Coeliac we are both casual observers and have not been position to see the full technical facts so I leave that to the BGS who are highly qualified in the work they do and are professional at the job they do.
Now if they think that there is up to 60 billion barrels of oil has been generated then I will take there word on it, like when you have a tooth which is chipped you go to the dentist to get it fixed you dont go to a hairdresser.
There will be always doubters and its up to them to read the information which is available on the internet to make sense of it.
6 Wells were drilled in this basin in 1998, 5 of which encountered good oil and oil and gas shows.
The wells drilled in 1998 established the presence of a very thick (1,000metres+) lacustrine source rock (believed to be the second richest in the world). Only the bottom part of this source rock is mature for oil generation, and it is believed that the overlying immature source rock has operated as an effective, basin-wide seal, which may have prevented the migration of oil to the sandstone reservoirs encountered above it. These sandstones were the target of the initial drilling campaign and the presence of the seal could explain why these reservoirs are not charged with oil.
Only one well penetrated any depth below the source rock and, although it did encounter hydrocarbons, because the well was drilled in the centre of the North Falkland Basin farthest from a potential sand source, only siltstone reservoirs, of poor quality, were encountered. However, this result does suggest that, if suitable reservoirs do exist in traps below and/or adjacent to the source rock, they are likely to be charged with oil.
It has been calculated that very large volumes of oil (up to 60 billion barrels) may have been generated and expelled from the source rock
http://www.desireplc.co.uk/pdfs/figure-c.pdf