The Oil Drum

55 comments on It's Time for Summer Gasoline

Comments can no longer be added to this story.

elwoodelmore on April 16, 2008 - 11:49am

this problem has plagued oil reservoir engineers since the science was invented.
most of them simply treat every oil as a "black oil" (composed of methane which obeys the real gas law and heavy components which are liquid in the reservoir and stock tank). compositional models dont seem to get the job done either.
back in the old days, that was the mid '70's, texaco used fugacity(sp?)to try to calculate the part that would be liquid, that didnt work either.

Comments can no longer be added to this story.

skorpela on April 16, 2008 - 12:36pm

Here is the explanation of Raoult's law and vapor pressure in ideal and real solutions.

Raoult's Law

Comments can no longer be added to this story.

DIYer on April 19, 2008 - 5:33pm

Precisely.

If 10% of the molecules are butane, the vapor pressure of the resulting solution will be 10% that of pure butane, plus 90% of whatever pressure is contributed by other ingredients (of lower VP). There will be some deviation from this idel, but I believe hydrocarbons are pretty close to theoretical.

Comments can no longer be added to this story.

elwoodelmore on April 20, 2008 - 6:40am

hydrocarbon mixtures probably behave as ideal components at relatively low temperature and pressure (i.e. atmospheric). not true at higher temperatures and pressures.