 | DrumBeat: June 30, 2007 | The Oil Drum | "Energy Resources and Our Future" - Speech by Hyman Rickover in 1957 |  |
Refinery Utilization Rates and Increase in Use of Heavy/Sour Crudes
Posted by Prof. Goose on June 30, 2007 - 9:30am
Topic: Supply/Production
Tags: API gravity, gas inventories, gasoline, oil, oil inventories, oil refineries, peak oil, refining, sulfur [list all tags]
This is a guest post by Smokey. Smokey has a background in sustainability in transportation, and has conducted research on responding to fuel supply disruptions.
To what degree is the decline in quality crude affecting domestic refinery utilization rates and therefore gasoline stocks?
In recent years some analysis has suggested that light sweet crude oil may have peaked, with the world left to increasingly rely on lower quality crudes. See for example this story on The Oil Drum and this story on Energy Bulletin. Although the data on global peaking of light sweet crude may not yet be conclusive, data on the production of many regions that produce primarily light sweet crudes conclusive show that many of these regions are past peak.
Recently, gasoline inventories have been well below the normal range for this time of year, while crude oil stocks have been above the 5-year average. At the same time, refinery utilization rates have been well below normal for this time of year. Refiners and the EIA are well-aware that the crude oil mix has become increasingly sour and heavy.
Figure 1 shows refinery utilization rates and the API gravity of crude imports from 1978 to 2007. Light crude oil is defined as having an API gravity higher than 31.1, medium oil has an API gravity between 22.3 and 31.1 and heavy oil is defined as having an API gravity below 22.3.
Figure 2 shows refinery utilization, the API gravity of refinery inputs, and the API gravity of crude imports from 1995 to 2005. As shown in Figure 2, API gravity of both imports and the crude used in refineries has been on the decline, while refinery utilization has also been on the decline.
Figure 3 shows API gravity and sulfur content of US refinery inputs from 1985 to 2005. This figure shows that crudes used as feedstock to refineries are becoming increasingly heavy and sour.
Figure 4 shows total crude oil imports by API Gravity and Refinery Utilization. Total imports declined in both 2006 and first quarter 2007, while imports with an API gravity of 30.1 or higher also declined in 2005.
More gasoline can be derived from a barrel of light sweet than heavy sour crude, as shown in this figure from Natural Resources Canada.
From NRCAN: “Refinery yields by crude type: Figure 3 illustrates the product yield for six typical types of crude oil processed in Canada. It includes both light and heavy as well as sweet and sour crude oils. A very light condensate (62 API) and a synthetic crude oil are also included. The chart compares the different output when each crude type is processed in a simple distillation refinery. The output is broken down into five main product groups: gasoline, propane and butane (C3/C4), Cat feed (a partially processed material that requires further refining to make usable products), distillate (which includes diesel oil and furnace oil) and residual fuel (the heaviest and lowest-valued part of the product output, used to make heavy fuel oil and asphalt).”
Regarding differentials, an EIA presentation from March 2005 2004: Sign of the Future for Refiners? for the NPRA annual meeting suggested a couple of theories on light/heavy crude differentials.
“Theories on How Capacity Constraints Drove Light-Heavy Differentials:
1. Overall world refining capacity limit
2. Constraints on conversion capacity”
See the EIA presentation for a full analysis, which include potential indicators of one or the other theory above, such as:
- Light product stocks drop sharply
- Price for light products rise sharply
- Product price pulls crude prices up and pulls light crude up more than heavy
- Additional heavy crude oil won't be used
- Demand for light crude oil increases
- Added heavy crude oil run without benefit of conversion
- Residual fuel oil yield increases
- Over-supply of residual fuel oil
In the end, their analysis concluded that crude oil price was primary factor in 2004 differential increase, and that refiners made an economic choice to use more heavy crude oil as product values shifted.
Questions
A few questions that come to mind that readers of the Oil Drum may be able to offer thoughts on:
1. To what degree might low refinery utilization rates be a function of the inability of some refineries to process the heavier/sour crudes? Likewise, to what degree might refinery outages/unplanned maintenance be a function of the increasing use of heavy sour grades of crude? Finally, to what degree might low gasoline production rates also be a function of increasingly sour/heavy crude oil used as refinery inputs due to lower gasoline yields for the lower quality crudes?
2. Do trends in the quality of oil imports provide any evidence to support the theory that light sweet crude may have already peaked?
3. How long does it take to upgrade or expand a refinery to handle these lower quality crudes, and what kind of progress on this front has been made over the last several years?
I’m hoping there may be some insiders in the refining industry who could help answer these questions.
I am still on vacation, and probably won't be near a computer when this article posts. So, my apologies for commenting before it goes live. However, since I have commented on this several times, I want to make a note.
In the past, I have said that gravity has been relatively consistent for several years, which indicates to me that refinery utilization issues are not due to a sudden influx of heavy oil. Yes, over the longer term, crudes have heavied up as refiners have installed cokers and hydrocrackers. Due to the economics of processing heavy versus light oil, which I previously discussed here, if a refiner has a coker they are going to prefer heavy oil.
But if you look at the EIA numbers:
http://tonto.eia.doe.gov/dnav/pet/hist/mcrapus2m.htm
You will see that gravity in 2007 is almost the same as gravity in 2001. In fact, just eye-balling it I would say that the average in 2001 is a carbon copy of the average for 2007.
Sulfur tells a similar story - 1.4% in 2001 and 1.4% in 2007:
http://tonto.eia.doe.gov/dnav/pet/hist/mcrs1us2m.htm
I do believe that the lightest, sweetest crude has peaked, but refiners have been installing equipment to process heavy sour crudes. Overall, the product yields will be negatively impacted as this happens, but it didn't suddenly happen in the past 2 or 3 years (according to EIA data, which is data that refiners have reported).
Back to fishing with my boys. I will be back online some time next week, as we fly back to Scotland on June 30th. I won't be commenting a lot after that, but I will comment some.
I look forward to seeing you back, Robert!
BTW...I hope a few individuals take note of the refinery utilization for the past 22 years...
*wink*
>You will see that gravity in 2007 is almost the same as gravity in 2001. In fact, just eye-balling it I would say that the average in 2001 is a carbon copy of the average for 2007.
The EIA chart has to be wrong. The price spreads between Light and Heavy are tiny compared to the spreads back in 2004. I don't see how the demand for heavy has risen, while refineries statistic have remained unchanged. Valero was minting money before the spread collapsed. I suppose perhaps the figures may be escewed because of pre-refining upgrades. For instance, Oil produced from tar sands are upgraded before they are sent to refineries for production of consumer fuels.
Perhaps an insider from a refinery can set forward and provide some clarity.
The most recent price data (late May, EIA) show a spread of about $12 between Brent and Maya heavy crude, versus about $6 in late May, 2004.
>The most recent price data (late May, EIA) show a spread of about $12 between Brent and Maya heavy crude, versus about $6 in late May, 2004.
Thanks, I thought I had read somewhere that the spreads declined on increased demand, but I guess I was mistaken.
The light sweet stuff may have well peaked, but you can be sure that the refineries will install cat crackers to re-use the asphalt/bitumen. As we all know, when the crude goes into the fractionating distilling device, the bottom gets the asphalt. The asphalt can be broken down into smaller molecules in a cat converter or as we will call it a cat cracker. This however takes some amount of natural gas to supply the hydrogen for the cracking process.
The process to make the asphalt from Fort McMurray into "syncrude" does take a bunch of nat-gas. But nonetheless, the process of making heavy sour crude into something that can be refined is in progress. That does mean that asphalt will get expensive enough that fixing roads will eventually get too expensive. The asphalt from Fort McMurray is the mother of all heavy crudes. They dig it up as like strip mining. Then, it's made into "syncrude" to be pumped through pipelines to refineries. Then, after that journey, it's made into the gasoline, of course.
Petrol prices high enough yet? Just wait!
Smokey, thanks for your hard work! Those are great graphs.
since I'm in the upstream oil patch rather than refining, I can't add anything to this discussion.
I would add a fourth question:
4. What percentage of US (and OECD) commercial crude oil inventories consists of light sweet crude, and how many Days of Supply does that represent?
Note that on a Days of Supply basis, total US commercial crude oil inventories (light sweet + heavy sour) have fallen from around 30 days in the early Eighties, to the low 20 day range now.
Question.
The thesis is that even as crude has become heavier that refiners accepted this and produced a larger amount of side or low value products.
The spread has gotten large enough that is increasingly economic to switch to complex refining combined the low sulfur rules are having a negative impact on refinery utilization although gasoline per barrel may be higher. I think that the low sulfur requirements may be a big part of the current refinery problems.
So do we have the product mix per barrel ? Has it changed over time as refiners upgraded and became more efficient at handling the heavier crudes ? US refiners today seem to have a lot of control over the product mix they can produce has this always been the case ?
Next the US as one of the wealthier importers probably can control the grades of oil it chooses to import so one would expect them to move to heavier grades only as the profit margin increases. Now this may well be because of peak light sweet but thats secondary.
In general I agree with Roberts take on the situation except that I think the effects of the recent low sulfur rules coupled with the Ethanol requirements has caused serious refining supply issues.
So overall is their any evidence that the US is buying lower quality oil because it has no choice i.e the lighter oil are not economic or is it simply because we have complex refineries that can handle and are more profitable using lower quality oils.
In general however the depressed price of gasoline is causing problems attracting imports which is a whole different and probably more serious issue.
The thesis is flawed. Refiners could not accept larger production of low valued products. Simply no where to put them unless you price all the way down to replacing coal in thermal power stations (ugly!). Also with margins already poor, refiners couldn't afford to do this.
once you own a coker/resid hydrocracker + desulph capacity to make on spec products they run full. Even with shitty lith heavy differentials these units run full such that if their is over capacity, it's the simpler refiners that have to cry uncle and cut runs first.
ugh == "there" not "their"
It's a lost cause, dude.
I'm shocked at the illiteracy I see here at times.
Get a statistic wrong, and people will eviscerate you on TOD.
But confuse there/their/they're, its/it's, or be too g****** lazy to use the SHIFT key to properly capitalize, and no one cares.
Because it is trivial to determine the correct meaning, spelling and punctuation rarely matter. OTOH, it is hard to spot an error in a number, so accuracy here is important.
And what about those illiterate cretins who think it cool to mix case and put digits in place of letters, sheesh!
I agree with you. Right now reading to much into the US's supply of oil is probably a mistake. I think if any issues or strains exist in the system it will show up first in gasoline imports. However I think I came to the same conclusion once you have a complex refinery might as well use the lower grade oil and make money on the price spread.
Now you mention that its the simpler refiners that have to cut runs first but you would think that its the complex refiners that would fail more often so if we are having serious problems at or complex refineries we should see stronger imports of light sweet crude and the simpler refiners doing better now. This does not seem to be happening which is strange.
as long as the rest of the world is diesel driven, there will be plenty of surplus gasoline to export toward US markets especially if we continue to pay whatever it takes to attraat the oil. There are many many refineries that were built specifically to export toward us. Few examples -- Hess(no PDVSA) St. Croix. Venezuela's 4 biggies, Statoil Mongstat, . West coast UK refiners + several in the Mid East. Of course if another buyer pays more, we do without.
Refineries aren't usually single train systems such that when one element fails, the rest has to be shut. You work around the problem using intermediate feedstocks, storing offspec stuff, running the remainder differently etc. So the idea that complex refineries "fail more often" is too simplistic. They have more units to fail, but that doesn't mean they lose a larger percentage of their throughput due to failures.
Also simple refiners NEVER have better econs that complex ones. Even with a light heavy differential of zero(which never happens), the complex refiner can make more transportation fuels and less byproduct fuel oil than a topping/reforming refiner or a topping/reforming/cracking refiner. Once the investment is made for the cokers/resid upgraders etc, the cost is sunk. The units get run to the maximum extent possible as long as there is any extra margin to capture. Resid is still worth $20+/bbl less than gasoline so these units are staying full. So your expectation that imports of Lt. sweet should be up is off base IMO.
Sorry meant imports of light sweet into second third world refiners that tend to be of the simple variety in the poorer countries. You have to look at where the economic growth has been in the last few years and the bulk of the increasing demand is outside the western nations. Lists of refineries by country are readily available and the concentration of simple in the poorer countries seems pretty clear. Now this does not consider gasoline/diesel imports so its not a complete picture I'm sure they also import significant quantities of finished products but you can see they are probably paying more than their fair share for the recent price spikes.
I just don't think looking at US numbers without understanding the world situation better is not a good idea. I've never liked the focus on the US. I've always felt that by the time real problems start happening here we will be well and obviously past peak. Assuming we peak in 2005 this would mean late 2008-2009 before we should begin to see supply issues here. In the interim reading to much into data from the US is probably a mistake.
I've got no idea why we let our gasoline prices slide so we are not attracting the imports we need this summer this just seems to be simple stupidity but I'd have to guess that the first place we will get hit will be with gasoline imports at some point in the future people are simply not going to cause shortages at home to keep the US market supplied or we are going to fail to compete with closer customers who pay less of a premium. Note the Koreans ship to the Asian markets and the US the US has to cover the additional shipping costs beyond simple price competition. And if things get tight I suspect the jocking for export gasoline will not just be done on pure economics and its not clear th e US will win every round.
So all I'm saying is that when the US eventually has problems it will in my opinion show up in problems securing gasoline imports not oil. And I think the earliest this could occur would be summer 2008. Also if you think about it the oil market itself could be changing fairly rapidly right now so what was true three or six months ago may not hold right now in general we are looking at data thats inexact and often wrong so its fair to consider that we may not really know whats happening for some time. Right now the problems are probably generally in areas we don't have good data which I don't like but the gasoline import/export situation could easily get difficult fast so its something to watch.
Why don't you tell us how you think peak oil will first effect the US besides the obvious of increasing prices.
You will stay confused as long as you keep putting the cart before the horse. We don't "let our gasoline prices slide so we are not attracting the imports we need this summer"
First, we are getting plenty of imports. Imports are well above the typical levels of years before Katrina (ie, have to ignore fall 2005 to summer 2006). See
http://tonto.eia.doe.gov/dnav/pet/hist/wgtimus24.htm
Second, who is the overarching "we" that decides to lower prices? Prices slid because production is coming back restoring inventories to a safer level. Speculators liquidated their length when it became apparent there would be no shortfall. The market isn't prescient but it does reflect the common wisdom of the moment. There are more sellers than there were so prices have move back to just too high from obscene.
I don't think peak oil will effect the US beyond increasing prices. There is still a lot of wasteful demand out there that can be trimmed. Ditto countries that import that cannot compete with us for the marginal bbl. They may suffer, but we'll get all the mogas we wish to pay up for.. the only caveat is if Venz, with their enormous export capacity mostly aimed at us, decides to supply other nations for less money instead.
Its not like suddenly one day the world will be short 10% of demand (barring some political upheaval). The tightening will be slow strangulation like a boa constrictor. We'll have a flat supply curve for years and years. And as prices rise, we'll shift demand to other energy sources -- electric cars etc. Kunstler's collapse is bollocks IMO.
The cart may well be before the horse as you say but US gasoline inventories have slid to dangerous levels. A hurricane anywhere in the gulf that causes refineries to shutdown simply as a safety precaution could well lead to shortages. Letting our gasoline inventories get close to critical levels is a national problem not a industry issue.
I'm not happy with the current situation and it has nothing to do with prices if we have a hurricane this summer I suspect I'll not be alone in this sentiment.
This is the problem.
http://tonto.eia.doe.gov/oog/info/twip/gtstusm.gif
The west coast is the only place we seem to have decent gasoline stocks so we should be importing gasoline like mad.
Considering a 1%+ demand increase each year and the refinery problems we are having we should have already seen record breaking imports of gasoline. Instead we seem to have embarked on a grand experiment to discover exactly what our minimum operating levels are before we see widespread shortages. But hey I live on the west coast and we get our gasoline from Korea so its not my problem. We at least are not playing the same game.
And finally I am in agreement at least initially for the US I don't see sudden shortages. Later on I disagree mainly since I can't see us going forever without upheaval a world of ever increasing energy costs will not be a nice one.
As far as Kunstler a simple observation once living hours from work and commuting is not perceived as efficient then the value of the far flung suburbs will decrease all thats needed is a trend downwards to stall and reverse suburban expansion people will not buy a deprecating asset. I know for a fact that at least in my field Americans will no longer move too silicon valley to work if they have families and a lot of the senior programmers are leaving and working remotely like a lot of the American employees that work for silicon valley companies. The only people left are either rich executives or H1B's/immigrants living in crappy apartments and condo's with illegal migrant workers. At each economic downturn the immigrants scatter and the H1B's go home.
This goes into the general problem that prices are set at the margin slow squeeze concepts although nice tend to ignore this at some point the situation changes. Silicon Valley has changed into a overpriced slum unless your rich.
you seem to approach this perceived problem (gasoline shortfall) from a command and control economy viewpoint. Just who is the "we" in the system that would import gasoline as a buffer and take the price hit if it isn't needed?
We are NOT at some scary level of stocks. We're on the low end of normal and I suspect just like NAIRU, the predicted level at which the shit is supposed to hit the fan is higher e than the reality. When push comes to shove, the system will get by on a bit less. 200 million bbls is a hell of a lot of oil. It's roughly a tank and a half for every person in the country.
Your West Coast gas is not coming from Korea to any great extent. I'm going to guess 90%+ is made in the PAD V refineries. Just 20 years ago, I was exporting US mogas to Japan and Korea. Korea overbuilt refinery capacity not long after so now at time they may well have a tad of surplus for export. California gas is pain to make. We used to find it in odd spots like Finland for example. You need refineries that can make octane without aromatics and with low RVP. Not any easy equation.
Hello OcE,
Thanks for your comments. I've asked previously and still wonder:
1) re: "There is still a lot of wasteful demand out there that can be trimmed."
- Where do you see this? Could you explain a little further?
- Can it "be trimmed" without altering (presumably in a negative fashion) the economy that relies upon it?
2) re: "... beyond increasing prices."
How do you expect the price increase to effect the economy?
3) re: "Ditto countries that import that cannot compete with us for the marginal bbl."
So, those countries (as entire countries) can "be trimmed"?
What does this look like?
And...what about say, China, deciding to simply purchase contracts, rather than bid for or "pay for" barrels?
And...how does the "we wish to pay up for..." come into it? does this rely on a "healthy dollar"? Or what?
What about US debt?
4) "...suddenly one day"
What about Memmsl's idea concerning the probability of shortages?
5) "As prices rise..."
What about Deffeys' (and others') argument that we will see, not a gradual rise, nor a "slow strangulation", rather increasing volatility in price?
6) And then, of course, the "finale" of a question:
re: "...we'll shift demand to other energy sources..."
And use those energy sources to...
--devour the last fish in the sea?
--in other words, introduce other non-energy resources, which are nonetheless critical in the spot they occupy?
Example, water supply.
7) And may as well ask you about Venezeuala:
re: "...with their enormous export capacity mostly aimed at us, decides to supply other nations for less money instead."
What do you see as the deciding factors on the part of Venz. - either way?
What do you see as "pre-emptive" actions US can take, if any?
Do we have numbers like this for some other country thats reasonably wealthy but not the US and imports oil?
For example does the Philippine's post this information or New Zealand for example ? Its hard to understand the US numbers without some frames of reference. What about Israel Korea ?
I found this news article that indicates that heavy sour seems to be a issue world wide.
http://www.iht.com/articles/2005/11/22/bloomberg/sxrefiners.php
http://www.iht.com/articles/2005/06/20/bloomberg/sxrefine.php
I think if you had world wide data you might see a stronger move to heavy sour oil then just looking at the US.
So a bit of googling seems to show the move to handle heavier sour is not just a US economic move but a worldwide move. Real numbers would be cool.
The change in gravity is there but does not look that dramatic yet. But the change in sulfur is nothing short of amazing - an approximately 50% increase in sulfur content from 1985 to 2000! Since we know that sulfur causes maintenance issues, this would seem to be a fruitful area to explore as to one reason why refinery utilization rates are down. (There's never any single reason but this one may be a large part of it.)
Ghawar Is Dying
The greatest shortcoming of the human race is our inability to understand the exponential function. - Dr. Albert Bartlett
Do you have a take on the effect of the new low sulfur rules on top of this dramatic increase in sulfur content ?
I agree with you that at the moment sulfur looks like the biggest problem.
A link from the past but it seems the problems we have today where foreseen in 2003. Four years seems to be able time to meet demand with refinery upgrades so it makes you wonder a bit.
http://www.npra.org/news/testimony/20030610Testimony.cfm
My understanding is that sulfur is a real problem in refineries, being highly corrosive. This might explain both lowered utilization rates and the apparent increase in unexpected downtimes.
As Robert has noted, the gravity of the oil, whether taking the EIA data or Smokey's data, does not show what I would consider a really dramatic decline. There is change there but not so swift as other issues. But the increase in sulfur is far more recent (2000) and it may have just taken this long for the maintenance issues to start popping loose.
Unfortunately, I am not an expert on refinery operations so this is just a hunch, given that the sulfur increase is the clearest change in what we are refining.
Ghawar Is Dying
The greatest shortcoming of the human race is our inability to understand the exponential function. - Dr. Albert Bartlett
Is high sulphur content the reason that many earlier descovered resevoirs were not produced and are only now being brought back on stream? I can't think of a specific, but reading Matt Simmons book a few months ago I seem to remember this being the case.
Marco.
Marco,
In years past many different reasons could lead an operator to abandon a hole as dry, even with good shows. Sulfur is one, but mostly it was a flow rate issue. The first major reservoir produced on the Texas Gulf Coast was Spindletop at Beaumont in 1901. The Lucas Gusher blew in at 100,000 bbls a day, and the oil from the caprock is sour and 18 gravity, and had hydrogen sulfide in the produced gas, as well as 25% CO2 content. But it was prolific. Spindletop salt dome was a sulfur mine later.
In contrast, everyone knew that the Buda Lime would produce a sulferous crude from at least the 1950's, but it wasn't completed as a reservoir rock until the late 1970's in the Giddings field area. It had to wait for modern geophysics to know how to complete the wells.
Sources: Bulletin of the AAPG on Spindletop, volume number 1, personal recollection of Giddings field development
If the refinery is making gasoline and using a catalytic reformer then sulfur can poison the metallic catalyst, which would be a big headache. Most of the refinery is anhydrous, so generalized corrosion wouldn't be a major problem. Of course, when fuel with sulfur is burned water and SO2 is formed so anything corrodes big time.
virtually all refineries have a cat reformer. But the first stage is a feed desulfurizer which removes sulfur to the necessary levels to protect the platinum/palladium catalsyt si the reformer proper. with poorer feeds, you just add feed desulph capacity.
just a matter of money. Refiners spent billions to make the new gasoline/diesel sulfur specs.
Hmm very low levels of sulfur poison catalytic converters so I'm not clear how they got by with the higher sulfur levels to begin with unless the sulfur was only removed when going to the catalytic converter or it was cheaper to redo the catalyst then to drop the sulfur content. The old sulfur levels would have I would have poisoned the converters fairly quickly in my opinion. Maybe the regenerated periodically in situ ?
You might want to invest some time in reading up on how refineries work. Your fingerpainting is wasting you a lot of thinking time. I wish I knew a good text to point you to but I don't.
IIRC (and I'm no reformer expert by far) cat reformer feed needs to be desulfurized down to about 10 ppm ish. And they do regen insitu fairly often but that is to remove coke building up on the catalyst.
But all of the gasoline pool doesn't come from the reformer. there is straight run gasoline (if your crude has decent mogas octane ), FCC gasoline, hydrocracker gasoline, coker gasoline, alkylate, polymerization plant streams, petchem byproduct streams, etc depending on the specific design of your refinery. In the old days, you blended via linear program to hit all the specs with 500 ppm sulfur as a constraint. Gasoline components with shitty sulfur levels (like FCC gasoline) could go in without further treating. Current, lower sulfur specs require more of these streams to pass through desufurizers or to deeper desulph levels.
LOL!
Memmel works on a little knowledge and a lot of typing. It's a bit like the million monkeys principle. ;)
the finger painting is assuming the old sulfur levels poisoned catalysts. That's just ignorance. The same level of feed desulfurization is needed now as then for cat reformer feed. The difference is in what is happening to rest of the pool.
I find you make an assumption, often pulled from thin air, and then fingerpaint about how that assumption affects the situation. GIGO.
Maybe you did not understand my point is its doubtful that they are running high sulfur into the cat converters.
This means the technology to remove sulfur down to low levels is common and well tested therefore I don't think the new low sulfur requirements are a huge burden to the industry and responsible for our problems. Sulfur content has risen lately but I don't see it as a major problem. The sulfur has to be removed early and now they are doing it across all feeds.
I assure you I understand catalysts very very well and much better than you. I've worked on gas phase catalytic systems in the past. I'm a chemist not a chemical engineer and industrial process and constraints are quite different from the small scale reaction oriented systems I work on and I've often seen assumptions you make in the lab not holding for industrial production. Sometimes the trade offs are surprising since cost is and overriding factor. So I do know enough to never assume the way I see it as a chemist applies to the chemical manufacturing reactions are just a small part of chemical engineering. I could not see them allowing the catalyst to poison but if poisoning is slow and they can regen in situ maybe its cheaper I don't know I did see how but its not all that uncommon for catalyst to be regenerated often in say plastic synthesis a lot of processes toggle between catalysis and regeneration.
"what i would consider a really dramatic decline"
huh? what sort of decline would you consider dramatic ?
The change in gravity was less than 10% change. The change in sulfur was about over 50% change. I don't mean to minimize the gravity change as much as point out the extreme change in sulfur content of the oil being processed.
Ghawar Is Dying
The greatest shortcoming of the human race is our inability to understand the exponential function. - Dr. Albert Bartlett
The ENI World Oil and Gas Review 2007 has a table that breaks down wo