towards catastrophe, there was certainly no one engineer who ran the operation minute to minute and whose word was law. There weren’t even 2 or 3 such engineers. There were several corporate teams of engineers each answerable to their own management with their own team philosophy. There were three principal teams [there were others] working on the drilling.

There was BP as the operator of the lease on this part of the sea bed. It itself had a subsurface team as well as a well engineering team that was presumably based on land.
There was the Transocean team who owned and crewed the floating rig and had been operating and working it for BP for nine years.
Then there was the Halliburton team providing cementing services.

 We will see that each team had or will claim to have had a different view on responsibilities. The drilling task was extremely elaborate and ever-changing hour-by-hour or even minute-by-minute. Despite this the costs involved mean that this argument is almost certain to grind through the courts for years. In the real world it isn’t the end when the engineers agree about the errors. Then; the blame game blossoms. This game features the financial specialists and the lawyers are at point.

We cannot yet be sure that the early analysis has got the details exactly right and one or more may not have occurred at all or in exactly this form. Longer and more detailed investigations that will take place stemming from the expenditure of more money and investigatory manpower will almost certainly fill in the detail. What, by the way will drive this further investigation. It is simple – more money. But why will this be spent and from where will the treasure come from? Why from several players. One is of course an extremely angry government. The others are, of course, the engineering protagonists who are extremely large and very rich. Because they are very rich this means that they can spend a lot to justify their actions and, they hope, show that the actions of the others were to blame. Because they are very rich also means that should they be shown to be at fault then their large treasure houses will be pillaged by fines and damages, Powerful driving forces indeed.

Whilst ever the global consumption of hydrocarbons runs, as it does, at such a febrile rate, men will continue to reach down under the ocean and ever deeper in the rocky strata. The economic pressure is still there so the engineers will work to successfully overcome the problems and, as usual, accommodating the problems.

The US President’s Commission has, at the time of writing November 2010, seemed to consider that the concrete failed to do its job and played a part in the accident. There are also arguments that the depth at which a single concrete plug was set is significant. The Lad recommends that you visit their website [link following] and you will find excellent graphics that explain and clarify the engineering of this and, by extension, other oil wells. For completeness after that, I have added the BP website that leads to the BP report.

http://www.oilspillcommission.gov/

http://www.bp.com/sectiongenericarticle.do?categoryId=9034902&contentId=7064891

All engineers will agree that if they are so responsible for so much of our modern world, then engineers must also bear proper responsibility for when there are failures. …But… Edward Phelps, a lawyer turned diplomat, observed back in 1899 that,

“The man who makes no mistakes does not usually make anything”

It is as true today as it was then.

http://www.giga-usa.com/quotes/authors/edward_j_phelps_a001.htm

Edward John Phelps.The Columbia Encyclopaedia, Sixth Edition. 2008.

In summary, I repeat that there is no sign that the accident was caused by the drill site being in deep water or not on land. Neither was the depth of the drill bore below the sea bed. The cause was a series of errors that occurred in an unbroken chain. These errors could have occurred in drill site on land or an ocean bore that was shallow.

It is the error chain overseen by teams of engineers that needs to be studied. The causes must be discovered and never repeated by future engineers. Engineers seek to make things happen and to bend natural forces to convenience of humanity. This aim must never be allowed to fall victim to hubris or a gung-ho attitude or a cavalier attitude that risks health and safety. That is the lesson that has to be continually re-learnt by BP, its contractors and all engineers everywhere.

[P.S. – I do not work for BP and never have. Nor have I ever had any connection with it or any other organisation in the oil industry.]

[P.P.S. – I do buy petrol for my car though.]

Quantas A 380 Incident – again

 

A very few words from R-R

Four days ago I concluded that there had been an oil fire in the incident on 4 November. I had not seen the press release of the previous day, Monday 8 November 2010. This is an extract.

“… Rolls-Royce has made progress in understanding the cause of the engine failure on the Trent 900 powered A380 Qantas flight QF32 on 4 November 2010. It is now clear this incident is specific to the Trent 900 engine.

As a result, a series of checks and inspections has been agreed with Airbus, with operators of the Trent 900 powered A380 and with the airworthiness authorities. These are being progressively completed which is allowing a resumption of operation of aircraft in full compliance with all safety standards. We are working in close cooperation with Airbus, our customers and the authorities, and as always safety remains our highest priority.

The Trent 900 incident is the first of its kind to occur on a large civil Rolls-Royce engine since 1994. Since then Rolls-Royce has accumulated 142 million hours of flight on Trent and RB211 engines.  …”

See   http://www.rolls-royce.com/civil/news/2010/101108_trent_900_statement.jsp

Then there was another press release yesterday, 12 November 2010 and this is an extract which is the only engineering statement.

“….  Immediately following this incident a regime of engine checks was introduced on the Trent 900s to understand the cause and to ensure safe operation. These have been conducted in parallel with a rigorous examination of all available evidence, including data from the damaged engine and its monitoring system, analysis of recovered material and interrogation of the fleet history.

These investigations have led Rolls-Royce to draw two key conclusions. First, as previously announced, the issue is specific to the Trent 900. Second, the failure was confined to a specific component in the turbine area of the engine. This caused an oil fire, which led to the release of the intermediate pressure turbine disc. 

Safety continues to be Rolls-Royce’s highest priority.”

See  http://www.rolls-royce.com/investors/news/2010/121110_interim_mgt_statement.jsp

Now those will be – I expect, the only and last words from the engineers to the general public.

Oil fires are a great fear of aircraft engineers. The oil is a more or less flammable liquid that is being pumped throughout the internals of the engine even close to the hottest parts. Here the failure of some component has resulted in the oil fire.  The engineers probably had to look at and rule out or rule in over a hundred possible causes. As it is confined to the Trent 900 it seems less likely to have been an elastomeric oil seal than a failure of some component that contained oil. RR have said above that the fire ‘led to the release of the intermediate pressure turbine disc’

The word ‘release’ seems to be a very carefully chosen word that is, perhaps intentionally, slightly vague. The consequent fire may have destroyed and ‘released’ the highly stressed turbine disc into fragments. These could have burst centrifugally out of the engine and might have damaged the rest of the aircraft.

I think that there is a more likely alternative. That would have been the fire destroying by overheating the connection between the turbine and the compressor that it was driving. This could have resulted in relatively few fragments if any.

Quantas A380 Incident – My rethink

A few days ago I said, “I wonder if the failure is to the engine cowling or by-pass ductiong rather than to the engine core.”

I have seen a better photograph in the papers since then showing more detail. In this the rear end of the engine core still shows little structural damage. However the rear of the outer cowling structures that normally enclose this part have disappeared. The remaining forward cowling shows what appears to be smoke or oil stains and its rear edge has an incredibly shredded appearance.

I now think that large parts of the aft core cowl or thrust reverser, if it has one, has been consumed by fire. Except that si from any part that fell to earth. Engineers know that metals can actually burn if immersed in oxygen. Whether that has happened in this incident I do not know. for although the aircraft was travelling at high speed with the chance of ‘fanning’ any flames, it was also at high altitude with relatively little air and thus oxygen to burn.

It seems to me now a more likely possibility that there was an oil leak, perhaps in the bypass duct or intercase, that was ignited by the high temperature part of the engine. This, presumably, was not or could not be extinguished by the activation of on-board fire extinguishers.

The Rolls-Royce development engineers in Derby and in the Singapore Maintenance Base will still be working busily to pore over components; explain and calculate the cause; and the design engineers to design out any likelihood of this incident ever happening again with the Trent 900 engine.

I have to say that my guesses are based upon laughably sketchy evidence. The Rolls-Royce, Quantas and Singapore Airlines engineers will have volumes of data and evidence to think about and act upon. I am afraid, though, that they will not be telling the media much about it any time soon.

BP Deepwater Horizon Gulf Oil Spill

 WHAT WAS NOT THE CAUSE?

The CAUSE of the BP Deepwater Horizon Mexican Gulf oil spill was neither the engineers drilling below the ocean in itself nor the deep drilling in itself. 

The matter of the BP Deepwater Horizon Mexican Gulf oil spill has popped its head once more above the parapet in the prints; albeit with a much reduced prominence. It is now, you see, old news. It may have been considered to be important once: indeed it verged on the hysterical. Apparent importance as measured in the media though surely drains away merely with the passage of time if there is no new ‘shock horror’ or, worse, if the matter seems to resolve itself or even improve.

One reason for the return is that another report with important provenance [the US President’s Commission – see below for link] has supported the BP claim that the failings of BP were not the only causes of the accident. Another is because in this quarter, BP has returned to profit. But, let’s be honest, neither of these aspects are terribly sexy news topics

I have to confess that, as an engineer, I knew very little about the technology of drilling for oil.  I have to note that I am not connected to BP in any way. However, engineers can learn an enormous amount about a technology from the reports that appear in the sad wake of an accident. So it was, with the BP Deepwater Horizon Mexican Gulf oil spill. It was, undoubtedly, an extremely serious accident, killing 11 people and injuring 17  of the Rig crew, with the enormously widespread and expensive [to a vast number of innocent parties] consequences.

Everything that follows is an enormous simplification but not, as far as I can manage, greatly in error. I cannot give full details of the technology here, one, because I am far from an expert and, two, because I cannot spare at least 193 pages as in the preliminary BP report. However I will try to give a flavour of the difficulties and successes [and, in this case, failures!] of the engineers.

The technology used is quite remarkable and unlike, as far as I can see, any other engineering. In simplified terms, this is what the drilling engineers do as a matter of routine.

The engineers will drive down to a depth of three and a half miles below the surface of the ocean – not more or less – but precisely. The first part of this is to reach down to the sea bed that is itself about a mile down. Then they make a hole in the sea bed that varies in diameter from around 36 ins to around 7 ins. This hole is clad on the inside with joined up lengths of steel tube as they go deeper. Clearly, the tubes have to be somewhat smaller than the hole in order to pass down but, in order for them to be able to last for years; they have to be completely in contact with the surrounding rock. So what do the engineers do? They fill the gap at the outside diameter of the tubing with concrete. 

From the bottom of the hole upwards! 

The drilling engineers have to pump into the bottom exactly the right amount of concrete to fill the gap between the outside diameter of the tube and the hole in the rock. So they have to measure the tube clearance in the rock hole over the whole two and a half miles and calculate the volume of concrete required. And what varieties of concrete! There can be dozens of different mixes to perform properly in the different down-hole environments and to fulfil many different tasks.

When the drill hole reaches the correct depth, which is that of the oil-bearing stratum, they face another problem. A angry, heavy liquid is just bursting to surge unstoppably up the drilled hole. The crude oil is driven thus at nearly 12 000psi by a combination of artesian pressure and pressures due to dissolved gases. Similar problems face the engineers sometimes at some other strata in between

How do they stop the crude oil from thundering up the new opening to the surface that the oil has not known for some millions of years? Basically they fill the hole with a liquid that is heavier that the oil: this is what is called ‘mud’. A column of mud 3.5 miles high is enough to keep the oil down by overcoming the oil pressure.

Having arrived at this depth, the engineers have a string of tubes 3 5 miles long joined together. This string they now have to turn into a good pressure vessel that will withstand considerable pressures of around the 12 000psi. This staggering pressure can be both from the outside trying to get in but also, in other circumstances, from the inside trying to get out. Having managed to do that, by the way, the engineers have to find tests that will prove that the pressure tightness is good. No mean task in itself and highly significant it turns out.

The oil drilling engineers have always been very aware of the risks associated with the extraction of oil from the bowels of the earth. This has been in the forefront of their minds ever since the gusher became a strange symbol of oil industry success [through failure!] at least since the 1900’s. Even then they were recognised as a waste of money and a great risk to health of the drillers and damage to the equipment and the environment. From this came the first ‘blow-out preventers’.

The modern Blow Out Preventer, BOP is an enormously large complex and expensive piece of kit. Its purpose is to protect the well and the drillers and their equipment by providing several different ways of sealing the drill hole in greater or lesser emergencies. The several elaborate systems of pipe work, electrical power, electronic controls and pressure vessels make it a massive structure. It is so large and elaborate that I will not be able to say much about it here. I hope to investigate and return to discuss it further in a later posting. 

The BOP is meant to operate either on instructions from the surface drilling vessel or even, in dire emergency, automatically. That was the plan anyway.

The only effect of depth might have been that deciding on the correct mud pressures and concrete mix may have been affected by the pressures at such a great depth may have been affected by the well known exaggerated effect of the difference of two large numbers. But, compared to the other events, this is definitely a second order effect.

A Foreword to the report says many things, but it seems to be necessary to quote part of it as follows:

This is the report of an internal BP incident investigation team. The report does not represent the views of any individual or entity other than the investigation team. The investigation team has produced the report exclusively for and at the request of BP in accordance with its Terms of Reference

The Executive Summary says the following. It is rather wordy but I do not want to try to précis it and run the risk of misinterpretation.

The team did not identify any single action or inaction that caused this accident. Rather, a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces came together to allow the initiation and escalation of the accident. Multiple companies, work teams and circumstances were involved over time.

The BP Deepwater Horizon Gulf oil spill tells us so many things about the struggles of the engineers working on the needs of the world in the late Twentieth Century and the early Twenty First. None of the things that it tells us say that drilling below the ocean or drilling deep should be stopped because it is too dangerous.

Then if neither the depth nor the undersea were the cause, what was? See Part 2.

References and links

This is the BP website giving links to their initial Report in different media and at different amounts of detail.

http://www.bp.com/sectiongenericarticle.do?categoryId=9034902&contentId=7064891

An equally important website below is that of the US government Commission studying the accident and offshore drilling in general. This is a vital [in every sense of the word] resource that, at the time of writing is live. I was listening to part of one of the hearings streaming live with sound and slides this afternoon.

http://www.oilspillcommission.gov/

This is formally the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling. Its tasks are, firstly, to examine the facts and circumstances to determine the cause of the Deepwater Horizon Oil Disaster; secondly, to develop options for guarding against future oil spills associated with offshore drilling; and, finally, to submit a final public report to the President with its findings within 6 months of the Commission’s first meeting

You can find general oil drilling information below

http://en.wikipedia.org/wiki/Oil_drilling

This also is a good general description of the drilling process

http://www.oilprimer.com/oil-well-drilling.html

Some websites describing drilling jargon can be found at ‘Rigzone’

http://www.rigzone.com/training/

Also consider Schlumberger.

http://www.glossary.oilfield.slb.com/