At one point I read that there is 1000 cf of natural gas vented with each barrel of oil from this leak. The expansion of this gas causes so much cooling that the design has to have a double jacket pipe with oil in the inner pipe and the gas/water/alcohol antifreeze comes up in the outer jacket.
1000cf of gas per barrel seems like a huge number but if what I heard is true then the alcohol is probably a pollution source too.
A point to check is whether the volume of oil is measured before or after the gas comes out of solution, since the oil volume will shrink when the gas comes out.
In fact gas dissolution and oil volume shrinkage will happen at many stages during the path of the hydrocarbon stream from reservoir through the wellbore and processing plant to export. For light oils and rich gas condensates the ultimate GOR of export streams is strongly influenced by the efficiency with which the processing plant strips liquids from the gas phase. Reported GORs may be calculated from export volumes which may not be at standard conditions.
The GOR is usually measured in cubic feet of gas per barrel of oil or condensate.
If the GOR is greater than 10,000 cf/bbl, then the field is usually described as a gas well. If less than 10,000, then the field is generally described as an oil well.
I sure hope the folks who are designing this containment/recovery effort are taking this into account and realize that they are going to have to handle, in some fashion, all the gas that comes out of solution as the fluid they are trapping 5000 feet down works it's way to the surface.