"This Administration will constantly strive to promote an ownership society in America. We want more people owning their own home. It is in our national interest that more people own their own home. After all, if you own your own home, you have a vital stake in the future of our country."" GWB
In the Wake of the Exxon Valdez
On March 24, 1989, the oil tanker Exxon Valdez hit an underwater rock formation in Prince William Sound, Alaska. 11 million gallons of heavy crude oil spilled from the tanker over the next several days. It was one of the most spectacular environmental accidents in American history.News Analysis - Gulf Oil Spill Is Bad, but How Bad? - NYTimes.com
Engineers said the type of oil pouring out is lighter than the heavy crude spilled by the Exxon Valdez, evaporates more quickly and is easier to burn. It also appears to respond to the use of dispersants, which break up globs of oil and help them sink. The oil is still capable of significant damage, particularly when it is churned up with water and forms a sort of mousse that floats and can travel long distances.
Last edited by Jerry; 05-18-10 at 09:09 PM.
Lets just get this straightened out.
Oil Type: API Gravity Sulfer content
Alaska North Slope: 31.9° 0.93%
Heavy Louisiana Sweet 32.9° 0.35%
Light Louisiana Sweet 35.6° 0.37%
South Louisiana Sweet 35.9° 0.33%
Light crude oil is defined as having an API gravity higher than 31.1 °API. (less than 870 kg/m3)Sweet crude oil is a type of petroleum. Petroleum is considered "sweet" if it contains less than 0.5% sulfur...[[ame=http://en.wikipedia.org/wiki/List_of_crude_oil_products]List of crude oil products - Wikipedia, the free encyclopedia[/ame]When the total sulfur level in the oil is > 0.5 % the oil is called "sour."
[ame=http://en.wikipedia.org/wiki/API_gravity]API gravity - Wikipedia, the free encyclopedia[/ame]
[ame=http://en.wikipedia.org/wiki/Sweet_crude_oil]Sweet crude oil - Wikipedia, the free encyclopedia[/ame]
[ame=http://en.wikipedia.org/wiki/Sour_crude_oil]Sour crude oil - Wikipedia, the free encyclopedia[/ame]
According to this both the valdez and the deepwater horizon spill contained light crude oil. The valdez spill contained "sour" crude oil while the deepwater horizon conains "sweet" crude oil. Anything over 10 on the api scale floats so I'm assuming that the same problems here will apply.
Assuming the best case senerio, that the deepwater horizon spill is soley comprised of south louisiana sweet, using the equation:
it is reasonable to approximetaly assume there are 7.44 barrels per metric ton in the deepwater horizan spill and 7.26 barrels per metric ton in the exxon valdez spill. Perhaps this can better show the difference in the density of each oil.
The fact that this spill has a sweet crude may be significant though since a sour oil will tend to be more toxic since it may contain more hydrogen sulfide.
One thing I will point out, and something I have not read a lot about is the fact the this is an open pipe spilling rather than a ship spill. Despite the fact that this is sweet crude I gotta think that some nasty crap has to be coming out of that pipe (why do you think it blew up). I have not been around any drilling, but I have heard of things like bad gas that sometimes come out while drilling and this stuff will kill you in a heart beat.
The more I look I see there are different standards for light and heavy.
[ame=http://en.wikipedia.org/wiki/Light_crude_oil]Light crude oil - Wikipedia, the free encyclopedia[/ame]The clear cut definition of light and heavy crude varies because the classification is based more on practical grounds than theoretical. The New York Mercantile Exchange (NYMEX) defines light crude oil for domestic U.S. oil as having an API gravity between 37° API (840 kg/m3) and 42° API (816 kg/m3), while it defines light crude oil for non-U.S. oil as being between 32° API (865 kg/m3) and 42° API (816 kg/m3). The National Energy Board of Canada defines light crude oil as having a density less than 875.7 kg/m3 (30.1° API). The Mexican state oil company, Pemex, defines light crude oil as being between 27° API (893 kg/m3) and 38° API (835 kg/m3). This variation in definition occurred because countries such as Canada and Mexico tend to have heavier crude oils than are commonly found in the United States, whose large oil fields historically produced lighter oils than are found in many other countries.
[ame=http://en.wikipedia.org/wiki/List_of_crude_oil_products]List of crude oil products - Wikipedia, the free encyclopedia[/ame]Although crude oil assays evaluate various chemical properties of the oil, the two most important properties determining a crude's value are its density (measured as API specific gravity) and its sulphur content (measured per mass). Crude oil is considered "heavy" if it is high in wax content, or "light" if low in wax content: an API gravity of 34 or higher is "light", between 31-33 is "medium", and 30 or below is "heavy".
Apparently this is the US standard for light crude and it is significantly lighter than all of the crude oils in question:
[ame=http://en.wikipedia.org/wiki/West_Texas_Intermediate]West Texas Intermediate - Wikipedia, the free encyclopedia[/ame]
So most of the time around the world I think both are considered light, but in the US because of our generally ligher oils the exxon valdez could be conidered light or medium depending upon the standard, but it defenitely was not a heavy crude by any standard. The South Louisiana sweet could be considered light or medium depending upon the standard as well.
Heavy crude oil has been defined as any liquid petroleum with an API gravity less than 20°
Last edited by drz-400; 05-19-10 at 01:36 AM.
Alright, the final word,
The NYMEX actually specifies domestic grades to include: “Specific
domestic crudes with 0.42% sulfur by weight or less, not less than 37° API gravity nor more than 42° API gravity.http://www.cmegroup.com/trading/ener...mark_Study.pdfSweet crude is defined as having an API gravity of 30 or higher and a
sulfur content of less than 1%. Heavy crude is defined as having an API gravity below 28, and includes heavy, high sulfur grades as well as crudes that are heavy and low in sulfur, but have a high acid content. Finally, light sour is used to define those crudes that do not meet the criteria for inclusion into either the sweet or heavy categories.
So both are sweet crude according to the worlds largest futures exchange CME Group Inc. Just remeber, they do both contain a pretty big difference in sulfur still.
Just to confirm, exxon valdez was north slope crude:
http://www.evostc.state.ak.us/facts/details.cfmThe 987foot ship, second newest in Exxon Shipping Company's 20-tanker fleet, was loaded with 53,094,5 10 gallons (1,264,155 barrels) of North Slope crude oil bound for Long Beach, California.
and just based on geographic location I am assuming that one of the other crudes is the one we are currently dealing with since the rig was 40 miles off the coast of louisiana.
Last edited by drz-400; 05-19-10 at 02:15 AM.
Deepwater Horizon blast triggered by methane bubble, report shows
Investigation reveals accident on Gulf of Mexico rig was caused when gas escaped from oil well before exploding
The deadly blast on board the Deepwater Horizon oil rig in the Gulf of Mexico was triggered by a bubble of methane gas, an investigation by BP has revealed.
A report into last month's blast said the gas escaped from the oil well and shot up the drill column, expanding quickly as it burst through several seals and barriers before exploding.
The sequence of events, described in the interviews with rig workers, provides the most detailed account of the blast that killed 11 workers and led to more than 3m gallons of crude oil pouring into the Gulf.
drz-400, thank you for your links and thoughtful posts. I may have been wrong about the weight of the crude from the Valdez. I'm not yet sure I was wrong, but you gave a good argument and I'm reconsidering the point as I argued it. If I'm wrong then I accept my error.
You sir have won:
If I understand the information you presented correctly, the attribute of crude which most dictates how volatile a spill is to the environment gallon for gallon, and assuming everything else is equal, is the surfer content.