Getting gas from Crude

Some recent posts have dealt with coal production, so for a change I thought I would return to oil, for a couple of techie talks. It seems particularly relevant since the discussion has returned to the Canadian Oil Sands again, and the oil that is coming from them. But before getting there what I wanted to talk about was the differences that exist in what to some folk is just "crude oil," with the assumption that it is all the same, In writing about coal, it was fairly simple to show that the different stages of coal as it changes from peat to anthracite, mean that you get different amounts of energy from it, and it can be extracted with differing amounts of energy. The fact that there is a fair bit of difference in crude oils is not always as easily understood.

This then will be a relatively simplistic look at the different potential hydrocarbons that might make up a crude oil, and how we can get them apart. I'll post next time on how we can break the separated flows into other products. This, then, is a short techie talk in the oil production series, earlier posts in which are given at the end of the post.

Crude oil is made up of a mixture of hydro-carbons, which are the different ways in which carbon and hydrogen can combine, starting with such simple compounds as methane (CH4) and progressing to more complex ones with greater numbers of carbon atoms. Oils from different places have different combinations of the major constituents, for example, this is from Kuwait. Because they are fluids mixed together, it is not very easy to separate out the different valuable parts (known as fractions) by a mechanical means. However if you heat up the crude oil blend, then it will vaporize.

But the different fractions of the oil will boil at different temperatures (or boiling points b.p.), at which point they turn into gas. And so the first part of the treatment that the oil gets, when it reaches a refinery is that it is heated, so that it will all turn to gas, and then it is cooled in stages, so that the different fractions will condense back out. The total process is known as crude oil distillation and theUK Schools site has a simple sectional picture of what such a distillation column might look like.

As the combined vapors from the heated crude enter at the bottom of the tall tower (called a column) they pass up through different trays that are placed at set heights up the column. When the gas reaches a tray it passes up through it into a bubble cap, this is a cover over the hole that pushes the gas down so that it has to bubble up through the liquid that has already condensed onto that tray.

The liquids in each tray, as the vapor rises higher in the column, are kept at lower temperatures, so that the heavier oils, that condense at a higher temperature, will condense lower down the column. As the lighter vapor rises through successive trays, the temperature of the liquids drops, and lighter fractions of the oil also begin to condense out, until the very lightest are collected at the top, still as gas, and fed on to a cooler. The liquids then drain, either back down to a lower tray, or through a side-draw pipe that taps the fluid from the trays and takes it away for either further division or for storage and sale. A typical initial distillation might yield

Each year the EIA publishes its world distillation capacity which is the necessary part of getting from crude to useful product.

I will continue this next time, talking about the further stages in refining, and cracking of compounds to break them into lighter fractions, so that the next product from a refinery might at the end, look something like this (courtesy of the EIA).

This is part of an ongoing weekend series on technical aspects of oilwell (and natural gas) drilling. Previous posts can be found at::
the drill

using mud

the derrick

the casing

pressure control

completing the well

flow to the well

working with carbonates

spacing your well

directional drilling 1

directional drilling 2

types of offshore drilling rigs

coalbed methane

workover rigs

Hydrofracing a well

well logging

seismic surveying

gravimetric surveying

carbon dioxide EOR
As ever, if this is not clear, or if there is disagreement then please feel free to post, and I will try and respond.

I'm not sure if my question relates exactly to your topic, but it's this: is there a way to synthesize a liquid (crude or gasoline or something that can be made into gasoline that's not crude) from COAL?   I believe there's technology (and maybe it's been discussed here) that makes NG or LNG from coal.   But is there a way to get crude from coal?   I feel very ignorant asking, but appreciate your help.  Thanks.
yes the germans used it in ww2.
the problem was they could not make it fast enough, it's been theorized that if they were able to produce enough if it they would of lasted long enough to bring jets and the other weapons they had in the wings online.
Which reminds me of the Haber-Bosch process developed just prior to WW1 that freed the Germans from dependance on imported rock nitrates for explosives.

"The Haber process now produces 500 million tons of artificial fertilizer per year, mostly in the form of anhydrous ammonia, ammonium nitrate, and urea. 1% of the world's energy supply is consumed in the manufacturing of that fertilizer (Science 297(1654), Sep 2002). That fertilizer is responsible for sustaining 40% of the Earth's population."

Uses natural gas.
Estimated to have roughly doubled the amount of biologically available nitrogen on the planet.

Though it is true that Germans had shortages of fuel near the end due to the success of British and U.S. bombing campaigns, the binding constraint (i.e. most severe bottleneck) on the Luftwaffe at the end was pilots. Almost all their good pilots had been captured or killed, and at the end the Generals were flying along with seventeen-year-old kids with a hardly any skills compared to the expert pilots the Germans had in the early 1940s. The Luftwaffe had more Me262s than pilots skilled enough to fly them, and because they could stay airborne for only about forty-five minutes they did not guzzle much kerosene. The jets were shot down in large numbers by slower propeller aircraft, because the experienced British and U.S. pilots (who scornfully called the planes "blowjobs") were much better than all but a very few German pilots at the end.

Interestingly, the Germans had plenty of ethanol and liquid oxygen to fuel the V-2s until very close to the end of the war.

Which reminds me of an old Steve Allen joke:

The answer is: he shot down 23 Messerschmidts.

What was the question? Why was Hans Schmidt kicked out of the Luftwaffe?


I get blank stares when I tell it to young people.

Oh my god, I thought you were a young person. davebygolly, I always knew you were mature from your posts, but I never figured above 40. Holy Christ was I not paying attention. I still don't get the joke. Who the fuck is Hans Schmidt? I thought I knew something about WWII. Oh wait, half those Krauts were named Hans Schmdt? Is this like Dick Hurtz? Seriously, could you explain the joke so I don't have to google-detect it. I feel like such a jackass.
I guess this guy shot down 23 friendly planes and that's why was kicked out of Luftwaffe :)
Took me some time to understand the humor though.
I can't believe where you led me. This is something else.
You don't want to make real crude from coal. HO's paper above shows how complex the composition of crude oil is. As oilaholic told you, the germans achieved synthesis of oil from coal, a process still used in some plants in the world. Two main processes as known : direct synthesis of heavy/medium oil from brown coal which is the bergius process, and the fischer-tropsch process which is synthesis of light/medium/heavy oil from syngas. Syngas is made from coal and the process is very much discussed on TOD and HO in particular. Bergius and Fischer Tropsch protocols are very inefficient and costly.
The F-T Process reached a maximum at 16000 barrels per day
in 1944.  The German armed forces were still chronically short of all liquid fuels. Most evident in the battle of the Ardennes when even the crack units involved in the  attack were not equipped with enough fuel to reach the Meuse River. They were supposed to capture it along the way. Most German tanks just ran out of fuel and were abandoned rather than lost to US action.
F-T is very inefficient. But when desperate and have access to slave labour then you will try anything.
German tanks were always running out of fuel. One big reason that the defeated Brits got away at Dunkirk was that the panzers were immobilized from both lack of fuel and also the fact that the tankers had been going on benzedrine for about a week with no sleep at all.

My recollection from Speer's memoirs is that oil production from coal peaked higher and later than you state, but Speer could have been wrong, or (Yes, it has happened a couple of times.) my memory could be in error.

The Germans were always chronically short of gas, made much worse after the loss of the Rumanian Oil fields.
In fact , perhaps The Second World War should really be  called 'The First Oil War'. Japan and Germany both
had the same problems. Anyway, thats history. I believe that South Africa has made the best shot at the
F-T Process during the years when they were under economic sanctions. But again, more I think from desperation than economics.
It HAS been called the first oil war, but I forget by whom.

I suspect you might have slipped a decimal place there, and that it should really be 160,000 barrels per day instead of 16,000.

While I don't have the German synthetic fuel production for 1944, one of my military books cites a 1940 production of 4.25 million metric tons. That would translate into an equivalent average daily production rate of roughly 78,000 barrels per day. So, if the Germans ramped up production to reach a maximum in 1944, that would constitute about a doubling over the 1940 production level, and therefore indicating that 160,000 barrels per day is very likely the correct number.

While it took a tremendous effort on the part of the Germans to attain this level of synthetic fuel production, by modern standards it's pretty tiny, about the output of a medium-size oil refinery.

I bring this up not to nit pick about German production numbers but to perhaps add some perspective on what a major undertaking it will be to get even several million barrels per day of additional coal-to-liquid production.  

pay attention Mudlogger.
Goralski's "Oil And War" will tell you more than you really want to know about this. Basically, the Germans didn't have enough oil to train their pilots. They were so short of oil they had to use lower octane blends and their engines didn't get as good a performance.
I do recall that Hermann Goering was pissed off to the max about this problem of low-quality gas. He truly loved his pilots like a father and did all he could (which was nowhere near enough) to protect them. However, there is an interesting post-script here: Post World War II for at least twenty-five years the de-Nazified and loyal NATO new German Luftwaffe still had a horrendous accident rate among jet pilots due to inadequate training. By this time RAF fliers were big buddies with the sons of their father's enemies and felt so sorry for them, because one thing the RAF has understood from about late 1917 is that the key to an effective air force is good pilot training--something the Brits maybe are still the best in the world at, though U.S. Navy, U.S. Air Force and Israeli pilots vehemently disagree with this conjecture of mine. Oddly, everybody agrees the Israeli mechanics are the best and Russians the worst, or to be more precise, the least reliable. The best Russian pilots are as good as any in the world, but in a collapsing society they cannot do much. British mechanics are also excellent and have a pride and expertise that is remarkable; they have trained many of the best grease monkeys around the world.

What I am getting at here is that in regard to Peak Oil, you are only as good as your engineers, your geologists, and your managers. The focus on equipment limitations, etc. is valid, but I think in the real world often the most serious bottleneck is the shortage of highest quality well-trained talent.

The U.S. impending shortage of steel is scary. To me ten times scarier is our shortage of engineers.

Thanks Don, speaking for all us engineers out here.
Who needs engineers when we have law givers?
Right now on CPSAN, Arlen Specter is running a Senate Panel investigating the rising prices of Natural Gas (NG).
Their solution?
Pass laws.

The law shalt provide.
That is even more profound than the "free markets" providing.

As usual, looking for somebody to blame for the problems rather than looking for somebody with the foresight to avoid getting into the predicaments to begin with.  

Will they arrest and bring to trial Mother Nature when she refuses to comply?

That would be a great skit.  I've been wondering if any of my recent castmates, almost all teachers, would let me talk to their classes about energy depletion.
Hey right.  That would be a good one!  I wasn't envisioning it in my head before.
So Donal,
Are you writing the script and getting ready to videotape it?

Title: "Munity of the Oil Bounty"
Mother Nature is put on trial for refusing to put out anymore.

Role of Mother Nature: Sharon Stone (Whata ya going to do, arrest me for running out of lube?)

Captain Blight: Jack Nicholson (We don't want to hear the TRUTH. We can't handle the TRUTH!)

Young Ensign Christensen: Russel Crowe (We are masters and commanders of our own destiny. We got to turn the ship of state around! Call it mutiny if you must.)

I remember reading somewhere that a US state legisilated that Pi had to equal 4 by law in the 19th century. It was passed and stayed legal for a few years (don't know how many though.
I am sure that the UK have passed just as stupid laws in fairness.
That was the first attempt at digital math.

The best one is still the "monkey trial" of Creationism vs. Evolution.

Next one will be stem cells.

Just because the US is lagging in graduating engineers doesn't automatically mean there's a shortage.  Wouldn't this supposed shortage be reflected in steeply escalating salaries for engineers in general (you know - suppy & demand)?

 With so much of our manufacturing being outsourced, maybe we really don't need as many engineers as we used to (('m talking here in the aggregate, shortages or gluts in certain highly specialized areas notwithstanding).

Even if there really IS a shortage, no problemo - we just import more engineers from India, Pakistan, China, or wherever. Engineering has become fungible, like almost everything else.

Regarding steel, I was not aware that there is an actual steel shortage in the US, though heavy manufacturing is not something I follow anymore. We actually use far less steel than we used to. If I recall correctly, the peak year for US steel production was 1957 (big cars and a construction boom). One must also keep in mind that a large fraction of steel is recycled. I don't recall the actual figures, but a surprisingly high percentage of the steel in a junked car becomes new steel. I would think we're going to run out of energy to smelt, shape and manufacture steel goods long before we run out of iron ore + recyclable scrap.

We have lots of iron ore in Canada, and potential ore in Alaska. We run out of scrap every few years because scrap is from manufacturing plants, and as you may have noticed, we don't have many of those any more.
We could get iron by using our baseload power plants to electrolyse sulfide ores for metal, yielding electrolytic iron for feed for electric heated minimills, and also produce plenty of byproduct metals like copper, nickel, PGMs, zinc, lead, silver, gold, etc. This would not be economic at present prices. But if the dollar dropped 90%...
I have heard it over and over again from News people on TV talking about a winter blend and a summer bled relating to Gasoline. Is there such a thing used in Californiaand if so, just what is the difference?
There is no winter in California. Everybody knows that;-) Note that at different altitudes you use different octanes, but that is a different story.

Gasoline is way more complicated than most people know or want to know or need to know. Best people to talk to on this topic are the people actually in the business at the wholesale level; buy the guy a couple of drinks and he'll probably tell you a tale of woe (related to boutique blends) and way more than you wanted to know. What I find fascinating is the way prices are set in reality--and it has almost nothing to do with what is written in economics textbooks that are regarded as gospel truth by undergraduates.

HS, the summer and winter blends refer to the constraints on the allowable volatility of gasoline. Because gasoline is light and evaporates easily, refiners blend it to reduce the volatility in the summer (when temperatures are higher) and increase it in winter (when temperatures are lower). The measure of this volatility is called Reid Vapor Pressure (RVP), measured in (the US) in lbs per square inch (psi).

Volatility matters since the evaporated portion contains a lot of VOCs (volatile organic compounds) that contribute to air pollution, and thus are controlled in most locations. Volatility is why most pumps now have the hood on the nozzle to capture the vapors as you fill the tank.

The Federal blend formula requires 7 RVP in summer and 13 RVP in winter, but most states set their own blend constraints, sometimes county to county depending on the air pollution situation. In California, we have the California Air Resources Board (CARB) formula requiring 7 RVP in summer and 10 RVP in winter (because of our mild winters and bad air pollution).

Blending to RVP (and octane, and sulfur, and all the other simultaneous requirements of final gasoline) is tricky. For example, butane gives you a very high octane rating so is good for the octane target, but it is very volatile, so it is bad for the RVP. Refiners have to change their blending recipe between summer and winter to achieve these targets, sometimes creating shortages or surpluses of particular fractions (such as pentanes) in the refinery.

Naphtha seems to make a large percentage of the initial distillation run.  Can it be recombined to make heavier products?  What use is it?
Naphtha is a very light liquid fuel. It is the same stuff that Zippo type lighters use. It is also dry-cleaning fluid. And no, to my knowledge you cannot make long hydrocarbons out of short hydrocarbons.  Perhaps someone else can comment on this but joining short hydrocarbons to make long hydrocarbons would be the exact opposite of the cracking process, or taking long hydrocarbon strings and cracking them into shorter ones.

As might be expected you get a lot more naphtha from the distillation process than you can possibly use. In Saudi Arabia they use it, occasionally, as boiler fuel. I worked for awhile at the Gazland Power Plant, just about five miles west of Ras Tanura, in Saudi Arabia. About once a month, for a day or so we would use naphtha as a fuel. Occasionally we would use raw crude as well but most of the time we used natural gas. The plant had both gas and oil burners or injectors in the same boilers and you could switch from one to the other without ever losing your flame.

However in Saudi Arabia today, most of the naphtha is simply injected back into the wells to help keep the pressure up. At least that is what my son tells me. He has been in Saudi, working for Aramco, since 1991.

Note: Technically gasoline is sometimes considered naphtha, however as the term is normally used, it is the light colorless fluid that dry-cleaners and Zippo lighters used. It is also used in many manufacturing processes as well, blending naphtha with heavier compounds to make various household compounds. Gasoline has 7 to 9 carbon atoms and anything from 6 to 11 carbon atoms is considered naphtha.

"And no, to my knowledge you cannot make long hydrocarbons out of short hydrocarbons"
The biggest problem with naptha, I read, is the octane (35-40).  It is complicated, but one of the functions of a catalytic reformer is to convert naptha into higher-octance gasoline blending components.  The transformation isn't really adding carbon atoms, but rather the structure of the molecules are changed.
Actually, making longer hydrocarbons out of shorter ones is relatively easy and exothermic.  We do so in making polymers (plastics as in polyethylene).

It yields net hydrogen and is called dehydrogenation.

The problem is making shorter ones out of longer ones.  The basic issue is that you have to ADD hydrogen.  Refineries can do this and the more facility they have the higher the capital investment.  If we had a great source of cheap hydrogen or cheap energy, we could turn coal into gasoline.

As to octane ratings for naptha, remember that pure octane is 100 octane, by definition (research and motor.)  Shorter strings have lower octane rating until you get methane or ethane when it turns back up (methane is 120 octane?)

Hence, a naptha that has a lower vapor pressure than gasoline has an octane rating lower than standard gasoline.

On the other end, longer chains do not vaporize easily enough so are used for diesel fuel which burns as a mist.

The refiner will adjust his mix of output products based on his feedstocks, product market demands and prices, and capital investments.

Here are some more info on Naptha

My understanding it is more of a feedstock for Petrochemicals mainly olefins but not exclusively

More links for FUN and possible investment...

How can we have "Switch Grass for Victory!" if the wildfires keep burning the grass?

The Scuderi Group is an engine development company currently building an Air-Hybrid Engine which it claims will be to be the world's most fuel efficient internal combustion engine. Currently in production at Southwest Research in San Antonio, Texas, it is claimed that the Scuderi Air-Hybrid Engine will allow diesel and gasoline automobiles, commercial vehicles and other applications powered by internal combustion engines to be 60 percent fuel efficient (compared to today's 33 percent),

Researchers at GE say they've come up with a prototype version of an easy-to-manufacture apparatus that they believe could lead to a commercial machine able to produce hydrogen via electrolysis for about $3 per kilogram, down from today's $8 per kilogram.,295,p1.html  Hot Dog!  They will be ready for production "in a few years" Dang!

Solar concentrator company is claiming about $3.50 per PV watt...Not bad!

Iran threatened Saturday to use oil as a weapon if the UN Security Council imposes sanctions over its nuclear program. 72  Oh, wait a minute, we meant that we will use oil as a "what you ma call it..." 25315_RTRUKOC_0_UK-NUCLEAR-IRAN-OIL.xml  On the other hand, "Iran's Supreme National Security Council, which represents Iran in nuclear talks, has said Iran has no plans to play the oil card at present but could do so if "conditions change".  Now lets see how  the future's market responds yet again with instantaneous efficacy... My slow-moving inefficent self is buying a few more shares of XOM.


I hope the home insurance companies, the fire departments and ERs are clued in to mass H2 production.  Should make the coroners offices pretty much redundent though.
$64 guestion:  Will oil as a weapon constitute a WMD?
"Solar concentrator company is claiming about $3.50 per PV watt...Not bad!"

But not very good either.  That amounts to a capital cost of $3,500 per kilowatt capacity.  A big coal or nuke should cost less that $2,000 per kW.  

The capacity factor for solar is rarely 20% while the nuclear industry is averaging over 90% so a kW of nuclear capacity produces 4.5X the kW-hours of a kW of solar PV.

Adding fuel and O&M for nuclear of 1.5 cents per kW-hr and ignoring PV maintenance makes solar PV electricity about 7 times more expensive than nuclear power.....IF this claim is true and comes to eventual realization.

Yes, it's 2,000$ a kilowatt for nuclear capacity, and how much for a uranium mine, counting prospecting, drilling, and development? Cheaper for now, maybe not cheaper for later. Uranium prices keep going up.
Then again, prices going up may just be speculation.
Don't get me wrong, I LOVE nuclear power, and I hope that we burn every single atom of fissionable material on this planet.  However, I haven't figured out how to build a reactor next to my house.
"Researchers at GE say they've come up with a prototype version of an easy-to-manufacture apparatus that they believe could lead to a commercial machine able to produce hydrogen via electrolysis for about $3 per kilogram, down from today's $8 per kilogram."

But this is at current electric rates I presume -- it will go up as rates go up.

Or down. Think of it this way. Coal plants produce electricity for four cents a kilowatt hour. Gas plants produce electricity at, say, ten cents a kilowatt hour at present prices (which changes every week, these days), and prices may climb if the weather turns cold in the winter or warm in the summer.
Coal plants can't be turned off once every day because it plays hell with reliability when you go through the thermal shock, so you have to run them 24/7. How much do you charge for nonpeaking power if the coal plants are selling peaking power for only eight hours a day? 16 hours a day at 1/8th cents an hour, right?
You are right, electrolysis is dependant upon electric rates, I think that Deffeyes stated that we would see most production where there is cheap hydroelectric.

Like most on this blog, I think that hydrogen is a distraction, but if it is going to be forced on us we might as well see what's out there.

Electrolysis is a dumb way to make H2 for a fuel market.  You will always need 2 moles of electrons at 2 volts to make a mole of H2.

However, there are many current and possible applications for industrial H2 where capital costs are more important than operating costs (electricity rates).  This invention will allow many NEW applications of industrial H2 and will therefore increase aggregrate electricity demand.

Good point, just the need for cracking heavy hydrocarbons should suck up any additional hydrogen.
I assume you mean gasoline.

Nice interactive diagrams for moving through the refinery processes

So, if I've got this right.  Let's say the vapor is 1000'C, then the lowest tray might be 890'C, the second up 850'C, and the third up, 820'C, progressively cooling the vapor?
Thank you for all your efforts...
If you look closely at the top figure you can see the different tray temperatures on the figure.  Remember that these columns are quite tall.
Interesting what you were saying about oil prices earlier today, Sailorman. Crude has popped $1.80 or 3% on a couple of non-stories. The Iranian thing was played out 2 days ago, they still can't figure out whether or not to use the oil weapon. The other reason is a supposedly cold winter coming up at the end of this month in the Northeast. Nevermind that it's 50 degrees now and will be spring by the end of the month. Sounds more like some analysts were having a boring day and decided to call Bloomberg.
Maybe it was the quadrupling of the price of natural gas in the UK today?  There are industrial users in the UK who can switch between natural gas and oil.
Yeah, I took that into consideration. I think it was important. The issue I have with that situation though is that if most of us here know about it, can you really consider it news? So I consider a good deal of that "premium" already built in. It's still moving at $61.93 as I write this. Just seems strange.
quadrupling? link?
The Iranian thing will play for a while longer. But I did get the below item from another site. Thought it would be of interest and kind-a- sort-a fits here.


A Service of the Public Relations Dept., Saudi Aramco, Dhahran

Friday, March 10, 2006


  1. Saudi Arabia: Al-Qaeda vows more attacks - Aramco, Abqaiq, Yanbu' cited; Ali Al-Naimi quoted (Energy Compass)

  2. ENERGY COMPASS, March 10, 2006:

Saudi Arabia: Al-Qaeda vows more attacks

It's a nightmare scenario: A successful attack on a giant oil facility that cripples oil exports, sends oil prices soaring and damages the world economy. Such a nightmare was averted last month, when Saudi security forces foiled an attack on Abqaiq, the massive complex that processes 6 million-7 million barrels per day of Saudi Arabia's oil output, but it may have been a much closer shave than initial reports suggested (EC Mar.3,p8). Moreover, such is the determination of a small group of Islamic extremists to create havoc in the world's largest oil exporter and strike at the heart of the Saudi ruling family that the audacious suicide mission may well be repeated. "We expected something like this to happen," a Western executive in Riyadh said, "and we expect something similar to happen again."

For terrorists, Abqaiq is the same kind of "iconic" target as New York's Twin Towers or the Pentagon in Washington, and a successful attack would have inflicted maximum actual and psychological damage on the Saudi leadership, as well as the US. It is one of the world's most important oil installations, processing around two-thirds of the oil output of the world's biggest exporter. According to initial reports, the attack failed because alert security guards prevented the perpetrators getting beyond the first of two gates leading to the crude and gas processing plant, firing on the cars, which then exploded. Observers hailed it as proof the kingdom's oil installations were well protected: The US ambassador to Riyadh, James Oberwetter, said, "when they were needed, the systems worked, and the facility at Abqaiq was fully protected."

People familiar with the events of Feb. 24 tell a slightly different story. They say the two attackers, each driving vehicles packed with 1,000 kilos of explosives and with fake Saudi Aramco markings, managed to get through the outer gate of the complex, which is monitored by the Saudi National Guard. Luckily, security services had changed routes around the outer perimeter to make it harder to navigate. Armed with old maps of the complex, the terrorists are said to have become disoriented, panicked and detonated their devices prematurely, averting substantial damage to pipelines and other facilities.

While the attackers would have been unable to get to the heart of the complex because it was more heavily guarded by Aramco private security, damage to outlying facilities would have been enough to send prices stratospheric: As it was, they shot up $2 per barrel, reflecting the impact of the terrorist threat on the world's largest oil exporter. One of the most worrying aspects, sources say, was the apparent lack of communication between the National Guard, which protects the outer perimeter, and Saudi Aramco security, which is in charge of guarding the inner sanctum. The sources say the National Guard failed to alert their Aramco counterparts after the terrorists crashed through the first gate, which allowed them to drive round the outer perimeter without Aramco guards' knowledge. If the account is true, it undermines the widely held view that Abqaiq is one of the world's best-guarded facilities, and will do little to reassure markets nervous about security of supply.

The assailants came in disguise -- similar to the tactics adopted in a series of terrorist attacks carried out in Riyadh, the oil town of Al-Khobar and Yanbu over the past couple of years. They were dressed in Aramco overalls, which Saudi sources say can be obtained relatively easily. The same method has been used to even more brutal effect in Iraq, where insurgents often dress in military uniforms to get close to their targets. This week in Baghdad, for example, gunmen wearing Iraqi police commando uniforms kidnapped around 50 employees from the offices of a local security company.

Aramco, which has a security force of more than 30,000 people, aerial surveillance and other forms of protection, is taking no chances. Saudi Oil Minister Ali Naimi said this week that security has since been tightened at all Aramco facilities. "Naturally, after something like that security goes up. We have been taking additional measures," he said. Naimi added that the Saudi oil giant has the capability to use surface-to-air missiles to thwart any airborne attack and that the government plans to make more powerful weapons available to security forces. Industry sources in Riyadh say Aramco recently issued a tender to recruit 300 Western specialists to help tighten security at oil installations and train the Aramco security team. While that will make major facilities like Abqaiq more impregnable, pipelines remain an easier terrorist target. The strategy has worked effectively in Iraq, where attacks on the northern pipeline running from Kirkuk to Turkey have effectively rendered it inoperable.

Such measures by Aramco are unlikely to deter extremists, who have vowed to continue attacking oil installations in Saudi Arabia and Iraq. Saudi security forces have been battling supporters of Saudi-born Osama bin Laden for nearly three years and while they can claim some successes, a group calling itself "Al-Qaeda in Saudi Arabia" said it would continue the struggle against the infidels. "We renew our vow to crush the forces of the crusaders and the tyrants and to stop the theft of the wealth of the Muslims," it said.

The Abqaiq attack also sends an ominous message to smaller Gulf producers that, like Saudi Arabia, have close relations with the US and could become targets themselves. "There have been a lot of statements recently by Al-Qaeda members threatening to bomb, sabotage and destroy vital economic installations," Kuwaiti Oil Minister Sheikh Ahmad al-Sabah said days after the Saudi attack, adding he was in "no doubt" that security would be heightened around all oil installations.

By Paul Sampson, London

Good job, HO! I think it's also important to stress that petroleum refining, unlike most other manufacturing, is characterized by "coproduction"--that is, all these products are produced at the same time. I have found over the years that most people don't understand that refineries just don't produce gasoline, or diesel or some other product, but produce all at once. This is important when looking at strategies for substitution: for example, a (fantasy) miracle program that could replace all our gasoline with ethanol would actually be counterproductive to refiners, since they can't avoid producing the naphtha cut when they are producing diesel, or jet kerosene, or LPG or asphalt. Nor is there a big enough market to absorb the naphtha no longer needed for gasoline production, and the latitude refiners have to tweak their cut points couldn't eliminate the stream.

Coproduction imbalances are normally taken care of through trade, but if everyone moves in the same direction to displace transport fuels (without considering the non-transport coproducts), then the imbalances could be too large to absorb.

Similarly, if everyone ramps back refining throughput based on declining crude availability, then the output of all other products will decline as well. So though peak oil to most Americans is a transport fuel issue, and nearly all public policy here is geared towards transport fuel substitution, the absence of such policies for the other cuts from the stream will leave us just as vulnerable in those areas of use.

Why is it not possible to run motorized transport on naphtha?  Obviously, as the zippo lighters illustrate, the stuff burns and releases energy, right?

How hard would it be to reconfigure a conventionally-gasoline-powered car (my trusty Mazda, for example) to run on the stuff?  How hard would it be for automobile manufacturers and transport fuel suppliers, respectively, to reconfigure their factories and supply infrastructures so as to come up with a naptha-powered fleet?

I'm not a mechanical or a chemical engineer, but a structural (Our Motto: Concrete's Cheap and More is Better!) so I may be a bit off, but I don't see a reason you can't run engines off naphtha.  There may be some issues though.  I know with ethanol, the jets need to be enlarged because of a reduced energy content.  Naphtha may also leave some residues or produce other by-products (smog, etc)

I was surprised when I saw the large naphtha 'cut' in the distillation but have never heard it mentioned.  It would be interesting for the experts here to expand on this some more.

But wouldn't naptha be both cleaner burning and more energy dense on account of its relatively small molecules and relatively high H-to-C ratio?  Isn't the general rule that the larger the molecule in a fossil fuel, the less energy-dense and the dirtier it is?
Be aware that the naptha shown in the column diagram and the naptha cut shown in the bar charts are different.  The naptha cut shown in the bar charts include fractions used both for gasoline and for Zippo lighter fuel.  What refiners call the naptha cut is straight chain alkanes from hexane up to nonane (old name = paraffins), straight chain alkenes (old name = olefins), cycloalkanes, and benzene-ring aromatics.  Nowadays no gasoline come straight off the fractionating columns, it's all blended to some formula.

The closest thing to naptha right off the column is white gas, which is already used in small engines.

Think of naphtha as raw gasoline. Finished gasoline can have 40 or 50 other components from other units blended in, including naphthas of different compositions from other units. Why naphtha won't work? It doesn't have the octane required of modern engines (octane is the property that resists premature explosions). You also have to ensure low to no sulfur, not too much benzene or other aromatics, etc. It is of course combustible, but that's not the only property required in an engine fuel.

Naphtha is a major raw material for ethylene crackers in some countries (if natural gas isn't available or cheap), so it is the precursor of all the very PE, PP, PVC, etc plastics we use.

Thanks for all the help on this, folks.  Another question:  What is it about octane in particular that makes it resistant to premature explosion?  Does it have just the right combination of combustibility and stability due to the length of the carbon chain, or something like that?
I heard that you want straight chains for a high cetane number for Diesel cycle engines and bushy molecules for high octane numbers for Otto cycle gasoline engines. That may be old technology.