It CANNOT evaporate, duh
it has to make it to the surface before evaporation can take place.
and even of that, only the heptanes, pentanes and maybe the octanes have a chance of evaporating quickly.
all the heavier hydrocarbons WILL NOT an CANNOT evaporate at all. that is just a chemical fact.
Taken, this is light sweet crude, but I suspicion lotsa oil in that GOM jus' settin'